Impact of bottom water temperature change on the southernmost snow crab fishery in the Atlantic Ocean

Snow crab populations are found in the Northern Atlantic, Arctic and Pacific Oceans. Snow crab are generally considered to be a stenothermic species with distributions constrained by the available thermal habitat. Crab fishing area 4X on the western Scotian Shelf is at the southernmost extent of Snow Crab distribution in the Northwest Atlantic. Bottom temperatures in this area provide very limited snow crab habitat. An incursion of warm slope waters flooded the western Scotian Shelf in 2011/2012 and created positive temperature anomalies. These warmer bottom temperatures appeared to have had a negative impact on some life stages of snow crab in local populations, with juvenile stages being the most affected. Evidence of this decrease was supported by various fisheries independent and dependent data sources. Though 4X snow crab populations are now increasing, likely due to immigration from an adjacent snow crab fishing area, this warm water event was very detrimental to the commercial fishery in the area.