In recent years, the numbers of North American multi-sea-winter and one-sea-winter salmon have been steadily declining with multi-sea-winter salmon declining at a faster rate than one-sea-winter salmon (Fig. 1). Although the source of the mortality and its potential cause(s) remain largely unknown,...
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| Language: | English |
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| Online Access: | http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.590.8495 http://www.npafc.org/new/publications/Technical Report/TR4/page 24-26(Reddin).pdf |
| Summary: | In recent years, the numbers of North American multi-sea-winter and one-sea-winter salmon have been steadily declining with multi-sea-winter salmon declining at a faster rate than one-sea-winter salmon (Fig. 1). Although the source of the mortality and its potential cause(s) remain largely unknown, sea survival rates have declined substantially even with the almost complete closure of commercial fisheries at sea which should have resulted in dramatic increases in returns and survival rates; especially when the fisheries are located close to the natal river and are conducted during the main runs of salmon to the river (Dempson et al. 2001). In North America, there are regions in the southern area of the salmon’s range where stocks have become close to being extirpated (Anon. 2002). Due to these declines in overall abundance and near extirpation in some areas, sea research has become particularly important if the cause(s) of the at-sea mortality is to be found. Exploratory fishing in the Northwest Atlantic was begun by the Department of Fisheries and Oceans Canada in 1965 (Friedland and Reddin 1993). Surface gillnets of various mesh sizes were set out at dawn and fished for up to twelve hours depending on the weather and wave conditions. Nets were sometimes patrolled from a small open boat to obtain live salmon for tagging. Mortalities were sampled for biological characteristics, scales, and stomach contents. Salmon of all sea ages occurred seasonally over most of the Northwest Atlantic and were found concentrated in the Labrador Sea gyre throughout the year, at west Greenland in the summer and autumn, and along |
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