Research Document - 1999/071
Transport and development of cod eggs and larvae in Placentia Bay (3Ps) Newfoundland, 1997-1998.
By I.R. Bradbury, P.V. R. Snelgrove and S. Fraser
Abstract
Spawning location and timing of Atlantic cod can have a dramatic impact on predominant drift and temperature regimes experienced by developing eggs and larvae. We examined spatial and temporal pattern of cod egg and larval abundance in Placentia Bay with a series of ichthyoplankton and oceanographic surveys throughout the spawning and post-spawning seasons of 1997 and 1998. Mean current patterns suggest a counter clockwise flow around the bay, entering around Cape St. Mary's and exiting at the base of the Burin Peninsula on the western side. CHW egg densities were highest early in 1997 and in the head of the bay. The 1998 peaks, though lower in magnitude, showed a similar spatial pattern. Despite lower egg densities, 1998 larval densities were an order of magnitude higher than in 1997 and were concentrated on the south western side of the bay. A shift in spawning peak to mid summer in 1998 from early spring in 1997 suggests that more eggs were released in warmer waters in 1998, resulting in faster development times and shorter dispersal distances. In terms of larval production, late spawners may be particularly important to successful egg hatching, at least within the Placentia Bay ecosystem.
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