Dynamic Habitat Models Reflect Interannual Movement of Cetaceans Within the California Current Ecosystem

• Published in: Frontiers in Marine Science
• Main Authors: Elizabeth A. Becker, Karin A. Forney, David L. Miller, Jay Barlow, Lorenzo Rojas-Bracho, Jorge Urbán R, Jeff E. Moore
• Format: Article in Journal/Newspaper
• Language: English
• Published: Frontiers Media S.A. 2022
• Subjects: Baja California; cetacean; generalized additive model; habitat model; species distribution model; Southern California Current; Science; Q; General. Including nature conservation; geographical distribution; QH1-199.5; Baja; Pacific; Balaenoptera musculus; Blue whale; Fin whale; Humpback Whale; Megaptera novaeangliae; Physeter macrocephalus; Sperm whale
• Online Access: https://doi.org/10.3389/fmars.2022.829523; https://doaj.org/article/7acb72fe14f546798e4dcb3d2dac1eab

The distribution of wide-ranging cetacean species often cross national or jurisdictional boundaries, which creates challenges for monitoring populations and managing anthropogenic impacts, especially if data are only available for a portion of the species’ range. Many species found off the U.S. West Coast are known to have continuous distributions into Mexican waters, with highly variable abundance within the U.S. portion of their range. This has contributed to annual variability in design-based abundance estimates from systematic shipboard surveys off the U.S. West Coast, particularly for the abundance of warm temperate species such as striped dolphin, Stenella coeruleoalba, which increases off California during warm-water conditions and decreases during cool-water conditions. Species distribution models (SDMs) can accurately describe shifts in cetacean distribution caused by changing environmental conditions, and are increasingly used for marine species management. However, until recently, data from waters off the Baja California peninsula, México, have not been available for modeling species ranges that span from Baja California to the U.S. West Coast. In this study, we combined data from 1992–2018 shipboard surveys to develop SDMs off the Pacific Coast of Baja California for ten taxonomically diverse cetaceans. We used a Generalized Additive Modeling framework to develop SDMs based on line-transect surveys and dynamic habitat variables from the Hybrid Coordinate Ocean Model (HYCOM). Models were developed for ten species: long- and short-beaked common dolphins (Delphinus delphis delphis and D. d. bairdii), Risso’s dolphin (Grampus griseus), Pacific white-sided dolphin (Lagenorhynchus obliquidens), striped dolphin, common bottlenose dolphin (Tursiops truncatus), sperm whale (Physeter macrocephalus), blue whale (Balaenoptera musculus), fin whale (B. physalus), and humpback whale (Megaptera novaeangliae). The SDMs provide the first fine-scale (approximately 9 x 9 km grid) estimates of average species density and ...