1. Life-history Strategies of Elasmobranchii Rainer Froese IFM-GEOMAR Kiel

2. There are Six Classes of Fishes ClassesCommon ancestor (million y) Orders (n) Families (n) Genera (n) Species (n, %) Myxini (hagfishes) 600116710.2 Cephalaspidomorphi (lampreys) 450119420.1 Holocephali (chimaeras) 420136380.1 Elasmobranchii (sharks and rays) 42011451759753.4 Sarcopterygii (lobe-finned fishes) 420344110.04 Actinopterygii (ray-finned fishes) 400454704,64028,36396.1 Total 625244,84029,500100 Source: FishBase 09/2006

3. Most Fishes are Small Frequency distribution of maximum lengths in 23,685 species of fishes. Median = 15.9 cm.

4. Most Sharks are Large 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

5. Most Fishes are Low-level Predators Frequency distribution of trophic levels for 7,500 species of fishes: median = 3.4 herblow-level predatoromnivoremidtop predator

6. Most Sharks are Mid-level Predators 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.

7. How to Estimate Productivity ParameterHighMediumLowVery low r max (1/year)> 0.50.16 – 0.500.05 – 0.15< 0.05 t d (years)<1.41.4 - 4.44.5 - 14> 14 Interest rate (%)> 6517 – 655 - 16< 5 K (1/year)> 0.50.2 – 0.50.1 – 0.2< 0.1 Fecundity (1/year)> 10,000100 – 100010 – 100< 10 t m (years)< 12 – 45 – 10> 10 t max (years)1 – 34 – 1011 – 30> 30 Modified after Musick (1999 )

8. Most Fishes have High Productivity Observed (n = 2,621) and modeled (n = 24,649) productivities of fishes. Source: FishBase 11/2004; Froese 2005

9. Sharks have Low or Very Low Productivity Class / ProductivityHighMediumLowVery lown r’ max Myxini66 0.10 Cephalaspidomorphi710170.15 Holocephali37 0.10 Elasmobranchii5802127920.08 Sarcopterygii10 0.025 Actinopterygii4101059474672,0100.30

10. Occupation of Size-Troph Space

11. Occupation of Size-Productivity Space

12. Occupation of size–productivity– troph-space for 20,480 species of fishes. Full cell width is 1000 species.

13. Occupation of size–productivity– troph-space for 620 species of sharks and rays. Full cell width is 1000 species.

14. Occupation of size–productivity– troph-space for 620 species of sharks and rays. Full cell width is 145 species.

15. Competition among Low-level Predators Length group Product.MyxCephHoloElasmoSarcoActino Medium 42,752 Low7274260 Very low3151 LargeMedium645 Low2018145429 Very low407167 Very large Very low55

16. Competition between Mid-level Predators Length group Product.MyxCephHoloElasmoSarcoActino Medium 14418 Low1722833 Very low55 LargeMedium368 Low6123181 Very low59161 Very largeLow61 Very low72

17. Competition among Top-Predators Length group ProductivityMyxCephHoloElasm o SarcoActino Medium 98 Low4779 LargeMedium188 Low18447120 Very low45244 Very largeMedium4 Low97 Very low172

18. Strategies vs Species Numbers Number of strategies used by phylogenetic Classes plotted over number of recent species in the Class, with linear regression line forced through the origin; slope = 0.37

19. Salinity Tolerance 12,889 14,091

20. Climate Zones 3,194 4,023 16,840

21. Oceans 4,448 5,592 9,839

22. Habitat 4,137 9,953 8,732

23. Relative Brain Size 519

24. Reproductive Guild

25. Migratory Behaviour 1,872

26. 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 low productivity makes them vulnerable to exploitation and to competition from ray-finned fishes with typically higher productivity

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