Estimation of habitat suitability for the southern form of the short‐finned pilot whale (Globicephala macrorhynchus) in theNorthPacific

Abstract

Habitat models were developed from dedicated sighting survey data collected during summers between 1983 and 2006 in the North Pacific Ocean. Our aim was to examine the distribution pattern of the southern form of the short‐finned pilot whale (Globicephala macrorhynchus) in relation to the physical environment. We tested two different types of analytical procedures for habitat estimation: generalized linear models (GLMs) and ecological niche factor analysis (ENFA). The area under the receiver operating characteristic curve and the Boyce index suggested that GLM defined the core habitat well, whereas ENFA estimated the suitable habitat more correctly. These models indicated the core habitat within the subtropical gyre. Among the environmental variables used to construct the habitat models, the temperature at a depth of 200 m contributed most to both GLM and ENFA. This corresponds to the fact that the species mainly feeds on mesopelagic prey and that the axis of the Kuroshio Current, in the northwestern part of the subtropical gyre, is characterized by its temperature at 200 m. Habitat suitability in the coastal waters off southern Japan also correlated with the Kuroshio meander patterns. Thus, the southern form of the short‐finned pilot whale appears to be particularly well adapted to the ecosystem of the North Pacific subtropical gyre.

Biogeography of small odontocetes in relation to wide‐scale oceanographic structure in theNorthPacificOcean

“…Recent and historical sighting data cover almost the entire area of the North Pacific Ocean from the equator to the Sea of Okhotsk, and from the Japanese coast to the west coast of North America. These suggest that the North Pacific Ocean provides important habitats for a number of small odontocetes (Miyashita, , ; Miyashita et al ., ; Kanaji et al ., , ,b). The North Pacific Ocean is predominantly divided into three distinct gyres: the cyclonic Tropical Gyre, the anti‐cyclonic Subtropical Gyre and the cyclonic Subarctic Gyre (Fig.…”

Abundance estimates of six species of Delphinidae cetaceans off the Pacific coast of Japan between 1985 and 2015

“…In the waters off the Pacific coast of Japan, it has been suggested that the Kuroshio current significantly affect distributional patterns of dolphin species (Kasuya , Kanaji et al . ). The model‐based approach may also facilitate assessment of whether seasonal and spatial changes in oceanographic environments can affect the estimated abundances.…”

“…The survey areas were designed to cover the main habitat for common bottlenose dolphins and the southern form of short‐finned pilot whales (Kanaji et al . , , ; Fig. S1).…”

A treasure from the past: Former sperm whale distribution in Indonesian waters unveiled using distribution models and historical whaling data

“…Comprehensive knowledge on where marine animals occur, and which characteristics determine their habitat preferences, is important in understanding the ecology of the species and guiding appropriate conservation and management efforts (Kanaji, Okazaki, Kishiro, & Miyashita, 2015; Redfern et al., 2006). However, animal occurrence data are deficient for many marine species (Redfern et al., 2017) in many regions (Moura, Sillero, & Rodrigues, 2012).…”

“…These results can then be used for conservation, policy and spatial planning. SDMs have been constructed based on historical whaling data before, and this has helped scientists to identify the core habitats of certain species, which is valuable for understanding species ecology and for conservation management (Elith et al., 2011; Gregr, 2011; Pearce & Boyce, 2006; Torres et al., 2013) and provided improvements in the usability of the available data (Kanaji et al., 2015). Identifying important habitats can help minimize adverse human and cetacean interactions (Breen, Brown, Reid, & Rogan, 2016) by implementing spatially explicit conservation measures.…”