Date of Award

Summer 8-2021

Level of Access Assigned by Author

Open-Access Thesis

Degree Name

Doctor of Philosophy (PhD)

Department

Ecology and Environmental Sciences

Advisor

Yong Chen

Second Committee Member

R. Anne Richards

Third Committee Member

Gayle Zydlewski

Additional Committee Members

Walter Golet

Kate Beard-Tisdale

Abstract

The Gulf of Maine northern shrimp (Pandalus borealis) once supported a significant winter fishery for the Gulf of Maine (GOM). Although the shrimp fishery is not comparable to the lobster business, it provided fishermen and many coastal communities jobs and incomes in winters after lobster seasons. However, a moratorium has been put on the shrimp fishery since 2014 due to record low population abundance and perceived recruitment failures. The recruitment failures have been correlated with warming water temperatures over the past decade. The GOM has been recognized as experiencing rapid warming as a result of global climate change. Uncertain impacts of the changing environment on the life cycle and the fishery of northern shrimp could hamper the efforts to rebuild a resilient and sustainable shrimp fishery. Consequently, there is a pressing need to understand the impacts of climate change on the life cycle and population dynamics of the GOM northern shrimp. The objectives of this research project are to 1) develop a cost-effective sampling protocol for building a comprehensive fecundity database including maternal body size, and number and size of eggs; 2) examine the impacts of climate-induced environmental variabilities on egg mortality; 3) develop a complete size-fecundity relationship in order to derive a robust estimate of reproductive potential of the population; 4) illuminate the effect of water temperature on spatial structure for each life stage; and 5) investigate the relationship between environmental variabilities and habitat suitability in northern shrimp spawners’ distribution. The findings reveal that the GOM bottom temperatures might have changed considerably over the past fifty years; however, the correlation between water temperature and parasitic infection eggs was not significant and the changes in reproductive potential might be related to population density rather than bottom temperature. The results also showed that the distributions of mature groups were getting patchier and shifting northward, which were correlated with declined population abundance and warming temperature, respectively. Furthermore, the quality of habitat has declined significantly for mature groups in summer and fall, especially in the 2010s, which could result from warming temperature and subsequently lead to declined spawning stock biomass.

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