Whales change their tunes when ships appear

By Susan Scutti, CNN

Updated 1803 GMT (0203 HKT) October 24, 2018

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Sea puppy – You may melt a little when encountering an Australian sea lion, also known as Labradors of the sea.

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The largest remaining colonies of Australian sea lions are found on the islands of South Australia. Among them, Hopkins Island is the the most accessible destination to see the adorable mammal.

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Australian sea lion – The largest remaining colonies of Australian sea lions are found on the islands of South Australia. Among them, Hopkins Island is the the most accessible destination to see the adorable mammal.

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Despite being the largest fish on the planet, the Whale Shark is a gentle swimming companion. South Ari Atoll, a ring of 120 sunny islets in the Maldives, is a regular hangout for these sea giants.

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Whale Shark – Despite being the largest fish on the planet, the Whale Shark is a gentle swimming companion. South Ari Atoll, a ring of 120 sunny islets in the Maldives, is a regular hangout for these sea giants.

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It's the stuff of nightmares for some, but encounters with the white shark can be as exhilarating as they are terrifying. Cage-diving expeditions for the brave are operated around the Neptune Islands -- a series of uninhabited islets 30 kilometers southeast of Cape Catastrophe in South Australia frequented by the sharks.

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White shark – It's the stuff of nightmares for some, but encounters with the white shark can be as exhilarating as they are terrifying. Cage-diving expeditions for the brave are operated around the Neptune Islands -- a series of uninhabited islets 30 kilometers southeast of Cape Catastrophe in South Australia frequented by the sharks.

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As wide as an RV – "The largest great whites are six meters long but it's their girth -- as wide as a van -- that took my breath away," says writer Ian Neubauer.

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The swimmers on a humpback whale tour can hold on a line about 100 meters away from the marine creature. It's then up to the whales to come over and say hello. Humpback whale tour operator Sunreef says so far all its tours have successfully spotted whales but only half of them got to swim with one.

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Humpback whale – The swimmers on a humpback whale tour can hold on a line about 100 meters away from the marine creature. It's then up to the whales to come over and say hello. Humpback whale tour operator Sunreef says so far all its tours have successfully spotted whales but only half of them got to swim with one.

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Thanks to a successful wildlife recovery program, the number of humpback whales has increased in recent years. Humpback sighting is a popular activity in the southern waters like Australia. The species migrate to the north from June and return to the south in November.

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Humpback season – Thanks to a successful wildlife recovery program, the number of humpback whales has increased in recent years. Humpback sighting is a popular activity in the southern waters like Australia. The species migrate to the north from June and return to the south in November.

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Saleaula Turtle Reserve in the northeast corner of Savai'i -- Samoa's largest island -- is a safe haven for green turtles and the place for a safe turtle encounter.

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Green turtles – Saleaula Turtle Reserve in the northeast corner of Savai'i -- Samoa's largest island -- is a safe haven for green turtles and the place for a safe turtle encounter.

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Story highlights

Humpback whales use sound to find food and mates and to navigate around the ocean
Commercial ships emit low-frequency noise that disrupts whale communication

(CNN)Commercial ships emit low-frequency noise wherever they roam and this unwanted soundtrack negatively impacts marine life, new research suggests. Humpback whales stop singing or shorten their songs with the passing of ships, a new study published Wednesday in PLOS One reveals.

Ocean noise has been increasing in recent years, according to the study authors.