Oceanographic Basis of a DMS-Related Atlantic Cod ( Gadus morhua ) Fishery Problem: Blackberry Feed

• Published in: Canadian Journal of Fisheries and Aquatic Sciences
• Main Authors: Levasseur, M., Keller, M. D., Bonneau, E., D'Amours, D., Bellows, W. K.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Canadian Science Publishing 1994
• Subjects: Aquatic Science; Ecology, Evolution, Behavior and Systematics; Newfoundland; Belle Isle; Strait of Belle Isle; atlantic cod; Gadus morhua; Limacina helicina; Subarctic
• Online Access: http://dx.doi.org/10.1139/f94-087; http://www.nrcresearchpress.com/doi/pdf/10.1139/f94-087

Atlantic cod (Gadus morhua) caught along the Labrador and Newfoundland coasts and in the Strait of Belle Isle often smell strongly of sulfur, a problem locally called "blackberry feed". Early studies have shown that the sulfurous-smelling cod had fed almost exclusively on the pteropod Limacina helicina and that dimethylsufide (DMS) was responsible for the odor. In August 1991, we conducted a cruise in the northeastern Gulf of St. Lawrence and in the Strait of Belle Isle in order to confirm the algal origin of dimethylsulfoniopropionate (DMSP, the precursor of DMS) and to determine the factors responsible for its transfer in the food web. A significant correlation was found between the distribution of DMSP and the abundance of microflagellates, dinoflagellates, cryptomonads, and prymnesiophytes (mostly Chrysochromulina spp.). The concentration of DMSP in L. helicina and in particles were also linearly related, suggesting rapid accumulation of DMSP in pteropod. The weight-specific DMSP content of L. helicina was always high (1–21 mg DMSP/g) and apparently sufficient to create blackberry feed symptoms in cod. Results from bioassay experiments demontrated that L. helicina may significantly influence the DMSP–DMS dynamics in subarctic waters.