Run timing of pelagic fishes in Gulf of St Lawrence: area and species effects

Abstract

Run timings of four ubiquitous pelagic fishes in the Gulf of St Lawrence were compared for area and year effects. Run timing of alewife, Alosa pseudoharengus (Wilson), smelt, Osmerus mordax (Mitchill), and Atlantic salmon, Salmo salar L., was estimated at index rivers, and time of arrival of herring, Clupea harengus L., on spawning grounds was estimated from gillnet fisheries located around the Gulf, 1978–87. Time of pelagic fish migrations had strong species and area effects, but weak year effects. The species had their own unique migration times and durations, and could be divided into two groups: herring and smelt, which arrived in all areas of the Gulf at the same time; and alewife and salmon, which had significant area effects. Environmental data were not correlated with run timing. There was little annual variation in run timing among early‐run species; only alewife had significant year effects. There was annual variation in the timing of late‐run species, but it was not correlated with proximate environmental factors. Because run timing is an easily defined stock characteristic, observations over large areas and many years might be useful for understanding the impact of large‐scale environmental changes on natural populations.