State conservation officials say they continue to follow leads in their investigation of Sunday's death of an adult male Hawaiian monk seal at Makua Beach, and there were suggestions yesterday that the death could lead to a complete ban on nearshore gill netting.

The animal was found densely wrapped in gill netting. A necropsy showed it had drowned.

A second seal, an adult female, remained with the dead male for some time Sunday, occasionally barking at humans who came too close.

"This is the second seal death in a gill net in the past eight months, and the state may be at risk of legal action for failing to protect the endangered Hawaiian monk seal. If we were sued under the Endangered Species Act, a federal judge could potentially order us to shut down our nearshore fisheries, at least those gear types that take endangered species," said Dan Polhemus, administrator of the state Division of Aquatic Resources.

Polhemus urged people who follow the law to apply peer pressure on those fishing illegally, to protect their own interests.

"A lethal take of a monk seal is a really big deal. We're vulnerable. Monk seals are on a downward trend and our federal partners are not pleased," he said.

State officials said the net that killed the seal was illegal in that it was not properly tagged with identification markers, and was being illegally used in that it was not being watched by its owner. Under new gill netting regulations, enacted earlier this year, although netting is allowed at Makua during daylight hours, nets cannot be left unattended for more than 30 minutes, and they must be registered and tagged.

It is estimated there are no more than 1,200 or 1,300 Hawaiian monk seals left, down by half from the number a few decades ago.

Carroll Cox, of the environmental group Envirowatch, said he photographed the same two seals about two weeks earlier at Ka'ena Point, hauled out together and frequently nuzzling each other.

David Schofield, marine mammal response coordinator with NOAA Fisheries, said that "preventing these accidents is key, because we are at the point where every seal counts."

Fair Catch Hawai'i, a campaign by several organizations to promote responsible fishing, issued a press release urging people to protect threatened marine life.

"The new lay gill net rules that went into effect in March of this year are an important first step toward restoring our nearshore fisheries. However, better enforcement and a complete ban of this indiscriminate fishing method may be necessary to protect highly endangered species as monk seals and sea turtles," said Kim Hum, marine program director for The Nature Conservancy of Hawai'i, one of the members of Fair Catch.

Reach Jan TenBruggencate at jant@honoluluadvertiser.com.