Modelling the spatial distribution of cetaceans in New Zealand waters

• Published in: Diversity and Distributions
• Main Authors: Stephenson, Fabrice, Goetz, Kimberly, Sharp, Ben R., Mouton, Theophile L., Beets, Fenna L., Roberts, Jim, MacDiarmid, Alison B., Constantine, Rochelle, Lundquist, Carolyn J.
• Other Authors: MARine Biodiversity Exploitation and Conservation (UMR MARBEC), Centre National de la Recherche Scientifique (CNRS)-Université de Montpellier (UM)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Institut de Recherche pour le Développement (IRD)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2020
• Subjects: conservation; species distribution models; insights; boosted regression tree models; cetacean distribution; New Zealand; relative environmental suitability models; spatial management; blue whale; delphinus-delphis; demersal fish; grounds; habitat suitability models; pilot whales; southern right whales; geo; envir; Bounty Trough; Blue whale
• Online Access: https://doi.org/10.1111/ddi.13035; https://hal.umontpellier.fr/hal-03411065

Place: Hoboken Publisher: Wiley WOS:000510589200001 Aim Cetaceans are inherently difficult to study due to their elusive, pelagic and often highly migratory nature. New Zealand waters are home to 50% of the world's cetacean species, but their spatial distributions are poorly known. Here, we model distributions of 30 cetacean taxa using an extensive at-sea sightings dataset (n \textgreater 14,000) and high-resolution (1 km(2)) environmental data layers. Location New Zealand's Exclusive Economic Zone (EEZ). Methods Two models were used to predict probability of species occurrence based on available sightings records. For taxa with \textless50 sightings (n = 15), Relative Environmental Suitability (RES), and for taxa with \textgreater= 50 sightings (n = 15), Boosted Regression Tree (BRT) models were used. Independently collected presence/absence data were used for further model evaluation for a subset of taxa. Results RES models for rarely sighted species showed reasonable fits to available sightings and stranding data based on literature and expert knowledge on the species' autecology. BRT models showed high predictive power for commonly sighted species (AUC: 0.79-0.99). Important variables for predicting the occurrence of cetacean taxa were temperature residuals, bathymetry, distance to the 500 m isobath, mixed layer depth and water turbidity. Cetacean distribution patterns varied from highly localised, nearshore (e.g., Hector's dolphin), to more ubiquitous (e.g., common dolphin) to primarily offshore species (e.g., blue whale). Cetacean richness based on stacked species occurrence layers illustrated patterns of fewer inshore taxa with localised richness hotspots, and higher offshore richness especially in locales of the Macquarie Ridge, Bounty Trough and Chatham Rise. Main conclusions Predicted spatial distributions fill a major knowledge gap towards informing future assessments and conservation planning for cetaceans in New Zealand's extensive EEZ. While sightings datasets were not spatially comprehensive for ...