Demise of Herring in Prince William Sound Still a Mystery

By Margaret Bauman
Twenty-five years after the Exxon Valdez oil spill, and millions of dollars in
research, marine scientists still have no conclusions about the relationship
between that environmental disaster and the demise of Pacific herring in Prince
William Sound.
What we do know is that the Exxon Valdez oil tanker struck Bligh Reef in Prince
William Sound shortly after midnight on March 24, 1989, spilling 260,000 to
750,000 barrels of thick, toxic crude oil, creating one of the most devastating
human caused environmental disasters on record.
Then in subsequent storms and currents, the oil spread over
1,300 miles, fouling the shoreline, resulting in the deaths of vast numbers of
wildlife, including sea otters, herring and birds.
Some of that crude oil is still not cleaned up, and while
some species have recovered, herring have not. A once lucrative commercial
fishery, the herring, which also provided nutrition for seabirds, salmon and
marine mammals ranging from sea otters to whales, is still listed as “not
What is not clear is the direct relationship between the Exxon Valdez oil spill and the demise of the herring
fishery in Prince William Sound, but marine conservation scientist Rick Steiner
of Anchorage says that without doubt the oil spill had a significant effect on
the Prince William Sound herring population, and it is almost certainly one of
the reasons for the crash in 1993.
“Most of the 1989-year class, that was spawned as oil washed
ashore, was killed,” Steiner noted, in comments Sept. 10. “And, most of the
adults were exposed to varying levels of toxic oil. The Viral Hemorrhagic
Septicemia, Ichthyophonus, and Viral Erythrocytic Necrosis outbreaks were
likely caused, at least in part, by suppressed immune systems in adult herring
due to acute oil exposure, making them more vulnerable to such diseases and
Still, marine ecosystems are complex, and many variables go
into the herring equation – ocean conditions, zooplankton, stress induced by
capture for the herring pound fishery, predation, and so forth, he said. “There
are almost certainly multiple causes in the herring crash, but without doubt,
the oil spill is one of them,” he said.
Steiner points to the April 2013 final report on the Prince
William Sound herring survey program written by Scott Pegau of Cordova’s Prince
William Sound Science Center, a document that concludes that “there is no
consensus on the cause of the herring collapse in 1993 or the factors that have
led to the low recruitment levels over the past 20 years.”
The survey program was funded by the Exxon Valdez Oil Spill Trustee Council. The goal was to
develop an integrated research program to identify potential bottlenecks to
Pegau noted in the final report that there appears to be
agreement that Prince William Sound herring stocks are not likely to recover
without multiple large recruitment events, and that large recruitment events
can occur from a small adult spawning biomass.
“A single large recruitment event may be able to increase the
adult population to a level where future large recruitment events occur,” Pegau
wrote in his conclusions of the study. “The rapid increase in adults may cause
new spawning grounds to be used and therefore increase the possibility of
retention of larvae leading to strong recruitment.”
Pegau also observed that there is some evidence that change
in recruitment is related to zooplankton levels, but also noted that
researchers’ ability to identify the conditions that lead to a successful
recruitment event have been hampered by the fact that during all of the herring
observation periods there had not been a large recruitment event.
Steiner has been recognized by the British national
newspaper, The Guardian, as one of the world’s leading marine conservation
scientists, and one of the most respected and outspoken academics on the oil
industry’s environmental record. At the time of the oil spill disaster he was a
marine conservation professor with the University of Alaska, stationed in
As a university marine advisor for the Prince William Sound
region of Alaska from 1983 to 1997, he provided leadership in response to the Exxon Valdez oil spill, proposed and helped establish the
regional citizens advisory councils, the Prince William Sound Science Center,
and the billion dollar legal settlement between Exxon and the government, with
which much of the coastline of the oil spill region was protected. He has also
worked on oil issues in Pakistan, China, Russia, Lebanon, Nigeria, Shetland,
central Asia and the Gulf of Mexico.
Today he conducts the Oasis Earth project, a global
consultancy working with non-government organizations, governments, industry
and civil society to speed the transition to an environmentally sustainable
In science, Steiner said, there is a theorem called “Occam’s
Razor,” which is that among competing hypotheses to explain an observation, the
one with the fewest assumptions should be selected. “Essentially saying that,
when in doubt, the simplest hypothesis is usually the most accurate. Or,” said
Steiner, “as they say in the south, “if it quacks, it’s a duck.
“The simple explanation for the decline of Prince William
Sound herring, the hypothesis with the fewest assumptions, is the Exxon Valdez oil spill.
“Nowhere else in Alaska has the herring population crashed as
it has in the Sound, and nowhere else in Alaska has had 40,000 tons of a toxic
chemical (crude oil) dumped into it, right at the time of herring spawning.”
While it has become fashionable in the marine research
community to assert that there was no baseline data on the herring fishery in
Prince William Sound prior to the oil spill, that is simply untrue, he said.
Herring has been assessed and managed by government agencies for many decades
prior to the spill, and they had a pretty good idea of herring population
dynamics in Prince William Sound prior to the spill, he said.
Meanwhile, studies related to the demise of and hope of
rebuilding the Pacific herring stocks in Prince William Sound continue, with
marine biologists at Alaska Department of Fish and Game, the Prince William
Sound Science Center, and others.
“There are no conclusions,” said Rich Brenner, a research
biologist with ADF&G at Cordova. “That is the nature of scientific
consensus. We build information toward conclusions. That is the way it is.
“You think of science as building a glass house and people
throw objects at it, and when those objects no longer break the glass, then you
have reached scientific consensus,” he said.
Brenner also points to several studies on the herring
fishery, published from 2007 to 2011 in scientific journals, which came up with
different hypotheses.
One study published by the Ecological Society of America in
2008 noted effects of competition and predation by juvenile hatchery pink
salmon on herring juveniles, poor nutrition in the winter, ocean temperatures
in the winter, viral hemorrhagic septicemia virus and the pathogen Ichtyophonus
hoferi, and suggested that it may well be difficult to simultaneously increase
production of pink salmon and maintain a viable Pacific herring fishery.
The ADF&G studies include acoustic and aerial surveys,
said Brenner, whose role is to facilitate a variety of studies, including
current herring biomass trends. He also works with other agencies, including
the National Oceanic and Atmospheric Administration and the US Geological
Survey, on studies into physiology and disease related to herring.
ADF&G keeps in contact with researchers with the Prince
William Sound Science Center, who may be on the Sound at the same time, doing
acoustic surveys, he said.
“We have been fairly focused on adult herring and adult spawning
biomass. We are looking at prosecuting a fishery, and they are focused on
So the research continues, with many questions still to be
Did the initial absence of zooplankton from the herring diet
weaken their resistance to disease, ability to reproduce or defend themselves
against predators?
Did the oil spill somehow inhibit the ability of the herring
to fight off viruses and predators determined to have them for lunch?
Has there been too much competition with pink salmon from hatcheries
in the area for the same food?
How do changing temperatures and other environmental
conditions, or fishery management and harvests play into this picture?
Meanwhile, Steiner recently resubmitted a proposal he made to
the Exxon Valdez Oil Spill Trustees Council in 2002,
proposing a herring permit buyback initiative as a restoration effort.
When he first submitted that proposal to the council in 2002,
many permit holders were in support of the idea, Steiner said.
The money could then be used to buy individual fishing quota
or other salmon permits, thus giving the former herring fishermen an
opportunity to turn an inactive herring permit into some real fishing time.
And, said Steiner, this would clearly be best for the marine
ecosystem, leaving all the herring in the water for the many predators that
rely on them.
Unlike other fishery buyback, or capacity
reduction/rationalization programs, programs based on economic efficiency
rationale, the Prince William Sound herring fishery buyback for spill
restoration purposes would have to be applied on an all-or-nothing basis, he
Participation would have to be mandatory, not optional, and
to accomplish this, permit holders should be compensated at higher than current
market value for their permits, he said.