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Biodiversity of Fishes Sharks & Rays
Rainer FroeseGEOMAR
Kiel19.12.2013
Phylogeny of fishes
Classes Common ancestor(million
y)
Orders(n)
Families(n)
Genera(n)
Species(n, %)
Myxini (hagfishes) 600 1 1 6 78 0.2
Cephalaspidomorphi (lampreys)[Petromyzontida]
450 1 3 10 46 0.1
Holocephali (chimaeras)[Chondrichthyes]
420 1 3 6 50 0.1
Elasmobranchii (sharks and rays)[Chondrichthyes]
420 12 51 188 1,152 3.5
Sarcopterygii (lobe-finned fishes)
420 3 4 4 8 0.04
Actinopterygii (ray-finned fishes)
400 46 480 4,817 31,220 95.9
Total 64 537 5,031 32,554 100
FishBase 11/2013http://www.fishbase.org/tools/Classification/ClassificationTree.php
Most Fishes are Small
0
500
1000
1500
0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5
Length (log; cm)
Fre
qu
en
cy
Frequency distribution of maximum lengths in 23,685 species of fishes. Median = 15.9 cm.
Most Sharks are Large
1
10
100
1000
10000
1 Myx 2 Cep 3 Hol 4 Ela 5 Sar 6 Act
Classes
Le
ng
th (
cm)
Myxini with median 49 cm; Cephalaspidomorphi with median = 22 cm;Holocephali with median = 99 cm; Elasmobranchii with median = 78 cm; Sarcopterygii with median = 125 cm; and Actinopterygii with median = 16 cm.
small
medium
large
very large
Most Fishes are Low-level Predators
0
200
400
600
800
1000
2.0 2.5 3.0 3.5 4.0 4.5 5.0
Trophic level
Fre
qu
en
cy
Frequency distribution of trophic levels for 7,500 species of fishes: median = 3.4
herb low-level predatoromnivore mid top predator
Most Sharks are Mid-level Predators
2.0
3.0
4.0
5.0
1 Myx 2 Cep 3 Hol 4 Ela 5 Sar 6 Act
Classes
Tro
ph
ic le
vel
Trophic level by Class for 7,500 species with available data: Myxini with median = 4.2; Cephalaspidomorphi with median = 4.2; Holocephali with median = 3.5; Elasmobranchii with median = 4.0; Sarcopterygii with
median = 3.4; and Actinopterygii with median = 3.4.
How to Estimate Productivity
Parameter High Medium Low Very low
rmax (1/year) > 0.5 0.16 – 0.50 0.05 – 0.15 < 0.05
td (years) <1.4 1.4 - 4.4 4.5 - 14 > 14
Interest rate (%) > 65 17 – 65 5 - 16 < 5
K (1/year) > 0.5 0.2 – 0.5 0.1 – 0.2 < 0.1
Fecundity (1/year) > 10,000 100 – 1000 10 – 100 < 10
tm (years) < 1 2 – 4 5 – 10 > 10
tmax (years) 1 – 3 4 – 10 11 – 30 > 30Modified after Musick (1999)
Most Fishes have High Productivity
0
10
20
30
40
50
60
70
%
High Medium Low Very low
Productivity
Observed (n = 2,621) and modeled (n = 24,649) productivities of fishes.
Source: FishBase 11/2004; Froese 2005
Occupation of Size-Troph Space
Small Medium LargeVerylarge
Herb
OmniLow
MidTop
0
2000
4000
6000
8000
10000
12000
Source: FishBase 11/2004; Froese 2005
Occupation of Size-Productivity Space
Small MediumLarge
Verylarge
Very low
Low
MediumHigh
0
2000
4000
6000
8000
10000
Source: FishBase 11/2004; Froese 2005
Occupation of Troph–Productivity Space
HerbOmni
LowMid
Top
Very low
Low
MediumHigh
0
2000
4000
6000
8000
10000
Source: FishBase 11/2004; Froese 2005
Occupation of size–productivity–
troph-space for 20,480 species
of fishes.
Full cell width is 1000 species.
Small Medium Large Very largeSize
Very low
Low
Medium
High
ytivitcu
dor
P
2710 6785
2756
1211
17
59
3157
65
541
4192
9131
473
1245
1367
168
38
23
4
Source: FishBase 11/2004
Small Medium Large Very largeSize
Very low
Low
Medium
High
ytivitcu
dor
P
8
109
144
315
29
15
Occupation of size–productivity–
troph-space for 620 species of sharks and rays.
Full cell width is 1000 species.
Source: FishBase 11/2004
Small Medium Large Very largeSize
Very low
Low
Medium
High
ytivitcu
dor
P
8
109
144
315
29
15
Occupation of size–productivity–
troph-space for 620 species of sharks and rays.
Full cell width is 145 species.
Source: FishBase 11/2004
Competition among Low-level Predators
Length group
Product. Myx Ceph Holo Elasmo Sarco Actino
Medium Medium 4 2,752
Low 7 2 74 260
Very low 3 1 51
Large Medium 645
Low 20 18 145 429
Very low 40 7 167
Very large
Very low 5 5
Competition betweenMid-level Predators
Length group
Product. Myx Ceph Holo Elasmo Sarco Actino
Medium Medium 14 418
Low 17 2 28 33
Very low 5 5
Large Medium 368
Low 6 123 181
Very low 59 1 61
Very large Low 6 1
Very low 7 2
Competition among Top-Predators
Length group
Productivity Myx Ceph Holo Elasmo Sarco Actino
Medium Medium 98
Low 4 7 7 9
Large Medium 188
Low 18 4 47 120
Very low 45 2 44
Very large Medium 4
Low 9 7
Very low 17 2
Salinity Tolerance
0
200
400
600
800
1000
Myx Cepha Holo Elasmo Sarco Actino
Fresh Diadromous Marine
12,889 14,091
Climate Zones
0
200
400
600
800
1000
Myx Cepha Holo Elasmo Sarco Actino
polar temperate subtropical tropical
3,194 4,023 16,840
Global Species Richness of Actinopterygii
Source: www.aquamaps.org Nov. 2013
Global Species Richnessof Elasmobranchii
Source: www.aquamaps.org Nov. 2013
Relative Brain Size
0
50
100
150
200
250
300
Myx Cepha Elasmo Sarco Actino
large normal small very small
519
Reproductive Guild
0
500
1000
1500
2000
2500
3000
Cepha Holo Elasmo Sarco Actino
Bearers Guarders Nonguarders
No Sharks in the AbyssPriede, Froese, et al. 2006
Colonization of Deep SeaPriede & Froese 2013
Summary• Elasmobranchs are the second largest Class of recent
fishes• They use only 16 life-history strategies compared with 49
used by ray-finned fishes• They are mostly large, marine, demersal, migratory,
large-brained, long-living mid-level predators of low productivity
• Their niches are dominated by ray-finned fishes with typically higher productivity
• They survived because of superb hunting capabilities (electro-sensing, large brains) and low mortality
• Their large size and low productivity makes them highly vulnerable to exploitation
Exercises
• Explore one of these three species in FishBase:– Negaprion brevirostris Lemon shark– Rhincodon typus Whale shark– Heterodontus portusjacksoni Port Jackson
shark
• Discuss size, tropic level, productivity, reproduction and distribution