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