Status and trends of the fish community in the Flemish Cap (NAFO Div. 3M) bioregion
This report summarizes fish community trends for the Flemish Cap (NAFO Div. 3M) based on European Union summer trawl research vessel surveys between 1988 and 2018. Species were classified into eight functional groups and trends were described using biomass indices, biomass and abundance anomalies, a...
| Main Authors: | , , , , |
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| Format: | Article in Journal/Newspaper |
| Language: | English |
| Published: |
2018
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| Subjects: | |
| Online Access: | http://hdl.handle.net/10508/15346 http://hdl.handle.net/10261/329388 |
| Summary: | This report summarizes fish community trends for the Flemish Cap (NAFO Div. 3M) based on European Union summer trawl research vessel surveys between 1988 and 2018. Species were classified into eight functional groups and trends were described using biomass indices, biomass and abundance anomalies, and fish size (Biomass/Abundance Ratio) anomalies. In 2003, a replacement of the research vessel allowed extending the depth coverage of the survey from 700m to 1400m. The vessel change had an impact on survey catchability, so to account for it conversion factors were applied. Considering the change in depth coverage, trends were examined for 1988-2018 with data up to 700m, and for 2004-2018 with data up to 1400m. Fish community trends were similar between the two datasets, but the analyses including deeper waters showed a comparatively higher levels of benthivores, reflecting the changes in community structure with depth. Generally speaking, trends in average fish size as tracked by the Biomass/Abundance Ratio appeared driven by recruitment, where general declines in abundance and absences of good recruitments got reflected in increases of this ratio. Biomass of plankpiscivores (mostly Sebastes sp.) experienced a sharp increase in the early 2000s but then returned to levels comparable to the 1990s. Piscivores biomass showed a strong decline in the early 1990s due to the collapse of cod but has since shown signs of recovery. Shellfish, driven by northern shrimp, saw a sustained increase in biomass from the early 1990s until 2002, when started a decline that has persisted until 2018. The biomass of large benthivores decline in the late 1990s and remains low to this date. |
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