Abundance and changes in distribution, biology, and behavior of capelin in response to cooler waters of the 1990's
Indices of abundance for capelin in the Newfoundland area collected since the early 1980s include biomass estimates from offshore acoustic surveys, school surface area near spawning beaches from aerial surveys, and catch rates from the inshore commercial fishery. During the 1990s, the offshore acous...
| Main Authors: | , |
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| Format: | Text |
| Language: | English |
| Published: |
1997
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| Online Access: | http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.472.615 http://nsgl.gso.uri.edu/aku/akuw96002/akuw96002_part3.pdf |
| Summary: | Indices of abundance for capelin in the Newfoundland area collected since the early 1980s include biomass estimates from offshore acoustic surveys, school surface area near spawning beaches from aerial surveys, and catch rates from the inshore commercial fishery. During the 1990s, the offshore acoustic estimates declined dramatically but the inshore in-dices remained stable. This divergence was coincident with below nor-mal water temperatures and changes in capelin biology. The biological changes included large-scale changes in distribution and later spawning, both of which have been linked to the colder water temperatures, and smaller fish size. The dichotomy in the trends of abundance indices has never been fully reconciled. However, based on data from several sources, it appears that the acoustic surveys were underestimating the true population abundance of capelin offshore. It seems likely that the severe environmental conditions during the early 1990s were the major cause of the changes in biology and behavior of capelin, and these changes had their greatest impact on the acoustic estimates. |
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