Fishing guides, Indian tribes, biologists, and environmentalists showed up in force at a public hearing yesterday in Portland, Ore., to tell federal authorities that they want four dams on the lower Snake River in southeastern Washington to be breached to save salmon runs from extinction. A caravan of about 80 trucks hauling fishing boats and bearing signs such as “Salmon are jobs” circled the hearing site. The hearing was the first of 13 to be held in the Northwest and Alaska on the controversial issue of how to restore salmon runs in the Columbia River Basin. In the past, fishers have been generally quiet on the issue, but now some commercial fishing groups are urging their members to speak out and support breaching.