Juvenile Atlantic salmon (Salmo salar L.) abundance in the Experimental Ponds Area relative to subsequent adult returns to the Gander River as an index of marine survival : apparent evidence for density-dependent... : Fs70-1/1999-87E-PDF

The number of adult salmon returning to the Gander River should be primarily a function of the number of smolts migrating to sea the previous year and their subsequent mortality rate at sea because the returning adults are largely one-sea-winter fish. A marine survival ratio index has been developed which is calculated as the number of adult salmon returning to the Gander River divided by the total juvenile salmon populations in the Experimental Ponds Area (EPA) at the headwaters of the river in the previous spring. This survival index increased more than four-fold following closure of the commercial fishery in 1992 and has been used to predict adult salmon returns to the Gander River one year in advance. The survival index provides a metric for estimating changes in mortality during the difficult-to-monitor marine phase of the life cycle. Data suggesting an apparent negative relationship between EPA juvenile abundance and the subsequent marine survival index is presented herein. This relationship implies that there is an optimum range of juvenile abundance above and below which adult returns decrease.

Lien permanent pour cette publication :
publications.gc.ca/pub?id=9.805145&sl=1

• Format MARC XML
• Format MARC HTML

Demander des formats alternatifs