LE3 .A278 2022

2022

Billard, Mark
Redden, Anna

Acadia University

Bachelor of Business Administration

Honours

Biology

Biology

Stock assessments which include estimates of abundance or biomass, fishing mortality rates and biological reference points are used to provide a scientific basis for fisheries management. A key consideration when designing a field program for a stock assessment is ensuring that sampling is representative of the population being studied. A biological sampling method that accurately represents the characteristics of a stock is necessary to make management decisions, as a method with sampling biases could influence the calculated exploitation rate and exploitation status. For Alewife (Alosa pseudoharengus), mean body weight is an important biological characteristic that directly impacts the calculation of the exploitation rate, which is then used in determining the exploitation status of the stock. Alewife migrations are heavily structured, and it is important that the run structure is accounted for in the data with the use of an appropriate sampling scheme. In this study, I evaluated alternate sampling and data collection schemes that reduce the number of sampling days and how these changes in scheme affect the estimates of the mean body weight of the Gaspereau River Alewife stock. Four scenarios and sampling schemes were evaluated to determine how accurate each of the schemes were in comparison to the current full run sampling scheme. Biological characteristic data, including weight, were collected during the spawning migration as part of the annual stock assessment on the Gaspereau River. When alternate sampling schemes were applied to these data, significant differences were found in both the mean weight and exploitation rate of Alewife with the application of sampling schemes that employed large breaks in sampling. Sampling schemes with brief breaks in sampling showed no significant difference. Although some schemes produced significant differences in mean weight and exploitation rate, the effect on exploitation status was not significant enough to indicate a need for change in management action.

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https://scholar.acadiau.ca/islandora/object/theses:3818