Monster Seminar JAM - Rebuilding fish stocks for dummies
Dr. George Rose, Fisheries Conservation, Memorial University of Newfoundland
Many commercial fish stocks worldwide have been overexploited to the point of commercial extinction, with predictions of decline of all fisheries. Among depleted stocks, the great northern cod off Newfoundland and Labrador, once the largest cod stock in the world, is often held up as the icon for non-recovery. Several hypotheses have been put forward as to the reason for non-recovery, including fisheries induced evolution, trophic cascades, seal predation, too much food and complex cultivation effects. None of these esoteric hypotheses are supported by recent events, during which this stock has showing rapid increases after nearly 2 decades of zero population growth. In this talk I will discuss these events and data from trawl and acoustic surveys, tagging and laboratory experiments that suggest that simple depensative mortality, likely bottom-up forced and related to feeding, fits both sea and lab evidence as the cause of 2 decades of zero net productivity. Recent increases in productivity lead me to argue that management (largely near zero fishing and a large closed area) has worked, that it should be continued to enable this stock to rebuild to levels of optimum surplus production, and that all that it took was simple protection and patience. The fish are alright, and if this once greatest but most abused stock can recover, I believe there is potential to rebuild most depleted stocks.
Date and Time:
October 29, 2009,
11:00 am - 12:00 pm