HILO, Hawai'i — Crews yesterday responded to two incidents reportedly involving injured whales, trying to assist a whale entangled in thick line that was dragging a cargo net and searching for another whale struck by a vessel.

Wende Goo, spokesperson for the National Ocean & Atmospheric Administration Fisheries Service, said a crew searched about five nautical miles yesterday in an effort to confirm reports that a vessel struck a whale between Lahaina and Lana'i.

"Various sources" reported that they believed a whale had been struck shortly before 11 a.m. because they saw blood in the water, but an investigator working with the U.S. Coast Guard was unable to locate an injured animal, Goo said.

The search was discontinued, and the NOAA will now have to rely on other sightings to locate the whale that was reportedly involved, she said.

In the other incident, Goo said a disentanglement crew used a satellite tag to locate the stricken whale off the Big Island just before noon, and Goo was still waiting for a report on the animal's condition.

Capt. Jeff McConnel of Ocean Sports Waikoloa said the whale was spotted shortly after 10 a.m. Tuesday during what was supposed to be a two-hour whale-watching tour by the 65-foot catamaran 'Alala.

The boat came upon two whales near Kawaihae, and "we noticed that one was really light colored, almost like a pinkish color on its back, and we could tell as we got a little closer that the whale was looking sick and acting funny, and it never went down."

The crew and passengers initially thought the 40-foot humpback had a propeller cut a few feet forward of its dorsal fin, but then realized what they saw was actually a strand of yellow, one-inch Polypropylene line looped around the animal and biting into its flesh, causing an indentation that looked like a cut.

At the other end of the line and about 60 feet behind the whale appeared to be a submerged cargo net that the whale was dragging along behind it, McConnel said.

The crew reported the stricken whale, and the 'Alala stayed with the humpback as it headed south along the coastline.

"It just never went down, and we knew it was injured and sick, and it wasn't going to survive this" unless it could be disentangled, McConnel said.

The stricken whale was accompanied by a smaller companion measuring 30 to 35 feet that from time to time would exhibit aggressive behavior such as slapping a fin, McConnel said. The whale watchers interpreted that as an effort by the smaller whale to scare off predators, possibly including a tiger shark.

Federal officials met the 'Alala about 11 miles south of Kawaihae at 2:30 p.m. Tuesday, he said.

Goo said the whale was tagged at about 4 p.m. Tuesday so it could be located yesterday by a disentanglement team with the proper equipment. "We're hoping to do an assessment," she said yesterday.

Reach Kevin Dayton at kdayton@honoluluadvertiser.com.