Status of Atlantic Salmon in Selected Rivers of Cape Breton Island, 1997
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Fisheries and Oceans P6ches et Océans 1 + ® Canada Canad a Canadian Stock Assessment Secretariat Secrétariat canadien pour l'évaluation des stocks Research Document 98/31 Document de recherche 98/3 1 Not to be cited without Ne pas citer sans permission of the authors ' autorisation des auteurs ' Status of Atlantic salmon stocks in selected rivers of Cape Breton Island, 199 7 by T.L. Marshall, P . LeBlanc, K. Rutherford Department of Fisheries and Oceans Science Branch, Maritimes Regio n P.O. Box 550 Halifax, NS B3J 2S7 and R. Jones Department of Fisheries and Oceans Science Branch, Maritimes Region P.O. Box 503 0 Moncton, NB El C 9B6 ' This series documents the scientific basis for ' La présente série documente les bases the evaluation of fisheries resources in Canada . scientifiques des évaluations des ressources As such, it addresses the issues of the day in halieutiques du Canada . Elle traite des the time frames required and the documents it problèmes courants selon les échéanciers contains are not intended as definitive dictés. Les documents qu'elle contient ne statements on the subjects addressed but doivent pas être considérés comme des rather as progress reports on ongoing énoncés définitifs sur les sujets traités, mais investigations . plutôt comme des rapports d'étape sur les études en cours . Research documents are produced in the Les documents de recherche sont publiés dans official language in which they are provided to la langue officielle utilisée dans le manuscrit the Secretariat. envoyé au secrétariat . ISSN 1480-4883 Ottawa, 199 8 Canad' TABLE OF CONTENTS Page Abstract . .......... ...... ... ....... ... ... ...... ... ...... .......... ........ ... ... ......... ...... ... ... ... ....... ...... ... ......... ........ .......... ...... ...... .. 3 Summary Sheets.. ... ....... ...... ...... ... ....... ................. ... ... ... ... ... ...... ... ... ... ....... ......... ...... .. ........ .......... ....... ...... .. 4 Introduction Description of Fisheries . ... ...... ...... ......... .. ...... ... ... ...... ... ...... ... ... ... ...... ......... ........ ... ...... ... ....... ...... ......... 9 Fishery Data .. .......... ......... ...... ...... .................. ... ... ......... ...... ... ... ... ........................ .. ... ... ... ....... ...... ...... 1 0 Margaree River Returns .... ............. ... ......... ...... ... ... ... ...... ......... ... ... ...... ... ...... ... ... ... ...... .................. ... ... ... ... ............. ...... 11 Conservation Requirements ... ... ... ......... ... ... ... ... ... ...... ... ...... ... ... ... ...... .................. ... ... ... ... ...... ...... ....... 12 Escapement ... .......... ... ... ... ... ... ...... ... ...... .. ...... ... ... ......... ...... ... ... ... ...... ......... ........ ... ...... ... ...... ... .... ...... 12 Abundance of Juvenile Salmon .... ......... ......... ... ... ....:. ... ...... ... ... ... ...... .................. ......... ... ....... ...... .......12 Forecasts . ... ... .......... ...... ... ... ... ...... .................. ... ... ......... ...... ... ... ... ...... .......... ........ ........ .......... ....... ...... 1 3 Middle River Estimation/Estimates of Returns.. ........ ......... ... ... ...... ... ...... ... ...... ...... ... ....... ........ ... ...... ... ....... ...... ....... 14 Conservation Requirements ... ...... ......... ......... ... ... ......... ......... ...... ... ... ... ....... ........ ... ... ... ... ............. ....... 15 Escapem ent...... ...... ................ ... ... ......... ... ...... ... ... ........ ...... ... ... ... ...... ... ...... ........ ... ...... ... ...... ...... ...... 15 Abundance of Juvenile Salmon . ... ... ...... ... ... ......... ........ .......... ...... ...... ... ...... ......... ... ... ... ... ... ... ...... ....... 15 Forecast ..... ... ... .......... ... ... .......... ... ... ... ... ... ... ........ ........ ... ....... ...... ... ... ... ...... ... ...... ... ... ...... ... ... ....... .......1 5 Baddeck Rive r Estimation/Estimates of Returns ........ ...... ... ........ ... ...... ... ...... .......... ...... ... ... ... ... ... ... ... ...... ... ... ....... ....... 16 Conservation Requirements ..... ....... ... ......... ........ ... ... ... ... ...... ......... ...... ... ...... ... ... ...... ...... ... ... ....... ... .... 17 Escapement.. ... ... ...... .......... ...... ... ....... ........ ......... ... ...... ... ...... ... ....... ......... ...... ... ......... ......... ............. .... 17 Abundance of Juveniles ..... ...... .................. ... ......... ......... ... ... ... ................ ...... ... .................. ... .............. 17 Forecast . ....... ...... ...... ... ...... ...... .......... ........ ... ......... ......... ...... ... ...... .......... ...... ... .................. ...... ....... .... 1 7 North River Estimation/Estimates of Returns . ...... ......... ... ........ ................ ... ...... ......... ........ ........ ................ ....... ....18 Conservation Requirements ..... ... ...... ........... ........ .................. ...... ... ...... .......... ........ .......... ...... ....... ....19 Escapem ent........ ... ... ... ...... ....... ... ...... ... ...... ... ........ .................. ...... ... ...... ......... ........ .........•-•---. ....... ....19 Abundance of Juveniles .... .......... ...... ......... ... ........ ........ .......... ...... ......... ......... ........ ......... ...... ....... .... 19 Forecast . ...... ...... ... ... ... ...... .......... ...... ... ...... ... ........ ......... ......... ......... ...... ... ...... ........ ......... ....... ....... ....1 9 Grand River Returns ...... .......... ...... ...... ... ....... ...... ... ...... ... ........ ... ......... ...... .......... ...... ... ...... ... ...... ... ...... ....... ... ... .....20 Conservation Requirements. ....... ...... ... ... ... ... ........ ... ...... ... ...... ......... ...... ... ...... ......... ... ...... ....... ...... ..... 20 Escapement. ...... ... ... ... ...... .......... ...... ... ...... ... ........ ... ... ... ... ....... ...... ... ... ... ... ...... ......... ... ...... ....... ...... .... 21 Abundance of Juvenile Salmon ... ... ... ... ...... ... ........ ... ...... ... ...... ....... ... ...... ......... ......... ......... ....... ...... ..... 21 Forecast . ...... ...... ...... ... ...... ................ ... ... ... ... ........ ......... ... ...... ......... ...... ... ...... .. ...... ... ...... ....... ...... ..... 21 Sydney, Tillard, Skye and Mabou Rivers Abundance of Juvenile Salmon.. ....... ... ........ .. ...... ... ... ...... ... ... ... ....... ......... ...... ... ... ... ... ................ ... ..... 21 Ecological Considerations ..... ...... ...... ... ...... ......... ... ... ...... ... ...... ... ...... ...... .......... ......... ........ .......... ....... ... ... .. 22 Management Considerations ...... ... ... :.. ...... ......... ... ... ...... ... ......... ... ... ... ... ... ...... ......... .................. ...... ...... .. 22 Acknowledgements/Literature Cited . ... ...... ... ...... ... ... ........ ........ ...... ... ... ... ...... ......... ......... ... ....... ...... ....... .. 23 Tables/Figures ...... ...... ......... .......... ... ... ... ... ... ... ... ... ... ........ ......... ...... ... ... ... ... ... ......... ... ... ... ......... ....... ....... .. 25 Appendices . ... ...... ...... ... ...... ... ....... ...... ... ... ... ... ...... ... ........ ... ...... ...... ... ... ... ... ... ... ...... ... ...... ... ... ... ....... ....... ... ... i 3 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 21 rivers reportedly fished for salmon in 1997 . Juvenile salmon abundance was assessed on the Sydney, Tillard, Skye and Mabou rivers . Returning salmon were either counted at fishways or estimated by mark-and-recapture techniques. Estimated returns of 4,938 large and 756 small salmon to the Margaree, and 636 large and 122 small salmon to the No rth contributed to the attainment, in total, of 320% and 330% of respective conservation requirements . Returns of 346 large and 68 small fish to the Middle .River, 189 large and 62 small fish to Baddeck River, and a total of 152 fish to the Grand River contributed to the attainment of 72, 44 and 65% of their respective conservation requirements . Evidence of lateness of salmon returning to some rivers raised unce rtainty about completeness of estimates to the Middle, Baddeck and perhaps, No rth rivers . Prognoses for 1998, based on forecast models, juvenile salmon densities, recent estimates of an index of overwinter habitat in the North Atlantic and numbers of hatchery smolts stocked in 1997 are uncertain . However, large salmon of the Margaree and North rivers have achieved conservation requirements for over a decade and should continue to do so in 1998, the abundance of small salmon relative to conservation is less certain . Returns to the Grand River should approach conservation requirements, those of the Middle, and Baddeck rivers are unlikely to achieve conservation requirements in 1998 . RÉSUMÉ Des évaluations de l'état des stocks de saumon atlantique ont été réalisées pour les rivières Margaree, Middle, Baddeck, North et Grand des ZPS 18 et 19 de l'île du Cap-Breton