シャチは潜水と潜水の間に1回だけ呼吸することが研究で確認される(Killer whales breathe just once between dives, study confirms)

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2024-05-15 カナダ・ブリティッシュコロンビア大学(UBC)

新しい研究で、シャチが潜水の合間に一息しか吸わないことが確認されました。この研究は、カナダのブリティッシュコロンビア沖の11頭の北部と南部の居住シャチに吸盤タグを取り付け、ドローン映像と生物学的データを用いて行われました。PLOS ONEに発表されたこの研究によると、シャチはほとんどの時間を浅い潜水に費やし、ほとんどの潜水は1分未満で、最長でも8.5分でした。シャチが潜水の合間に一息しか吸わないことが確認されたことで、研究者はシャチの酸素消費量を計算し、そのエネルギー消費量や1日に必要な魚の量を推定できるようになりました。この情報は、特に絶滅危惧種の南部居住シャチの保護に役立ちます。研究では、シャチが休息中に1.2~1.3回、移動中や狩り中に1.5~1.8回呼吸することがわかりました。

<関連情報>

シャチの呼吸数 Killer whale respiration rates

Tess M. McRae ,Beth L. Volpov,Evan Sidrow,Sarah M. E. Fortune,Marie Auger-Méthé,Nancy Heckman,Andrew W. Trites
PLOS ONE  Published: May 15, 2024
DOI:https://doi.org/10.1371/journal.pone.0302758

シャチは潜水と潜水の間に1回だけ呼吸することが研究で確認される(Killer whales breathe just once between dives, study confirms)

Abstract

Measuring breathing rates is a means by which oxygen intake and metabolic rates can be estimated to determine food requirements and energy expenditure of killer whales (Orcinus orca) and other cetaceans. This relatively simple measure also allows the energetic consequences of environmental stressors to cetaceans to be understood but requires knowing respiration rates while they are engaged in different behaviours such as resting, travelling and foraging. We calculated respiration rates for different behavioural states of southern and northern resident killer whales using video from UAV drones and concurrent biologging data from animal-borne tags. Behavioural states of dive tracks were predicted using hierarchical hidden Markov models (HHMM) parameterized with time-depth data and with labeled tracks of drone-identified behavioural states (from drone footage that overlapped with the time-depth data). Dive tracks were sequences of dives and surface intervals lasting ≥ 10 minutes cumulative duration. We calculated respiration rates and estimated oxygen consumption rates for the predicted behavioural states of the tracks. We found that juvenile killer whales breathed at a higher rate when travelling (1.6 breaths min-1) compared to resting (1.2) and foraging (1.5)—and that adult males breathed at a higher rate when travelling (1.8) compared to both foraging (1.7) and resting (1.3). The juveniles in our study were estimated to consume 2.5–18.3 L O2 min-1 compared with 14.3–59.8 L O2 min-1 for adult males across all behaviours based on estimates of mass-specific tidal volume and oxygen extraction. Our findings confirm that killer whales take single breaths between dives and indicate that energy expenditure derived from respirations requires using sex, age, and behavioural-specific respiration rates. These findings can be applied to bioenergetics models on a behavioural-specific basis, and contribute towards obtaining better predictions of dive behaviours, energy expenditure and the food requirements of apex predators.

生物環境工学
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