Research Document - 1999/043

Changes in the timing and location of cod spawning in Placenta Bay (NAFO sub-division 3Ps), 1997-1998

By G. L. Lawson and G. A. Rose

Abstract

We examine changes in the timing and location of cod spawning in Placentia Bay between 1997 and 1998, through a combination of acoustic surveys and direct sampling of spawning aggregations. Three spawning grounds were located in spring of 1997, at Bar Haven, Perch Rock, and Oderin Bank. Spawner density at Bar Haven peaked at 0.008 fish/m² in April of 1997, but in 1998 peaked at 0.002 fish/m² in June, a delay of more than 80 days. The timing of peak spawning is not as easily ascertained from our data at Perch Rock and Oderin Bank. However, a delay in spawning at these sites is suggested. Furthermore, the densities of cod at the spawning grounds shifted dramatically from 1997 to 1998. Densities at Perch Rock decreased, and at Oderin Bank increased, by orders of magnitude. These results, together with related studies of larval abundance and juvenile settlement in Placentia Bay, suggest that later spawning has important consequences to successful cod recruitment within Placentia Bay.

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