Scientists are using underwater songs to uncover where elusive Omura’s whales live, what they may eat, and how they survive year-round in tropical waters.<\/p>\n
Spending the whole year in warm seas sounds like a comfortable arrangement. For a whale, though, warm water is only part of the deal: there also has to be enough to eat.<\/p>\n
Many whales travel between cold feeding grounds and warmer breeding waters, drawing on stored fat while they travel and breed. Omura\u2019s whale skips that routine and stays in the tropics.<\/p>\n
Off Australia, researchers have never documented what this elusive whale eats. Now, they have found a possible food clue by listening to its songs.<\/p>\n
The team detected whale songs most often in warmer waters, particularly where microscopic algae had flourished about a month earlier.<\/p>\n
That delay could help explain how a large animal finds meals in the same seas throughout the year, without making the long trip to colder feeding grounds.<\/p>\n
Finding whales through song<\/p>\n
Scientists only recognized Omura\u2019s whale as a separate species in 2003, having previously mistaken it for a small form of its relative, Bryde\u2019s whale. <\/p>\n
Most of what researchers know about its life still comes from a population off northwest Madagascar.<\/p>\n
Spotting one off Australia remains unusual, but its song gives researchers another way to find it. <\/p>\n
The whale repeats a two-part call lasting about 15 seconds, with some sounds lower than the deepest note on a piano.<\/p>\n
Ciara Browne, a PhD student at Curtin University<\/a> in Perth, led the team that searched recordings from 35 sites, collected between 2005 and 2023. <\/p>\n They reused sound files from other projects, letting software<\/a> flag possible calls before checking every detection by hand.<\/p>\n \u201cOmura\u2019s whales are notoriously difficult to study because visual sightings are rare, so listening for their calls provides an important way of understanding where they occur,\u201d Browne said.<\/p>\n From algae to dinner<\/p>\n The algae themselves are not the meal the researchers have in mind. They may start a chain in which small animals eat the algae, then become food for whales.<\/p>\n To look for that connection, the team used satellite measurements of chlorophyll, the green pigment in algae. <\/p>\n Those readings give scientists a rough idea of how much algae is growing, but readings from the day of a recording showed no clear connection to whale calls.<\/p>\n Looking back 30 days changed the picture. Higher algae levels a month earlier went with a greater chance of hearing whales, suggesting that food takes time to work its way through the ocean\u2019s food web.<\/p>\n Small algae-eating animals may need those weeks to become more plentiful, and researchers have seen a similar sequence off Madagascar. <\/p>\n There, algae blooms have preceded swarms of krill, the shrimp-like animals that attract feeding Omura\u2019s whales.<\/p>\n Where the whales sing<\/p>\n The recordings picked up calls in every month, with the busiest stretch running from September through May. <\/p>\n Calls became least common during the Southern Hemisphere\u2019s winter, from June through August.<\/p>\n The team\u2019s models showed a greater chance of hearing whales once surface water warmed beyond about 81.5\u00b0F (27.5\u00b0C). January through March offered the best odds.<\/p>\n Winter recordings placed more calling whales farther north<\/a>, toward the equator. <\/p>\n Recorders in the Joseph Bonaparte Gulf and off the Kimberley coast heard calls throughout the year, perhaps because those northern waters stay warm through winter.<\/p>\n A separate model also pointed offshore, with the best odds of hearing whales about 124 miles (200 kilometers) from the coast. <\/p>\n The pattern suggested that Australia\u2019s continental shelf and its outer edge could be important whale habitats.<\/p>\n Meals without migration<\/p>\n The shelf gives researchers a broad area to search for feeding whales, but plenty of details remain unclear. <\/p>\n Depth, distance from shore, and distance from reefs overlap, so the researchers could not tell which feature best explained the pattern.<\/p>\n Wind supplied another possible clue, although its connection to calls was weaker. <\/p>\n Strong winds can push surface water aside and allow nutrient-rich<\/a> water to rise from below, helping create conditions that concentrate krill<\/a> and small fish.<\/p>\n Near Scott Reef, researchers tracking the direction of songs found that some whales stayed in one place for long periods. <\/p>\n They may have been feeding while singing, although the songs alone cannot confirm that.<\/p>\n Together, the clues fit the possibility that Omura\u2019s whales keep eating throughout the year instead of depending mainly on one feeding season. <\/p>\n They probably still carry fat reserves, but regular meals could help sustain their tropical lives.<\/p>\n Sharing a noisy home<\/p>\n These whales live in waters that people use for shipping<\/a>, commercial fishing, and offshore oil<\/a> and gas operations. <\/p>\n Because they remain in the region throughout the year, they may face more sustained exposure to underwater noise than migrating whales.<\/p>\n That noise can interfere with communication and change animal behavior. It also makes whales harder for researchers to hear: near shipping lanes, the recorders picked up calls over shorter distances than in quieter deep water.<\/p>\n Knowing where whales spend their time gives people who plan offshore activity a better chance of considering them before making decisions. <\/p>\n Study co-author Christine Erbe directs Curtin\u2019s Centre for Marine Science and Technology<\/a>.<\/p>\n \u201cThis knowledge can help inform marine planning and improve our understanding of potential impacts from activities such as shipping, offshore industry and other sources of underwater noise,\u201d Erbe said.<\/p>\n The mysteries that remain<\/p>\n A recording tells researchers that a whale called within listening range, but it cannot reveal how many whales live there or what they ate. <\/p>\n Songs are the only vocalizations documented so far for Omura\u2019s whales, and if only males sing, as in other baleen whales, the results may largely miss females and calves.<\/p>\n The listening network also left gaps because researchers originally placed the equipment for other projects. <\/p>\n Different sites recorded in different years, and the analysis assumes the whales\u2019 range stayed fairly stable across those 18 years.<\/p>\n Sound-recording tags could capture calls beyond song, while genetic samples could help establish whether the singers are all male. <\/p>\n Scientists still lack enough information to judge the species\u2019 extinction risk, which explains its Data Deficient listing on the International Union for Conservation of Nature<\/a>\u2018s Red List.<\/p>\n As warming changes ocean temperatures and food supplies, these recordings give researchers a starting point for understanding where the whales\u2019 habitat may shift. <\/p>\n The study is published in the journal Marine Mammal Science<\/a>.<\/p>\n \u2014\u2013<\/p>\n Like what you read? Subscribe to our newsletter<\/a> for engaging articles, exclusive content, and the latest updates.<\/p>\n Check us out on EarthSnap<\/a>, a free app brought to you by Eric Ralls<\/a> and Earth.com.<\/p>\n \u2014\u2013<\/p>\n","protected":false},"excerpt":{"rendered":"Scientists are using underwater songs to uncover where elusive Omura’s whales live, what they may eat, and how…\n","protected":false},"author":2,"featured_media":811641,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[26],"tags":[90,56,54,55,4407],"class_list":["post-811640","post","type-post","status-publish","format-standard","has-post-thumbnail","category-wildlife","tag-science","tag-uk","tag-united-kingdom","tag-unitedkingdom","tag-wildlife"],"_links":{"self":[{"href":"https:\/\/www.newsbeep.com\/uk\/wp-json\/wp\/v2\/posts\/811640","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.newsbeep.com\/uk\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.newsbeep.com\/uk\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/uk\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/uk\/wp-json\/wp\/v2\/comments?post=811640"}],"version-history":[{"count":0,"href":"https:\/\/www.newsbeep.com\/uk\/wp-json\/wp\/v2\/posts\/811640\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/uk\/wp-json\/wp\/v2\/media\/811641"}],"wp:attachment":[{"href":"https:\/\/www.newsbeep.com\/uk\/wp-json\/wp\/v2\/media?parent=811640"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.newsbeep.com\/uk\/wp-json\/wp\/v2\/categories?post=811640"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.newsbeep.com\/uk\/wp-json\/wp\/v2\/tags?post=811640"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}