Graham C. Mair Sukonta Lakapunrat Wilson L. Jere Amrit Bart Comparisons of Reproductive Comparisons of Reproductive Parameters Among Improved Strains Parameters Among Improved Strains of Nile Tilapia of Nile Tilapia Oreochromis niloticus Oreochromis niloticus L. L. Aquaculture & Aquatic Resources Aquaculture & Aquatic Resources Mngt Mngt . . The Asian Institute of Technology, The Asian Institute of Technology, Bangkok, Thailand Bangkok, Thailand
Transcript
Graham C. MairSukonta Lakapunrat
Wilson L. JereAmrit Bart
Comparisons of Reproductive Comparisons of Reproductive Parameters Among Improved Strains Parameters Among Improved Strains
of Nile Tilapiaof Nile Tilapia Oreochromis niloticus Oreochromis niloticus L.L.
Aquaculture & Aquatic Resources Aquaculture & Aquatic Resources MngtMngt..The Asian Institute of Technology, The Asian Institute of Technology,
Bangkok, ThailandBangkok, Thailand
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ContextContext• A number of improved lines of tilapia have been
developed through selective breeding• Mainly focusing on growth in extensive and semi-
intensive systems• Correlated response to selection in reproductive
traits might be expected in selection for growth– Time of maturation– Fecundity– Spawning frequency
• No studies on comparative reproductive traits of improved tilapia stocks
• No long term studies on breeding patterns in tilapia
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Overall ObjectiveOverall Objective
To compare the initial growth, maturation and reproductive
performance of three selectively improved Nile tilapia strains (GIFT,
Fishgen-selected & Philippine -Selected) and one locally adapted
strain (Chitralada) in low input pond systems
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Specific objectivesSpecific objectives1. To compare the growth rates of strains
during grow out in fertilized pond systems (separate and communal stocking)
2. To evaluate traits of sexual maturation during initial grow-out
3. To evaluate initial reproductive parameters of broodstock following maturation
4. To carry out long term evaluation of comparative reproductive performance of the four strains
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The StrainsThe Strains• Chitralada
– Introduced to Thailand from Japan in 1965– Until recently was almost ubiquitous in Thai aquaculture.
Considered good performer– AIT maintained strain in isolation for 18 years (~10
generations). Good Ne but no selection
• GIFT (Genetically Improved Farmed Tilapia)– G7 from combined selection programme for growth (12-15%
genetic gain per generation, cumulative gains of 85%) on a genetically variable base population derived from 8 accessions
– Partially replaced Chitralada in Thai Aquaculture– Obtained from Philippines and distributed by Thai NAGRI– Anecdotal evidence for late maturation
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The StrainsThe Strains• Fishgen-selected
– Developed by Fishgen Ltd. (Philippines) as female line for crossing with YY males to produce GMT®
– Three generations of within family selection for growth with genetic gains estimated at 18 – 50%
– Not used in commercial production as stand alone strain– Broodstock obtained from Philippines via AIT
• Philippine - selected– Developed by FAC (Philippines) known as IDRC or FAST– Basic within family selection for growth (rotational mating)– 12th generation broodstock obtained from the Philippines– Genetic gains of 3.6% per generation (cumulative gain ≈ 45%)– Some commercial production in the Philippines
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Summary of growth rate evaluationsSummary of growth rate evaluations• Under replicated stocking (strains separate) in half ponds, no
significant differences in sex ratio, survival or growth were observed
• The empirical ranking of weight gain among the strains was:
F-S > P-S > GIFT = Chit • Under communal stocking of marked fish there were no
differences in survival or sex ratio but growth was ranked as follows:
• F-Sa > GIFTa,b > P-Sb,c> Chitc
• No significant differencesin GSI between strains
0102030405060708090
Chit-ralada
Phil-Select
GIFT Fishgen-Select
Wei
ght g
ain
(g)
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Staging of sexual maturation at Staging of sexual maturation at harvest in malesharvest in males
Maturity Stage (score) Appearance of testis
1. Immature Thread-like, colorless
2. Inactive Translucent, wider than above
3. Inactive Flesh color, still thin
4. Inactive - active White/yellowish, thickened, no milt
apparent when cut
5. Active - ripe Cream colored, thick and enlarged
6. Ripe Distended fully over length of visceral
cavity, milt evident if testis cut
7. Ripe - running White/silvery, milt runs freely under
pressure
From HFrom Höörstgenrstgen--Schwark and LanghSchwark and Langhöölz (1998)lz (1998)
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Sexual maturation staging Sexual maturation staging -- malesmales
0
20
40
60
80
100
120
Chitralada Fishgen-selected
GIFT IDRC
Strains
% o
f fis
h sa
mpl
ed in
eac
h st
rain
Stage 6
Stage 5
Stage 4
Stage 3
Stage 2
Stage 1
0
20
40
60
80
100
120
Chitralada Fishgen-selected
GIFT IDRC
Strains%
of s
ampl
ed fi
sh
Stage 6
Stage 5
Stage 4
Stage 3
Stage 2
Stage 1
Separate (119 days)Separate (119 days) Communal (127 days)Communal (127 days)
Phil-selected
Phil-selected
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Staging of sexual maturation at Staging of sexual maturation at harvest in femalesharvest in females
Maturity Stage (score) Appearance of ovaries
1. Immature/inactive No egg visible
2. Inactive-active < 20 eggs visible, size < 0.2 mm
3. Active > 20 eggs visible, size < 0.2 mm
4. Active - ripe Eggs yellow, size 0.2 – 1.1 mm
5. Ripe-ripe running Eggs yellow, size > 1.1 mm
6. Spent Absorption of yolk material, egg white
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Sexual maturation staging Sexual maturation staging -- femalesfemales
0
20
40
60
80
100
120
Chitralada Fishgen-selected
GIFT IDRC
Stra ins
% o
f fis
h sa
mpl
ed in
eac
h st
rain
Stage 6
Stage 5
Stage 4
Stage 3
Stage 2
Stage 1
0
20
40
60
80
100
120
Chitralada Fis hgen-s elected
GIFT IDRC
Strains
% o
f sam
pled
fish
in e
ach
stra
in
Stage 6
Stage 5
Stage 4
Stage 3
Stage 2
Stage 1
GIFT later maturing?GIFT later maturing?
Separate (119 days)Separate (119 days) Communal (127 days)Communal (127 days)
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Comparative assessment of Comparative assessment of reproductive capacityreproductive capacity
• Fish from grow out phase were stocked in hapas for breeding @ 180 days old
• Four 5 m² hapas per strain• 15 females and 5 males per hapa• Eggs/ collected every 7 days• Spawned females weighed, PIT tagged and returned• Eggs weighed, counted and staged• Data collection continued long term (70 weeks)
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Summary egg/fry production Summary egg/fry production –– 13 months13 monthsSome problems with counting fish!Some problems with counting fish!
0
2000
4000
6000
8000
10000
12000
14000
S S O O N N D D J J F F M M A A M M J J J J A A S S O O N N D D J J Fweeks
Tota
l No.
of e
ggs
colle
cted
per
str
ain
ChitraladaFishgen SelectedGIFTPhil. Selected
Replacement fish
Spawning cycles of individual fish varied widelySpawning cycles of individual fish varied widely
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Comparisons of overall egg/fry Comparisons of overall egg/fry production production (when no. of females stocked known)(when no. of females stocked known)
050
100150200250300350400450500
Sept 02 May 03 Sept '03
period
Mea
n N
o. o
f egg
s pe
r fem
ale
stoc
ked
Chitralada Fishgen Selected
GIFT Phil. Selected
nsdb
a
b
a,b
a
a,b
a,bb
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Spawning frequency for strainsSpawning frequency for strains
0
2
4
6
8
10
12
Chitralada FishgenSelected
GIFT Phil Selected
Spaw
ning
freq
uenc
y (m
ean
no. o
f spa
wni
ngs
pa)
n=77n=77 n=61n=61 n=65n=65 n=73n=73
No significant differencesNo significant differences
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Comparative fecundity Comparative fecundity (eggs per unit weight female per spawning)(eggs per unit weight female per spawning)
0.001.00
2.003.004.00
5.006.007.00
8.009.00
Chitralada Fishgen Selected GIFT Phil. Selected
Fecu
ndity
(No.
of e
ggs/
g of
fem
ale)
a ab b
n=386n=386 n=287n=287 n=347n=347 n=268n=268
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Comparative fecundityComparative fecundity(eggs per female per spawning)(eggs per female per spawning)
Chitralada Fishgen Selected GIFT Phil. SelectedFecu
ndity
(egg
s pe
r fem
ale
per s
paw
ning
)
a ab b
n=386n=386 n=287n=287 n=347n=347 n=268n=268
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0 1 2 3 4 5
Female age (years)
Fecu
ndity
Upon attainingsexual maturityfemales rapidlyreach peak fecundity Females remain at peak
total fecundity levels for a period of 1-2 years. As they age and grow egg numbers per batch increase whilst spawning frequency begins to decrease
Eggs per batch may continue to increase but spawning frequency declines. Total fecundity falls to levels where it is longer cost effective to maintain the larger, older broodstock
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Age (days)
700600500400300200100
Fecu
ndity
(egg
s pe
r fem
ale
per s
paw
ning
)
3000
2000
1000
0
-1000
Age (days)
700600500400300200100
Fecu
ndity
per
g w
eigh
t of f
emal
e
30
20
10
0
-10
Fecundity (per female) x ageFecundity (per female) x age
Fecundity (per g female) x ageFecundity (per g female) x age
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Spawning frequency of individualsSpawning frequency of individuals
• High variability between individuals• Many different spawning patterns• No indication that spawning frequency
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Spawning frequency over timeSpawning frequency over timeChitralada
y = 0.0194x + 0.9183R2 = 0.042
0
0.5
1
1.5
2
1 2 3 4 5 6 7
Fishgen-selected
y = 0.1347x + 0.5811R2 = 0.4195
0
0.5
1
1.5
2
1 2 3 4 5 6 7
GIFT
y = 0.1559x + 0.4512R2 = 0.5665
0
0.5
1
1.5
2
1 2 3 4 5 6 7
Phil-selected
y = 0.0896x + 0.5221R2 = 0.3667
0
0.5
1
1.5
2
1 2 3 4 5 6 7
No.
of
spaw
ning
s pe
r 10
wee
ks p
erio
d
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InterInter--spawn interval vs. agespawn interval vs. age
y = 0.0019x + 5.6139R2 = 0.0024
0
5
10
15
20
25
180 280 380 480 580 680
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Relationship between growth of females and Relationship between growth of females and spawning frequencyspawning frequency
y = 0.0414x + 3.1382R2 = 0.2383
0
5
10
15
20
25
-50 0 50 100 150 200 250
Weight gain
Spaw
ning
freq
uenc
y
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Relationship between egg production Relationship between egg production and growth of femalesand growth of females
y = 1011.2x + 3129.5R2 = 0.0035
02000400060008000
100001200014000160001800020000
-0.2 0 0.2 0.4 0.6 0.8 1
growth rate (g.day-1)
Egg
prod
uctio
n pe
r fem
ale
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0 1 2 3 4 5
Female age (years)
Fecu
ndity
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Hatching and fry survivalHatching and fry survival
• Compared for different stages of eggs– Downwelling incubators for eggs– Hatching trays for hatchlings
• Huge variability between replicates• No significant difference detecting between
strains over 2 month period
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SummarySummary• Indications that both males and females are late maturing in
GIFT based on gonad development• GIFT has lower relative fecundity than other strains • Fecundity (per female) increases with age but relative fecundity
remains constant• No clear trend of changing spawning frequency or ISI over time• Huge variability in fecundity and ISI within and between
females• No evidence for negative correlation of reproductive capacity
and growth• Production has not peaked by 680 days
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ConclusionsConclusions• Environment plays a major role in determining seed
production• Anecdotal evidence of late maturation and lower
fecundity of GIFT in commercial hatcheries partly supported
• Two years would appear to be a minimum useful lifespan for broodstock in this type of system
• Expected inverse relationship between growth and fecundity not seen indicating that correlated response may not be major factor
• Means of selecting regularly spawning individuals could dramatically improved efficiency of seed production
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Conflicts between the needs Conflicts between the needs of the hatchery manager of the hatchery manager and the grower may not and the grower may not
represent a major represent a major constraint to breeding constraint to breeding
programmesprogrammes
Partial funding for this research was provided by thePartial funding for this research was provided by the
Aquaculture Aquaculture Collaborative Research Support Collaborative Research Support
ProgramProgram
The Aquaculture CRSP is funded in part by United States Agency for International
Development (USAID) Grant No. LAG-G-00-96-90015-00 and by participating institutions.
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Growth rate evaluationsGrowth rate evaluations• Fry with max age difference of 14 days• Nursed in hapas then tanks at standard densities• Stocked at 5-6g at 3 per m²• Separate stocking
– 3 replicate half ponds (100m²) per strain (6 ponds) – Grown for 91 days with sampling (wt, SL & sex) every 21 days– 30 fish (10%) sampled; 20 fish removed for determination of SM
• Communal stocking– Fish marked with combination of fin clip and CWT– Stocked communally in a single 200 m² pond (with excess)– Grown for 85 days with sampling at 21 days– 25 fish per strain sampled, 20 fish removed for determination of
SM
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Experimental layout & dataExperimental layout & data• Individual wt & SL of 30 fish
per strain plus bulk wt of sample
• 20 fish sacrificed– Stage of maturation– Hepatosomatic index (HSI)– Gonadosomatic index (GSI)
• Data management (growth)– Corrections for sample bias– Corrections for pond effects– Transformed if necessary
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Results Results –– Growth in separate stockingGrowth in separate stocking
• Differences in growth parameters not significant among 4 genotypes
• Before correction:FS=GIFT>FAST>>Chit
• After correctionFS>FAST>GIFT=Chit
• No significant differences in sex ratio or survival
0
10
20
30
40
50
60
70
0 17 36 63 91Days after stocking
Mea
n w
eigh
t (g)
Chitralada
Fishgen-selected
GIFT
IDRC
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Results Results –– Growth in communal stockingGrowth in communal stocking
• Significant differences in growth parameters in both raw and corrected weight data
• FS > GIFT > FAST > Chit• FS > FAST & Chit (P>0.05)• GIFT > Chit (P>0.05)• No significant
differences in sex ratio0
102030405060708090
0 19 46 85
Days after stocking
Mea
n w
eigh
t (g)
Chitralada
Fishgen-selected
GIFT
IDRC
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Initial spawning activity (from 180 days old)Initial spawning activity (from 180 days old)
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