Publisher : Oxford Journals
Place of publication :
Publication year : 2007
Thematic : Climate Change and Biodiversity
Language : English
Note
Traditionally, trawl surveys were designed to collect fishery-independent data for assessing the population dynamics of commercially
exploited species. However, trawl survey data are increasingly used to describe the abundance, distribution and ecology of a wide range
of species in studies of climate change and fishing effects. These new uses of survey data suggest that improved understanding of the
value and limitations of existing survey designs is required. We compared the power of different survey designs (where stations are
fixed, fixed stratified, random, or random stratified) to detect known trends in the abundance of depleted populations. Modelled
populations were characterized by different temperature preference, density-dependent habitat selection, and patterns of smallscale
aggregation (patchiness). Temperature preferences and local patchiness had an influence on the power of different surveys to
detect increases in abundance, and in some scenarios, survey-area indices would consistently underestimate or overestimate trends
in overall abundance. As the distributions of many fish populations have shifted in response to climate change, exhibit distribution-
abundance relationships, and have been depleted by fishing, we conclude that survey indices may provide partial or unreliable
information on changes in the true abundance of the wider range of species now of interest. To disentangle the effects of fishing,
climate, and biology on the abundance of fish populations, and to monitor the depletion and recovery of species threatened by
fishing, there should be greater emphasis on coordinating the timing, areas of coverage, and methods of sampling of surveys of
the Northeast Atlantic continental shelf.
Go to source
Keywords : Callosciurus notatus
Encoded by : Pauline Carmel Joy Eje
