Research Document - 2012/059

Recent Studies of Lobster, (Homarus americanus), Size at Onset of Sexual Maturity in Nova Scotia 2008-2011: Canso, Tangier, Port Mouton and Lobster Bay - A Progress Report

By M.A. Silva, M.J. Tremblay, and D.S. Pezzack

Abstract

This research document presents an update of ongoing studies of female lobster maturity research in four lobster fishing areas (LFA 31A, LFA 32, LFA 33 and LFA 34) in Nova Scotia. The main aim of this study is to provide updated information on the current status of size at onset of maturity for areas where older information existed, compare with previous evaluations and provide new information for areas where information did not exist. The main criteria to discriminate mature female lobsters was based on assessment of cement gland development in pleopods that have at least reached stage 2, and females that have eggs. Sampling of female lobsters took place during spring in fishing areas of Canso - LFA 31 (2008-2011) and Tangier -LFA 32 (2010-2011) and from late spring to summer in Port Mouton – LFA 33 (2009-2011) and in two areas within Lobster Bay - LFA 34 (2010-2011). A greater proportion of legal size lobsters (82.5 mm and larger) were sampled in Canso (51%-77%) and Tangier (69%-75%) than in southwest areas off Port Mouton (38%-40%) and Lobster Bay (24%-47%). Of all areas sampled, Canso had the highest proportion of mature female legal (82.5 mm and larger) and sub-legal (<82.5 mm) lobsters. In Canso, mature legal lobsters fluctuated from 41% to 100% for all years, where maturity was expressed earlier in the spring. Fewer mature legal lobsters were found in Tangier (38%-84%), Port Mouton (10%-59%), Lobster Bay Outside (6%-51%) and Lobster Bay Inside (12%-29%). Mature sub-legal lobsters were also most abundant in Canso (32%-92%) and had an increasing trend each season, while fewer were found in Tangier (5%-22%) with no clear trend. A smaller proportion of sub-legal mature lobsters were found in Port Mouton (0-5%), Lobster Bay Outside (0-14%) and Lobster Bay Inside (0-5%).

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