Relationships between water mass characteristics and estimates of fish population abundance from trawl surveys
| Autor: | R. Ian Perry, L. Paul Fanning, Stephen J. Smith |
|---|---|
| Rok vydání: | 2013 |
| Předmět: |
Water mass
education.field_of_study biology Fishing Population General Medicine Management Monitoring Policy and Law biology.organism_classification Pollution Bottom water Fishery Oceanography Abundance (ecology) Environmental science Gadus Groundfish sense organs skin and connective tissue diseases education Population dynamics of fisheries General Environmental Science |
| Zdroj: | Environmental monitoring and assessment. 17(2-3) |
| ISSN: | 0167-6369 |
| Popis: | The Canadian Department of Fisheries and Oceans conducts annual bottom trawl surveys to monitor changes in the abundance of the major commercially important groundfish populations. Some of these surveys have been in operation for almost 20 yr. The estimates from these surveys often indicate rapid changes in abundance over time beyond that expected from the population dynamics of the fish. Much of this interannual change has been interpreted as variation, the magnitude of which has often made it difficult to measure anything but the most severe effects of fishing, pollution or any other intervention on the population. Recent studies have shown that some of this variation may be attributed to changes in catchability of fish due to the effects of environmental variables on fish distribution. Annual changes in abundance as estimated from such field surveys may be confounded by changes in catchability due to annual changes in environmental conditions. In this study, trawl catches of age 4 Atlantic cod (Gadus morhua) from surveys conducted during March 1979–1988 were compared with concurrent measurements of bottom salinity, temperature and depth. Large catches of age 4 cod are more likely to occur in water characterized as the intermediate cold layer defined by salinities of 32–33.5 and temperatures |
| Databáze: | OpenAIRE |
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