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By Liu Yu-ching and Jonathan Chin / Staff reporter, with staff writer
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Taiwanese scientists have hatched the eggs of Penghu Island octopuses under lab conditions, in a potential breakthrough for artificially breeding the endangered species.
The cephalopods, designated octopus sp. TW-10 — which researchers in 2006 identified as a previously undocumented species — is threatened by population decline from overfishing, the National Penghu University of Science and Technology said in a statement last week.
The miniature octopuses are a scientific mystery, famous for being seen almost exclusively during spawning, which takes place between March 29 and April 12, said Lee Meng-fang (李孟芳), an associate professor of aquaculture at the university.
A Penghu Island octopus is pictured in an undated photograph.
Photo courtesy of Lee Meng-fang
The species’ short lifespan of about a year and its female members’ habit of retreating into the ocean’s depths immediately following mating make the octopuses difficult to observe or study, he said.
The program to breed the octopuses in captivity, which took a decade to achieve results, utilized specimens captured during the spring spawning season, he said.
Female octopuses of the species carry only about 100 of the tiny, 16mm-long eggs, compared with other small cephalopods that lay thousands of eggs at a time, Lee said.
No eggs were documented until the Penghu branch of the Fisheries Research Institute found four caught in the filter of a tank, he added.
Female octopuses of the species carry inseminated eggs internally for between three and four months, then lay clutches of eggs that they protect for three more months, he said, adding that this gestation period takes up almost half of the octopuses’ life cycle.
The research found that female octopuses are highly sensitive to light and other interference when guarding their eggs, often preferring to dispose of the eggs if they are disturbed, he said.
This suggests that light pollution in the seas around Penghu might have contributed to the decline of the octopus population, Lee said.
The study produced 30 octopus larvae, which matured rapidly and attached themselves to the simulated ocean floor as soon as they hatched, bypassing the planktonic phase of normal octopods, he said.
Preliminary success achieved in the captive breeding program could allow the octopuses to be farmed throughout their lifecycle for food, similar to the sea urchins currently being cultivated in Penghu, he said.
