Research Document - 1999/108
Follow-up to the assessment of Atlantic salmon in selected rivers of Cape Breton Island, 1998.
By T.L. Marshall, K. Rutherford, P. LeBlanc, and R. Jones
Abstract
Assessments of the stock status of Atlantic salmon were conducted on the Margaree, Middle, Baddeck, North, and Grand rivers of SFAs 18 and 19, Cape Breton Island. These rivers account for 90+% of the total recreational fishing effort exerted on the Island's 33 rivers reportedly fished for salmon in 1998. Juvenile salmon abundance was assessed on the Sydney, Tillard, Skye, Cheticamp, Inhabitants, Gaspereaux, and Mabou rivers.
Returning salmon were counted at fishways or estimated by mark-and-recapture techniques. Estimated returns of 2,949 large and 757 small salmon to the Margaree, 358 large and 74 small salmon to the North, and 23 large and 221 small to Grand River Falls contributed to the attainment, in total, of 268, 177 and 102% of respective conservation requirements. Returns of 155 large and 82 small fish to the Middle River and 146 large and 54 small fish to the Baddeck River contributed to the attainment of 70 and 52% of the respective conservation requirements of those rivers.
Prognoses for 1999, based on forecast models and juvenile salmon densities, contain a large element of uncertainty. However, large salmon of the Margaree and North rivers have achieved conservation requirements consistently for over a decade and should continue to do so in 1999; the abundance of small salmon relative to conservation requirements is less certain. Returns to the Grand, Middle and Baddeck rivers are unlikely to exceed those of 1998 and are unlikely to meet conservation requirements in 1999.
Comparison of now similarly derived conservation requirements for the Margaree, Middle, Baddeck and North rivers does not resolve the similarities/differences between estimated escapements, resultant juvenile densities and proximity of densities to the Elson (1967) norm. It does highlight the facts that adult numbers are only a "fair" proxy for assessing the attainment of conservation requirements and that, where possible, the assessment of that attainment should be based on eggs.
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