DFO - Library I MPO - Bibliotheque
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Project Report No. 32
Canada. Fisheries Service. Industrial Development Service. PROJECT REPORT
Progress Reports Nos. 1 to 5 of ~the ,,/
American Eel (Anguilla rostrata) Studies in Canada
by
Vadim D. Vladykov, Ph.D., Professor of Biology,
Faculty of Pure and Applied Science, University of Ottawa,
Ottawa
for
I ndustrial Development Branch, Fisheries Service,
Department of Fisheries and Forestry, April 1970
Progress Reports Nos. 1 to 5 of the American Eel (Anguilla rostrata) Studies
in Canada
by
Vadim D. Vladykov, Ph.D.
This was a project carried out by Dr. Vladykov under contract to the Industrial Development Branch, Fisheries Service, Department of Fisheries and Forestry,
Ottawa, Canada.
.•
- 1 -
PROGRESS REPORT NO. 1 OF 'l'HE jJ'1l<~IUC./'i N iEL (ANGUILLA H.O~TH.A'l'A) S'l'UDI.ES IN CANADA
by
VADIM D. VLADYKOV
My initial work in regard to the eel studies in Canada
was devoted to the following three aspects.
TAGS AND TAGGING
In order to understand better the seasonal movement, rate of growth,
intensity of fisheries and many other ~spects of eel biology in freshwater
habi tat, an extensive t".gging programme was prepured.
TYPE OF TAGS
As the American eel in freshwater habitat usually hides under rocks
or buries itself in the mud, they Can be tagged successfully only with
specially designed tags. Some years ago, I (Vladykov, 1957) developed
such a type of tag.
This model I named "split ring and plate tag". Three sizes of
split rings, made of stainless steel piano wire, were manufactured:
J/8, 5/8 and 7/8 inch in diameter. They can be opened sideways by means
of specially designed pliers, one for each ring size. The plate or tag
proper is made of laminated vinylite of different colours and in two
sizes: about 1 x 1/4 of an inch and 9/16 x 3/16 of an inch. Four colours
are used. The numbers are stamped on one surface (face), prefixed by a
letter cor responding to the colour: B (blue), G (green), W (white) and
Y (yellow). On the under surface of the plate is printed "Cana.da".
2
'l'he split rings and tags are attached around the lower jaw of the eel.
To prevent accidental opening of the sp: it I'ings, the ends are welded
by using a portable electric welder.
After an extensive correspondence with two firms and several telephone
calls, eventu~lly on June 28, 1967 we agreed to terms as to the dimensions of
the vinylite plate and size of the number and letters.
A) The vinylite plates were ordered from the Stanley Manufacturing Co.
(230 Bartley Drive) Toronto. Our order consists of 20,000 large plates
and 12,000 small plates to the global amount of $1,706.40, tax not included.
b) Split rings of three sizes in a combined quantity of 9,000 and 6 pairs
of pliers were ordered from Accessories Manufacturers Ltd., (595 St. Remi
Street) Montreal, to the global amount of $1,542.50, tax not inc1udl'-d.
The above plates and rings have not been received as yet, but this
delay does not affect our studies. This year I plan to tag eels only
during the late summer and fall months.
ELVERS
The term elver applies to recently metamorphosed "glass eel". The
glass eel is intermediate between the early larval stage or leptocephalus
and elver proper.
Knowledge of the time when elvers first reach the estuaries of different
rivers, their abundance and the duration of their run is very important.
This year we limited our observations on elvers, close to the two
biological stations on the Atlantic coast: St. Andrews, N.B. and the
Bedford Institute of Oceanography, Dartmough, N. S. The proximity to the
research stations is extremely useful for our future studies.
3
Bedford Basin, N.S.
At the head of the Bedford Basin, is found the Sackville river.
This locality is not very far from the Bedford Institute of Oceanography.
Mr. S. Miles, graduate student of Dalhousie University, N. S. during
June 1967 collected about 10,000 elvers. They were so plentiful at a
certain date th~t he could c~tch several hundred by using an aquarium
dip net ~j.bout four inches in diameter.
St.Andrews, N.B.
Around the area of this Biological station are located three
brooks in which elvers are found in considerable numbers. These localities
are as follows: Birch Cove Pond (about 6 miles distant), Digdeguash river
(about 16 miles distant) and Bocabec river (about 13 miles distant) •
Mr. D. James with an assistant, used a hand seine, four feet in
length and provided with a wooden stick at either end, to catch elvers
in this area. During the period May 13, to June 6, 1967 he caught
about 2') ,000 elvers.
During his second collecting trip from July 21, to 25, 1967 he
obtained in the estuary (at the falls) of the Digdegu~ sh river 11,000
elvers.
""hite Lake Hatchery. Ontario
After severa.l unsuccessful attempts to locate a convenient pond
within a radius of 100 miles from Ottawa, I eventually decided oh
Pond No.1 at White Lake Hatchery, located on Highway No.7 about
100 miles from Ottawa.
4
On June 15th, I wrote to the Authoritips of the Ontario Department
of Lands and Forests, Maple, Ontario. At last, on June 29th, I received a
f~vourable answer to my request. However, this pond is at our disposal
only until the Spring of 1968. This pond is very rich in natural food.
On July 27th, D. James liberhted 10,000 elvers in Pond No.1. These
elvers were caught by him at Digdeguash river. The size of these elvers
varies from 2 1/2 to 3 inches. There are about 4,000 elvers per pound.
After spending the winter in the pond, we shall know about the rate
of growth of the elvers and the changes in their otoliths. The age
determination of an eel is made by their otoliths. There are successive
transparent (winter) and opaque (summer) layers. However, it is not
known as yet whether each transparent layer ("annulus") corresponds
to a single winter period or whether more than one annulus is fonned
each winter.
COMMERCIAL POSSIBILI'fr8S
Eel catches in Canada during recent years were given by Vladykov
(1966). The Province of Quebec yields about twice the eel catch of all
the other provinces put together.
From T~ble 1 it is evident that eel fisheries in the Maritime
Provinces are not extensively developed.
5
Table 1. Mean annual catches of the American eel (Anguilla rostrata)
in Canada per 5-year periods.
Five-year periods Province 1950-54 195.5-59 1960-64
1bs Ibs 1bs
Newfoundland 23600
Prince Edward Island 40800 43600 42000
New Brunswick 7)400 75200 147000
Nova Scotia 112200 113600 118600
Quebec 793600 981200 955000
Ontario 57400 100800 162200
Total 1077400 1314400 1454300
A recent survey of eel fisheries in the Maritime provinces by
ERles (1966) confirms this.
In my opinion in order to increase catches of eels, fishermen
should be assured that their catches will be sold and at reasonable
prices. To do so there should be organised one or several centres
could be kept alive until potential buyers come for them.
So far two of the larger European buyers in their reply to me
expressed their desire to buy both green (immature) and bronze (mature)
eels from Can~da. These buyers are as follows:
1. Fa. Joh. Kuijten Import and Export Spaarndam, Holland
2. Masala Pasquale Industria Allevamento Novellame San Vero Milis (Cagliari), Italy.
6
REFER.8NCES
Eales, J.G. 1966 (MS). A survey of eel fishing in the Maritime Provinces.
57 pp. OTTA't:A.
Vladykov, V. D. 1957. Fish tags and tagging in ~uebec waters Trans. Am.Fish
Soc. Vol. 86 (1956), pp. 345 - 49.
Vladykov, V. D. 1966. Remarks on the American eel (Anguilla rostrata
LeSueur). Sizes of elvers entering streams;
the relative abundance of adul t males and females.;
and present economic importance of eels in North
America. Verh. Internat. Verein. Limmol. Vol. 16,
pp. 1007 - 17.
July )1, 1967. Ottawa.
- 7 -
PROGRESS REPORT NO. 2
ELVERS OF THE AMERICAN EEL (ANGUILLA ROSTRATA)
IN THE MARITIME PROVINCES
by
VADIM D. VLADYKOV
INTRODUCTION
The American eel (Anguilla rostr~) like the European species,
A. anguilla, passes through several larval stages. The earliest
stages, known as preteptocephalus and leptoceEbalu~, are shaped like
willow leaves, are completely transparent, and have long, needle
sharp larval teeth. They live in the open sea and actively feed on
plankton.
Later, the leptocephali gradually transform into gjass eels,
which have the cylindrical shape of an adult eel. The glass eels
lose their teeth and do not feed. In their early stage they are
completely transparent. After, they acquire dark pigmentation on
the top of the head and at the base of the caudal fin. In this
latter stage they approach the shore. Needler (1929) in the latter
half of May 1928 found many glass eels in the stomachs of haddock
at Ingonish, Cape Breton. Schmidt (1909) observed that leptocephali
of the European eel during their transformation into the glass eel
- 8 -
stage shrink in length on the average from 75 mm to 60 mm, and their
average weight decreases from 1.5 g to 0.15 q. Similar phenomena
take place in the American eel.
European authors (Gilsonj
1908; Strubberg, 1913) have established
several stages in the metamorphosis of the European eel. For the time
being, we apply, with some reservations, their definitions to the
Ameri can eel 1/.
MATERIAL
The present report is based on a study of over 7,000 elvers
collected in Nova Scotia and New Brunswick. This material can be
grouped into two sections, based on the dates of collections.
Early Collections, 1952-1960
Table 2 contains collecting data for this period. The main
collections were made at Ingonish Beach, Nova Scotia, in June 1955,
and in the Digdeguash River, New Brunswick, July - August 1955 and
on May 13, 1960. Altogether 820 specimens are available.
Elvers of early collections belong to either the VI Al or VI A2
stages; while those collected at later dates are either in the
VI A3 or VI B stages.
1/ We are working now to properly define the different stages of the
transformation of the American eel, particularly from the glass eel
to the elver stages. In France the elver is called "civellell•
- 9 -
In all t he co 11 ect ion s, i rrespec t i ve of 1 oca 11 ties., made between
May 13 and July 4, the lengths of the elvers varied between 50'mm
and 69 11m. On the other hand, in the collections made between July 12
and August 8, 1955 in the Digdeguash River, the size of the elvers
was from 50 mm to 89 mm (Table 5). The frequency in percentages of
different length-classes is given in Table 5 and Figure 1.
Collections made in 196]
Early this year collections of elvers were made in the
Sackville River, Nova Scotia, and in four New Brunswick streams
near the Biological Station at St. Andrews. Altogether 6,417 elvers
were available for the present study. Details of the different
samples are given in Tables 4 and 6 and Figure 2.
With the exception of samples taken in the Digdeguash River
between July 21-25, the collections contained elvers only in stages
VI Al to VI A3-
It is interesting to note that our material clearly shows that
elvers shrink on the average from 57.6 mm to 56.2 mm (about 2%)
during their transition from stage VI Al to VI A3, and to VI B.
This reduction in size is not as great as changes in their weight.
For instance, in stage VI At one hundred elvers weighed 17.6 g.
In stage VI B their weight only totaled 13.8 g, that is a loss of
about 21% (Table 7 and Figure 3).
- 10 -
VARIATIONS IN THE SIZE OF ELVERS
It is of considerable importance to be able to properly
ascertain the size of an elver in order to make correct analyses
among samples. There are two principle causes for length variations
among elvers.
Variations due to Stages of Development
Table I shows that the length (and weight) of an eel varies
according to its stage of development. In its earlier stages., from
a full grown leptocephalus to a glass eel, the fish decreases in
size. The same phenomenon is observed during the transition from
the glass eel to the elver stage. Moreover, the elve~ stage itself
can be subdivided into several phases, from the "early elver" (stage
VI At) to the "tate elver" (stages VI A3 and VI B).
During this entire transitory period until the earty VI B stage,
the elver does not feed and so shrinks in size. It loses its "baby
fat" and its flesh becomes coarse and unsuitable for human consumption.
In the Maritime Provinces elvers taken in fresh-water streams
during May and June vary in length from 50 mm to 69 mm. For our
study purposes these fish belong to two length-classes, namely,
50-59 mm and 60-69 mm. The interrelationship between these
- 11 -
classes in different samples is most interesting. Among early'elvers
from 59 to 64%, or approximately 60%, belong to the 50-59 mm class
and 34 to 42%, or around 40%, to the 60-69 mm class.
In collections made late in June the interrelationship between
the length-classes changes. Class 50-59 mm occurs in 79 to 85 % of
the samples, but class 60-69 mm, only from 16 to 28%. In other words,
the relative abundance of class 50-59 mm among elvers of the same run
increases with their stay in the stream. More details are given it .
Table 6.
There are other cases. On June 5, 1967, a sample of elvers
was taken in Chamcook Creek (Table 6). The two length-classes,
namely, 50-59 mm and 60-69 mm, occurred in nearly equal proportions.
There is no explanation readily available. It could be that this
sample contained elvers from several runs.
When samples are collected during consecutive months from the
same stream, and even in different years, the changes in the inter-
relationship between the lenght-classes are striking. Collections
of elvers from the Digdeguash River illustrate this:
3;
Date Occurrence of length-classes in % W
............. 50-59 mm 60-69 mm 70-79 mm 80-89 mm
Q
May 13, 1~0 78.7 21.3
June 4, 1955 90.7 9.3
July 12-Aug. 8, 1955 18.7 41.5 27.3 12.5
- 12 -
There is a noticeable difference in the length composition
of the third sample. This may be explained by the fact that fish
in the 70-79 mm and 80-89 mm classes are no longer elvers, but are
newly transformed eels that have begun to feed and grow.
Variations according to Geo~phicaL Region
The author's recent study (Vtadykov, 1966) of elvers, obtained
from various geographical regions, clearly showed that a pronounced
difference exists between the average lengths of the fish.
For the present report we selected only three localities (Table 8);
a) southerly; b) intermediate; and c) northerly. These localities
are as follows:
a) The Patuxent River, flowing into Chesapeake Bay, Maryland,
where collections of elvers were made on April 20, 1960
by the late Dr. R.J. ~ansueti;
b) Turnvil1e Creek, near Ocean City, Maryland, where collections
were made on April 14, 1960 by Mr. E.M. Barry; and
c) The Sackville River, N.S., where collections were made during
May 15-25, 1967.
The average lengths of elvers from the three above localities
varied from south to north as follows: 52.9 mm, 55.7 mm and 58.6 mm.
From Table 8 it is also evident that elvers of the American eel
from the above three localities were represented by three length
classes: 40-49 mm, 50-59 mm and 60-69 mm. However, their frequencies
- 13 -
are not the same in different regions. The class 50-59 mm is always
present, although its occurrence varies somewhat with 10ca1ity~ 86.9%
in the south, 91.5% in the intermediate locality and 62.2% in the north.
Much more interesting are the occurrences of 40-49 mm and 60-69 mm classes.
The abundance of the 40-49 mm class decrease~rom south to north:
11.7% in the Patuxent River, 0.5% in Turnvi11e Creek, and it is completely
absent in the Sackvi11e River. The reverse situation exists for the
class 60-69 mm. Its predominance increases from south to north, res
pectively being: 1.4%, 8.0% and 37.8% (Table 8).
On the basis of the above observations it may be definitely
stated that the size of elvers of the American eel along the Atlantic
shore increases from south to north.
In the same fashion the weight of A. rostrate elvers varies
according to the locality: those fro~ the Chesapeake Bay weighed
an average of 104 milligrams each and those from Nova Scotia, 169
milligrams. In other words, there are 4,441 elvers to a pound
~0.454 kg) from Chesapeake Bay and 2,691 from Nova Scotia (Vladykov,
1966).
The elvers of A. anguilla are not only longer than the American
elvers, but their average weight in milligrams is greater, being from
170 to 369. Frost (195~ and Deeldnr (1952) calculated that there
are 1,400 European elvers to the English pound.
- 14 -
IMPORTANCE OF THE STUDY OF ELVERS
Detailed knowledge of the biology of elvers of the American
eel is extremely valuable. In general, there are three important
aspects of this study.
Elvers in Streams
According to our present knowledge, elvers of the American
eel are easily collected in a great many North American streams
emptying into the Atlantic Ocean. Practically every river or brook
in the Maritime Provinces receives at one time or another a considerable
influx of young elvers o We presume (although at the present time
there is no definite proof}) that many elvers, instead of entering
freshwater, remain in the sea. Therefore, our observations are
limited to elvers found in either freshwater streams or brackish
estuaries.
The following aspects of elver biOlogy should be considered
in this connection:
1) Time of first arrival (or first run) of elvers into Maritime
streams emptying into the Atlantic and Gulf of St. Lawrence.
2) Seasonal variation from year to year in the time of arrival
of the first run and the total duration of all runs in
the same stream; also variation in the abundance of elvers
from month to month and from year to year.
3) Factors influencing the elver migrations, such as tide,
floods, temperature, wind, light, etc.
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4) Details of the transition fro~ the glass eel stage to the
actively feeding young eel stage.
5} Variation in the growth rate of elvers in different streams,
their density and its possibl~ influence on the sex of the
adult eels.
6} What is the relationship between the number of elvers in
the river system and the quantity of adult eels available
for commercial exploitation?
7) Interrelation between elvers and other fishes found in the
same stream. Do elvers actively prey upon young Salmonid
fishes, or do the elvers constitute a valuable diet for
the latter?
Elvers for Transpl~ntation
In many European countries, it is customary to fish for
A. anguilla elvers or to buy them from special agencies for
transplantation purposes. Elvers or newly transformed eels are
liberated in lakes in which they feed and grow for several years.
The adult eels during their descent from these lakes to the sea are
captured for commercial purposes. This is a lucrative fishery that
involves very little capital investment.
Among European countries where elvers are available in large
numbers (for transplantation) are the Netherlands (Deelder, 1952)
and Northern Ireland (Frost, 1950; Lowe, 1951).
- 16 -
It was noticed by people who buy elvers for transplantation
that those from certain areas produce predominantly large eels
(females), whereas elvers from other areas produce mainly small
eels (males). Unfortunately, these observations are not supported
by critical scientific studies.
In this connection should be mentioned interesting observations
by Bellini (1907). His experiments showed that the larger elvers
yielded predominantly female eels, while the smaller elvers became
mainly male eels.
Our study (Vladykov, 1966) showed that the size of elvers of
the American eel, vary with the geographical region. Those popula
ting the Maritime Provinces are much larger(57-58 mm), than those
found in southern waters, such as Chesapeake Bay or Florida, where
the average size of elvers is 52-53 mm. It is of importance to note
that in the Maritime Provinces, female eels which are considerably
larger than males, are much more abundant than in southern waters.
Tms situation is comparable with results obtained by Bellini (1907).
Elvers of intermediate size (55-56 mm) are found along the coast of
the Middle Atlantic (New Jersey; Ocean City, Maryland).
Near Ocean City, Maryland, in Turnville Creek, the Maryland
Fishery Division collected elvers for the Pennsylvania Fish Com
mission. Thanks to Messrs. E.M. Barry and G.S. Rogers of the
Maryland Game & Inland Fish Commission, we were able to obtain the
interesting information that is summarized on the next page o
- 17 -
Number of elvers collected in Turnvil1e Creek, Maryland, during 1958-1960
Date Number of Number of elvers days fished captured
. -April 18-23, 1958 4 590,000
Apri 1 10-16, 1959 2 1,000,000
Apri 1 14-25, 1960 4 4,850,000
From the above data it is apparent that elvers of the American
eel are as abundant as those of the European eel. Unfortunately,
published information such as that by Jeffries (1960) gives the
opposite impression. His paper is based on findings of only six
elvers taken off Rhode Island during January - March.
Elvers for Human Consumption
In many southern European countries such as France, Spain,
Portugal, the early elvers (stage VI Al ) that are still rich in
IIbaby fat II are fished conmercia1ly and considered a gourmet dish.
The elvers are usually fried in olive oil.
Elvers are also taken in great quantities and used as food in
south-western Great Britain. "They are either fried in cakes or
stewed, and are accounted very delicious ll (Schmidt, 1906; 197-204).
- 18 -
In Canada and the United States, elvers are not eaten as yet.
Nevertheless, in Ottawa, in some grocery stores, a canned Portugese
delicacy called "Engyias" is available. It is "fried baby eels with
spices".
In conclusion, we feel that the great abundance of American eel
elvers in the Maritime Provinces could be exploited for a number of
commercial purposes.
ACKNOWLEDGEMENTS
The preparation of this report was made possible with the help
of several persons in the United States and Canada whose names
appeared in Tables 2 and 3 and in the text. The author is indebted
to his assistants, Messrs. P. Burns and D. James, who measured the
elvers and prepared the tables, and to Miss H. March, who drew the
graphs.
REFERENCES
Betlini, A. 1907. Experiences sur 1 'elevage de 1 'Anguilla en stabulation
~ Comacchio. Bull. Soc. Centre Aquic. P8ch~ !2, 186-225.
Deelder, C.l. 1952. On the migration of the elver (Anguilla vulgaris
TurtJ at sea. J. du Conseil, ~ 187-218.
E 1950 The eel fisheries of the River Bann, Northern Frost, W. • •
Ireland, and observations on the age of the silver eels. ~ du Conseil,
!i (3): 359-383.
- 19 -
Gilson, G. 1908. L·anguille. Sa reproduction, ses migrations et son
inter8t economique en Belgique. ~. Soc. roy. Zoot. et Malacol. de Betg.,.
~ 7-58.
Jeffries, H.P. 1960. Winter occurrences of AnguilJa rostrata elvers in
New England and middle Atlantic estuaries. Limnot. a~eano9r. i (3):
338-340.
Lowe, R. H. 1951. Factors influencing the runs of elvers in the
River Bann, Northern Ireland. J. du Conseil, lL (3): 299-315
Needler, A.W.H. 1929. Unpigmented elvers (Anguilla rostrata Le Sueur')
in haddock stomachs at Ingonish, Cape Breton. Copeia, !1lJ 41-42
Schmidt, J. 1906. Contributions to the life-history of the eel
(Anguilla vulgaris Flem.). Con. perm. inter. expl. mer. Rape. & Proc.
Verb., V: 135-265.
Schmidt, J. 1909. On the distribution of the fresh-water eels
(Anguilla) throughout the world. I. Atlantic Ocean and adjacent regions.
A biogeographical investigation. Medd. Komme Hav. Fisk., 1 (7): 45pp
Strubberg, A.C. 1913. The metamorphosis of elvers as influenced by
outward conditions. Medd Komm. Hav. Fisk., ~ (3): llpp
VTadykov, V.D. 1966. Remarks on the American eel (Anguilla rostrata
Le Sueur). Sizes of elvers entering streams; the relative abundance
of adult males and females; and present economic importance of eels
in North America • . Verh. Internat. Verein. Limnot., ~ 1007-1017.
Sentp.mhpT'~ lQh7
- 20 -
Table 1. Later stages of transformation of the European eel
(A. angui!! a )
Designation Stages Characters
Glass eel v Dark pigmentation on the top of the head
and at the base of the caudal fin; body
transparent, without dark pigmentation;
toothless, non-feeding but containing some
fat; shorter than a leptocephalus stage
but longer than stage VI.
Elver VI A Dark pigmentation appears over the back
and flanks, but not on the sides below the
lateral line; adult teeth appear; length
shorter than in stage V; a little fat still
present; non-feeding stage.
Elver VI B Dark pigmentation allover the fish except
belly; the length shrinks to its shortest;
"baby fat" completely lost; teeth on jaws
visible; early in this stage elvers do not
feed, but at the end begin to take food and
grow again.
- 21 -
Table 2. Number of elvers collected during the years 1952-1960
Locality
Sackville River, N. S.
1ngonish Beach, N. S.
Ingoni sh Beach, N. S.
Birch Cove Creek, N. B.
Bocabec River, N.B.
Digdeguash River, N.B.
Digdeguash River, N.B.
Digdeguash River N. B.
Total
;
Date
May 25, 1953
June " 1955
May 10-12, 1960
April 24, 1952
June 19, 1952
May 13,1960
Jul y 4, 1955
July 12-Aug. 8, 1953
1952-1960
Number of elvers
75
262
90
122
54
176
820
t; =
Collector
J.p. Cuerrier
J. P. Cuerd er
J. Po Cuerri er
L.R. Day
L.R. Day
L.R. Day
L.R. Day
L.R. Day
-:: Indicates small saflllles that have been excluded from further consideration.
- 22 -
Table 3. Number of elvers collected during 1967
Locality Date
Sackvil1e River, May 15-25 N. S.
Chamcook Creek, May 14 .. June 5 N.9.
Birch Cove Creek, May 15-July 16 N.B.
Bocabec River, May 30- J.lne 4 N.B.
Digdeguash River, May 14-Jul y 25 N.B.
-~--
Total May 14-Jul y 25
Number of elvers
566
1,503
1,838
939
1,571
6,417
S"
D.
D.
D.
D.
Collector
Miles & D. James
James & H.. McSheffrey·
James & H. McSheffrey
James & M. Wood
James & M. \>,bod
- 23 -
Table 4. List of localities in the Mar"it;me Provinces designated
by the Roman numerals (1 - VI) on Figures 1 and 2
Roman numerals Locality Years of collection
I Sackvil1e River, N.S. 1953 and 1967
II Ingonish Beach, N.S, 1955
III Bocabec River, N.B. 1952 and 1967
IV Digdeguash River, N.I3. 1955, 1960 and 1967
V Birch Cove Creek, N. B. 1967
VI Chamcook Creek" N. B. 1967
- 24 -
Table 5. Occurrence in percentages of different length-classes (mm)
among elvers from the Maritime Provi~ces, 1952-1960
Locali ty Date of Length-classes ~mm)
collection 50-9 60-9 70-9 % % %
Sackvi 11 e Ri ver May 25, 1953 78.7 21. 3
Ingonish Beach June I, 1955 62.6 37.4
Bocabec River June 19, 1952 83.3 16.7
Digdeguash River May 13, 1960 78.7 21.3
Digdeguash River July 4, 1955 90.7 9.3
Digdeguash River July 12-Aug. 8" 18.7 41.5 27.3 1955
80-9 %
=
12.5
- 25 -
Table 6. Occurrence in percentages of different length-classes (mm)
among elvers from Maritime Provinces, 1967
length-c1 asses (mm) Locali ty Date of
c011ecHon 50-9 60 .. 9 % %
Sackville River May 15-17 61.0 39.0
Sackvi lIe River May 25 64.0 36.0
Bocabec River May 30 58.5 41.5
Bocabec River June 4 74.0 26.0
Birch Cove Creek May 15 64.0 36.0
Birch Cove Creek May 28 63.5 36.5
Birch Cove Creek June 4 68.7 31. 3
Digdeguash River May 14 66.7 33.3
Digdeguash River May 28 80.5 19.5
Digdeguash River June 3 81.0 19.0
Digdeguash River July 21-25 84.5 15.5
Chamcook Creek May 14 66.0 34.0
Chamcook Creek June 1 72.0 28.0
Chamcook Creek June 5 49.0 51.0
- 26 -
. Table 7. Variation in the length (mm) of individual elvers an~
the weight (g) per 100 fish in different stages from
Stage
VI Al
VI A2
VI A3
VI B
the Digdeguash River, N.B. collected in June and July
1967. Earlier stages, VI At - VI A3, were taken on
June 3, and the late stage, VI B, on July 21-25
Total length (mm) Weight (g) per
Range Mean 100 elvers =
51-65 57.6 17.6
49-68 57.0 17.2
50-65 56.2 16.8
46-65 56.2 13.8
- 27 -
Table B. Geographical variation in the average length (mm) and
frequency of length-classes (mm) of elvers of the
American eel along the Atlantic coast
Locali ty Patuxent River, Turnvi 11 e Creek, Sackvi t le River, Maryland Maryland Nova Scotia
--Date of Co 11 ecti on Apd 1 20, 1960 Apr; 1 14, 1960 May 15-25, 1967
Number of elvers 213 201 200
Average length
of elvers (mm) 52.9 5507 58.6
Frequency (%) of Length-Classes
40-49 mm 11.7 0.5 0
50-59 mm 86.9 91.5 62.2
60-69 mm 1.4 B.o 37.B
- 28-
LOCALITIE S
100 I II " lIT TIL A ,--A--, I ,.---A---, A
I
~ 80 COLLECTION DATES:
Z .-Ilt 81- 2 nd
en §-3rd UTI- 4 th &II
u Z &II j
0 IaJ
I A: I IL
~ en en en en en en en en en en I I I I , I I I I I
0 0 0 0 0 0 0 0 0 0 10 CD 10 CD 10 CD ." CD ~ CD
LENGTH C LASSES (mm)
Ire 1. rrequencies in percentages of different length-classes (mm) among elvers
from the Maritime Provinces, 1952-1960. Details of localities and
collection dates are given in Tables 4 and 5.
Figure 2. Frequencies in percentages of different length-classes (mm) among elvers from the. Maritime Provinces, 1967.
Details of localities and collection dates are given in Tables 4 and 6.
- 30 -
18
17 58
- mm 16 E ~
E 0-
--- ~ 9 ---.. • •
% 57 15 .t-.... % CD CD Z -1&1 &IJ
..J • 56 13
3lIAI JZIA 2 1lIA3 JITB
STAGES
Figure 3. Variation in the length (mm) of individual elvers and the weight (g)
per 100 fish in different stages, from the Digdeguash River, N.B. collected
in June and July 1967. For further details see Table 7.
- 31 -
100
• 40- 49 mm CLASS
[:J .. 50-59 CLASS •• mm ..
*- § 60-69 mm CLASS
Z 60 -U)
40 LLI -(,)
Z &&I 20 :l 0 &&I 0= 0 LL . . .
a: a: a:: 0 .... &&.I &&.I
Z ..J ..J L&.I ..J ..J X :;; :;; :::> z lr::: f- a: 0 ~ ~ cr
~ en
LOCALITIES
Figure 4. Frequencies in percentages of different length-classes (mm)
among el~~rs from three different localities from South to
North.
- 32 -
PROGRESS REPORT NO. 3
AGE DETERMINATION AND AGE OF THE
AMERICAN EEL (ANGUILLA ROSTRATA )
FROM
NEW BRUNSWICK WATERS
I NTRODUCT! ON
In order to properly utilize local populations of the American
eel, as with any other fish species, a knowledge of their sizes,
sex, and age composition is essential.
This report deals only with methods of age determination,
variation in age with size and locality of the fish. Other infor
mation pertaining to size and sex will be presented in future reports.
METHODS OF AGE DETERMINATION
Very little information is available on the age of the
Amer i can ee I .
Seal es
An attempt by Smith and Saunders (1955) to determine the age
of eels from certain New Brunswick waters was based on a study of
scales. Unfortunately, the scales of both species, AnguilLa anguilla
and A. rostrata.are not formed at a definite age, and moreover scales
from the same fish may possess different numbers of winter marks (an
nuli). European authors such as Hornyold (1937) and Frost (1945)
concluded that the "readingll of scales for age determination of eels
• __ ..t.... __ ...J .a..L _ _ _.J ~ 1_. _... _ • , ... I
- 33 -
The otoliths of eels, as with other fish species, are composed
principally of calcium carbonate and found in the inner ear of the
fish. There are three on each side: the lapillus, the astericus,
and the sagitta. This last, the largest, is the only one that is
used to determine the age.
Even the sagittae of eels are small. For instance, those from
American eels 822-965 mm in length are only 4.0-4.5 mm long and
2.3-2.5 mm wide. Nevertheless eel otoliths are rather thick and
their growth zones are not readily visible, especially in larger
fish. Therefore, it was necessary to make the otoliths more
transparent by grinding and polishing them on a fine carborundum
stone. Even this preparation did not always give satisfactory
results.
The growth zones of the otoliths consist of alternate bands
of predominantly organic matter and inorganic matter. To make
them more visible, the otoliths are heated over a Bunsen flame,
that carbonizes the organic substances more than the inorganic
ones. This results in a greater distinction between the zones.
- 34 -
Christenson (1964) successfully used the method of heating
otoliths with a variety of species of fishes, including the
European eel (Ansuilla anguilla). Christenson's technique consisting
of heating, breaking and counting the number of zones along the
broken edges of the otoliths was tried with the American eel, but
it did not give satisfactory results. Therefore, Mr. D. James,
my assistant, was obliged to find a new technique for determining
the age of the American eel. Preliminary information on this
new method was recently published (James and Vladykov, 1967).
Due to the fact that this new technique has been further
improved, it is desirable to describe it in more detail.
- 35 -
Method of Preparing Eel Otoliths for Age Determination
In order to obtain the otoliths, the eel's head is split longi
tudinallyon the dorsal surface along a line midway between the
eyes. The two halves of the brain are removed together with the
inner ear sacs of the fish. The largest otoliths (sagittae) are
then cleaned between the fingers and placed for a short time in
ethyl alcohol (70%). For prolonged storage otoliths are kept dry.
To make the growth zones and nucleus of the otoliths more
visible the otoliths are carefully ground. Before grinding, the
otolith is mounted on a black paraffin wax block, with the dorsal,
convex surface exposed. The otolith is ground under a binocular
microscope (25 X), with a steel "bur" 1/ rotated by a small por
table dentist drill. To obtain the best results, grinding usually
takes from 5 to 20 minutes. During grinding the otolith is kept
continuously moist with ethyl alcohol (70 - 80%), which clarifies
the otolith's layers and cools the paraffin block •
. 1/ Dentists use burs of various shapes and sizes made either from
steel or ~ungsten carbide. We found that the smallest (No 1/4)
steel bur of regular pattern, round plain cut, was the most satis
factory for our purpose. These burs could be used for about 3
otoliths before they became too dull for grinding purposes. The
price for this type of bur is 80 cents per dozen.
- 36 -
The thinned otolith is removed from the paraffin block and
heated for I - 2 minutes on a porcelain plate over a Bunsen flame
until it becomes dark brown. Then the otolith is placed on a
glass microscope slide and cooled for a short time to prevent its
shattering when placed in creosote. Only a chemically pure creosote
should be used. The examination of the ground otolith is done in
reflected light against a black background under a binocular micro
scope at approximately 25 X magnification. During this examination
the otolith is kept submerged in creosote on a glass microscope
depression slide. After the study the otolith is again stored dry.
Heating and immersion of the otolith in creosote make the pre
viously opaque and transparent zones distinct yellow and dark brown
bands respectively.
Otoliths from elvers or small eels, less than 200 mm, are thin
and transparent. Since they do not require grinding they are
mounted in ·"permount ll mounting medium 2/ on depression slides
for storage and subsequent study.
2/ IIPermount" is a solution of synth~tic resin material
made and sold by Fisher Scientific Company.
- 37 -
Growth Zones on the Otoliths
The nucleus consisting of tightly packed zones is found in the
middle of an eel otolith (Figure 1). These are the sea rings or
zones representing that part of the otolith laid down in the
leptocephalus stage and during the life of the "glass eel" (or
"early elver"), until H reaches the coast. The alternating
broad and narrow zones which surround the nucleus, represent, on
the other hand, the successive stages of the life of the eel in
fresh water.
The eel otolith, when seen by reflected light against a dark
background, shows alternating light and dark concentric zones;
the former are whitish and opaque and were laid down in the
summer (summer growth), the 1 atter are darker and comparati vel y
trans 1 ucent and represented the wi .nter growth. The i nterpreta
tion of such zones as annual and thus as records of the age of
the European eel has been justified by the experiments of Ehren
baum and Marukawa (1913), 3/ who took glass eels and kept them
in aquaria from I to 5 years.
3/ We are conducting a comparable experiment with the American eel.
On July 27, 1967, about 10,000 eivers from a New Brunsl.'Jick stream
were transplanted to a pond at the White Lake Hatchery, Ontario
Department of Lands and Forest. Periodical samples of these elvers
were taken regularly, and their otoliths were studi ,~d. During the
spring and summer of 1968 the otoliths from our young eels shall
show us what type and how many "winter zones" have been formed.
- 38 -
They found that the zoning on the otoliths of such eels, with few
exceptions, registered the number of summers and winters of capti
vi ty.
The experience gained from European authors can be applied
with some reservation to the American eel as well. Therefore, the
IIreading" of otoliths for age determination is based on two sets
of rings or zones:
a) those, composing the nucleus, formed during
the larval period in the sea, 4/ and
b) those formed in fresh water.
Around the nucleus, on the otolith of a young eel, which
entered a brook in the spring as an elver the year before, is
formed a rather wide white opaque zone, the first zone having
been recorded in fresh water and laid in the first summer there,
then followed by a rather narrow dark translucent zone which had
4/ It is presumed that many elvers of the American eel captured
on their entrance into the river in the spring are one year old.
However, I have some leptocephali of the American eel, which,
no doubt, spent 2 years in the sea.
- 39 -
been formed during the first winter in fresh water. This eel had
spent a year in fresh water.
The subsequent alternating opaque and translucent zones mark
the summers and winters of the successive years in the freshwater
life of the eel. In normal conditions only one opaque (summer)
zone and one translucent (winter) zone are formed during a
single year. However, there are cases where between normal
opaque and translucent zones have been laid down one or more
secondary translucent rings. The reason for this abnormal
formation of new zones is unknown at the present.
The winter zone indicates completion of the yearly growth;
hence it can be called the annulus, or the yearly mark. Further
examples illustrate how the "reading" of eel otoliths can be
applied to age determination. For instance, otoliths with 2
summer and 2 winter zones laid down in addition to the nucleus
are found in eels which have spent 2 complete years in fresh
water. In the case of an eel which has passed 3 winters and
4 sUl11llers in fresh water, the fourth winter mark has not been
laid down as yet.
It is of importance to note, that on eel otoliths, which were
heated, the opaque (summer) zones remained practically unstained,
while the translucent (winter) zones became dark brown.
- 40 -
LENGTH AND AGE RELATIONSHIP
In 1965 we started to collect samples of eels from different
Canadian provinces for age determination. Many hundreds of eels
have been preserved frozen awaiting otolith removal.
The two preceeding chapters of the present report not only
explained the technique of removing and preparing otoliths for
age determination but also gave some idea that age determination
of eels is a time consuming study. In almost every case, even
in otoliths with distinct growth zones, repeated observations
were required. Moreover, a sketch of each otolith and its zones
are made. To measure, weigh and register the fish and to remove
the otolith in preparation for its study requires at least one
hour per fish.
- 41 -
The present report contains some information about eels
from New Brunswick waters collected during 1967 (Table I). . 5/
The total number of fish studied is 205, of which only 148
eels (Table II) possessed otoliths of high quality in rela-
tion to the clear distinction of the growth zones.
we followed the lead of Jensen (1965) and subdivided the
otoliths into three categories according to the degree of
distinction between summer (opaque) and winter (translucent)
zones.
Category of Otoliths
Vladykov (present report)
Jensen (1965)
A o
B
c 2
Quality
Good
Fair
Poor
Explanation
The zones are plainly visible with a generally good definition between translucent and opaque zones.
The zones are visible but not well defined.
The zones are vaguely marked.
5/ It is of importance to note that all eels used for age
determination in the present report were females.
- 42 -
Eel specimens discussed in the present report range from late
elvers (60~69.mmf/ to an adult of 760 mm in length.
Elvers
Glass eels at the time of their arrival to freshwater streams
are still unpigmented, except for a dark spot at the base of the
caudal fin. They are actually "earlyU elvers ,,,hose otoliths
consist only of the nucleus (Figure 1) with no zones acquired
in fresh water. It is very difficult to state definitely the
age of these early elvers.
The late elvers, which are completely pigmented, start to
feed and grow in fresh water. The length of these elvers
varies from 60-69 mm. Table III shows that the majority of
these elvers have spent only part of a summer in fresh water
and hence no winter zone (annulUS) is present on their otoliths.
6/ More information on the sizes of elvers from New Brunswick
were given in Progress Report No.2.
- 43 -
Small Eels
Elvers from the end of the first summer in fresh water
through the first winter gradually become young eels. The
smallest length class (70-79 mm) is characterized by the
presence of only one annulus on their otoliths. The next
class (80-89 mm) comprises fish with one, two and three
annuli acquired in fresh water. In this class as in the
following class (90-99 mm) which consists of fish with two
and three annuli~fish with two annuli predominate.
Small eels of the three length-classes (100-159 mm)
are fish predominantly with three and four annuli on their
otoliths. The next two classes (160-199 mm) are fish with
five and six annuli. The upper groups (200-349 mm) of
small eels showed from six to nine annuli (Table III).
- 44 -
Large Eels
Although the total number of eels which could be considered
as "large" is HmHed (only 54 fish) nevertheless, preliminary
data showed interesting features (Table IV).
The smallest length-class (350-399 mm) consists of eels with
6-14 annuli. The next group (400-549 mm) are predominantly fish
with 9 and 10 annuli. The group (550-699 mm) display a conside
rable range in the number of annuli, mainly from 9 to 17. How
ever, the most common number of annuli is from 11 to 15.
The two largest eels, one 711 and the other 750 mm showed
respectively 14 and 18 annuli on their otoliths (Table IV). In
other words the last fish spent co~plete 18 years and a few
months in fresh water. Up to the present this eel was the
oldest one examined from New Brunswick waters.
In future reports we plan to give information on the age
of much larger American eels from Quebec and Ontario waters.
- 45 -
General Remarks
The age determination of 148 eels from the New Brunswick waters
has been considered in the present report. The relationship between
the number of otolith annuli and the lengths of eels are given in
Table V. Excluding ~he elvers (61-66 mm) which spent a few months
in fresh water and did not acquire a single annulus, the remaining
eels showed from 1 to 18 annuli.
The eels with I to 11 annuli showed a progressive increase in
their average size from 75 to 533 mm. The exception is evident for
the group with seven annuli because it was represented by a single
fish.
Among older eels with the number of annuli ranging from 12 to
16, the progressive increase in their lengths with age is not clearly
shown (Table V) no doubt because of the small number of eels available
for the present study.
If we compare our observations on the age-length relationship
among American eels with those made on the European eel (Frost,
1945) we find that they are quite similar.
It is rather surprising to find that both,A. anguilla and A. rostrata,
are slow growing fish. For instance eels about 600 mm or 24 inches in
length are fish 15 to 16 years of age.
ACKNOWLEDGMENTS
In the preparation of this report the following assistants
were particularly helpful: Miss H. March prepared the figure,;
Mr. P. Burns made calculations, and Mr. D. James prepared the
otoliths and determined the age of the eels.
December 14, 1967
- 46
------} ----- "
Itntn
Figure I. A semi-schematic drawing of the right otolith
(sagitta) of a female American eel (Anguilla
rostrata),435 mm long, weighing 150 g, taken
on August 25, 1967, in Kouchibouguac Bay, New
Brunswick.
The otolith, examined by reflected light, shows
10 summer zones as white and 9(1-lX) winter
zones (annuli) as cross-lines in the drawing.
All these zones were formed in fresh water,
while the nucleus (n) was formed in the sea.
- 47 -
REFERENCES
Christensen, J.M. 1964. Burning of otoliths, a technique
for age determination of soles and other fish,J. du Conseil
29 (1): 73-81.
Ehrenbaum, E. und H. Marukawa. 1913. Ueber Altersbestimmung
und Wachstum beim Aal. Z. Fisch. ~: 89-127.
. -.-~
Frost, W. E. 1945. The age and growth of eels (Anguilla anguilla)
from the Windermere catchment area. Part I. J. Anim. Ecology,
~ (1): 26-36. Part II. Ibidem, l!! (2): 106-124.
Hornyold, A. c. 1937. La frequence des ecailles avec le
nombre maximum de zones sur quatre regions du corps de
l l anguille. Rive Bi01. Firenze, ~ (2): 201-212.
James, D. T. and V. D. Vladykov. 1967. A method of prepadng
eel otoliths for age determination.Anna1es de 1 ' ACFAS, 33: 69.
Jensen, A. C. 1965. A standard terminology and notation for
otolith readers. ICNAF Res. Bull.) 2: 5-7.
Smith, M. W. and J. W. Saunders. 1955. The American eel
in certain fresh waters of the Maritime Provinces of Canada.
J. Fish, Res. Bd. Canada, 1! (2): 238-269.
- 48 -
Table I. Collection data for eels from New Brunswick, 1967, used for age determination.
locality
hamcook Creek
irch Cove Creek
ocabec River
'i gdeguash Creek
~ichibucto River
it. lou; s Ri ver
~uchibouguac Bay
:ocagne
.aie du Vi" River
TOTAL
Date
Hay 14
Hay 15 - September 26
May 30
May 13 - July 25
June 4 - August 23
August 25
August 25
August 23-24
October 1
May 14 - October 1
Number of spedmens
3
77
29
20
22
10
36
6
2
205
Range (1Ml)
67-68
61-236
144-468
62-151
311-678
329-711
407-692 , 609-687
671-760
61-760
- 49 -
Table II. Number of eels from different localities in New Brunswick,
collected from May 13 to October 1, 1967.
Number of fish Number of fi sh
Length-Class Quality of otoliths Total
Length-Class Quality of otoliths (mm) A B C (mm) A B C
Sr all Eels Lc rge Eel
60-69 10 13 - 23 350-99 7 2 1
70-79 14 3 - 17 400-49 8 2 -80-89 9 1 - 10 450-99 8 1 1
90-99 10 - - 10 500-49 10 - -100-19 9 I - 10 550-79 8 1 I
120-39 8 2 - 10 600-49 6 3 1
140-59 7 3 ... 10 650-99 5 3 2
160-79 5 3 2 10 711 1 - -180-99 5 3 - 8 760 1 ... -200-49 10 2 - 12
250-99 4 1 - 5 Sub Total 54 12 6
300-49 3 4 1 8 % 75.0 16.7 8.3
Sub Total 94 36 133 Grand Total 148 48 9
% 70.7 27.1 2.2 . 100.0 % 72.2 23.4 4.4
Tot.
10
10
10
10
10
10
10
1
1
72
100
205
100
length-Class (mm)
60-69
70-79
80-89
90-99
00-19
20-39
40-59
60-79
80-99
00-49
50-99
100-349
TOTAL
- 50 -
Table III. Percentage frequency and range of the number of otolith annuli, according to the length of eels from New Brunswick, 1967.
Small Eels
Number Number of annuli
of sped mens 0 I II III IV V VI I VII'
10 90.0 10.0 - - - - - -14 - 100.0 - - - - - -9 - 33.3 55.6 11. 1 - - - -
to - - 80.0 20 - - - -9 - - 33.3 55.6 11.1 - - -8 - - - 62.5 37.5 - - -7 - - - 14.3 71.4 14.3 - -5 - - - - - 60.0 40.0 -5 - - - - - 20.0 80.0 -
10 - - - - - 20.0 70.0 -4 - - - - - - 50.0 -3 - - - - - - 33.3 33.3
94
VIII IX
- -- -- -- -- - -
- --- -
- -- -
10.0 -25.0 25.0
33.3 -
-
Length-Class (mm)
350-99
400-49
450-99
500-49
.550-99
600-49
650-99
711
760
TOTAL
- 51 -
Table IV. Percentage frequency and range of the number of otolith annuli according to the length of eels from New Brunswick, 1967.
Large Eels
Number Number of annul i of speci mens . VI VII VIII IX X XI XII XIII XIV XV XVI XVII
7 14.3 - .. 57.1 14. - - - 1/ •• 3 - - .. 8 .. - - 62.5 37. ! - - - - .. - -8 - - .. 50.0 12. ~ 37.5 - .. .. - .. -
10 - - .. 40.0 50.( - - - .. 10.0 .. -8 .. - - 37.5 .. - 12. I 25.0 - I 12.5 .. 12.5
6 - .. - .. 16. 7 .. 33.3 - 33.3 .. 16.7 .. 5 - .. - 20.0 .. 20.0 - .. 20.0 20.0 20.0 -1 - .. - - - .. - .. 100.0 - - -1 .. . .. - .. - - - - - .. - ..
-
54
XVII
---..
-..
.. -
100. (
Number
- 52 -
Table V. Relationship between the number of otolith annuli and the length of eels from New Brunswick, 1967.
Number Length (nm)
of annul i of speci mens Average
0 9 63.7
I 18 74.9
II 16 94.0
III 14 114.0
IV 9 138.4
V 7 181. 7
VI 17 227.5
VII 1 343.0
VIII 3 275.7
IX 22 470.2
X 11 492.0
XI 4 532.5
XII 3 618.0
XIII 3 514.3
XIV 4 648.0
XV 3 599.0
XVI 3 627.3
XVII - -XVIII 1 760.0
TOTAL 148
Range
61-66
66-87
82-112
84-155
118-157
158-212
168-365
343
221-317
288-657
366-633
472-687
584-640
391-593
605-711
510-692
567-678
-760
- 53 -
PROGRESS REPORT NO. 4
LENGTHS OF AMERICAN EEL (ANGUILLA ROSTRATA) IN
COMMERCIAL CATCHES OF EASTERN CANADIAN PROVINCES
INTRODUCTION
There is very little information available on sizes of the
American eel taken commercially in different Canadian Provinces.
In future reports, after studies of representative samples from
all the Maritime Provinces, detailed information on the weight
and lengths of eels taken there will be given.
The present paper is only a preliminary guideline to lengths
of eels taken commercially in different provinces. Even this in
complete information could be useful to government agencies or
buyers of eels. It will be clearly shown that there is a very
distinct difference between the sizes of eels caught in various
provinces.
In this report, the length of eels refers to the total length
which is measured in a straight line from the tip of the lower jaw
to the posterior end of the middle caudal ray (Vladykov, 1966).
The samples of eels were usually obtained from commercial
fishermen, whose methods of fishing vary according to region.
In the Maritime Provinces and in Lake Ontario, eels are taken
with hoopnets.
In the Ottawa River, near Ottawa, small quantities of eels
are taken commercially or used for personal consumption. They
are usually taken on nightlines. In the same river, during the
summer months, great concentrations of eels are foulld below hydro
electric dams, such as Chats Falls and Carillon. According to
- 54 -
our present knOWledge, these eels in attempting to ascend the
river have difficulty in passing these dams. In order to obtain
information on the sizes of these eels, two samples were collected
below Chats Falls with a small mesh seine (Table VIII).
In Quebec, in the estuary of the St. lawrence River, the
common method of fishing consists of building tidal weirs locally
known as IIp€ches ll • A description of typical "p€chesll is given
by Vladykov (1958).
The present report is based on the examination of 3,326 eels
from five provinces (Table I). Unfortunately, we were unable to
secure a representative sample from Prince Edward Island • . To gain a comprehensive picture of sizes of eels taken com-
mercially, fish smalter than 200 mm in length, which are occa-
sionally taken in hoopnets, were excluded from the present study.
The only exceptions were the small eels (100-199 mm) in samples
obtained immediately below the Chats Falls Hydro Electric Dam
on the Ottawa River. This was done purposely to show the minimum
size of eels ascending the Ottawa River and being retained and
concentrated below the Hydro Electric station.
- 55 -
LENGTH VARIATION ACCORDING TO PROVINCE
The size of eels is not governed by provincial boundaries
but rather by geographical locations of the watersheds and their
types. On the other hand, fishermen and hence their gear are
governed by local traditions and provincial regulations.
The method of fishing and mesh size of the gear used in
various provinces are somewhat different. It is quite probable
that the size of eels in our samples could be affected by the
mesh size,method of fishing, and by differences in fishing
seasons. However, at the present time at least, we must con
sider that the size of eels in our samples does correspond to
that of the respective populations from which they were drawn.
In other words, we could say that our samples from the Maritime
Provinces, from the St. Lawrence River in Quebec and from Lake
Ontario are random samples, whereas those from the Ottawa River
tend to be biased.
To better express the local differences of eel populations
from different watersheds the samples from different provinces
should be treated separately.
- 56 -
Maritime Provinces
Of the four Maritime Provinces unfortunately, we have no
samples from Prince Edward Island. Our sample from Nova Scotia
is rather small (Tables II and V). Samples from the other two
provinces are substantial.
Nova Scotia. From this province, only 36 eels were
available to us. Nevertheless, the two length-classes, 400-99 mm
and 500-99 mm are predominant and their frequency corresponds
closely with those from the other two Maritime Provinces (Table V).
Newfoundland. - From this island province, we have 172 eels
collected during the summer of 1960 from four rivers, from the
Little Codroy to the Salmon, along the southern coast.
The two length-cl asses, 400-99 mm and 500-99 mm represent
nearly 74 % of the total number of eels in the samples. It is
of interest to note that one large eel, 930 mm in length and
with a weight of 2,350 g (5.2 Ibs), was taken in the estuary
of the Little Codroy River on June 17, 1960. In the other
Maritime Provinces (Table V), the largest eels captured were
less than 800 mm in length.
New Brunswick. - Our largest sampJes came from this
province. Early collections, consisting of 163 adult eels, were
obtained during the summer of 1960 from the St. John and Digdeguash
- 57 -
Rivers,along the Bay of Fundy shore. Later collections of 680
specimens were obtained during August - September 1967 in five
different rivers, from the Miramichi southward to the Cocagne,
along the coast of the Gulf of St. Lawrence (Table II). Alto
gether, 843 eels have been studied from New Brunswick waters.
The two length-classes, 400-99 mm and 500-99 mm represent
72% of the fish in these samples (Table V). The most striking
feature with the New Brunswick samples is a scarcity of large
eels. Only seven fish (0.8%) were in the length-class 700-99 mm,
whereas the occurrence of this class exceeded ~~ in Newfoundland
and 8% in Nova Scotia.
Ontario
From this inland province we have samples from three
different areas: South Bay, Lake Ontario, the Ottawa River,
near the city of Ottawa,and below the Chats Falls Hydro Electric
dam. Altogether, 659 eels were available (Table III).
Lake Ontario. - A regular eel fishery with hoopnets exists
along the north shore of Lake Ontario in Prince Edward County,
Ontario, particularly in South and Smith's Bays. Our samples
were obtained during May and June of 1965 and 1966 (Table VI)
from South Bay.
- 58 -
The three most numerous length-classes, 600-99 mm, 700-99 mm
and 800-99 mm, represented 88% of the sample in 1965 and 84% in
1966. The close similarity between these two samples is noticeable
also in the length-class of 900-99 mm which is effectively 10% for
each year. In both years even larger eels were present, although
in small numbers. For instance, in 1965 one eel measuring 1,000 mm
and weighing 2,211 g was taken, and in 1966 the following three
large eels were captured: 1,017 mm (2,640 g), 1,032 mm (3,040 g),
and 1,047 mm (3,021 g). Thus their weight varied from 5 to 7 pounds.
On the other hand, in the Lake Ontario fishery the length
class 500-99 mm was very poorly represented: 1.1% and 4.2% in
1965 and 1966 respectively. This same class in the Maritime
fishery was the second most predominant, comprising 25% of the
total catch (Table V).
Ottawa River. - Only a small commercial fishery for eels
exists in this river, near Ottawa. The usual method of fishing
is with baited nightlines. This gear is not very selective (even
small eels have relatively large mouths), thus eels of a great
range of sizes are taken (Table VII). This range extends from
the length-class 200-99 mm to the class 900-99 mm. The most
common sizes were from 400-99 mm to 700-99 mm.
- 59 -
This method of fishing, particularly with the small number
of eels available for our studies, does not give a clear picture.
It can be said only that there is a variety of sizes available
ranging from 242 mm to 940 mm.
Chats Falls. - A high Hydro Electric dam across the Ottawa
River prevents the direct ascent of eels through the gates. How
ever, there is a remote possibility that eels can by-pass this
obstruction.
To learn about the length-classes of eels found below Chats
Falls we collected two samples. One was obtained between June 22
and August 24, 1965, when many eels were caught with a small mesh
seine. We retained only 75 eels, including the smallest (104 mm)
and the largest (510 mm) ones.
During the 1966 season, we collected between July 8 and
August 25 with the same seine as in the previous year. From
the specimens collected we retained only 152 fish, ranging in
length from 123 mm to 514 mm (Table VIII).
The most surprising feature is the occurrence below Chats
Falls, at such a great distance from the sea, of many small (104-
123 mm) eels. However, these seemingly young fish spent at least
two and often three years in fresh water. Thus, they are in ro
ality stunted specimens. More information will be available when
Mr. D. James completes the determination of th~ ago of eels from
these samples.
- 60 -
Quebec
The most important eel fishery in Canada is found in this
province. Some information on the method of fishing, annual
catches, and the sizes of eels taken is given by Vladykov (1955,
1958 and 1966).
Table IX contains information regarding the length compo-
sition of a large sample of eels taken in tidal weirs in the
St. Lawrence River near Quebec, during 1944, as well as similar
data on less valuable, smaller samples from the same province,
taken between 1953 and 1960.
Considering the large sample from 1944 as being more typical
of the Quebec fishery, the smaller one can be excluded from
further discussion.
The striking feature of the Quebec samples is the unusually
large size of the eels. Although in Lake Ontario large eels are
found (Table VI), they are not as abundant as in Quebec. The
following table illustrates this point:
Length-Class % of occurrence
(mm)
800-99
900-99
1,000-99
1,100-99
Lake Ontario
29
10
St. Lawrence River Que. 43
45
8
0.4
"
- 61 -
It should be added that large eels weighing 5-8 pounds are
taken regularly in Quebec. The largest specimen was taken in
Quebec near Ile d'Orleans during the autumn of 1943, when, ac
cording to the fisherman, it weighed 13 pounds and 5 ounces.
When we received this female eel, which had been kept in cold
storage for one year, it weighed 11.5 pounds and measured 50
inches (1,275 mm) in length.
As it was mentioned earlier (Vladykov, 1955), the average
length of eels taken in the Quebec fishery is 36 inches, and
their average weight is close to 3.5 pounds.
General Observations
In order to obtain a clearer view of the differences in
eel lengths from different provinces, Figure 1 is added. In
the Maritime Provinces, more specifically in New Brunswick,
the dominant length-class is 400-99 mm.
In Lake Ontario, the three dominant classes are: 600-99 mm,
700-99 mm and 800-99 mm. In the St. Lawrence River, in the vi
cinity of Quebec City, the dominant length-classes of about the
same strength are: 800-99 mm and 900-99 mm.
- 62 -
SEX RATIO AMONG EELS FROM DIFFERENT PROVINCES
Although the method of collecting adult eels for our studies
was not uniform throughout the different areas, certain conclusions
can be drawn about the relative abundance of sexes among eels from
different provinces.
In Ontario, no male eels were observed in any of our samples.
The same holds true for Nova Scotia. In other provinces males
were present, but their frequency varies with the region.
In Quebec, from the many thousands of eels examined, so far
only three males were observed: one, 255 mm long, was taken at
Barachois on November 17, 1956; and two others were caught, one
(400 mm) on August 15, 1967 in Riviere Petits Escoumins, Cote Nord,
and the last one (402 mm) in Petite Riviere Blanche, Comte de
Matane, on September 20, 1967.
The males are particularly abundant in Newfoundland and
in some parts of New Brunswick. Table X contains information
on the sizes of these males.
Up to the present, no male American eel examined by us
exceeded 450 mm in length. To be on the safe side, we can
consider all eels 600 mm or more in length to be female.
- 63 -
ACKNOWLEDGEMENTS
The preparation of the present report was made possible
with the help of several persons, too numerous to be mentioned
individually. Our thanks goes to government employees, both
federal and provincial, and to many fisherman from different
provinces. The author is indebted to his assistants, Messrs.
P. Burns and D. James, who measured the eels and prepared the
tables, and to Miss H. March, who drew the graph.
REFERENCES
1. Vladykov, V.D. 1955. Eel, fishes of Quebec. Album No.6:
1-12. Dept. of Fisheries, Quebec.
2. Vladykov, V.D. 1958. Deux peches caracteristiques du
Fleuve St-Laurent. Actualites Marines, Departement des
Pecheries, Quebec. Vol. 2(1): 6-12.
3. Vladykov, V.D. 1966. Remarks on the American eel (Anguilla
rostrata Le Sueur). Sizes of elvers entering streams;
the relative abundance of adult males and females; and
present economic importance of eels in North America.
Verh. Internat. Verein. Limnol., ~: 1007-1017.
March 15, 1968
50
4 0
30
10
0') en I
o o. ",
- 64 -
-MARITIMES
• •
0 .x._ en en en en I I
0 0 0 0 10
,.. LEN G T H - C LAS S· E S
FIG URE
e- -e
-QUEBEC
o L.ONTARIO
o
( mm )
- 65 -
Table I. Number of eels studied for the present report •.
Collection Area
Mad time Provinces
Quebec, St. Lawrence River
Lake Ontad 0
Ottawa Ri ver, near Ottawa
Ottawa River, Chats Falls
Total
Number of
Specimens
1,053
1,614
323
107
229
3,326
Collecting Method
Hoopnets
Ti dal wei rs (IIPSches ll )
Hoopnets
Nightline (baited hooks)
Sma 11 Mesh Sei ne
- 66 -
Table II. Collecting details on eels from the Maritime Provinces, 1960-1967.
Date
June-Sept. 1960
Aug.-Sept. 1960
Aug.-Oct. 1960
Aug. -Sept. 1967
Total
Locality
Newfoundland
4 rivers (Little Codroy-Salmon), along southern shores
Nova Scoti a
7 different rivers
New Brunswick
St. John & Digdeguash Rivers, along Bay of Fundy shore
5 rivers (Miramichi-Cocogne), along the Gulf of St. Lawrence
Number of eels
174
36
163
680
1,053
- 67 -
Table III. Collecting details on eels from Ontario, 1959-1966
May-June 1965-1966
April-Oct. 1959-1960
June-Aug. 1965-1966
Total
Locali ty
Lake Ontario
Ottawa River near Ottawa
Ottawa River
Chats Falls
Number of eels
323
107
229
659
Table IV. Collecting details on eels from Quebec, 1944-1960
Date
Aug.-Oct. 1944
Ju1 y-Oct. 1953-1960
Total
Locality
St. Lawrence River near Quebec City
St. Lawrence River near Quebec City
Number of eels
1,487
127
1,614
Province
- 68 -
Table V. Number of eels of different length-classes (mm) taken with hoopnets in the Maritime Provinces during 1960 and 1967.
Newfoundland Nova Scotia New Brunswick Total
Length-class Specimens collected
Specimens coll ected
Specimens collected
Specimens collected
(mm) Nunber % Number % NuiTlber % Nun6er %
200-99 2 1.15 22 2.61 24 Z.28
300-99 23 13.22 3 8.33 155 18.39 181 17.19
400-99 79 45.41 12 33.33 398 47.21 489 46.44
500-99 49 28.16 12 33.33 211 25.03 272 25.83
600-99 14 8.04 6 16.68 50 5.93 70 6.65
700-99 6 3.44 3 8.33 7 0.83 16 1.52
800-99
900-99 1 0.58 0.09
Total 174 100.0 36 100.0 843 100.0 1,053 100.0
Year
Length-class
(mm)
500-99
600-99
700-99
800-99
900-99
1000-99
Total
- 69 -
Table VI. Number of eels of different length-classes (mm) caught with hoopnets in South Bay, Lake Ontario, during the fishing seasons (May-June) of 1965 and 1966.
1965 1966 Total
Specimens collected Specimens collected Specimens collected
Number % Nunber % Nunber %
2 1.12 6 4.17 8 2.48
50 27.93 35 24.31 85 26.31
56 31.29 45 31.25 101 31.27
52 29.05 41 28.47 93 28.79
18 10.06 .14 9.72 32 9.91
0.55 3 2.08 4 1.24
179 100.0 144 100.0 323 100.0
- 70 -
Table VII. Number of eels of different length-classes (mm) caught with nightlines in the Ottawa River, near Ottawa, during the summers of 1959 and 1960.
Specimens collected
Len~th-C1aSS Number % mm)
200-99 0.93
300-99 2 1.87
400-99 17 15.89
500-99 30 28.04
600-99 29 27.10
700-99 19 17.76
800-99 8 7.48
900-99 0.93
Total 107 100.0 :
Year
Length-ctass
(11'111 )
100-49
150-99
200-99
300-99
400-99
500-99
Total
- 71 -
Table VIII. Number of eels of different length-classes (mm)
caught with small mesh seine in the Ottawa. River
below Chats Falk Hydro Electr;c Dam, during the
summers of 1965 and 1966.
N.B. Samples were selected and not taken at random.
g
1965 1966 Total
Sped mens collected Sped mens cot tected Spedmens collectet
Number % Number % Number %
26 34.67 31 20.t3 57 24.89
20 26.66 35 22.73 55 24.02
6 8.00 25 16.23 31 13.54
13 17.33 25 16.23 38 16.59
8 10.67 36 23.38 1f4 19.21
2 2.67 2 1. 30 4 1.75
75 tOO.O 154 100.0 229 100.0
Year
Length-class
(mm)
500-99
600-99
700-99
800-99
900-99
1000-99
1100-99
Total
- 72 -
Table IX. Number of eels of different length-classes (mm). caught with tidal weirs in Quebec, 1944-1960.
1944 1953-1960 Total
Specimens collected Specimens collected Specimens collected
Number % Number % Number %
--0.07 0.79 2 0.12
3 0.20 27 21.26 30 1.86
52 3.50 57 44.88 109 6.75
642 43.17 28 22.05 670 41.51
668 44.92 14 11.02 682 42.26
115 7.73 115 7.13
6 0.41 6 0.37
1,487 100.00 127 100.00 1,614 100.00
- 73 -
Table X. Number (N) and lengths (mm) of male eels from
Newfoundland and New Brunswick, 1960.
Length-ct ass Newfoundland New Brunswick Total
{mm} N Mean length N Mean length N Mean length {mm} {mm} (mm)
200-49 3 229.7 3 229.7
250-99 6 271.8 5 281.0 11 276.0
300-49 3 343.3 3 322.0 6 332.7
350-99 357.0 357.0
Total 12 9 21
- 74 -
PROGRESS REPORT NO. 5
EEL TAGGING IN NEW BRUNSWICK WATERS.
I. LENGTH AND COLOURATION OF TAGGED EELS
INlRODUCTION .
Due to the active interest on the part of the New Brunswick
Government, the eel fishery in that province has developed to a considerable
level. For instance, during the 1967 season, about 200,000 pounds of
eels were taken from the New Brunswick waters. There is a definite
possibility of increasing the yield to a much higher level, by modifying
fishing gear in use at present and extending fishery operations to
several rivers of the Bay of Fundy and the Gulf of St. Lawrence coasts.
The principle fishing method for eels in New Brunswtk waters
is the use of hoopnets made of nylon netting. This stationary method
can only be effective if the eels are swimming up or down stream, whether
on daily or seasonal movements, or most particularly during their final
migration to the sea for reproductive purposes.
To understand properly the direction and extent of daily or
seasonal movements of eels the tagging of these fish is essential.
Furthermore, by the recapture of tagged fish, the efficiency of present
fishing methods can be ascertained. The rate of growth and changes
in colouration, which relate to sexual maturation of the eels, may also
be learned properly by tagging methods.
While waiting for returns on recaptured eels, a subject which
will be dealt with in Part II of the present study, this report will
describe the size and colouration of tagged eels at the time of their
liberation. CORRECTION
Throughout the present report, including tables and Figure 1, the tagging locality mentioned as the St. Louis de Kent River, should correctly be called the Kouchibouguacis River.
- 75 -
TAGGING
As the American eel in freshwater habitat usually hides under
rocks or buries itself in the mud, it can be tagged successfully only
with specially designed tags. Some years ago, the author (Vladykov, 1956)
developed such a type of tags.
Type of Tags
This type was named "Split-Ring and Plate Tag". Two sizes of
split-rings, made of stainless steel piano wire, were manufactured:
5/8 and 7/8 inch in diameter. They can be opened sideways by means
of specially designed pliers, one for each ring size. The plate or
tag proper is made of laminated vinylite of different colours, about
1 x 1/4 of an inch. Four colours are used. The numbers are stamped
on one surface, prefixed by a letter corresponding to the colour:
G (green), 0 (orange), W (white), and Y (yellow). On the undersurface
of the plate is printed "Canada". These split rings and tags are attached
around the lower jaw bone of the fish (Figure 4). Eels, taken commercially
in the New Brunswick waters, are small or medium size fish (Table IX),
therefore 5/8 inch split-rings were used to tag them. To prevent
accidental opening of the split-rings, the ends are welded by using a
portable electric welder.
- 76 -
There are several models of such welders, among which the
"Uni tek" model ; s parti cularl y sui table, as its el ectrodes are connected
to the welder by cables which permit free movement while soldering of
the rings on the fish (Figures 1, 3 and 5).
Length of Tagged Eels
All eels previous to tagging were anesthetized in a water
solution (1 :3,000) of tricaine methanesulfonate (MS-222) for a
duration of about 10-20 minutes. As soon as the eels stopped active
movements, their total length was measured in a straight line, from
the tip of the lower jaw to the posterier end of the middle caudal
ray, to the neares t mi l1imeter, on a speci a 1 lime as uri ng board"
(Figure 2-3). Details are given on Table III.
Colour of Tagged Eels
During tagging, the tag number, length of the fish and its
colouration were noted. The most imporatant colours of eels fell
into two catagories: a) half-grown, immature fish, predominantly
of yellow or green colouration; and b) adult, maturing fish, pre
dominantly of bronze colour. For further details see Table I.
- 77 -
Condition of Tagged Eels
While eels were being measured, observations on their state
of health was made. Only healthy, vigorous eels were used for tagging.
However, on some fish, particularly from the Big Tracadie River,
healed "la~rey marks", made by the sucking disc of the sea lamprey
(Petromyzon marinus), were present. But a much larger number of eels
carried healed spear marks. No doubt, these eels had escaped when
they were speared during the past winter. Goldman (1967:25) correctly
remarked, that: "these injured eels are practically worthless on
an export market featuring wholly smoked eels as the gash mars their
appearance."
- 78 -
LENGTH OF TAGGED EELS
Nearly 3,000 (2,893 to be exact) eels were tagged and liberated
by us in N~~ Brunswick waters during the fall fishing season of 1967 and
the spring season of 1968 (Table I). All eels, except those from the -Bocabec
River, were caught in hoopnets with stretched mesh of 1 inch. Bocabec
River fish, for demonstration purposes, were collected with an electric
shocker.
Practically all tagged eels came from rivers, emptying into
the Gulf of St. Lawrence. These rivers can be considered under two
different sections: the Miramichi Estuary (Figure 1, localities 2-4)
and individual rivers (Figure 1, localities 1, 5 and 6). Small samples
from the Shediac River and Bocabec River are excluded from detailed
discussion.
Miramichi Estuary
Two samples of eels from this general area were tagged in
October, 1967 and one sample from the Black River during May, 1968.
Miramichi River - A sample of 200 eels were tagged and liberated
in this river, in the vicinity of Newcastle (Figure 1). The average
length of these fish was 487.3 mm. These eels and those from the Black
River, taken in the spring of 1968, were somewhat larger than the eels
from the Baie du Vin River (Table III).
- 79 -
Baie du Vin River - A sample of 251 eels, tagged on October 2,
1967, represents on the average (451.6 mm) the smallest fish of all
the rivers of the Gulf of St. Lawrence.
Black River - During May 24-27, 1968, 1,315 eels were tagged
and released in this river. Their average size was 476.3 mm (Table II).
The average length of the three samples of tagged eels from the
Miramichi Estuary, was equal to 474 rrm(Table III). Grouping tagged
eels into 100 rrm length-classes reveals that in all three Miramichi
samples, irrespective of locality or season, the length-class 400-99
mm is the most important and represents 55.6% of the total number of
eels in the samples. The 500-99 mm class is next in importance, and
represents 25.3%. The 300-99 mm class is equal to 13.1%.
Individual Rivers
Eels from two different and widely separated rivers of the
Gulf of St. Lawrence were tagged during the spring of 1968.
Big Tracadie River - On May 28, 1968, 377 eels were tagged and
liberated in this river. Their average size was 561.5 mm (Table II).
St. Louis de Kent River - During the pertod of May 29-June 1,
1968, 736 eels were tagged from this river (Table III). The majority
of fiSh (64]) wi th an average length of 544.6 mm were 1 iberated in St.
Louis de Kent River, while a sample of smaller fish (477.4 mm) was
released in the Shediac River (Table 11). The a11-over average length
of St. Louis de Kent eels was equal to 536.5 mm (Table III).
- 80 -
By combining the samples from the above two rivers, their average
size is 544.6 mm. Among length-classes, the 500-99 mm was predominant,
being equal to 55.7%. The two neighbouring classes, 400-99 mm and 600-99 mm,
were nearly equally represented, being 18.1% and 19.~~, respectively. Two
eels frOm the ,St. Louis de Kent River, fell into the 800-99 mm class. Such
large eels were observed by us for the first time in New Brunswick waters
(V1adykov»: 1ge8~.
The length of eels from the Miramichi Estuary, taken in spring
and during the fall months does not differ greatly. All these fish,
as it was mentioned-already, are decidedly smaller than those from either
Big Tracadie River, or the St. Louis de Kent. It appears that variation
in length does not depend on the season, but rather on the type of
'rivers inhabited by the eels.
Table III, based on the study of 2,879 fish, presents clear
evidence that the average length of eels, commercially taken in New
Brunswick, is 20 inches (or 500 mm) and their weight is about 3/4 of
a pound. In other terms, eels from New Brunswick waters are much
smaller than eels taken in Quebec, where the average length is equal
to 3 1/2 feet (or ~OO mm) and their weight is 3 1/2 pounds, or 1.6 kg ',
(V1adykov, 1955).
- 81 -
COLOURATION OF TAGGEO EELS
Among fishermen from the Maritime Provinces, there exists an
opinion that several kinds of eels are found because some of the fish
are yellow, others are green, and some dark with a metallic shine. The
eel buyers, especially those from Europe, are looking for "silver-eels"
which are so important on the European market. Although the silver
eel phase in North American waters does not exist (Vladykov, 1955),
there is, however, the bronze eel phase, which is comparable to its
European counterpart by its rich content of fat. Both silver eels
of Europe and bronze eels of North America are equally suitable for
smoking purposes.
Because in Europe silver eels are taken principally during
the fall season, the European buyers are wary of buying American
eels taken during spring months. The object of the present report
is to find out if American eels (Anguilla rostrata) taken in New
Brunswick during fall months are different from those taken in spring.
Phases of Colouration
Among American eels, half-grown and adult specimens which
are fished commercially, there are found several colour phases.
-- 82 -
Yellow Eels or Green Eels - Immature eels, due to length differences
between sexes (males are always small, less than 2 feet in length), vary
considerably in size and are predominantly of yellow or green ~ints. The
younger fish acquire, first of all, a yellow colour, and later on become
green. In some specimens, a combination of both yellow and green are found.
Bronze Eels - In the process of maturation, the colouration of
an eel changes considerably: from yellow or green tint, they gradually
display bronze colouration. The American eel, in advanced stage of
maturity, displays a bronze shine over the sides and back. In addition,
along the lateral line, dark pigment develops, thus giving the appearance
of a black line. The pectoral and caudal fins become black also. The
diameter of the eye enlarges considerably. Furthermore, these bronze
eels stop feeding. Eels under such conditions are referred to in our
TablesIV-VIII under gro~p IIBII. Such eels are taken in New Brunswick
in rather small numbers during the fall or spring season and they
represent 0.7 to 6.2% of total catches.
Ee'ls, in early maturity, display a combination of yellow or
green and bronze tints. These eels feed voraciously, as we observed
during the spring and fall seasons in New Brunswick. Since bronze eels
are particularly valuable for smoking purposes, they command higher
prices. Unfortunately, there is no information about differences in the
fatness of flesh existing between bronze and bronze-green (or bronze-
yellow) eels. we are planning in the future to fill this gap in our
knOWledge.
- 83 -
Table IX, where eels of different degrees of "bronzenes~" are
combined under the title of "Bronze Eels", clearly shows that there is
no practical difference between eels taken during the spring or fall
seasons, in New Brunswick waters. The fish of the Baie du Vin River
represent an exception as only 10% of the eels there are bronze.
In general, in New Brunswick waters, bronze eels, irrespective
of the season, represent about 1/3 of the fish (29.5%) against 70.5%
of immature or yellow eels (Table IX). In our opinion, there shocld
be no discrimination among buyers.between spring and fall eels.
ACKNOWLEDGEMENTS
During the tagging operations, the author was helped by several
persons. During the 1967 season, Messrs. P. Burns and D. James were
involved, while during 1968, the tagging team consisted of Messrs. O.
Doiron and D. James. In addition, eel fishermen were most helpful in
bringing fish from nets or holding trunks to the tagging table and
carrying tagged eels back to the water. Several other fishermen, too
numerous to mention individually, were kind enough to give us permission
to use their electricity for our spot welder.
In the tedious work of arranging nearly 3,000 eels according
to their length-classes and colour-phases the author was helped by
his assistants, N. Khan, D. James and Miss. H. March. Typing was done
by Mr s • R. Se 1 wood.
Photographs of·eel tagging operations were expertly taken
by Mr. W. McMullon, of Fisheries Research Board Biological Station
at St. Andrews, New Brunswick~
- 84 -
REFERENCES
Goldman, J.W. 1967. (MS) Report on New Brunswick
experimental eel project. 27 pp.,5 tables, 8 figures.
Vladykov, V.D. 1955. Eel, fishes of Quebec. Album No.6:
1-12. Dept. of Fisheries, ~ebec
June 20, 1968
1956. Fish tags and tagging in Quebec waters
Trans. ~. Fish. ~., ~: 345-349
1968. (MS) Lengths of American eel (Anguilla rostrata)
in commercial catches of Eastern Canadian Province.
Prog. Rep. No.4, 12 pp., 10 tables, 1 figure, Ottawa.
Table I. Characteristic colouration of half-grown and adult American eels (Anguilla rostrata).
I.
II.
Half-grown, imnature fish:
Adult, maturing fi sh:
Symbol
Y
G
Y-G (G-Y)
B
B-G (B-Y)
G-B (Y-B)
Definition
predominantly yellow in colour over flanks and sides of the belly; this colour phase, irrespective of the size of fish, characterizes an immature eel; it gradually changes into green tint.
predominantly green or olive colour over flanks and sides of the belly; it succeeds the yellow phase.
combination of yellow and green tints.
Remarks: on Tables IV - VIII colour phases Y, G, Y-G (or G-Y) are included into Total Y & G.
Fishermen usually call both yellOW and green phases ye I 1 ow-ee 1 •
any American eel in advance stage of maturity, previous to undertaking seaward reproduction migration, acquires a metallic shine with bronze or purple reflections, which are particularly pronounced on back and sides.
00 V1
although the bronze colour is predominant, green and yellow tints are still clearly visable.
mixture of green and bronze or yellow and bronze, but the bronze colour is subordinate to either of the green or yellow.
Remarks: on Tables III - VIII colour phases B, B-G (or B-Y), and G-B (or V-B) are included into Total !.
Fishermen call "bronze eel" either black-eel, or (under influence of the European buyers) silver-eel.
"abl e II. Details of eel tagging in various New Brunswick rivers.
Date of Ori gin Release Fishermen Nunber Length of Fi sh (nm) ag Sedes Tagging of Fi sh locality of Fi sh Range Average
1967 Season
'. I. 200-399 October 1 Miramichi R. Miramichi R. M. Cormier 200 343-760 487.3 / .
I: 200-399 October 2 Baie du Vin R. Bafe du Vi n R. B. Jenki ns 200J 294-670 451.6 : 900-950 II II II II 51
1968 Season
) : 1-1319 May 24-27 Black R. Black R. F. MacRae 1315 301-794 476.3
():)
1320-1599 May 28 Big Tracadie R. Big Tracadie R. G. Savoie 280J 0\
I: 399-712 561.5 , : 3-99 II II .. II 97
1 (;O-74j' May 29 c~ 31 St. louis de Kent R. St. louis de Kent R. A. Richard 647 330-819 544.6
109-197 June 1 .. Shedfac R • II 89 301-8Lf4 477.4
,: 101-108 Ma Shed; ac R. St. loui s de Kent R. C. LeBlanc 8 401-581 497.5
19~.199 400-403 Jun~
, Bocabec R. St. Croix R. Estuary D. James 6 291-395 343.0 J
·' .
Table III. Length frequencies of eels tagged in various New Brunswick rivers, 1967-1968
Tagging Date of Locality Tagging
200-99 300-99 400-99 500-99 600-99 700-99 800-99 Total Range Average
N % N % N % N % N % N % N % N % (nm) (nm)
Hiramichi R. October 1, 1967 - - 21 10.5 104 52.0 63 31.5 6 3.0 6 3.0 - - 200 100.0 343-760 487.3
Bafe du Vin R. October 2, 1967 2 0.8 71 28.3 111 44.2 52 20.7 15 6.0 - - - - 251 100.0 294-670 451.6
Two Rivers October 1967 2 0.4 92 20.4 215 47.7 115 25.5 21 4.7 6 1.3 - - 451 100.0 294-760 467.4
Black R. Hay 24-27, 1968 - - 139 10.5 766 58.3 332 25.2 64 4.9 14 1. I - - 1315 100.0 301-794 476.3 - I
Hi rami chi Estuary 1967-1968 2 0.1 231 13. I 981 55.6 447 25.3 85 4.8 20 1.1 - - 1766 100.0 294-794 474.0 00 --.J
I
81 g Tracad1 e R. Hay 28, 1968 - - 7 1.9 40 10.7 241 63.9 82 21.7 7 1.8 - - 377 100.0 399-712 $61.5
St. Louis de .. Hay 29-June 1, Kent R. 1968 - - 43 5.8 161 21.9 379 51.5 133 18.2 18 2.4 2 0.2 736 100.0 301-844 536.5
Two Rivers Hay-June 1968 - - 50 4.5 201 18.1 620 55.7 215 19.3 25 2.2 2 0.2 1113 100.0 301-844 544.9
Grand Total 1967-1968 2 0.1 281 9.7 1182 41.0 1067 37. I 300 10.4 45 1.6 2 0.1 2879 100.0 . 294-844 501.4
Table I\f~ , · Number of eels fn various colour groups and length classes, based on taggfng, October 1, 1967, in the Hiramichi River, New Brunswfck.
Number and percentage of eels in various colour sroues
B 8-G G-B Total 8 Y G Y-G Total Y" G Grand Total
length-Class N % N % N % N % N % N % N % N % N % . (1\111)
300-99 - - 1 0.5 8 4.0 9 4.5 2 1.0 8 4.0 2 1.0 12 6.0 21 10.5
400-99 2 1.0 14 7.0 31 15.5 47 23.5 21 10.5 36 18.0 - - 57 28.5 104 52.0
500-99 3 1.5 6 3.0 18 9.0 27 13.5 15 7.5 20 10.0 1 0.5 36 18.0 63 31.5
600-99 - - 2 1.0 2 1.0 4 2.0 - - 2 1.0 - - 2 1.0 6 3.0 _.-
700-99 1 0.5 1 0.5 2 1.0 4 2.0 - - - - 2 1.0 2 1.0 6 3.0
Grand T.,~ al 6 3.0 24 12.0 61 30.5 91 45.5 38 19.0 66 33.0 5 2.5 109 54.5 200 100.0 --
00 00
Table v~;
Length-Class (mm)
200-99
300-99
400-99 -
500-99
600-99
Grand Total
~r of eels in various colour groups and length classes, based on tagging, October 2, 1967, in the Hiramichi Estuary (Baie du Vin River), New Brunswick.
Number and percentage of eels in various colour groups
B B-G G-B Total 8 Y G Y-G Total Y" G
N % N % N % N % N % N % N % N %
- - - - - - - - - - 2 0.8 - - 2 0.8
1 0.4 - - 1. 0.4 2 0.8 31 12.4 38 15.1 - - 69 27.5
- - - - 7 2.8 7 2.8 53 21.1 51 20.3 - - 104 41.4
2 0.8 2 0.8 10 4.0 14 5.6 17 6.8 21 8.4 - - 38 15.1 -
2 0.8 - - -. - 2 0.8 9 3.6 4 1.6 - - 13 5.2
5 2.0 2 0.8 18 7.2 25 10.0 110 43.9 116 46.2 - - 226 90.0
Grand Total
N %
2 0.8
71 28.3
111 44.2
52 20.7
15 6.0
251 100.0
Table VI. Number of eels in various colour groups and length classes, based on tagging, Kay 24-27, 1968, in the H;ram;chi Estuary (Bl ack Ri ver), New Brunswf ck.
Number and percentage of eels in various colour groups
B B-G G-B Total B Y G Y-G Total Y 6- G
Length-Cl ass N % N % N % N % N % N % N % N % (nm)
300-99 1 0.1 13 1.0 5 0.4 19 1.5 62 4.6 14 1.1 44 3.3 120 9.0
400-99 27 2.1 161 12.2 26 2.0 214 16.3 217 16.5 113 8.6 222 16.9 552 42.0
500-99 45 3.4 106 8.1 14 1.0 165 12.5 68 5.2 31 2.3 68 5.2 167 12.7
600-99 8 0.6 22 1.7 1 0.1 31 2.4 26 2.0 3 0.2 4 0.3 33 2.5
700-99 - - 2 0.2 - - 2 0.2 9 0.7 - - 3 0.2 12 0.9 -
Grarnl Total 81 6.2 304 23.2 46 3.5 431 32.9 382 29.0 161 12.2 341 25.9 884 67.1
Grand Total
N %
139 10.5
766 58.3
332 25.2
64 4.9
14 ' 1.1
1315 100.0
\0 o
Table VII. Number of eels in various colour groups and length classes, based on tagging, Hay 28, 1968, in the Estuary of the Big Tracadfe River, New Brunswick.
Number and percentage of eels in various colour groups
B B-G G-B Total B Y G Y-G Total Y" G
Length-Class N % N % N % N % N % N % N % N % (11111)
300-99 - - - - - - - - 7 1.9 - - - - 7 1.9
400-99 - - 3 0.8 4 1. 1 7 1.9 15 4.0 3 0.8 15 4.0 33 8.8
500-99 2 0.5 35 9.3 27 7.2 64 17.0 70 18.6 12 3.2 95 25.1 177 46.9 ---
600-99 2 0.5 10 2.7 11 2.9 23 6.1 13 3.4 4 1.1 42 11.1 59 15.6
700-99 - - - - - - - - 2 0.5 - - 5 1.3 7 1.8
Grand Total 4 1.0 48 12.8 42 11.2 94 25.0 107 28.4 19 5.1 157 41.5 283 75.0
Grand Total
N %
7 1.9
40 10.7
241 63.9
82 21.7
7 1.8
377 100.,0
Table VIII. Number of eels in various colour groups and length classes, based on tagging, Hay 29 & 31, and June 1, 1968, in the Kouchfbouguac Bay (St. Louis de Kent River), New Brunswick.
Number and percentage of eels in various colour groups
B B-G G-B Total B Y G Y-G Total Y " G
Length-Class N % N % N % N % N % N % N % N % (nrn)
300-99 - - - - 3 0.4 3 0.4 33 4.4 - - 7 1.0 40 5.4
400-99 - - 4 0.5 14 1.9 18 2.4 82 11.2 24 3.3 37 5.0 143 19.5
500-99 2 0.3 37 5.0 91 12.4 130 17.7 114 15.5 37 5.0 98 13.3 249 33.8
600-99 2 0.3 18 2.5 30 4.1 50 6.9 43 5.8 8 1 .1 32 4.4 83 11.3
-
700-99 1 0.1 4 0.6 1 0.1 6 0.8 8 1.1 - - 4 0.5 12 1.6
800-99 - - 1 0.1 - - 1 0.1 1 0.1 - - - - 1 0.1 ""
I Grand Totai I 5 0.7 64 8.7 139 18.9 208 28.3 281 38.1 69 9.4 178 24.2 528 71.7
Grand Total
N %
43 5.8
161 21.9
I
379 51.5 ~ I
133 18.2
18 2.4
2 0.2
736 100.0
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Table IX. Number of bronze and yellow eels in commercial catches of New Brunswick, 1967-1968.
Locali ty Date Bronze Eel s Yellow Eels Tota 1 Number N % N % of Fi sh
Miramichi R. October 1, 1967 91 45.5 109 54.5 200
Baie du Vin R. October 2, 1967 25 10.0 226 90.0 251
Two Rivers October, 1967 116 25.7 335 74.3 451
Black R. May 24-27, 1968 431 32.9 884 67.1 1315
Hiramichi Estuary 1967 &- 1968 547 31.0 1219 69.0 1766
Big TracadiE: n. May 28, 1968 94 25.0 283 75.0 377
St. Louis de Kent R. Hay 29-June 1, 208 28.3 528 71.7 736 1968
Two Rivers Hay 28-June 1, 302 27.1 811 72.9 1113 1968 -
Grand Total 849 29.5 2030 70.5 2879
- 94 --
BATHURST
N
s
Figure 1. Eel tagging localities in New Brunswick,. 1967-1968: 1- estuary of the Big Tracadie River; 2- Miramichi River, in the vicinity of Newcastle; 3- Black River in the Miramichi Estuary; 4- Baie du Vin River in the Miiamichi Estuary; 5- estuary of the St. Louh de Kent River of thE: Kouchibouguac Bay; 6- estuary of the Shediac River.
"
- 95 -
Figure 2. Tagging of eels along seashore of New Brunswick. Field equipment includes a portable IIUnitek" electrical spot welder for soldering stainless steel rings; a measuring board to determine the length of eels, and portable table used to keep tagging records. To protect the records from the rain a golf umbrella is used.
- 96 -
Figure 3. Details of measuring eels. On left, plstic dishes containing tags attached to rings and strung by hundreds on rubber tubing. The Unitek spot welder has the tweezer handpiece with electrodes connected to the welder by cables which permit free movement in soldering of rings on eels.
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-- 97 -
Figure 4. Stainless ring with tag on special pliers is passed around the lower jaw of the eel.
- 98 -
Figure 5. Soldering of ring on tagged eels with copper electrodes on the tweezer handpiece of Unitek spot welder.
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