In whaling days, savvy sailors predicted with deadly accuracy where leviathans would emerge from the ocean after they sounded. Finding whales was half a whaler’s job; the other important half was knowing where it was going.

The National Marine Fisheries Service could use some old whalers in its service today, to improve upon its scorched sea approach toward tracking endangered right whales through coastal Maine waters.

Late yesterday, NMFS called off its essential shutdown of the Downeast lobster fishery, set for Saturday, after an aerial pass Oct. 5 had observed three right whales offshore of Machias. To protect the whales, the agency instituted a two-week “Dynamic Area Management” zone in adjacent waters.

In DAM zones, fishermen must remove gear potentially harmful for whales. For lobstermen, this means standard floating trap lines. Traps with sinking lines, a mandate come October 2008, may stay, but few in the fleet say they’ve undertaken this costly retrofit.

Plus, they argued, who knows where the whales are, anyway. U.S. Sen. Olympia Snowe and others pressured NMFS to check again for whales in the affected area (about 841 square miles). The search revealed the whales had, in fact, departed the grounds, prompting the agency to cancel the DAM.

Right whales, hunted to near-extinction by whalers, are vulnerable to ship strikes and gear entanglements, and deserving of federal endangerment protections. But if protection is the primary concern, it should be imperative to know the whale’s specific location.

Using inexact estimates of whale location to dictate sprawling ocean closures is deeply flawed; unless whale travels are followed and understood, there’s nothing government regulators or fishermen can do to protect them from actual harm. Ordering dangerous gear removed won’t save a whale entangled in unmoved lines.

And hamstringing a fishery for potential harm to whales, several days after they were first observed, is just as unacceptable, because whales can leave the fishing grounds. (Just as these whales did.) Or, even worse, these whales could have been harmed in their extended unobserved interim before the DAM.

Scientists understand this conundrum, as although tracked for centuries, little is known about right whales. This year, the Maine Department of Marine Resources and others attached suction-cupped radio tags to right whales traveling between Mt. Desert Rock and Jeffrey’s Ledge, to record their travel.

In the hands of a Nantucket whaler, this specific information could have wiped this endangered species from the world’s oceans. But given to scientists, regulators and fishermen, detailed knowledge of whale travels will provide for the formation of solid, sensible and effective protective policies.

Which are opposite of what’s available now, when NMFS must declare a wide swath of ocean off-limits, because there could be whales swimming in it. This gives little practical protection to whales.

But it does entangle fishermen from making a living.