College of Earth, Life, and Health Sciences

11:15  John Carlucci: Understanding spatial Variability in Life History of Cod (Gadus morhua) in the Eastern Gulf of Maine.

Over the past several decades, the Atlantic cod (Gadus morhua) stock in the Gulf of Maine (GOM) has experienced a steep decline in abundance and exhibited changes in spatial distribution. Although the cod fishery in the Eastern Gulf of Maine (EGOM) remains open to fishing, low stock density and complex bathymetry has resulted in little fishing effort and sparse data collection. The established Gulf of Maine cod stock assessment/management assumes that there is one stock in which life history parameters among individuals across the GOM are consistent enough such that any differences would not impede the stock-rebuilding plan. Given the variation in habitat, ecosystem structure, and food availability across the GOM, it is unlikely that these assumptions work to rebuild the overall cod stock and reduce overfishing across the GOM. We will develop allometric keys (e.g. length at age, weight at age) for cod in different regions of the Gulf of Maine, which will allow us to identify possible spatial variability in life history parameters. We will use statistical models to make inferences about inter-regional growth rates between the EGOM, western GOM, and George’s Bank. This study can help us evaluate the significance of spatial variability in life history parameters of cod in the Gulf of Maine.
Committee Members: Yong Chen, Keith Evans, Josh Stoll (policy ), Anne Richards (Scientist at NEFSC)

Northern shrimp, Pandalus borealis, support the last remaining open access commercial fishery in the U.S. Though an important winter fishery in the Gulf of Maine, it has remained closed since 2014 after the stock experienced multiple years of low stock abundance and recruitment. As a protandrous hermaphrodite, northern shrimp mature and spawn first as males before transitioning to female at 2-3 years of age. Past studies show the age at which male shrimp become female is inversely related to size at age, with earlier transitions occurring commonly for larger shrimp. However, additional factors such as temperature and commercial fishing may also cause variation in size and age at sex change. In this study, I evaluate spatio-temporal trends in size at sex change, identify possible environmental and anthropogenic sources of influence, and identify the underlying mechanisms causing variation in this important life history process. Furthermore, I will use these results to predict future trends in size-at-sex-change, as well as the implications of projected impacts of these shifts on future recruitment and abundance of the northern shrimp fishery in the Gulf of Maine. Understanding the biological response of shrimp to changing environmental conditions and fishing activity can provide critical information for the development of a sustainable fishery.
Committee Members: Yong Chen, Keith Evans, Josh Stoll (policy), Anne Richards (Scientist at NEFSC)

Red Tree Coral, Primnoa pacifica, is a conspicuous species of deepwater emerged gorgonian coral in the North Pacific and provides important habitat for a number of associated species. As a part of the Glacier Bay National Park Exploration of March 2016, ROV video footage will be analyzed to compare community structure along the length of the fjord system. Ten sites where chosen for ROV dives in the East Arm, West Arm and Central Channel of Glacier Bay. Geological features, such as substrate type, seafloor roughness, slope and aspect that are associated with colonies of P. pacifica will be described alongside the species composition at each of the ten sites. The results of this analysis will show how the patterns of community succession occur along a transect of glacial retreat in the area. Preliminary studies that describe assemblage patterns such as this help create a foundation of knowledge and context for more complex biological and ecological questions. This expedition included a public education component and these results will be of educational value to the National Park Service as well.
Committee Members: Yong Chen, Keith Evans, Josh Stoll (policy), Anne Richards (Scientist at NEFSC)