Environmental Quality Assessment of Georges Bank for Atlantic cod (Gadus morhua)

Sellers, Ana M.

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Environmental Quality Assessment of Georges Bank for Atlantic cod (Gadus morhua)

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The Georges Bank area in the northwest Atlantic Ocean plays an important role in New Englandâ€™s economy. Overfishing has led to a rapid decrease in cod population numbers, leading to a collapse in certain stocks. Currently, the rate of decrease in cod numbers has slowed; however, population numbers are still low. In this study, I use Growth Rate Potential (GRP) to assess the current environmental quality of Georges Bank and its suitability to support a cod population. GRP is the amount of growth predicted for a fish with known prey availability and environmental conditions. With prey availability and temperature data obtained during the fall fisheries acoustics surveys in 2000, 2001 and 2002, I developed spatially explicit GRP maps, using bioenergetic and foraging models, for Atlantic cod to determine the ability of the Georges Bank environment to support a cod population. Results show that Georges Bank is able to support growth for adult Atlantic cod. In addition to GRP analysis, I studied nucleic acid concentrations of Atlantic herring. Nucleic acids play an important role in growth and development, and have been used to assess physical condition of fish as well as and current growth rates. In this study, I determine total nucleic acid concentrations of Atlantic herring caught during three different spawning stages: pre-, post-, and non-spawning, to determine how nucleic acid concentrations and energy allocation vary seasonally. Results support the hypothesis that nucleic acid concentrations can be used as condition indicators, and are highly sensitive to the spawning stage of fish showing a significant difference between the three groups, which may affect their ability as condition indicators.

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