|Death from near and far: alternate perspectives on size-dependent mortality in larval fish|Pepin, P. (2016). Death from near and far: alternate perspectives on size-dependent mortality in larval fish. ICES J. Mar. Sci./J. Cons. int. Explor. Mer 73(2): 196-203. hdl.handle.net/10.1093/icesjms/fsv160
In: ICES Journal of Marine Science. Academic Press: London. ISSN 1054-3139, more
Fish larvae; Mortality; Predation; Marine
Ecosystem structure; Prey–predator interactions; Size dependent; Trophodynamics
This essay contrasts the inferences about the patterns of size-dependent mortality in larval fish based on the traditional catch-curve approach with that achieved through the vertical life table method in an application to data from coastal Newfoundland. Although both approaches reveal that the average mortality rates decline with increasing body size, the rate of decline estimated using the vertical life table approach is much less pronounced than estimated from the catch-curve method. More important, however, is that on a case-by-case assessment the vertical life table reveals that mortality increases with increasing body size in 70% of the cases and declines in the remainder. Instances with greater rates of loss in larger individuals are consistent with larvae becoming more susceptible to the dominant planktivore in the study region. The contrasting results indicate that the patterns of change in mortality rates need to be measured over relatively short-time and/or length intervals. Such inferences have important implications for the development of studies dealing with larval fish dynamics. To be effective and applicable, comparative analyses that aim to develop macroscopic principles for the early life stages of fish must take the local food web structure into consideration to gain appropriate understanding of the trophic interactions that most strongly affect losses from larval fish populations.