13 bio 3115 conservation biology consequences of

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Unformatted text preview: loitation I: reductions in population size: cod harvesting in the Gulf of St. Lawrence Harvest (t) M7.27 BIO 3115 Université d’Ottawa / University of Ottawa 2012 Consequences of exploitation II: changes in size/age/sex-structure Harvesting often targets particular age/size categories, especially larger individuals. If larger, older individuals are the most productive, then loss of relatively few of these individuals may have dramatic effects on the population growth rate. However, these effects may not be manifested until some time later, when offspring enter the harvestable population. M7.28 BIO 3115 Université d’Ottawa / University of Ottawa 2012 M7.14 BIO 3115 Conservation Biology Changes in age and size of harvested sturgeon at Cumberland House, 1954-1982 26 1 .0 B 24 0 .5 A g e ( yr s ) Principal component 1 1 .5 0 .0 - 0 .5 22 20 18 - 1 .0 16 - 1 .5 50 5 5 6 0 6 5 7 0 7 5 8 0 85 5 0 55 60 65 70 75 8 0 8 5 Ce n s u s ye a r C e n su s ye a r M7.29 BIO 3115 Université d’Ottawa / University of Ottawa 2012 Changes...
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