Should I stay or should I go? Modelling year-round habitat suitability for fin whales in the California Current

• Published in: Diversity and Distributions
• Main Authors: Scales, KL, Schorr, GS, Hazen, EL, Bograd, SJ, Miller, PI, Andrews, RD, Zerbini, AN, Falcone, EA
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2017
• Subjects: Conservation; Earth Observation - Remote Sensing; Marine Sciences; Pacific; Balaenoptera physalus; baleen whale; Fin whale
• Online Access: http://plymsea.ac.uk/id/eprint/7551/; http://plymsea.ac.uk/id/eprint/7551/1/KScales_FinWhale_DivDist_Revisions.pdf; https://doi.org/10.1111/ddi.12611

Aim Understanding the spatial ecology of endangered species is crucial to predicting habitat use at scales relevant to conservation and management. Here, we aim to model the influence of biophysical conditions on habitat suitability for endangered fin whales Balaenoptera physalus, with a view to informing management in a heavily impacted ocean region. Location We satellite-tracked the movements of 67 fin whales through the California Current System (CCS), a dynamic eastern boundary upwelling ecosystem in the Northeast Pacific. Methods We use a multi-scale modelling framework to elucidate biophysical influences on habitat suitability for fin whales in the CCS. Using Generalised Additive Mixed Models, we quantify the influence of a suite of remotely-sensed variables on broad-scale patterns of occupancy, and present the first year-round, high-resolution predictions of seasonal habitat suitability. Further, we model the influence of contemporaneous biophysical conditions on individual-level residence times in high-use habitat. Results We present evidence of year-round habitat suitability in the southern California Current System, robust to inter-annual variability, establishing that North Pacific fin whales do not follow the canonical baleen whale migration model. Within the high-use habitat in the Southern California Bight (SCB), individual-level residency to localised areas (n=16 for >30 days; n=4 for >6 months) was associated with warm, shallow, nearshore waters (>18°C, <500m); with cool waters (14-15°C) occurring over complex seafloor topographies and convergent (sub-)mesoscale structures at the surface. Main Conclusions Biophysical conditions in the southern CCS generate productive foraging habitats that can support the fin whale population year-round and allow for extended periods of residency in localised areas. High-use habitats for fin whales are co-located with areas of intense human use, including international shipping routes and a major naval training range. Seasonal habitat suitability maps ...