Dear colleagues, My co-authors and I are excited to announce the publication of our new paper, “Diving Behavior of Common Bottlenose Dolphins Around the Main Hawaiian Islands: Individual Variation and Responses to Diel and Lunar Cycles”, in Marine Mammal Science. Please feel free to request a PDF copy from us via email at *[email protected]* <[email protected]>. You can find the abstract (in both English and ʻŌlelo Hawaiʻi) below, and at *https://onlinelibrary.wiley.com/doi/10.1111/mms.70232* <https://onlinelibrary.wiley.com/doi/10.1111/mms.70232>. You can also download a copy of the supplemental materials at *https://cascadiaresearch.org/files/Harnish_etal_2026MMS_supplemental.pdf* <https://cascadiaresearch.org/files/Harnish_etal_2026MMS_supplemental.pdf>
Annette Harnish Research Biologist Cascadia Research Collective *www.cascadiaresearch.org* <http://www.cascadiaresearch.org> CITATION: Harnish, A.E., R.W. Baird, and M.A. Kratofil. 2026. Diving Behavior of Common Bottlenose Dolphins Around the Main Hawaiian Islands: Individual Variation and Responses to Diel and Lunar Cycles. Marine Mammal Science 42(3): e70232. doi: 10.1111/mms.70232 ABSTRACT: Marine mammals navigate their environment both horizontally and vertically, adding an additional layer of complexity to understanding their behavior and developing effective conservation strategies. Here, we use data from 14 tagged common bottlenose dolphins (*Tursiops truncatus*) from Hawai’i to explore how their diving behavior varies in response to temporal and demographic variables. Overall mean dive depth (for dives ≥50m) was 206m (max=896m), and duration was 5.9min (max=13.6min). However, individual variation was considerable and explained most of the variation in dive depths and durations. Dive rates varied between diel periods, with rates at night more than double those during the day. Dive depths and durations also varied between diel periods, with animals generally conducting their deepest and longest dives during dusk and their shortest and shallowest dives at night. Regular dives to or close to the seafloor occurred in depths of up to 800m, but animals spent the majority of their time in the top 50m of the water column. These findings represent the first baseline data on diving behavior for this species in Hawai’i and will be critical in evaluating potential impacts stemming from planned marine infrastructure development. HŌ‘ULU‘ULU MANA‘O: Hoʻokele nā māmala kai i ko lākou kaiapuni ma ka papakū me ka papamoe, a he kūʻonoʻono ke ʻano o ka maopopo ʻana i kā lākou lawena, i ko lākou ʻano, a pehea e hoʻolālā a hoʻomōhala aku ai i mau kaʻakālai maluō kūpono. I kēia pepa, kālailai aku mākou i ka ʻikepili mai ʻumikūmāhā mau naiʻa nuku poko (*Tursiops truncatus*) o Hawaiʻi i lepili ʻia i mea e kālailai aku ai i ke ʻano o ko lākou luʻu ʻana a pehea e loli ai i hāpane i nā kumuloli kaime a henua. ʻO ka ʻawelike hohonu o ka luʻu ʻana (no nā luʻu i ʻoi aʻe a like paha me ke 50m), he 206m (ka hohonu loa=896m), a ʻo ka lōʻihi he 5.9 minuke (ka lōʻihi loa=13.6 minuke). He nui nō naʻe nā ʻaui ʻana ma nā pākahi, a ʻo ia nō ke kumu nui o nā ʻaui ʻana ma ka hohonu a me ka lōʻihi o ka luʻu ʻana. Ua pā ka heluna o ka luʻu ʻana i ka lā, ʻoi aku, ma ka pālua hoʻi, ka nui o ka heluna luʻu ma ka pō ma mua o ke ao. Pēlā pū ka hohonu a me ka lōʻihi o nā luʻu ʻana, aia nō i ka māhele o ka lā, a ma ka maʻamau, helu ʻia nā luʻuna hohonu a lōʻihi loa ma ka mōlehulehu, a ʻo nā luʻuna pōkole a pāpaʻu loa ma ka pō. Helu ʻia nā luʻuna maʻamau i kokoke i ka papakū ma ka hohonu a hiki i ka 800m, noho naʻe ma kahi o nā 50m o luna o ke kolamu kai i ka hapanui o ka manawa. ʻO kēia mau hua nā ʻikepili kahua mua ma ke ʻano o ka luʻu ʻana no kēia lāhui ma Hawaiʻi, a he mau ʻikepili waiwai a koʻikoʻi nō ma ka loiloi ʻana i nā hopena e pā aku ana paha kēia ʻano kaiāulu i ke kūkulu kumuhana kai e hoʻomākaukau ʻia ana.
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