Endangered fish may face new threat: sexual harassment

2008-02-01 20:09:41 Xinhua English

BEIJING, Feb. 2 (Xinhuanet) -- Scientists revealed that the critically endangered Mexican fish Skiffia bilineata might face new threat: male Trinidadian guppies (Poecilia reticulata) are constantly sexually harassing the endangered females, media reported Saturday.

Scientists knew that male Trinidadian guppies sexually assault females of their own species, and were concerned over whether they harassed the endangered fish as well.

The researchers found that when put in aquaria together, male Trinidadian guppies persistently tried having sex with the female S. bilineata, even when seven of their own females were present.

Normally S. bilineata have sex by simply uniting their genital pores in a copulatory embrace. Male Trinidadian guppies, on the other hand, have sex using a hooked organ -- their "gonopodium." As such, they can damage the endangered females, and female S. bilineata have to spend a lot of energy dodging the guppies.

"Sometimes we observed harassed females jerking away from guppy males when the males appeared to have inserted their gonopodium," said researcher Alejandra Valero, a behavioral ecologist at the National Autonomous University of Mexico in Mexico City. "We are assessing several possible ways in which female Skiffia can be damaged by guppy sexual activity."

The guppies could be contributing to the decline of the Mexican fish. "Half of the species in the Goodeinae tribe to which Skiffia bilineata belongs are already at risk of extinction," Valero said.