Just months after the state enacted new lay gill net regulations, an apparently illegal net killed a Hawaiian monk seal at Makua Beach Sunday.

The seal's head and upper torso were thickly entangled in a gill net strung with orange floats.

A NOAA Fisheries necropsy found that the 450-pound adult male animal drowned. The seal was known to frequent the area around Ka'ena Point and was described by NOAA Fisheries veterinarian Robert Braun to have been in excellent physical condition.

In a poignant subtext to the story, an adult female seal stayed with the net-wrapped body for an extended period, appearing to guard it when humans came too close.

"At one point, a large wave came up and washed the dead seal back down into the water and the other began to follow. Two of the (state conservation) officers ran to the dead seal and attempted to haul it back up, while a third tried to distract the live one, who began barking and appeared to want to defend the dead body, moving toward the officers," Lisa Seng Dooling wrote in an e-mail to The Advertiser. Dooling was part of a group of divers at the beach Sunday.

NOAA Fisheries, in a press release, confirmed that responding enforcement officers "were challenged by the presence of another monk seal that refused to leave the side of the dead seal."

A third seal was also seen in the water near the shore, but it did not come up on the beach.

Under state regulations, gill nets are permitted during daylight at Makua, but each net must be marked so its owner can be identified, nets cannot be left in the water more than four hours, or left without being inspected for more than 30 minutes. It appeared the net that killed the seal Sunday was neither properly marked nor attended, said Debbie Ward, public information officer for the state Department of Land and Natural Resources.

State conservation enforcement officers are investigating the case. Anyone who has information about the case can call the DLNR Enforcement Hotline anonymously at 643-DLNR, or 643-3567.

Dooling said she heard from other people on the beach that beachgoers had seen "a commotion out in the water where the net was, probably the seal getting entangled." She said she wondered whether the other seals might have interfered if anyone had tried to release the seal.

"I also heard that the seals in that area are known to pick from the nets, setting them on a collision course as happened on Sunday," she said.

Sunday's death was the fifth case of a seal reported caught in a gill net in the past six years in Hawaiian waters.

In November 2006, a 5-month-old female seal was killed in an unattended net off Makai Pier. The animal was well known to monk seal volunteers, who had nicknamed her Penelope.

In 2005 a netted seal near Barbers Point was cut free before fisheries arrived. In 2004 a fisherman cut a seal out of a net at Kapa'a, Kaua'i.

And in 2002, at Makua Beach, a diver was able to cut free a seal trapped in a gill net. In that case, the seal was entangled but had been able to drag the netting to the surface to breath.

Hawaiian monk seals are listed as an endangered species, but their numbers have continued to fall despite that protection. Most are found in the Northwestern Hawaiian Islands, but in recent years they have been appearing in the main Hawaiian Islands as well.

"With only 1,200 monk seals left, and only 80 in the main islands, we can't afford to lose any," said David Schofield, marine mammal response coordinator for NOAA Fisheries.

Reach Jan TenBruggencate at jant@honoluluadvertiser.com.