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Marine
Major Commercial Fish Stocks: 1960s-2004
Estimated SSB and Bpa (thousand tonnes)
Stock 3 | 1967 | 1980 | 1990 | 2000 | 2004 | Bpa |
|---|
NS Cod | 237 | 170 | 76 | 51 | 43 | 150 |
|---|
NS Haddock | 254 | 150 | 76 | 102 | 289 | 140 |
|---|
NS Herring | 920 | 130 | 1,181 | 824 | 1,892 | 1,300 |
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NS/WoS Saithe | 151 | 235 | 97 | 190 | 238 | 200 |
|---|
The health of a fish stock is indicated by its Spawning Stock Biomass ( SSB) - the total weight of fish capable of spawning in any one year. 4 Each stock has a safe biological limit (Blim). To take account of scientific uncertainty in stock assessments, managers use a precautionary biological limit (Bpa). If a stock's SSB falls below its Bpa then the stock may suffer from reduced reproductive capacity and may not be able to replenish itself.
A ban on herring fishing in the North Sea between 1977 and 1983 allowed the stock to recover from a collapse, caused largely by overfishing in the 1960s and 1970s. A decline in the early 1990s meant that further measures were introduced in 1996. The North Sea cod stock has been declining since the late 1960s. Despite regulatory measures, fishing pressure on cod has been high since the early 1980s and the SSB remains low. The high SSB in 2004 of the North Sea haddock was mainly due to the exceptionally strong 1999 year class. Most subsequent year classes are below average and it is expected that the SSB will decline to below Bpa in the short term at current fishing mortality rates. After a 20-year period of decline, the SSB of North Sea/West of Scotland saithe has been increasing since the early 1990s.
SOURCE: FISHERIES RESEARCH SERVICES, ICES5
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