1. Biodiversity of Fishes Summary
Rainer Froese
( )

2. Phylogeny of fishes
Classes
Common
ancestor
(million y)
Orders
(n)
Families
Genera
Species
(n, %)
Myxini (hagfishes)
600 1 6 78
0.2
Cephalaspidomorphi (lampreys)
[Petromyzontida]
450 3 10 47
0.1
Holocephali (chimaeras)
[Chondrichthyes]
420 50
Elasmobranchii (sharks and rays) 12 51
188
1,158
3.5
Sarcopterygii
(lobe-finned fishes) 4 8
0.04
Actinopterygii
(ray-finned fishes)
400 46
487
4,833
31,608
95.9
Total 64
549
5,047
32,949
100
FishBase 11/2014

4. Fish Diversity of the Oceans
Arctic 130
Atlantic
4,900
Pacific
10,500
Pacific
10,500
Indian
6,000
Antarctic 370
Total: ~16,000 marine or diadromous fishes, several thousand in more than one Ocean

5. Diversity in Large Marine Ecosystems
Greenland
190
North Sea
190
Alaska
320
Mediterranean
700
East-China
1,040
California
800
Caribbean
1,600
Canary
1,300
Red Sea
1,200
Hawaiian
840
Bay of Bengal
700
Indonesian
2,400
South Brazil
970
Agulhas
1,400
Polynesian
810
Humboldt
750
Benguela
820
West
470
Australian
East
1240
Patagonian
340
Weddell Sea 25

6. Six Zoogeographic Realms
Alfred Russell Wallace, The Geographical Distribution of Animals

7. Permian, 225 m
Triassic, 200 m
Jurassic, 135 m
Cretaceous, 65 m

8. Size Matters Largest fish: Whale shark, 18 m, 34 t
Smallest fish: attached male anglerfish, several tiny cyprinids & gobies, 1 cm, 0.01g
Max growth rate, fecundity, speed, trophic level, life span increase with size
Metabolic rate, relative brain size, relative gill area and K, rmax and M decrease with size
topt = 1.65/M, max growth = Winf, max age tmax at 0.95 Linf = 4.5/M are constant

9. Size Distribution
Frequency distribution of maximum lengths in 23,685 species of fishes, Median = 15.9 cm

10. Relationship Between Weight and Length
W = a * Lb
with weight in grams and length in cm
For parameter estimation use linear regression of data transformed to base 10 logarithms
log W = log a + b * log L
Typical value for b ~ 3 -> isometric growth
For a = 0.01 (fusiform), 0.1 (roundish), (eel-like)

11. Von Bertalanffy Growth Function
Lt = Linf (1 – exp(-K * (t – t0)))
Where
Lt = length (cm) at age t (years)
Linf = asymptotic length if t = infinite
K = parameter indicating how fast Linf is approached (1/year)
t0 = hypothetical age at L = 0 (years)
Wt = Winf (1 – exp(-K * (t – t0)))b
b = 3 or exponent of length-weight relationship

12. Growth in Weight

13. Whale shark vs Fin whale

14. The M Equation Nt = N0 e –M t Where
M is the instantaneous rate of natural mortality
N0 is the number of specimens at a t = 0
Nt is the number of specimens at time t

15. M = 0.2

16. Average Adult Life Expectancy
where Ex is the average life expectancy after reaching age x and l are
the probabilities of reaching x and subsequent ages. If mortality M is constant,
then the equation simplifies to

17. Reproductive Strategies
Froese & Pauly 2013, Fish Stocks, Encyclopedia of Biodiversity, Academic Press

18. Length at Maturity for Different Reproductive Strategies
Froese & Pauly 2013, Fish Stocks, Encyclopedia of Biodiversity, Academic Press

19. Stock-Recruitment Relationships
Recruits
(N)
Spawning stock biomass
(tonnes)

20. Use of Hockey-Stick in Management
Conceptual drawing of the hockey stick relationship between spawning stock size and recruitment.
SSBlim marks the border below which recruitment declines, SSBpa marks a precautionary distance to
SSBlim, and 2 * SSBpa can be used as a proxy for SSBmsy, the stock size that can produce the maximum
sustainable catch [ContHS.xlsx]. (Froese et al. in prep.)

21. Population Growth
BioDivPopGrowthMSY.xls

22. Logistic Curve Properties
BioDivPopGrowthMSY.xls

23. The Schaefer Production Model
BioDivPopGrowthMSY.xls

24. Surplus Production Implications
Surplus production (Y) is the production of biomass beyond what is needed to maintain current population size
If a fishery only catches the surplus production, then the population size remains
If a fishery catches more, then the population shrinks
If it catches less, then the population grows

25. Fisheries Management Basics
MSY
MEY
Cost of fishing €
Growth
overfishing €
Economic
overfishing
Fpa
Recruitment
overfishing
Flim ? †

26. EU Fisheries Management
MSY
MEY
Cost of fishing € €
Subsidies
Flim ? †

27. The Mechanics of Sex under Water
Eggs have to be fertilized (or activated) by the right sperms
Eggs are few and large (>1mm - 10 cm) or numerous and small (< 1 mm), internal, attached or drifting
Sperms are very small, very numerous, mobile, outside
Survival of gametes in water is short (few minutes)
Courtship and mating aims to increase fertilization rate

28. Three trawling
revolutions
1376 – the beam trawl is invented
1880s – trawlers gain steam power
Late 20th century – the deep sea comes within reach of the trawl

29. The Piscatorial Atlas
1883

30. Questions?