Date of Award

Fall 12-2017

Level of Access Assigned by Author

Open-Access Thesis

Degree Name

Master of Science (MS)


Marine Biology


Yong Chen

Second Committee Member

James Wilson

Third Committee Member

Gayle Zydlewski

Additional Committee Members

Keith Evans

Paul Anderson


Fisheries science conducted and used for management strategies in the Gulf of Maine (GOM) is conducted at broad spatial and temporal scales. There is a tendency for fisheries-independent monitoring programs, which play a critical role in fisheries assessment and management, to miss fine-scale dynamics, especially given the complex hydrographic structures characterizing the GOM. In New England, fishermen participating in a heterogeneous groundfish fishery within the GOM may have varied perceptions of fish abundance or distribution depending on the scale at which they participate in the fishery. Overlooking fine-scale life-history dynamics coupled with scale-mismatch in science and management may perpetuate a cycle of mismanagement and mistrust in the groundfish fishery.

We developed and evaluated a collaborative fisheries-independent survey called the Eastern Gulf of Maine Sentinel Survey-Fishery (Sentinel Survey). We used demersal longline gear and jig gear to sample the eastern Gulf of Maine (EGOM), which is an area characterized by unique hydrographic features and complex benthic structure, and is sparsely sampled by regional monitoring programs. The survey has two major objectives: to evaluate fine-scale groundfish dynamics in eastern Maine, and to involve fishermen directly in the data collection and analysis process. The outcomes of the first objective will provide important abundance, distribution, and life-history information for groundfish species in a region not well-covered by existing fisheries-independent monitoring programs, which is useful for stock assessment. Outcomes of the second objective help establish a collaborative framework for evaluating fine-scale groundfish dynamics in the EGOM, align perceptions of scale between fishermen, managers, and scientists, and to build trust between them.

Catch data from the Sentinel Survey was evaluated to derive abundance indices and examine distribution for Atlantic Cod (Gadus morhua), Atlantic Halibut (Hippoglossus hippoglossus), White Hake (Urophysis tenuis), and Cusk (Brosme brosme). This information provides important insight into spatial and temporal variability for groundfish dynamics in the region. To evaluate life-history parameters for these species, we created Weight-Length Relationships (WLRs), then used Fulton's K to evaluate condition factor. Generalized Additive Models (GAMs) were used to evaluate spatial, temporal, and environmental effects on life-history parameters and condition. We then evaluated the Sentinel Survey design using GAMs to identify potential sources of variability affecting catchability for four key groundfish species. We found depth to be the most consistent and significant variable affecting catchability. Additionally, we evaluated and optimized the longline gear used on the Sentinel Survey to alleviate financial and logistical concerns. Finally, we used the Sentinel Survey as a case study to describe how a collaborative research program can be used to identify and evaluate complexity within an ecosystem, align perceptions of scale in science and management, and reconcile mistrust between scientists, fishermen, and managers.


Joint M.S. in Marine Biology and M.S. in Marine Policy