PGHERS07.pdf (7.65 MB)
Report of the Planning Group for Herring Surveys (PGHERS)
reportposted on 2007-01-01, 00:00 authored by ICESICES
• During the Planning Group for Herring Surveys (PGHERS) meeting in 2007 thestock estimates were done for the first time by the means of FishFrame, a softwaretool to calculate estimates derived from acoustic surveys. FishFrame performedsatisfactorily and was used to combine the national data into the integrated surveyresult.• The total combined estimate of North Sea spawning stock biomass (SSB) is 2.1million t. This estimate is comparable to the 1.9 million t SSB in 2005 and the 2004estimate of 2.6 million t. The stock is dominated by the 2000 year class. Growth ofthe 2000 year class still seems to be lower than average, individuals of this year classhaving almost the same size and weights than the one year younger fish of the 2001year class. The West of Scotland estimate of SSB is 472,000 tonnes (190,000 in2005). This is a substantial increase compared to last years estimate, and the SSB hasmore than doubled. The SSB is in the same order of magnitude that it had during thelast ten years. The surveys are reported individually in Annex 2A-2F.• The total sprat biomass was estimated as 452,000 t in the North Sea (down from563,000 t in 2005). The biomass is dominated by mature sprat (98%). The total spratin the Kattegat was estimated as 33,600 t, including 63% immature sprat (down from59,800 t in 2005). There is no clear indication that the southern distribution has beenreached. However, the highest concentration of sprat was observed off the coast ofScarborough, on the east coast of England.
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