Boston — It is a question many people are asking, but to which no one seems to have the definitive answer: How serious a threat is offshore oil exploration and production to the marine ecosystem of Georges Bank?
The question is at the very center of the current debate in Massachusetts over how best to apportion offshore tracts for oil and gas exploration. The question arises as the Massachusetts attorney general's office and federal attorneys for the United States Interior Department prepare to face off in court to determine if the scheduled Sept. 26 auction of some 6.3 million acres of offshore exploration tracts will go ahead as planned.
The state is seeking a federal injunction to block the auction. State officials contend that widespread oil and gas exploration might pose an environmental hazard to the Georges Bank fishing grounds.
Federal officials contend the environmental risk is minimal compared with the potential gains of reducing America's dependence on foreign sources of crude oil.
Who is right? Can scientific studies help identify a compromise?
The problem, according to one scientist who has studied the possible effects of an oil spill on Georges Bank, is that there are a number of natural forces at work on the productive fishing grounds which can and do cause fluctuations in the fish stocks.
Malcolm Spaulding of the University of Rhode Island says he and other researchers found in a 1981 study for the Interior Department's Minerals Management Service that there would be a decline in fish stocks as a result of a major oil spill or oil-well blowout - but that the decline would probably be less severe than population reductions that are regularly caused by natural forces on the Georges Bank.
''We can show that indeed there are impacts (of an oil spill). The impacts are, however, below the environmental variability in the system,'' Dr. Spaulding says. ''While the impacts are there, it is very, very hard to sort them out.''
Mark Reed, also a participant in the Georges Bank research team and now a Rhode Island consultant, says the group used a computer model to simulate a large oil spill of 60 to 70 million gallons of oil over a 30-day period. The group found that in terms of cod, the spill ''could result in a 20 percent loss of one year's yield from the fisheries,'' Mr. Reed says. ''But that would happen over a period of several years - it wouldn't happen all at once.''
''We are probably not looking at a catastrophe,'' he adds. ''Nothing in our study suggests that we are going to wipe out the fishery on Georges Bank as a result of a large oil spill.''
The Rhode Island study has been cited by both the Interior Department and the American Petroleum Institute (API), among others, as evidence that oil production and the fishing industry can thrive side by side.
Others don't see it that way. Some environmentalists say the study underlines the widespread uncertainty and lack of information about the effects of oil production on fisheries.
''It's frustrating. You'd like to make a simple answer one way or another - but it is not a simple problem,'' says Robert Howarth, a marine ecologist with the Marine Biological Laboratories at Woods Hole, Mass. ''We honestly don't understand the basic biology that controls fish.''
He adds, ''I think there is potential for serious harm from offshore oil drilling, but you can't prove it at the moment.''
Oil industry officials point to the Gulf of Mexico as an example of how offshore oil rigs and the fishing industry can coexist. According to the API, the fish catch in the Gulf of Mexico has increased from 571 million pounds in 1950 to 2.4 billion pounds in 1983. The group notes that the catch equals nearly three times the size of the catch in the North Atlantic and mid-Atlantic areas combined.
The API says more than 20,000 wells have been drilled in the Gulf, and some 4 ,000 oil and gas platforms are currently working in Gulf waters. A press release adds: ''In all of the US offshore lease offerings of the past 30 years, not a single area leased shows evidence of degradation to the fishing industry, the marine environment, or the coastal zone.''
Mr. Hobarth disagrees. He says that while the fishing catch in the Gulf of Mexico has risen - in part as a result of better techniques and more boats - the total number of fish in the Gulf has declined from levels prior to oil exploration. But he is quick to add that this decline has probably come more as a result of the destruction of coastal marshes where the fish spawn, rather than as a result of oil exploration or production.
The Woods Hole scientist says that the Georges Bank ecosystem is different from that of the Gulf, in that more than 50 species of fish use the offshore area - rather than coastal marshes - to spawn. He says this makes the Georges Bank an environmentally sensitive area.
''We do know that oil can cause a lot of biological harm,'' he says. ''My own feeling is that we have to be very careful under those circumstances. I'd hate to see us rush into what we know are sensitive areas, knowing as little as we do now.''
He adds, ''The oil companies take a different approach and say, 'Well, if it isn't proven, lets just go ahead and hope it doesn't happen.' ''