Predicting Larval Dispersal and Population Connectivity of Sea Scallops (Placopecten magellanicus) on the Maine Coast through an Individual-Based Model

Author

Kelsey M. Ward, University of MaineFollow

Date of Award

Spring 5-3-2024

Level of Access Assigned by Author

Open-Access Thesis

Degree Name

Master of Science (MS)

Department

Marine Biology

Advisor

Paul Rawson

Second Committee Member

Huijie Xue

Third Committee Member

Sarah Kingston

Abstract

A hydrodynamic model of the coastal currents in the Gulf of Maine has been adapted to include an individual-based scallop larval development and behaviors module and used to estimate sea scallop (Placopecten magellanicus) larval dispersal along the eastern Maine coast. Larvae are released along the coastline out to a 40 m isobath during September and October, and dispersal is driven using the hydrodynamical model result for the region from 2014 through 2017. The origins of particles that “settle” in focal areas, such as Blue Hill Bay, Jericho Bay, and Narraguagus Bay, are determined from model runs, and the frequency with which recruits settling at focal sites originate from various source regions is analyzed. Larval dispersal in the region is balanced between the Eastern Maine Coastal Current (EMCC) and complex inshore eddies. In most years, Narraguagus Bay receives most of its larval recruits from various points along the coast from Gouldsboro Bay eastward through the Bay of Fundy, including from around Grand Manan Island. By contrast, recruitment to Blue Hill Bay is dominated by local recruitment, with the rest of the spat to this bay arriving from eastern Penobscot Bay and Frenchman Bay. Recruitment to Jericho Bay is similarly supplied by larvae from eastern

Penobscot Bay but with much lower local recruitment than was seen in Blue Hill Bay. The proportion of spat that come into Blue Hill and Jericho Bays from the eastern Gulf of Maine via the EMCC varies seasonally and interannually, with higher connectivity to the eastern Gulf in some years than in others. Some of this variability can be explained by severe weather events such as nor’easters. The ability of the model to predict changes in larval dispersal patterns with variations in weather conditions could be a valuable tool in fisheries and aquaculture management.

Recommended Citation

Ward, Kelsey M., "Predicting Larval Dispersal and Population Connectivity of Sea Scallops (Placopecten magellanicus) on the Maine Coast through an Individual-Based Model" (2024). Electronic Theses and Dissertations. 3923.
https://digitalcommons.library.umaine.edu/etd/3923