Evaluating assumptions underlying a line transect an alysis of a 2004 Northwest Atlantic shipboard abundance survey for cetaceans ...

• Main Author: Palka, Debra Lynn
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: ASC 2005 - R - Theme session 2024
• Subjects: Fisheries and aquaculture; Ecosystem observation, processes and dynamics; Northwest Atlantic
• Online Access: https://dx.doi.org/10.17895/ices.pub.25350535; https://ices-library.figshare.com/articles/conference_contribution/Evaluating_assumptions_underlying_a_line_transect_an_alysis_of_a_2004_Northwest_Atlantic_shipboard_abundance_survey_for_cetaceans/25350535

No abstracts are to be cited without prior reference to the author.Like all statistical inference methods, the reliability of the results rests on the validity of the assumptions made. Line transect sampling has four essential assumptions: 1) measurements are accurate; 2) animals do not response to the observer; 3) animals directly on the transect line are detected with certainty (g(0)=1); and 4) probability of detecting animals vary only with respect to the perpendicular distance between the animal group and the ship’s track line. These assumptions were evaluated for a 2004 shipboard line-transect survey conducted to estimate the abundance of northwest Atlantic cetaceans. Using distance experiments, it was determined that measurement error and rounding was minimal. Using swim directions, it was determined that pilot whales (Globicephala spp.) were attracted to the ship, while Risso’s dolphins (Grampus griseus) avoided the ship. Using data collected from two observation teams, it was determined that ...