MEPS 751:189-209 (2024)  -  DOI: https://doi.org/10.3354/meps14742

ABSTRACT: Large-scale climatic phenomena, like the El Niño-Southern Oscillation (ENSO) cycle, influence marine systems across the Pacific and beyond. The effects of these cycles on Hawaiian marine communities, particularly their impact on cetaceans, remains understudied. Using location data obtained from satellite tags deployed on Blainville’s beaked whales Mesoplodon densirostris and goose-beaked whales Ziphius cavirostris, and sightings data from 2 decades of surveys off the west coast of Hawai‘i Island, we examined the effects of ENSO, season, and 2 other climatic cycles on the space use and sighting rates of these species. Beaked whale sighting rates during El Niño phases were more than double those during La Niña periods, and every period of effort during Central Pacific-‘flavored’ El Niño conditions yielded sightings of both species. Seasonal variation in goose-beaked whale sighting rates was also found. Moreover, both species exhibited variation in space use between climatic phases, with goose-beaked whales displaying a higher propensity to use the windward side of the island after extended La Niña conditions. Shifts in prey availability or predation avoidance in relation to seasons or ENSO events may be the primary drivers behind these findings. More tagging and sighting effort will be necessary to confirm the level of cycle intensity at which these species respond to ENSO cycles, as well as which combinations of climatic phenomena most intensely influence their environment. Our results provide valuable insights for the potential of climate change to influence space use by beaked whales and other odontocetes.

HŌ'ULU'ULU MANA'O: Pā nā mea aniau nui, e like ho'i me ke au o ka Unena Hema o El Niño (ENSO), i nā kaiaola kai ma ka Pākīpika a ma 'ō aku paha. 'A'ole nō nānā a kālailai 'ia nā hopena o ia mau aniau nui ma nā kaiaola kai Hawai'i, keu ho'i ka pā 'ana o nā māmela noho kai. Ho'ohana 'ia ka 'ikepili kahua i loa'a mai nā lepili ho'oka'a'ike lewa i kau 'ia ma nā koholā nuku pa'apū (Mesoplodon densirostris) a me nā koholā nuku nēnē (Ziphius cavirostris), a ho'ohana pū 'ia ka 'ikepili 'ikena o nā ana'ikena o 'elua kekeke i mālama 'ia ma kapakai komohana o Hawai'i mokupuni no ka nānā 'ana i nā hopena o kahi a me ka helu 'ikena o ia mau lāhui ma muli ho'i o ENSO, ke kau, a me 'elua hou aku au aniau. Pālua ka helu 'ikena o nā koholā nuku pa'apū ma ke au El Niño ma ka ho'ohālikelike 'ana me nā au La Niña, a 'ike 'ia nā lāhui 'elua ma ke au o El Niño ma ka Pākīpika Kūwaena. Ua 'ike pū 'ia ka 'aui 'ana o ke kau ma ka helu 'ikena o nā koholā nuku nēnē. Eia kekahi, hō'ike nā lāhui 'elua i ka 'aui 'ana o ko lākou wahi ma waena o nā 'epaki aniau, 'oi aku ka nui o ka papaha, 'o ka wahi o nā koholā nuku nēnē ka 'ao'ao ko'olau o ka mokupuni ma hope o ka wā lō'ihi o ka La Niña. 'O nā kumu nui paha o ia mau hopena, 'o ia ho'i ka loli o ka hiki ke loa'a i ka 'ai, a i 'ole ho'i ka hō'alo 'ana i ke 'ano luapo'i i loko o nā kau a hana ENSO paha. Pono e ho'onui i ka ho'olepili a 'ike 'ana i mea e hō'oia aku ai i ka ikaika o ke au ma ka wā e pā ai kēia mau lāhui i nā au ENSO, a i mea e hō'oia pū aku ai i nā huihuina aniau e pā nui ana i ko lāua kaiapuni. Hō'ike kā mākou mau hua i ka 'ike waiwai no ka hiki i ka lolina aniau ke pā i nā wahi o nā koholā nuku a pēlā pū i nā koholā niho 'ē a'e.

KEY WORDS: El Niño-Southern Oscillation · Mesoplodon densirostris · Ziphius cavirostris · Pacific Decadal Oscillation · North Pacific Gyre Oscillation · Long-term data sets · Killer whale · Interannual variability