The humpback whales were back in Alaska's Prince William Sound this summer, but whale researcher Jan Straley was not there to meet them. The funding to finance her research into how many herring are eaten each year by the 30- to 50-ton behemoths had run dry.
Herring are the last major touchstone of the Exxon Valdez oil spill. As the Sound has steadily recovered in the 21 years since Exxon's tanker hit Bligh Reef and spilled 11 million gallons of crude, the herring have been the species around which the oil giant's critics have always been able to lament serious, ongoing environmental damage.
"The spill stopped after just a few days," The New York Times' William Yardley wrote in May of this year. "Recovery may not have an end date ... The mountain views are still stunning but the herring fishery is gone."
Yardley was among the many reporters who gathered up their fleece and foul-weather gear to troop north to Alaska to report on the legacy of Exxon's oil as the crude of BP spewed a geyser beneath a sunken drilling rig in the Gulf of Mexico earlier this year. The stories all had a similar theme: Old oil can still be found beneath the beaches of the Sound, and the herring have never come back.
"Two decades after the Exxon Valdez spilled almost 11 million gallons of crude oil into Alaska's Prince William Sound, the herring still have not come back," wrote Cindy Chang for the New Orleans Times-Picayune. "Without that cornerstone species, the commercial fishing season now starts two months later, in May instead of March."
Those claims are partially true. Though the herring did come back after the spill, and though there were a couple of Marches after the spill when commercial herring fisheries took place, the herring population eventually shrank and remains at a size that has blocked commercial fishing for a more than a decade.
There are still plenty of herring in the Sound. It's just that there isn't the volume of surplus herring fisheries biologists say is needed to support a commercial fishery. Straley thought she could be on to the reason why. Humpback whales, the University of Alaska Southeast professor of marine biology discovered, were not only feasting on the herring as they had in summers past, but a significant number of the whales had stopped migrating away from the Sound in the winter, choosing instead to hang around and keep chomping herring year round.
Preliminary research, she said back in 2009, showed whales "were exerting predation pressure on Prince William Sound herring, which is potentially impeding the recovery."
Straley wasn't the only one taking note of this. National Oceanic and Atmospheric Administration scientist Stanley "Jeep" Rice in a 2009 report to the Exxon Valdez Oil Spill Trustees stressed that in order to determine what was going on with Sound herring "a necessary piece of information is the whale predation on juvenile herring. Targeted predation on herring is much greater that presumed prior to the start of these studies, and has a large impact on the standing biomass of herring."
Predation on juvenile herring is exactly what Straley would have liked to have been studying in the Sound this summer, but in an e-mail in July she could only observe that "(I) wish I was there. We never got to finish our study looking at what age class is targeted by humpbacks."
Straley couldn't quite understand why the money ran out. How is it, she wondered, that "when science says X, the responsible agency does Y ... makes no sense to anyone, but someone knows why this happens."
Publicly, the answer to this question is that research into whale predation on herring is not directly linked to what damage oil did to the small forage fish. Privately, some say the real answer is that Straley might have been closing in on an uncomfortable answer to the question of why Sound herring stocks these days are too small to support a commercial fishery.
For commercial fishermen in Prince William Sound, who have made something of a second industry as victims of the Exxon Valdez spill, it is better to blame Exxon for the decline of the herring stocks than humpback whales. And this is doubly true for environmentalists, who still consider the humpback whale endangered despite a population more than 10 times the size of what it was in 1966 when the International Whaling Commission banned hunting for the species.
And who knows what crazy Alaskans might propose if the whales were found to be the cause of the decline of a fishery once worth $6 million to $11 million per year? Aerial whale hunts, maybe? Because there is some strong evidence to indicate that what wolves have been able to do to moose in some well-documented cases in Alaska -- knock their populations down and then hold them low -- whales have been able to do to herring in the Sound.
Richard Thorne, a scientist with the Prince William Sound Science Center in Cordova, even used the term "predator pit" in describing the status of the herring to Seattle Times reporter Hal Bernton, who examined the situation in October 2009. Bernton's well-researched reportage was unfortunately buried beneath the fallout from BP's Deepwater Horizon oil spill, which sent a swarm of Outside reporters to Alaska looking for the sky destined to fall on the Gulf of Mexico.
They found those herring that still hadn't come back, though in report after report since the middle of this decade, Thorne has been hinting at a very visible reason why. Field observations he has made while surveying herring populations repeatedly talk about whales taking up residence in the Sound in such numbers that they actually alter the behavior of herring in much the way large concentrations of wolves and bears have been shown to move moose toward the comparative safety of Anchorage cities and villages to calve their young.
"The fish distribution over the time period (of March 29 to April 2, 2007) was also clearly influenced by marine mammal predation, especially whales," he wrote in one of those reports. "These fish also showed atypical distributions, very near the bottom even during the night. It was only immediately adjacent to the spawning beaches that the herring came into midwater. Whale predation was intense, with at least 15 humpback whales foraging on the herring concentration. There were also about 300 Steller sea lions."
The sea lions are another endangered species. Who wants to know that they, too, might be implicated in a herring decline more comfortably blamed on a rich, greedy multi-national oil company? Sometimes people are most comfortable simply believing what they most want to believe.
In fact, as Gary Marty, a scientist at the University of California Davis pointed out, no one has ever even shown a mechanism for how Exxon oil might have started -- let alone continued -- the latest Sound herring decline. Marty, whose research in the Sound was financed by the federally financed Exxon Valdez Oil Spill Trustees Council and not by Exxon, believes that predation is probably part of the reason for the decline, along with disease and possibly other environmental factors.
All could work to feed each other, he said. Diseased herring living in a warming ocean might be weaker and more vulnerable to predation than their healthy counterparts. And, he adds, there was clearly a time early in the spill when oil was toxic to herring.
As to toxicity over the past decade, however, he points to a report offering the consensus of all the federally funded EVOS scientists. It concludes that "although there is evidence of biologically available Exxon Valdez oil in PWS, these intertidal areas do not include historical herring spawning habitat, and their zone of influence is relatively small. In general, water in PWS is characteristic of the least-contaminated portions of the world's ocean, suggesting that oil exposure is inconsequential for Pacific herring.
"One hypothesis is that 'oil metabolites,' produced by microbial action, chronically affect the herring population. There is no evidence and no mechanism to suggest that more chemically reactive, thus more readily degraded, metabolites would be present after the hydrocarbon source is gone. Thus we find no support for this hypothesis."
And yet the herring population remains depressed below its peaks prior to the Exxon Valdez oil spill. Could the whale watchers have the answer?
"We have observed a change in the PWS herring wintering and prespawning distributions over the past (eight) years," Thorne wrote in 2008. "Prior to 2003, both the overwintering and prespawning distributions were around Montague Island. Since 2003, the overwintered distribution has altered, and the prespawning distribution has shifted to Port Fidalgo and Port Gravina. We speculated that the change may have been forced by the high numbers of foraging whales that we had observed around Mountague Island throughout winter and spring.
"A recent survey of PWS (January 2008) observed over 50 whales. This trend may not bode well for the continued success of the (herring) population."
On the other, the whale watching in the Sound is now good pretty much year round.
Contact Craig Medred at craig(at)alaskadispatch.com.