The threat of fishing to highly fecund fishes

The last decade has witnessed a growing awareness that fishes can not only be severely overfished but could also be threatened with extinction through over-exploitation. Among commercially important species, those particularly at risk are large and slow to mature, iteroparous and may have sporadic recruitment. The threat of extirpation or extinction may be greater if species are particularly valuable, have a limited geographical range, are part of mixed-species fisheries, or are distributed solely within areas of intense fishing activity. Significantly, there is little empirical or theoretical basis for hypothesizing that highly fecund species are any less at risk than those of low fecundity, as is often assumed. Indeed, the use of fecundity in estimating reproductive output in long-lived, highly fecund, pelagic egg-producing species, may be deeply flawed. A general resistance to accepting that fecund marine fishes could become endangered through exploitation stems from poor understanding of population dynamics, especially in the early post-settlement phase, coupled with assumptions of fishery models that ignore critical components of life history theory. Moreover, faith in the ability to manage exploited species effectively leads to the perception that severe declines are management, rather than conservation, issues. The growing list of threatened marine species and a realization of the many factors that place them at risk indicate the need to be precautionary about the possibility of extinction, and about the criteria used to assess such risk, with important implications for research, monitoring and management.