Scientist still fishing for cause of low salmon survival in waters off Newfoundland and Labrador

The survival of Atlantic salmon stocks at sea remains low throughout the province despite the drastic reduction in directed fishing since 1992.

And fisheries scientists fail to understand why.

The Department of Fisheries and Oceans has released the Newfoundland and Labrador 2007 Atlantic Salmon Stock Assessment report. The report states that low marine survival of Atlantic salmon since the late 1980’s continues to be the major factor affecting abundance of Atlantic salmon within the region.

Within insular Newfoundland, particularly low abundance of both large and small salmon was noted in 2007. Within Labrador, abundance of small salmon has increased since 2004, but overall abundance of large salmon has remained particularly low since the late 1980’s.

Scientists note they cannot offer advice to fishery managers on the status of salmon stocks as they are constrained by “our inability to understand the causes of the low survival of salmon at sea.”

Fisheries scientists say that unrecorded removals of salmon from the stock need to be quantified as there is some evidence that those removals could be higher than the recorded fishing mortality on some stocks. High unrecorded mortality is of particular concern at present stock levels, the report states.

The report notes that other sources of uncertainty include current rates of egg production versus historical information from individual stocks, annual changes in sex ratios and variation in biological characteristics that could, collectively, impact on the reproductive potential of stocks.

Priority research is required to address the lack of understanding of factors contributing to low survival of salmon at sea, as there is some indication that, in some years, higher mortality may occur near shore. There is also a lack of understanding of factors responsible for variation in freshwater (egg-to-smolt) survival, which can be similar to or even higher than the variation observed in marine survival.

(From The Telegram)