Large-Scale Changes in Abundance of Breeding Herring Gulls (Larus argentatus) and Great Black-Backed Gulls (Larus marinus) Relative to Reduced Fishing Activities in Southeastern Canada

Abstract

Abstract. Large-scale relationships between changes in abundance of coastal breeding Herring (Larus argentatus) and Great Black-backed (L. marinus) gulls and commercial fisheries landings of bottom-dwelling groundfish spanning 28 years in four of Canada's east coast Provinces were investigated. Herring and Great Black-backed gull abundance data were compared between survey periods prior to (1986–1990) and following (2002–2006 and 2010–2014) the widespread reduction of groundfish fishing activities due to a moratorium that began in 1992. Regionwide declines in the number of breeding Herring and Great Black-backed gulls were observed between the 1986–1990 and 2002–2006 survey periods (Herring Gull: -3.7% per year; Great Black-backed Gull: -3.6% per year) and between the two periods following the moratorium (Herring Gull: -1.6% per year; Great Black-backed Gull: -4.1% per year). Total groundfish landings reported for the study area declined by 76% between the 1990–1992 and 2002–2006 fishing periods, and decl...