The pilot of a sportfishing boat had gone below deck and left no one at the helm just before a collision with a 564-foot tanker outside Los Angeles Harbor late Thursday night, Coast Guard officials said Saturday. Coast Guard Cmdr. Chris Desmond said 2nd Mate Tim Filson of the fishing boat Shogun was primarily to blame for the crash with the tanker Sealift Antarctic. He said Filson may have his operating license suspended. The Coast Guard spokesman said Filson, 25, broke one of the "basic rules of navigation" by failing to keep a proper lookout before the crash, which injured seven people and spilled 2,000 gallons of jet fuel at the mouth of the harbor. But Desmond, head of the Coast Guard's Marine Safety Office in Long Beach, said that both vessels were to blame and that Capt. Arthur Irish of the Antarctic could also have his license suspended for failing to give way to the smaller vessel. Desmond said the fishing boat had the right of way at the time of the crash. Desmond said that at the completion of its investigation in about two months, the Coast Guard will probably recommend that Filson and Irish have their licenses suspended for an undetermined period.