Research Document - 2011/077
Recovery potential assessment of Roundnose Grenadier (Coryphaenoides rupestris Gunnerus, 1765) in Northwest Atlantic waters
By M.R. Simpson, C.M. Miri, J.M. Mercer, J. Bailey, D. Power, D. Themelis, and M. Treble
Abstract
In 2008, Roundnose Grenadier (Coryphaenoides rupestris) was designated as endangered in the Northwest Atlantic by the Committee on the Status of Endangered Wildlife in Canada; based on declines noted in research trawl surveys conducted by Fisheries and Oceans Canada over 1977-2007 in NAFO Div. 2J3K. There has been no directed fishery for Roundnose Grenadier in Canadian waters since 1997, but it does occur as bycatch in other directed fisheries inside and outside Canada’s 200-mile limit; especially in the Greenland Halibut fishery. A Bayesian state space implementation of the Schaefer surplus production model was used to estimate population parameters of Roundnose Grenadier in Canadian waters. Catch, bycatch, stock biomass estimates from Canadian research vessel autumn surveys, and commercial catch per unit effort data from NAFO and Canadian Fisheries Observers were incorporated into the model. Projections were made 20 years forward using various levels of fishing mortality; in order to estimate the impact on recovery potential of this species. These models predicted that catch levels above 1.25 kt∙year-1 likely result in population decline. At a bycatch level of 1 kt∙year-1, slow recovery of Roundnose Grenadier is predicted. Continued monitoring of abundance and biomass, and any reductions in commercial bycatch of Roundnose Grenadier in other directed fisheries, may prove crucial to the slow recovery of this population over many years. Given the sources of uncertainty described herein, this paper provides an assessment of the recovery potential of Roundnose Grenadier in the Northwest Atlantic, and updates catch data on this species from research vessel surveys and commercial fisheries prosecuted in Canadian waters and in the NAFO Regulatory Area. In the absence of data suggesting local adaptation and genetic differentiation for this species in the Northwest Atlantic, this paper also considers that Roundnose Grenadiers comprise a single Designatable Unit in these waters.
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