Charlie Phillips, of the Whale and Dolphin Conservation Society, said porpoise sightings had been reported.

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Toni Collette plays Muriel, the shyest member of a bored and bulbous family living in Porpoise Spit.

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The common name of Burrunan dolphins derives from the Aboriginal Australian for "large sea fish of the porpoise kind".

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The mammals have smaller triangular dorsal fins than dolphins, which also make "more of a commotion" than porpoise when hunting.

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The largest was a group of 44 bottlenose dolphins spotted near Anglesey, while others included minke whale and harbour porpoise.

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He said porpoise had not been seen around the bridge with any frequency for a number of years, but several have been sighted so far this year.

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In the 17th century the waters around southwest England were home to blue whales, as well as large numbers of porpoise, dolphins, and blue and thresher sharks.

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The move also provides protection for the harbour porpoise.

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