A comparative approach to life-history strategies and tactics among four orders of teleost fish

Whereas a life-history strategy is defined as a complex pattern of co-evolved life-history traits designed for a particular environment, a tactic is the plasticity of these traits that allows populations to cope with environmental variability. Strategies and tactics are sought by comparing traits from a large number of populations of different species. An autoregressive method allows partitioning the variability of demographic traits into two parts: a phylogenetic part (broad strategies inherited from the past) and a population part (the remaining variability, including tactics). The following traits are analysed: adult size as a scaling parameter because life-history traits are known to change with body size; survival, which accounts for fishing and natural mortality; age and size at maturity, and total reproductive output for an individual life-time. Data have been assembled for 67 stocks of four orders: Clupeiformes, Gadiformes, Perciformes, and Pleuronectiformes. It is concluded that these four orders have different life-history strategies, and that tactics are different among strategies. At low abundance, the compensations allowed by these tactics are much less efficient in Clupeiformes than in the other orders considered. (C) 2000 international Council for the Exploration of the Sea.