In a rapid communication just published in the Canadian Journal of Fisheries and Aquatic Sciences, biologist Douglas Swain of the Gulf Fisheries Centre and Robert Mohn, emeritus scientist, at the Bedford Institute of Oceanography present findings that suggest the delay in recovery of Atlantic cod on the eastern Scotian Shelf could be attributed to increased predation by grey seals or other governing factors and not the effect of forage fish as previously thought.

"Swain and Mohn provide provocative scientific evidence challenging the commonly held belief that species interactions with forage fish have impaired the recovery of Atlantic cod on the eastern Scotian Shelf during the 15-year fishing moratorium," says Rolf D. Vinebrooke, Co-editor of the Canadian Journal of Fisheries and Aquatic Sciences.

"They report a lack of a direct relationship between forage fish biomass and cod recruitment rates, suggesting that density-dependent effects of competition and predation by forage fish cannot therefore account for lack of recovery by cod stocks.

"Most importantly, their data show that the lack of resilience stems from as of yet unidentified factors affecting high death rates among adult cod."

The authors conclude that further investigation is required to ensure proper understanding and appropriate management to improve the chances for recovery of Atlantic cod stocks.

Swain, D.P. and Mohn, R.K. Forage fish and the factors governing recovery of Atlantic cod (Gadus morhua) on the eastern Scotian Shelf. Canadian Journal of Fisheries and Aquatic Sciences. 69(6) doi: 10.1139/F2012-045.