The Herring Red Herring

by Lou Dolinar

A perennial red herring of Gulf-oil-spill alarmists is the evil long-term side-effects of oil. There may be such effects, but they are far from proven. A case in point is the herring fishery of Prince William Sound, supposedly still decimated 20 years later by the Exxon Valdez spill. Virtually every media outlet, in recent days, cites this without qualification as the penultimate example of what can go wrong over decades in the Gulf.

Except, surprise!, it isn’t that simple. The Prince William Sound herring crop initially met expectations for a few years after the fishery was closed because of oil. It subsequently collapsed. This may have happened because the oil had hit during spawning season and killed off a year’s class of fish. But a number of peer-reviewed papers have suggested other causes — disease as well as competition from other fish, including salmon (a predator on herring), which had been artificially stocked in the area around the same time — that might have kept the long-term numbers down.

More recently, a happier theory has emerged to account for the persistently low population of herring, a keystone forage species upon which other species depend. It seems that humpback whales, once occasional visitors to the sound, have taken up permanent year-round residence. Jan Straley, a marine-biology professor at the University of Alaska, says the year-round visitors — a recovering but still endangered species — are primarily eating herring.

According to the Anchorage Daily News, researcher Ron Heintz modeled the the impact of all these new whales numbering perhaps 100:

“Heintz’s model gave a range of how much herring the whales might be eating — 1.5 to 4 gigajoules per day — the caloric equivalent of 600 to 2,200 Big Macs. That translates to a lot of herring, somewhere between 2,200 metric and 13,000 metric tons over the winter and a significant portion of the estimated total.

“The whales were able to consume somewhere between 10 and 66 percent of that prespawning biomass,” Heintz said. “Another way to look at that is that the last commercial fishery in Prince William Sound was about 3,500 metric tons, so the whales are clearly capable of consuming a biomass that would be in the ballpark of a commercial fishery in Prince William Sound.”"

Leaving aside the image of 2,200 Big Macs comprised of herring, it’s pretty clear that long-term effects are complicated — something you’re not going to hear from agenda-driven environmentalists trying to pass laws, or reporters trying to win prizes. The real problems of the Gulf are long-term — take a look at my oil-spill retrospective over on the homepage.    

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