Date of Award
© 2013 Caitlyn Little
Master of Science in Marine Sciences
Due to the questionable status of sturgeon populations along the east coast of the United States, there has been considerable research focus on these species in recent years. Previous studies have overlooked the Saco River as an important habitat for sturgeon in the Gulf of Maine. However, the incidental capture of a sturgeon in the Saco River in the fall of 2007 raised questions about the presence of this species and the role that the Saco River might play in the life cycle of these fish. The goals of this thesis were to evaluate the utilization of this habitat by sturgeon species and determine the sex ratio of the population inhabiting the river. Chapter one documents the first reported occurrences of the shortnose sturgeon (Acipenser brevirostrum) in the Saco River. Two shortnose sturgeon were captured in the Saco River between August of 2010 and June of 2011. In addition to these two individuals, six other shortnose sturgeon that were tagged in the Merrimack River, MA were also detected in the Kennebec and Saco Rivers in Maine. This indicates that coastal movements in the Gulf of Maine may be more important than previously thought. Smaller rivers, such as the Saco, may play an important role as foraging habitat on these longer migrations. Chapter two examines the habitat use and sex ratio of Atlantic sturgeon in the Saco River using acoustic telemetry, stomach content analysis and quantification of circulating sex steroids. During this study a total of 196 individual Atlantic sturgeon (Acipenser oxyrincus oxyrinchus) were captured in gill nets in the Saco River. Internal acoustic transmitters were implanted in 43 of these sturgeon to track movements within the Saco River system. Of these tagged sturgeon 42 were subsequently detected on the acoustic receiver array in the Saco River and 40 were detected in the Saco River during more than one sampling season. Lattice-based density analysis of all detections from the Saco River indicated that sturgeon in this system primarily utilize the area at the mouth of the river. Stomach content analysis revealed that American sand lance (Ammodytes americanus) was the primary food item in the diet of Atlantic sturgeon in the Saco River. Steroid hormone analysis indicated that the sex ratio of Atlantic sturgeon in the river is biased toward females. However, there was some degree of uncertainty in assignment of sex, and further investigation into steroid hormones is warranted to fine-tune the methodology.
Little, Caitlyn, "Assessing The Habitat Use, Diet, And Sex Ratios Of Atlantic (Acipenser Oxyrinchus) And Shortnose Sturgeon (Acipenser Brevirostrum) In The Saco River, ME" (2013). All Theses And Dissertations. 82.