Research Document - 1999/142

Plankton and Nekton of the Northeast Newfoundland Shelf and Grand Banks in 1998.

By E.L. Dalley, J.T. Anderson, and D.J. Davis

Abstract

A comprehensive broad-scale survey of temperature, plankton, and nekton of the marine pelagic environment was carried out for the fifth consecutive year during late summer 1998. The study area covers inshore and offshore waters from southern Labrador to the southern Grand Banks (NAFO Divisions 2J3KLNO). Spatial and/or annual (1994-98) effects accounted for significant variation in all variables examined. Area differences were larger and generally associated with latitudinal or inshore/offshore clines. Mean surface temperatures during the 1998 survey ranked in the middle of the 5 years behind 1994 and 1996, but warmer than 1997 and 1995. There was a large body of relatively warm water on the Grand Bank in 1998 with cooler water to the south. In 1998 biomass of the smallest zooplankton size fraction ranked second behind that of 1997 and was significantly higher than 1996, 1995 and 1994. The mid size fraction ranked highest and was not significantly greater than any year, except 1994. The largest size fraction ranked second last but was significantly less than any other year. In 1998 capelin larvae were more widely distributed than any other year, extending as far north as sampling occurred on the Labrador coast and also on the Southeast Shoal. Capelin and sand lance dominated total nekton. Mean catch rate of Arctic cod, which decreased the previous 3 years in succession, ranked third in 1998 following diel adjustments. Mean total nekton biomass (including jellyfish) was significantly higher than any other year in 1998. After adjusting for daynight difference capelin (mostly age 1-2) catch rate in 1998 ranked lowest and was significantly lower than all years except 1995. The mean catch rate of pelagic 0-group Atlantic cod was also the highest since 1994 as a result of relatively high catch rates on the Grand Bank and not the more northern areas. Six species groups that occurred mainly on the Northeast Newfoundland Shelf were all less abundant than they were in 1997, whereas species that occur mainly on the Grand Banks tended to be more abundant in 1998.

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