WAILUKU, Maui — Greg Kaufman, of the Pacific Whale Foundation, yesterday testified for a ninth day in a Maui Circuit Court hearing to determine whether Hawaii Superferry should be allowed to resume interisland service while an environmental assessment is conducted on ferry-related improvements at four ports.

The hearing, now in its fourth week, appears headed for a conclusion by week's end. Kaufman, testifying on the potential effects of the high-speed ferry on humpback whales and other whales and dolphins, has been a key witness for the Sierra Club, Maui Tomorrow and the Kahului Harbor Coalition, which have been pushing for an environmental review.

The three groups, which won a Hawai'i Supreme Court ruling ordering the state to perform the assessment, are trying to convince Judge Joseph Cardoza that allowing the ferry to operate before the environmental study can identify mitigation measures would unnecessarily threaten whales, risk the spread of invasive species and cause other problems.

Hawaii Superferry suspended service between Honolulu, Kahului and Nawiliwili on Aug. 27 because of a Maui court order and anti-ferry protests on Kaua'i.

Kaufman's testimony has been slow going, and was interrupted on several occasions to allow other witnesses facing scheduling issues to appear. The Maui-based whale researcher has testified that the size and speed of the 350-foot ferry pose a grave risk to whales and dolphins, and that the vessel's routes take it through areas favored by humpback whales that spend winter in Hawai'i.

He proposed slower speeds of 13 knots in shallower waters favored by whales, and a year-round Honolulu-to-Maui route farther north of Moloka'i than what the company plans to use.

Superferry attorneys have questioned Kaufman's credibility, noting that the Pacific Whale Foundation is the largest operator of whale-watch tours in Maui waters, with a fleet of seven tour vessels, one of which was involved in a 2006 whale collision.

As the hearing draws to a weary close, attorneys for Hawaii Superferry, the state Department of Transportation and the three groups have traded accusations of "mudslinging" and "filibustering."

Hawaii Superferry attorney Lisa Munger yesterday renewed her claim that opposing attorney Isaac Hall was dragging out Kaufman's testimony in an attempt to delay a court decision and further damage the company. She said the company had lost $1 million just in the time Kaufman has been on the stand.

While breaking up yet another verbal exchange between the lawyers yesterday, Cardoza, who has demonstrated exceptional patience throughout the hearing, seemed as close as he's come to expressing exasperation with the proceedings.

"The Hawaii Superferry and the plaintiffs have spent a considerable amount of time with the witnesses in this hearing, and it wouldn't be fair to say one side is filibustering. We've had many, many objections to the questions asked, and it is the right of the parties to object and protect the record — I don't have any problem with that," he said.

"Both sides have asked a lot of questions for the witnesses, and I don't think one can say that the other is responsible for the fact this hearing has been a long one. Why don't we just get on with the testimony?"

Kaufman is to take the stand for the 10th time at 10 a.m. today. He is expected to be followed by Hawaii Superferry marine mammal expert Mark Fraker. Still to testify is company President and CEO John Garibaldi.

Reach Christie Wilson at cwilson@honoluluadvertiser.com.