Background Beaked whale response to Navy sonar is a global concern due to past stranding events coinciding with training activity. Often, controlled exposure experiments involve tagging cetaceans with short-term, high-resolution tags and exposing them to relatively short, single bouts of mid-frequency active sonar (MFAS). In contrast, longer-duration satellite-transmitting tags deployed around Navy ranges enables behavioral response studies of animals exposed to realistic Navy training activities over extended periods and spatial scales, with multiple exposures to different sources.
Methods To study their behavior relative to extended periods of realistic Navy training, satellite-transmitting tags were deployed on four Blainville’s beaked whales (Mesoplodon densirostris) on the Pacific Missile Range Facility (PMRF) off Kauai. Tags were deployed in 3 years, ahead of Submarine Command Courses (SCCs) with multiple sources of MFAS. Dive behavior of two tagged together were compared to acoustically detected group vocal periods (GVPs) on the range. Pre-exposure dive behavior metrics were compared to those during exposures. Horizontal movement behavior metrics were analyzed using Kruskal-Wallis non-parametric and Tukey-Kramer multiple comparison tests.
Results Two whales remained together and highly synchronized in their dive and movement behavior until the onset of MFAS, at which time they appeared to separate. Twenty-three deep foraging dives were matched to GVPs, including three during MFAS. Of the dive behavior metrics, only the depth of one intermediate dive during an exposure was outside the 95th percentile of baseline behavior. Three of the four movement behavior metrics (75%) were atypical relative to baseline for at least one whale across SCC phases, but response varied by individual. However, throughout the SCCs, the whales remained within tens of kilometers of PMRF, near areas used before and after SCCS.
Conclusions These data demonstrate some apparent short-term changes to dive behavior and horizontal movement in response to MFAS. However, these beaked whales did not demonstrate sustained avoidance responses, remaining in the area west of the range during MFAS and in two cases returning to the range after the SCC. Additional tagging and photo-identification studies are critical to understand Blainville’s beaked whale habitat use and residency and to assess the potential impact of repeated exposures to MFAS.
Hōʻuluʻulu Manaʻo: ʻŌlelo Hawaiʻi
Ke Kahua He pilikia a puni ka honua ka hāpane ʻana o nā koholā nuku i ke ana pīnaʻi hawewe kani a ka ʻOihana Moku ma muli hoʻi o nā hana pae wale i ka wā hoʻokahi o nā hanana hoʻomaʻamaʻa. ʻO ka maʻamau, lepili ʻia nā māmala kai loa me nā lepili miomio kūmanawa ma nā hoʻokolohua pā kāohi, a pā hoʻokahi manawa lākou i kahi pīnaʻi hawewe kani alapine waena (MFAS) pōkole. Ma kekahi ʻaoʻao, ma o ka loaʻa o nā lepili hoʻoili ukali kūloa a puni nā wahi ʻOihana Moku, hiki ke kālailai ʻia ka hana o nā holoholona i pā i nā hanana hoʻomaʻamaʻa maoli a ka ʻOihana Moku ma nā wā lōʻihi a ma nā henua pālākiō, me ka pā mau ʻana i nā kumu ʻokoʻa.
Ke Kiʻina Hana I mea e kālailai ai i ka lākou lawena i ka pā ʻana i nā wā hoʻolōʻihi ʻia o nā hanana hoʻomaʻamaʻa maoli a ka ʻOihana Moku, lepili ʻia aku nā lepili hoʻoili ukali ma ʻehā koholā nuku paʻapū (Mesoplodon densirostris) ma ka ponoō kao lele Pākīpika (PMRF) ma kai o Kauaʻi. Lepili ʻia nā lepili ma ʻekolu makahiki, mua o nā papa kauoha mokuluʻu (SCCs) me kekahi mau kumu MFAS. Hoʻohālike ʻia ka lawena luʻu o ʻelua mea i lepili pū ʻia me nā wā leo pūalu (GVPs) i lohe ʻia ma ia wahi. Hoʻohālike ʻia ka lawena luʻu ma mua o ka pā ʻana me ka lawena o nā wā e pā ana. Kālailai ʻia ka lawena holo papamoe ma ka hoʻohana ʻana i ka hōʻike mahuʻi ʻole Kruskal-Wallis a me ka hōʻike hoʻohālike nui Tukey-Kramer.
Nā Hopena Ua noho pū ʻelua koholā a lōkahi nō lāua i ka lawena luʻu a holo a hiki i ka wā MFAS, a ma ia wā nō i kaʻawale ai lāua. Hoʻopili ʻia he iwakāluakūmākolu luʻu ʻai hohonu i nā GVPs, e pēlā pū nō ʻekolu luʻu ʻana ma ka wā MFAS. Ma ka nānā ʻana i nā ʻikepili lawena luʻu, ʻo ka hohonu o hoʻokahi wale nō luʻu waena ka mea i noho ma waho aku o ke kanaiwakūmālima pākēneka lawena kahua ʻikepili. ʻEkolu mai loko mai o ka ʻehā ʻikepili lawena holo (75%) i ʻokoʻa mai ke kahua ʻikepili no hoʻokahi koholā ma nā wā SCCs, ʻokoʻa naʻe ka hāpane ma ka pākahi. Ma nā SCCs naʻe, ua noho nā koholā i loko o nā kilomika he ʻumi o ka PMRF, kokoke i nā wahi i hoʻohana ʻia ma mua a ma hope o nā SCCs.
Nā Manaʻo Pani Hōʻike kēia mau ʻikepili i kekahi mau loli hikiāpoko o ka lawena luʻu a me ka holo papamoe ma ka hāpane i nā MFAS. ʻAʻole naʻe i ʻike ʻia nā hāpane hōʻalo o kēia mau koholā nuku, eia kā noho lākou i kahi komohana o ia wahi ma ka wā MFAS a ua hoʻi kekahi i ia wahi ʻelua manawa ma hope o ka SCC. Koʻikoʻi nō ka lēpili ʻana a me ke kālailai kiʻi no ka maopopo ʻana i ka hana a noho ʻana o ke koholā nuku paʻapū i kona kaianoho a no ke ana ʻana i ka ke ʻano o ka hopena i ka pā mau ʻana i ka MFAS.
Citation:
Henderson, E.E., M.A. Kratofil, R.W. Baird, C.R. Martin, A.E. Harnish, G.C. Alongi, S.W. Martin, and B.L. Southall. 2025. Exposure and Response of Satellite-Tagged Blainville’s Beaked Whales to Mid-Frequency Active Sonar off Kauai, Hawaii. Movement Ecology 13:29. doi: 10.1186/s40462-025-00550-9
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https://movementecologyjournal.biomedcentral.com/articles/10.1186/s40462-025-00550-9#Sec18