Research Document - 2001/056
Summary of 2000 herring acoustic surveys in NAFO Divisions 4WX
By Melvin, G.D., Power, M.J., Fife, F.J., Clark, K.J., Stephenson, R.L.
Abstract
Atlantic herring distribution and abundance in NAFO Division 4WX was documented and estimated from data collected primarily by commercial fishing vessels with and without automated acoustic logging systems during structured, mapping and research surveys. In contrast to previous years, the surveys for German Bank (4) and Scots Bay (3) were conducted according to established protocol and provided excellent coverage of the spawning area. As a result, the estimated biomass was considered representative of the spawning components. Surveying on Trinity Ledge was poor with only a single survey of the spawning component late in the season. The total biomass for each of the main spawning components was estimated by summing the results of surveys conducted at approximately two week intervals. Biomass estimates for Scots Bay, Trinity Ledge and German Bank were approximately 106,000t, 621t, and 256,000t for a total stock complex minimum spawning biomass of 463,300t. Although the minimum spawning stock biomass' (SSB's) do not directly reflect trends in stock abundance due to changes in coverage, the decline in observed biomass on German Bank and on Trinity Ledge is cause for some concern. Biomass estimates for coastal Nova Scotia and the offshore Scotian Shelf are presented and discussed.
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