Characterizing residence patterns of North Atlantic right whales in the southeastern USA with a multistate open robust design model

• Published in: Endangered Species Research
• Main Authors: Krzystan, AM, Gowan, TA, Kendall, WL, Martin, J, Ortega-Ortiz, JG, Jackson, K, Knowlton, AR, Naessig, P, Zani, M, Schulte, DW, Taylor, CR
• Format: Article in Journal/Newspaper
• Language: English
• Published: Inter-Research 2018
• Subjects: Zoology; QL1-991; Botany; QK1-989; Eubalaena glacialis; North Atlantic
• Online Access: https://doi.org/10.3354/esr00902; https://doaj.org/article/2601e2fc7ce64ebfaa9cb2d72eedce13

Effective conservation of endangered North Atlantic right whales Eubalaena glacialis requires information about their spatio-temporal distribution. Understanding temporal distribution is particularly important, because a portion of the population migrates between high-latitude summer feeding grounds off the northeastern USA and Canadian Maritimes coasts and lower-latitude calving and wintering grounds off the southeastern US coast (SEUS). Here, we modeled SEUS residence patterns using photo-identification data from coastal South Carolina, Georgia, and Florida from 7 winter seasons (2004/2005-2010/2011). We used multistate open robust design models to evaluate effects of reproductive status, demographic group, and environmental conditions on SEUS residence. Model estimates accounted for temporal variation and imperfect detection and provided probabilities of entering the SEUS, staying in the SEUS, and being sighted in the SEUS. We also derived estimates for residence time and seasonal abundance. We observed staggered arrival and departure patterns and demographic differences in residence patterns that are characteristic of a differential migration strategy. Calving females arrived earliest and, in most seasons, had mean residence periods more than twice as long as other demographic groups. Conversely, adult males arrived the latest and had the shortest residence times. Within-season detection was positively influenced by survey effort, and overall seasonal mean (±SE) detection rate estimates ranged from 0.83 ± 0.08 for non-calving adult females to 0.98 ± 0.02 for calving females. Results provide insights into right whale behavior, biology, and temporal distribution in the SEUS and can be used to evaluate spatially and temporally dynamic management measures.