Biodiversity of Fishes Summary Rainer Froese (05.02.15)

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 http://www.fishbase.org/tools/Classification/ClassificationTree.php FishBase 11/2014

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

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

Six Zoogeographic Realms Alfred Russell Wallace, 1876. The Geographical Distribution of Animals

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

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 = 0.296 Winf, max age tmax at 0.95 Linf = 4.5/M are constant

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

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), 0.001 (eel-like)

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

Growth in Weight

Whale shark vs Fin whale

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

M = 0.2

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

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

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

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

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.)

Population Growth BioDivPopGrowthMSY.xls

Logistic Curve Properties BioDivPopGrowthMSY.xls

The Schaefer Production Model BioDivPopGrowthMSY.xls

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

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

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

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

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

The Piscatorial Atlas 1883

Questions?