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Research Document - 2012/028

Development of Reference Points for Inshore Lobster in the Maritimes Region (LFAs 27-38)

By M.J. Tremblay, D.S. Pezzack, and J. Gaudette

Abstract

Progress in the development of Reference Points (RPs) for lobster in the Maritimes Region is described. The rationale for using empirical (or “trend-based”) RPs for lobsters, and for using landings as a proxy for biomass in the near to medium term, is given. In addition, the role of secondary indicators in applying the RPs and in the application of Harvest Control Rules is discussed. Landings are the only biomass proxy that has a significant time series (at least 2.years). Although there are clearly uncertainties in using landings as a proxy for biomass, two lines of evidence indicate that increased landings since the 1980s are primarily the result of increased lobster abundance: 1) the correlation between landings and trap catch rate; and 2) the correlation between landings and lobster catch in fishery independent surveys that record lobsters.

The median of the lobster landings from 1985-2009 is used as a BMSY proxy. For the upper stock reference (USR) and limit reference point (LRP), the values of 80% and 40% are proposed, as is suggested in the Department of Fisheries and Oceans’ guidance document on application of the Precautionary Approach. These values are set out for each LFA. Where there were observations of lower landings from 1985-2009 from which the fishery recovered, the lowest point of a 3-year running average was used as the LRP.

Given the uncertainties and caveats associated with the use of landings as a biomass proxy, the proposed RPs should be used only with additional reference to secondary indicators. In addition, steps should be taken to incorporate some fishery independent indicator of abundance. .For some Lobster Fishing Areas (LFAs), fishery independent surveys could be in the form of available surveys directed at other species that also record lobsters. Alternatively, periodic directed lobster surveys could be established to monitor the response to conservation measures.

Where time series are available (LFAs 27-33), there has been no upward trend in exploitation for the last 11-12 years. Lobster abundance has continued to increase during the last 11 years in most areas. Under current conditions, lobster stocks appear to have been resilient to the levels of exploitation measured in the last decade or more.

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