C. Fu, T. J. Quinn II and G. H. Kruse
Juneau Center, School of Fisheries and Ocean Sciences, University of Alaska Fairbanks
11120 Glacier Highway, Juneau, AK 99801-8677 USA
Source - Journal of Northwest Atlantic Fishery Science, Volume 27: 247-260
ISSN-0250-6408
Fu, C., Quinn II, T. J. and Kruse, G. H. 2002. J. Northw. Atl. Fish. Sci. 27: 247-260. https://doi.org/10.2960/J.v27.a21
Abstract
Harvest strategies for the northern shrimp (Pandalus borealis) population in Kachemak Bay, Alaska, were analyzed using a length-based population model under various levels of instantaneous fishing mortality (F) and a biomass-based management threshold (BBMT). With constant instantaneous natural mortality (M) 0.4 or constant recruitment (R), threshold management, i.e. closing the fishery at population levels below BBMT, is unnecessary when the fishery is managed with an optimal fishing mortality rate (Fopt). However, for a population with a Beverton-Holt recruitment relationship, threshold management is essential to reduce the risk of population extinction. The robustness of establishing guideline levels for F to mis-specification of M and R was examined with values of M and R set higher than, lower than, or equal to their perceived true levels. Assessment surveys were assumed to occur once every 1 to 3 years. Underestimation of M results in Fopt values associated with higher cumulative yield and higher risk of falling below population-at-risk threshold taken to be 20% of virgin spawning stock biomass. More frequent surveys help to reduce this risk. On the other hand, mis-specification of R has very little effect on forecasting population abundance if the population is sampled annually. Less frequent sampling induces higher risk if R is specified too high, but it has little effect if R is specified too low. In conclusion, frequent sampling and good understanding of M are essential for sound management of fisheries such as those for northern shrimp in Kachemak Bay.
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Language - English
Publisher - Northwest Atlantic Fisheries Organization (NAFO), Dartmouth, N.S., Canada
Piblication Date - December 2000
Publication Type - Journal Article
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