SS1.06 The Ecological Impacts of Pelagic Longline Fisheries
Date: Monday, June 10, 2002
Time: 11:00:00 AM
Location: Carson A
 
KoslowJA, CSIRO Marine Research, Perth, Australia, tony.koslow@csiro.au
Tuck, G, N, CSIRO Marine Research, Hobart, Australia, geoff.tuck@csiro.au
 
THE BOOM AND BUST OF DEEPWATER FISHERIES: IMPLICATIONS OF EPISODIC RECRUITMENT VARIABILITY
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Deepwater fisheries characteristically undergo a boom and bust, crashing within about ten years of their initial development. For some early deepwater fisheries, this could be attributed to lack of management, combined with the extreme longevity and low productivity of many of these species and their tendency to aggregate on seamounts and banks, where they are extremely vulnerable. However, these factors alone should not lead to over-exploitation, if appropriate catch limits are set in place. Despite efforts to manage orange roughy in New Zealand and Australia, these fisheries continue to be depleted, even when quotas are reduced to levels at which assessment models indicate the stocks should be re-building. One possible explanation is that recruitment variability is incorrectly parameterized in the assessment models. Long-lived deepwater fishes are characterized by highly episodic decadal-scale recruitment variability. Simulations indicate that management scenarios that are stable assuming random recruitment variability have a high probability of leading to stock collapse, if recruitment is episodic.