Publication Abstract

Effects of fishing on non-target fish species

Effects of fishing on non-target fish species

S.P.R. Greenstreet and S.I. Rogers

1. An unfortunate feature of all the studies reviewed is that, despite some time series extending back over seven decades or more, no data are available which allow us to compare the current fished situation with the original unfished ecosystem present prior to fishing.

2. Attempts to correlate time series trends in the abundance of non-target species with fishing disturbance trends have to date proved inconclusive.

3. A better approach towards determining fishing effects on non-target species lies through the development of underlying theory and the establishment of specific testable hypotheses. In particular, the development of hypotheses to predict the effects of fishing on species diversity is required. This would enable diversity changes to be more strongly related to changes in fisheries exploitation patterns, allowing changes in the abundance of different non-target species in time and space to be linked more directly to fishing.

4. Current applied theory has identified specific life-history characteristics likely to make a species vulnerable to-fishing disturbance. These life-history characteristics include large ultimate size, slow growth rates, and large size and higher age at maturity.

5. The elasmobranchs have been identified as a group of species which have such life history characteristics as to render them susceptible to fishing disturbance. In general, trends in the abundance of the different shark, skate and ray species can be attributed to fishing mortality since they follow predictions based on the life-history characteristics of each species.

6. A further benefit of the development of underlying theory lies in the ability it should provide us to predict the likely consequences of continued high levels of fishing disturbance.

7. Whilst fishing undoubtedly causes increased mortality for many non-target species, for some, fishing may instead provide enhanced opportunity, through scavenging and reduced predation and competition, allowing increased scope for population growth.

Reference:

S.P.R. Greenstreet and S.I. Rogers, 2000. Effects of fishing on non-target fish species. pp217-234 In: Effects of fishing on non-target species and habitats: biological conservation and socio-economic issues (ed. M. J. Kaiser and S. J. de Groot). Oxford: Blackwell Science.

S.P.R. Greenstreet and S.I. Rogers*

pp217-234 In: Effects of fishing on non-target species and habitats: biological conservation and socio-economic issues (ed. M. J. Kaiser and S. J. de Groot). Oxford: Blackwell Science.