Migrations saisonnières du homard (<i>Homarus americanus</i>) entre la côte et les lagunes des Îles-de-la-Madeleine

Abstract

During the summers of 1978 and 1979, the lobster population of the lagoons of the Magdalen Islands was investigated using tag/recapture techniques and direct observations by divers. The results show an active migration pattern of lobsters into (from mid-May to the end of June) and out of (from the beginning to the end of October) the lagoons, linked to seasonal water temperature variations. Following migration out of the lagoons the lobster stay mainly close to the entrance of the lagoons; this principally explains the high percentage of returns to the lagoon the following spring. To explain the much higher percentage of males in the lagoons than in the coastal area, we suggest the existence of a positive selection for mobility of the males during the spring migration. However, the differences in size structure distribution between the coast and the lagoons are mostly due to variations in commercial fishing pressure.