Presentation on theme: "Biodiversity of Fishes Understanding Longevity Rainer Froese 09.01.2014."— Presentation transcript:
Biodiversity of Fishes Understanding Longevity Rainer Froese 09.01.2014
Longevity in Fish Maximum age on record for a species Maximum time available for growth and reproduction Used as –proxy for natural mortality M ~ 4.5/t max –1 of 5 criteria to estimate resilience
Taylor (1958) Longevity as age at 95% of L ∞ Longevity (years) = 3 / K where t is age, L ∞ is the asymptotic body length, K indicates how fast L ∞ is approached, and t 0 is the hypothetical age at zero length. Taylor, C.C., 1958, Cod growth and temperature., J. Cons. Int. Explor. Mer. 23:366-370.
Facts Relative size at maturity (L m / L max ) –Fish 0.44 (n=530, 95% LCL =0.421, UCL=0.451) –Marine mammals 0.76 (n=9, LCL=0.716, UCL=0.803) –Birds 1.0 Relative age at maturity (t m / t max ) –Fish 0.24 (n=229, LCL=0.224, UCL=0.253) –Marine mammals 0.13 ( LCL= 0.0913, UCL = 0.198) –Birds 0.05 (LCL=0.0364, UCL=0.0695)
Whale shark vs Fin whale The largest fish, the Whale shark (Rhincodon typus) needs about 9 years to reach maturity at about 5.5 m and 750 kg, and about 60 years to reach a maximum length of 14 m and 12 tons. The fin whale (Balaenoptera physalus) needs about 7 years to reach maturity at a size of about 20 m and about 36 tons, with a maximum size of about 25 m and 70 tons.
White shark vs Killer whale Great white shark females take about 12 years to reach maturity at 4.5-5 m and about 0.8 tons; they need 36 years to reach a maximum size of 7.2 m and 3.4 tons; Killer whales (Orcinus orca) reach maturity in 6-10 years at 5-6 m length and about 1.8 tons, with the typical size of about 7 m and 3.8 tons reached a few years later.
Conclusion Because of physics (e.g. gravity), organisms have a ‘bauplan’ optimized for a certain adult size; they maximize their fitness if they reach that size as fast as possible Fish growth is limited by the oxygen-temperature window, and thus they need all their life to reach maximum size Birds and mammals do not have this limitation (air breathers with constant body temperature) and reach maximum size early in life Gills suck, but they last: bowhead whales reach 130 years, cockatoos 60 years, humans 121 years, turtoise 180 years, fish (kois) > 200 years
Exercises Select one of these species: –Orange roughy (Hoplostethus atlanticus) –Beluga (Huso huso) –Anchoveta (Engraulis ringens) –Transparent goby (Aphia minuta) Discuss age (t max, t m ), habitat, food, growth, reproduction, suitability to fishing Use the graphs in FishBase to make your point