Effects of climate variability and fishing on gadid-crustacean interactions in subarctic ecosystems

Abstract

Snow crab (Chionoecetes opilio) are a vital economic and biotic resource to many subarctic ecosystems. Their abundance varies greatly, but what causes large changes in production and early life survival is unknown. My overall goal is to improve our understanding of snow crab population dynamics during early life history stages. Chapter 1 provides background information on subarctic ecosystems, addresses possible mechanisms of population control and potential drivers of variability, describes snow crab life history, and reviews recent population trends in snow crab and their major cod predators. Chapter 2 details a regression study examining the effects of snow crab spawning stock biomass, environmental conditions, and Pacific cod (Gadus macrocephalus) or Atlantic cod (Gadus morhua) biomass on snow crab recruitment. This study compares three ecosystems: the eastern Bering Sea, the Newfoundland-Labrador Shelf, and the southern Gulf of St. Lawrence. Cold ocean conditions during early life history were associated with increased snow crab recruitment or recruitment indices in all three ecosystems. However, there was no consistent observed effect of spawning stock biomass or gadid predation on subsequent recruitment. The dominant role of environmental conditions in driving snow crab recruitment highlights the importance of an ecosystem-based management approach for these stocks.