Section 8
Chapter 7,433

Impact of compensatory responses on assessment advice for the northwest atlantic mackerel stock

Overholtz, W.J.; Murawski, S.A.; Michaels, W.L.

Fishery Bulletin (Washington D C) 89(1): 117-128


ISSN/ISBN: 0090-0656
Accession: 007432531

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Annual assessments of the Northwest Atlantic mackerel stock have occurred every year since 1973, providing useful advice to fishery managers involved in the decision making process for this important pelagic resource. Since 1985, assessment advice based on an F0.1 management strategy has indicated that catches in the 300,000 mt range are feasible because stock biomass has increased greatly after the collapse of the fishery in the mid-1970s. However, indications from previous research are that compensatory processes are very important, so a stochastic simulation model with density-dependent growth, maturity, and natural mortality was constructed to study how these mechanisms might affect our ability to provide short- and long-term advice for this important stock. Model results suggest that our present assessments may be too optimistic relative to yield projections and that minimum spawning-stock biomass levels may be difficult to maintain even with an F0.1 fishing strategy. Model results also reveal that natural mortality rates are probably much higher than previously thought and are important in determining trends in abundance in this stock.

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