Environmental and biological cycles and their possible effect on some Maritime Canada fisheries
LE3 .A278 2014
Bachelor of Science
Fisheries management practices often focus on the effect of fishing mortality and stock-recruitment relationships in order to make predictive models of stock abundance. Such models often ignore the effect of natural, long-term physical and biological cycles, because the relationship of the abundance of fisheries resources to these variables is often not apparent. Cross-correlation analyses of long-term data of fisheries landings and environmental variables were used to highlight some of these relationships. American lobster landings for the Bay of Fundy along a portion of the New Brunswick coast and also along the Maine coast were compared with the 18.61 year lunar nodal precession cycle which affects tidal intensity and coastal sea surface temperatures. American lobster showed a significant positive correlation with sea surface temperature and a significant negative correlation with tidal intensity for both areas. Correlations of tidal activity to both lobster landings and temperature show similar relationships to each other with significant correlation lags of around 20 years. Striped bass and American shad landings for the Saint John River were also compared to natural cycles, and reveal a possible predatory relationship between these two species. However, the presence of outliers obscures the relationship. Atlantic salmon fisheries landings for the Saint John River were compared to both flow rates and water levels of the Saint John River, and there appear to be significant negative correlations between water levels and landings for the summer months, which may indicate reduced catchability during high water levels, and for the month of February, which may indicate an effect of seasonal snowmelt freshets on salmon parr survival.
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