LIHU'E, Kaua'i — After examining a young humpback whale carcass on a West Kaua'i beach yesterday, scientists still aren't sure why it died.

Preliminary findings are that the 17-foot long female calf had abnormalities in some organ systems, but scientists found nothing that indicates a conclusive cause of death, said Wende Goo, spokeswoman for the National Oceanic and Atmospheric Administration.

NOAA Fisheries staff, a contract veterinarian and the Hawai'i Pacific University Marine Mammal Response Team conducted a necropsy at the Pacific Missile Range Facility yesterday.

The animal washed up Monday at Kekaha Beach and was moved to the nearby base with the help of the Coast Guard and Kaua'i lifeguards.

Tissue samples from the whale will be sent to laboratories for analysis that could help determine cause of death, Goo said.

Kekaha Beach remained open because there were no shark sightings, said Randy Ortiz, ocean safety trainer for Kaua'i lifeguards.

It was the second whale calf carcass spotted off Kaua'i's west coast in the past two weeks, Ortiz said. A carcass had been reported on privately owned Ni'ihau Island in late January.

Investigators from the state departments of Land and Natural Resources, and Health, weren't able to find a whale carcass when they were on Ni'ihau to investigate a fish kill there last week, DLNR aquatic biologist Don Heacock said.

The results of that investigation, which found hundreds of dead reef fish on several Ni'ihau beaches, are pending results from various labs, Heacock said yesterday.

While on Ni'ihau, investigators observed dozens of monk seals for possible signs of trouble, but they appeared to be healthy, Heacock said.

Fish species found dead were more than 90 percent triggerfishes (humuhumu), Heacock said, but included some rudderfish (nenue), a snapper (ta'ape), and several other nearshore species.

Until the cause of the fish kill is determined, people are advised not to eat reef fish caught off Ni'ihau.

Possible causes of the kill include some type of unknown contaminant from a ship or from a land-based source, or a parasite, disease or marine toxin, Heacock said.

The Health Department lab is checking dead fish for any presence of diphacinone, an anti-coagulant, rodent-killing bait used that was used on the islet of Lehua, north of Ni'ihau, in January by the U.S. Fish & Wildlife Service, said Watson Okubo, of the Health Department's clean water branch.

"Normally the (rodenticide) concentration in pellets are small," Okubo said. That it would have caused a fish kill is "possible but not probable. We need to check what people are pointing fingers at."

The Fish & Wildlife Service used a helicopter to drop pellets of the rodent killer on Lehua twice in January in an attempt to rid it of rats, to benefit seabirds that nest there.

"As far as we know, everything went well," Fish & Wildlife Service spokeswoman Barbara Maxfield said.

Pacific Missile Range Facility spokesman Tom Clements would not speculate on whether any military training exercises at the range, most of which is in the open ocean, could have affected fish or whales.

"Our activities on the range in January and February were completely consistent with range requirements and not unlike activities that have been conducted here over the last 40 years," Clements said.

When the investigation is completed, the whale will be buried on the missile range grounds, with participation of a Hawaiian cultural practitioner, Goo said in a release about the incident.

Anyone with information on the fish kill is asked to contact: Don Heacock, DLNR Division of Aquatic Resources (Kaua'i), at 808-274-3344, or Watson Okubo, DOH Clean Water Branch, at 808-586-4309.