Recent excursions of capelin (Mallotus villosus) to the Scotian shelf and Flemish cap during anomalous hydrographic conditions

Episodic occurrences of capelin (Mallotus villosus) outside their normal range were evident from examination of current and historical records of the Scotian Shelf and Flemish Cap. Capelin reappeared in both locales, beginning in the late 1980s (Scotian Shelf) and early 1990s (Flemish Cap); concomitant with anomalous meteorological and hydrographic conditions and an abrupt decline in offshore abundance in their principal centre of distribution (division 2J3KL). Movement of capelin to these regions is associated with lower than normal ocean temperatures but not with warmer than normal conditions. In both locales adult capelin were the first to appear, and spawning was evident; successful reproduction has occurred on the Scotian Shelf (a 1993 year-class formed). The increase in capelin abundance was not limited to the eastern Scotian Shelf and Flemish Cap, and capelin was not the only species involved. Capelin in the southern Gulf of St. Lawrence exhibited a very similar temporal pattern of abundance, and two Arctic-boreal species (Greenland halibut (Reinhardtius hippoglossoides) and checker eelpout (Lycodes vahlii)) exhibited spatial and temporal patterns of abundance similar to those of capelin on the Scotian Shelf. We suggest that capelin may serve as an instructive analog for assessment of the relative influences of environmental effects and fishing on heavily exploited species.