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.