The threat of fishing to highly fecund fishes

Abstract

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. 2001 The Fisheries Society of the British Isles

Influence of population decline, fishing, and spawner variability on the recovery of marine fishes

“…Given the myriad direct and indirect effects of fishing on marine ecosystems (Pauly et al, 1997;Jennings & Kaiser, 1998), the potential for Allee effects at small population size (Liermann & Hilborn, 1997;Frank & Brinkman, 2000), and the difficulty in predicting the responses of fish populations even to potentially large changes in mortality (Yodzis, 2001), perhaps such a result is not surprising. Indeed, such a finding is consistent with the observation that many fish stocks have failed to recover after extended periods during which directed fishing for the stock in question ceased (Sadovy, 2001). Most Canadian stocks of Atlantic cod, for example, have not shown substantive signs of recovery almost a decade after cessation of targeted commercial fishing activity.…”

“…data); (3) high variability in spawner biomass may not be associated with faster recovery rates (present study); (4) marine fish (with the possible exception of clupeids) do not typically recover rapidly after collapse (Hutchings, 2000a;Sadovy, 2001), even following a reduction in fishing mortality (present study); (5) high fecundity is not associated with rapid population recovery (Hutchings, 2000b(Hutchings, , 2001Sadovy, 2001); (6) marine fishes may have slower recovery rates than non-marine, anadromous salmonids (Hutchings, 2001).…”

“…Predicted population sizes of marine fish stocks 5 and 15 years after 15 year declines, ranging from 50 to 99%, that correspond to the IUCN's proposed and the AFS's current population-decline criteria for marine fishes. The regressions used to predict future population size following collapse are those in Table II The present study is one of a series (Hutchings, 2000a(Hutchings, , b, 2001Sadovy, 2001;R. A. Myers & J.…”

Assessing reproductive resilience: an example with South Atlantic red snapper Lutjanus campechanus

“…Most exploited marine fishes are highly fecund and can produce large year classes even at reduced levels of SSB; thus they will have relatively high steepness and would be considered 'resilient' by this measure. However, highly fecund marine fish can be overfished and are not immune to extinction risk (Sadovy 2001, Sadovy de Mitcheson et al 2013, suggesting a need to integrate additional information on a stock's reproductive potential into our stock assessments (Mangel et al 2013).…”

Ethnobiology of snappers (Lutjanidae): target species and suggestions for management

“…Observing and measuring marine resources is costly [27], and there is an urgent need to obtain data on marine tropical fisheries [28]. Data are especially lacking for rocky and reef fishes that have slow growth and late reproductive maturity, including groupers and snappers [29]. This study was motivated by an urgent need to improve our understanding of the biology of snappers, and data were gathered based on the knowledge of the scientific community and that of local fishermen.…”