The two Master’s students in the Read Lab, Dani Crain and Katie Sweeney, recently presented the results from their completed Master’s Project (MP) research at the Marine Lab. They will be graduating in Durham this weekend with a Master of Environmental Management (MEM) Degree. The abstracts from their MPs are below.
Dani Crain Katie Sweeney
Danielle D. Crain
Remote biopsy sampling is a common method used in field research with cetaceans. Using this technique, researchers obtain a small sample of skin and blubber using a biopsy tip typically fired from a crossbow or modified air rifle. Analysis of these tissues can provide important information on sex, diet, and reproductive status of free‐ranging cetaceans. Biopsy sampling is generally considered to be a relatively benign procedure, but all prior attempts to evaluate its impact have been subjective assessments of the behavioral response of individuals limited to surface observations. The goal of the present study is to provide a quantitative assessment of the immediate effects of biopsy sampling on short‐finned pilot whales (Globicephala macrorhynchus) equipped with Digital Acoustic Tags (DTags) off Cape Hatteras, North Carolina. A series of fine‐scale behavioral metrics, such as body orientation, vocalization rate, and fluke stroke rate were examined to determine if these parameters changed immediately after a biopsy attempt. These short‐term reactions to biopsy attempts appear to be ephemeral and should not compromise the fitness of the animal. The results of this analysis provide the first subsurface, quantitative assessment of the short‐term effects of biopsy sampling on cetaceans.
Kathryn L. Sweeney
The US Steller sea lion population experienced a precipitous decline of approximately 80% since the mid‐1970s. While the endangered western Distinct Population Segment (DPS) in Alaska has stabilized, stark regional differences have been observed with net increases being largely offset by significant regional declines—the threatened eastern DPS is recovering and being considered for delisting under the ESA. Sea lions were measured from vertical digital images collected during the NOAA 2008 abundance aerial survey. Linear regressions were performed to correct for bias in altitude measurements and finite mixture distribution modeling of converted “true” lengths resulted in means and proportions for three age‐sex classes—adult female and male, and juvenile. The eastern DPS was found to be significantly smaller than the western DPS, while slight differences were observed regionally within the western DPS.