Abundance and Site Fidelity of Minke Whales (Balaenoptera acutorostrata) Off the Atlantic Coast of Nova Scotia, Canada Using Photo-identification Methodology

• Main Author: Barnacle, Gemma
• Format: Other/Unknown Material
• Language: unknown
• Published: NSUWorks 2009
• Subjects: minke whale; Balaenoptera acutorostrata; abundance; site fidelity; photoidentification; mark-recapture; photo quality index; SOCPROG; Nova Scotia; Marine Biology; Oceanography and Atmospheric Sciences and Meteorology; Canada; North Atlantic; Northwest Atlantic
• Online Access: https://nsuworks.nova.edu/occ_stuetd/245; https://nsuworks.nova.edu/cgi/viewcontent.cgi?article=1151&context=occ_stuetd

Minke whales, Balaenoptera acutorostrata, are the most abundant species of mysticetes in the North Atlantic Ocean; however, little is known about their site fidelity and population size in the Northwest Atlantic Ocean. Field work was conducted off the coast of Halifax, Nova Scotia Canada, mostly during the summer months of 1997 to 2000 and 2002 to 2005 with some field seasons starting as early as April and ending as late as October. During 218 days of boat-based surveys, 614 photographs (black and white film and digital) of minke whales were collected. All photographs were assigned a qualitative quality value (Q1-Q4, best to poor, respectively), and 321 were assigned Q3 or better. A total of 111 individuals were identified, although only 80 individuals had at least one high quality photograph (Q3 and higher). While many individuals were re-identified on the same day, only five individuals were resighted on separate days. Two individuals were resighted within the same year (up to 90 days apart), and three individuals were resighted in separate years (a little over three years apart). Additional photographs collected opportunistically in 2007 yielded two additional resightings of the same individual sighted four years earlier. A discovery curve that failed to reach an asymptote indicated that new individuals continued to enter the study area, thereby classifying the study area as open. Using the POPAN module available in SOCPROG 2.3, abundance was estimated to be 454 individuals (Jackknife s.e. = 398) with an estimated mortality rate of 26% per year (Jackknife s.e. = 27%). It is likely that permanent emigration and mark-loss account for much of this estimated mortality rate. Continued long term photo-identification within the study area is required to improve the abundance estimate and properly assess the degree of site fidelity. A lack of site fidelity could signify either unreliable or low density prey distribution, a limited sample size or a much larger home range than the study area. Therefore, expansion of both the study area and field effort is recommended.