In September 2002, a number of beaked whales were stranded and killed in the Canary Islands during a NATO naval exercise. It was the first time we started to get a real understanding of the negative effects of sonar sounds on cetaceans, which includes whales, dolphins and porpoises.
於2002年9月，在北大西洋公約組織(NATO：North Atlantic Treaty Organization)的一次海軍演習期間，一些喙鯨在(西班牙最南端的)加那利群島擱淺、死亡。這是我們首次真正瞭解，聲納的聲音對於包括鯨魚、海豚及鼠海豚等，鯨目動物的負面影響。
But why did the noise of sonar seem to affect beaked whales in particular, rather than other species of cetacean? In our new research, we’ve discovered that the response of each species to predators could explain why some whales and dolphins are more sensitive to this human-made noise.
不過，為何聲納的噪音，似乎特別影響喙鯨，而不是鯨目動物的其他物種？ 在新的研究中，我們已經發現，每一物種對捕食者的反應，能解釋為何一些鯨魚及海豚，對於這種人為噪音較為敏感。
It was back in the early 2000s that we (along with other researchers around the world) began to study the impact of sonar on free-ranging whales. These new “behavioural responses studies” exposed different cetacean species to gradually increasing levels of sonar – with careful monitoring to keep the animals from harm. We were then able to identify the level of sonar noise at which behavioural changes began to occur.
早在2000年代初期，我們(連同世界各地的其他研究人員)就開始研究聲納，對於自由放養之鯨魚的影響。這些新的“行為反應研究”將不同的鯨目動物暴露於，逐漸增加的聲納水平中。藉由仔細監視，以防止動物受傷害。 然後，我們能夠確認，開始發生行為改變時的聲納噪音水平。
From that early research we knew that feeding is commonly affected when marine mammals are disturbed by sonar, and some species are markedly more sensitive to this exposure than others.
從上述的早期研究中，我們知曉，當海洋哺乳動物受到聲納干擾時，進食普遍受到影響，且某些物種對此種曝露，顯著比其他物種更為敏感。
For example, Cuvier’s beaked whales showed dramatically more severe changes in their feeding habits (swimming rapidly and silently away while extending their length of dive and non-feeding period) than blue whales.
譬如，柯維氏喙鯨，在其進食習慣(迅速且安靜遊走，同時延長其潛水及非進食時間)上，展現了比藍鯨顯著更為嚴重的改變。
But until now the reasons for this differing response between species were unclear. So, we decided to investigate whether they were responding to human-made sound in a similar way to their response to predators, as some theories suggested.
不過直到現在，在物種之間，這種不同反應的原因不詳。因此，我們決定調查研究，它們是否如同一些理論所暗示，以其對捕食者的類似方式，對人造的聲音作出反應。
Most cetaceans are themselves the prey of another cetacean, the killer whale. Some species, including beluga and beaked whales, have few defence mechanisms. But others are safer due to their large body size, like sperm whales, or large social groups, such as pilot whales.
大多數鯨目動物本身是，虎鯨(另一種鯨目動物)的獵物。包括白鯨及喙鯨的一些物種，幾乎沒有防禦機制。不過，其他鯨目動物，由於體型較大，像抹香鯨，或諸如領航鯨等，大型群聚的群體較為安全。
This means that different species respond differently to the presence of killer whales. We set out to discover whether four cetacean species respond to navy sonar in the same way they respond to the sounds of predatory killer whales – and whether differences across the species related to their natural level of risk from these fearsome predators.
這意味著，不同物種對虎鯨的存在有不同反應。我們著手探索四種鯨目動物，是否以其對掠食性虎鯨聲音作出反應的相同方式，對海軍聲納作出反應。及物種之間的差異，是否與其來自此些可怕捕食者的自然風險水平有關。
By tagging the animals with suction-cupped recording devices – which capture the timing of both sound and movement – we were able to monitor the feeding and movement of 43 tagged whales off the coast of Norway: three toothed whale species (northern bottlenose, sperm and long-finned pilot) and one baleen whale species (humpback).
藉由使用捕捉聲音及活動時序的吸盤記錄裝置，來標記動物。我們能夠監視挪威海岸外，43頭被標記之鯨魚的進食及活動：三種齒鯨物種(北方瓶鼻鯨、抹香鯨及長鰭領航鯨)及一種鬚鯨物種(座頭鯨)。
We measured their reduction in feeding time when exposed to naval sonar – varying from one to four kilohertz – and compared it to their response to recordings of predatory killer whale sounds.
我們測量了，它們曝露於海軍聲納(從1千到4千赫茲不等)時，在進食時間上的減少狀況，並比較了這與其對捕食者之虎鯨聲音記錄的反應。
We found that both naval sonar and the predator sounds caused a clear reduction in feeding time across the four whale species. By contrast feeding activity was unaffected when we exposed them to the sounds of sea vessels without sonar or other control sounds.
我們發現，海軍聲納與捕食者的聲音，皆導致上述四種鯨魚物種的進食時間，明顯減少。相較之下，當它們被曝露於，沒有聲納或其他控制聲音的海船聲音中時，進食活動不受影響。
Strikingly, each species responded similarly to sonar and predatory sounds: northern bottlenose whales had the strongest response and ceased foraging for food entirely (100% loss of feeding time), followed by humpback whales and long-finned pilot whales (both approximately 75%). Sperm whales had the lowest response, reducing time spent feeding by approximately 50% to both sounds.
引人矚目的是，每一物種對聲納及捕食者的聲音，同樣作出了反應：北方瓶鼻鯨有最強的反應，完全停止覓食(失去100%的進食時間)，其次是座頭鯨及長鰭領航鯨(兩者大約75%)。抹香鯨有最少的反應，對這兩種聲音的進食時間，花費減少大約50%。
It’s clear that the different hearing sensitivity of each species is not sufficient to explain the observed difference – that’s because the humpback whales, which have the best hearing in the frequency band of the sonar, were not the most sensitive.
很明顯，每一物種的不同聽力靈敏度，不足以解釋此觀察到的差異。那是因為，在聲納頻帶中，座頭鯨有最好的聽力。不過，並非最敏感的。
Instead our findings indicate that risk from killer whales plays a role in driving the responses, and that adaptations to their predators can explain cetacean sensitivity to human-made noise.
反而，我們的研究發現顯示，在驅動此些反應上，來自虎鯨的風險，扮演了一種角色，及鯨目動物對其捕食者的適應性變化，能解釋其對人為噪音的敏感性。
The northern bottlenose whales, who rely on crypsis (staying hidden) and flight to reduce their risk of death by killer whale, were very cautious and gave up feeding when detecting sounds of potential threats – but the species that are less vulnerable to predation were also less responsive to sounds of killer whales and sonar.
仰賴隱匿(保持隱藏)及飛躍，來降低遭虎鯨殺死風險的北方瓶鼻鯨，非常謹慎。因此，當察覺潛在威脅的聲音時，放棄了進食。不過，較不易遭受捕食的物種，對虎鯨及聲納的聲音也較不敏感。
Our findings can help to predict which cetaceans are likely to have extreme responses to human generated ocean noise – and help us to set appropriate conservation priorities.
我們的研究發現能有助於，預測哪些鯨目動物，對人類產生的海洋噪音，可能有極端的反應，及協助我們確定適當的優先保護事項。
The findings are particularly relevant to cetacean species in the Arctic as they are at highest risk of predation.
此些研究發現，特別與北極地區的鯨目物種相關聯。因為，它們冒有最高的捕食風險。
For example, Narwhal behaviour and distribution is influenced by Arctic killer whales and, as we would expect, they are sensitive to human-made sounds such as airgun pulses and ship noise.
譬如，獨角鯨的行為與分佈，受到北極地區之虎鯨的影響。如同我們常認為的，它們對於諸如氣槍脈衝及船舶噪音等，人造聲音很敏感。
As sea ice rapidly decreases, Arctic cetaceans face a double whammy of impacts – increasing levels of predation from more killer whale movements into ice-free zones, as well as increasing levels of noise from human activities, such as seismic exploration, military and shipping.
隨著海冰迅速減少，北極地區的鯨目動物面臨了，除了增多來自諸如，地震勘探、軍事及航運等，人類活動的噪音水平之外，來自更多虎鯨進入無冰區的捕食水平，也增加之影響的雙重致死打擊。
As well as the risk of immediate injury or death, it will be important to consider the effects of human disturbance on their feeding and other behaviours.
除了立即之傷害或死亡的風險外，考慮人類對其進食及其他行為之干擾的影響，這也會是很重要。
網址：https://theconversation.com/weve-discovered-why-some-whales-stop-feeding-in-response-to-the-sound-of-sonar-179541
翻譯：許東榮
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