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Clues left by decaying salmon at the bottom of five Alaska lakes point to climate change and over-fishing as two causes of the state's boom and bust salmon runs, according to a recently-published study by Alaskan and Canadian researchers in the journal Science. Commercial fishing was found to have negative impacts on Kodiak Island salmon runs, the study also found.

Researchers determined the size of sockeye salmon runs going back 300 years by measuring levels of the stable nitrogen isotope, N15, in lake bottom sediments. As each generation of salmon returned home to spawn and die, their decomposing bodies left behind a nitrogen fingerprint in the sediment. Scientists took core samples and measured the nitrogen isotope in the sediment layers. From that, they calculated the relative size of salmon runs over time. Markers, such as ash from known volcanic eruptions, helped scientists fix a date to the layers.

Scientists then were able to link abrupt changes in the size of sockeye runs with large-scale climate shifts in the North Pacific Ocean, as indicated by sea surface temperature records and tree ring analysis. In general, sockeye runs were larger during periods of warm climates, and smaller during cold periods.

"We got some pretty strong signals," says lead author Dr. Bruce Finney, associate professor of marine science at the University of Alaska Fairbanks Institute of Marine Science. For example, Finney and his colleagues from Queen's University and the University of Toronto noted that salmon runs were low during the early 1700s and again in the early 1800s. "These periods were particularly cold, some of the coldest in the past several centuries," he points out.

Salmon runs became larger during warm periods, such as the late 1700s, mid 1800s, and early 1900s. However, the researchers' ability to measure changes during more recent decades was hampered by the influence of commercial fishing.

"Even though the catch went up in the late 1970s, and reached records in the 1990s, we don't see that in the core samples," says Finney. "That's because the management philosophy is to manage for a constant, optimal numbers of spawning salmon in each system. So, essentially they harvest the excess salmon, and so the nitrogen levels in the sediment remained relatively constant."

On the other hand, commercial fishing was found to have negative long-term effects on the size of Kodiak Island's sockeye runs. Harvests of sockeye salmon from the Karluk Lake system, for example, began to decline shortly after commercial fishing began in 1882. By the 1970s, salmon catches that had peaked at nearly four million fish declined to just 100,000. Finney says the decline was hastened by commercial catches, which deprived the lake of nutrients, provided by decaying salmon and needed by subsequent generations.

The findings have important implications for commercial fisheries management in Alaska. Traditionally, fisheries managers assumed the environment was constant when they calculated the maximum number of salmon fishermen could harvest. The study suggests a need for new, flexible management policies that take climate and lake nutrient levels into account.

Source: Finney, B.P. et al. 2000. Impacts of Climatic Change and Fishing on Pacific Salmon Abundance Over the Past 300 Years Science Oct 27: 795-799.

Contact: Dr. Bruce Finney, University of Alaska Fairbanks.
Tel: (907) 474 7724. E-mail: finney@ims.uaf.edu

Doug Schneider, Information Officer, Alaska Sea Grant/University of Alaska Fairbanks.
Tel: (907) 474 7449.
E-mail: fndgs@uaf.edu.

Eight years after authorities responded to the collapse of groundfish populations off New England, there remains a strong difference of opinion among the scientific community, the fishing industry, and among the general public about how the crisis developed. A paper in the journal Coastal Management, noting that the collapse did not come abruptly but followed a continuous and serious decline in the groundfish catch from 1983 to 1993, argues that it was clearly "a consequence of the long-standing failure of fishery managers to solve problems of chronic overfishing associated with an open-access fishery."

In particular, the paper's authors argue that the groundfish collapse fits a model first postulated in a 1993 essay in Science by Don Ludwig, Ray Hilborn, and Carl Walters. This model, which Ludwig and colleagues termed the "ratchet effect" and which the authors of the new paper dub "Ludwig's Ratchet", "dismissed natural science as having any significant influence on renewable resource conservation. Instead, [the model's authors] argued, a series of political and economic imperatives drives the system in a downward spiral."

Such imperatives, say the authors of the Coastal Management study, "drive fisheries to overcapitalize and overexploit despite scientific evidence that stocks are declining. When the fishery is no longer economically viable, governments provide financial assistance to minimize economic hardship. When stocks increase there is another rush to invest, and the cycle repeats itself."

The history of groundfish management in New England, they say, "conforms well to this model. Optimism among fishers and government … in 1977 stimulated successive rounds of investment that built up excessive fishing capacity despite warnings from scientists that stocks were becoming weaker. Management regimes designed by the New England Fishery Management Council were ineffective in constraining fishing effort. Collapse of the stocks has led to severe restrictions on fishing and to government assistance."

The paper details, step-by-step, the developments which led to the groundfish collapses, and proposes a series of measures by which similar events could be avoided in the future. In particular, it notes that whereas over "the past century, science, management, and harvest have evolved into three separate and largely independent solitudes," the "recent evolution of resource management theory … has emphasized a new integration of these activities under the banner of ecosystem-based management." Such integration of science, management, and harvesting through ecosystem-based management "appears to be the most promising avenue of escape from Ludwig's ratchet."

Meanwhile, the collapse of the New England fisheries is the subject of a new book, which examines the "virulent disagreement between government scientists and fishermen over how many fish are in the sea, and therefore over how many should be caught." In The Great Gulf: Fishermen, Scientists, and the Struggle to Revive the World's Greatest Fishery, author David Dobbs chronicles the evolution of the crisis, and sketches portraits of fishers, scientists and others involved in the debate. Dobbs agrees with the authors of the Coastal Management paper that had the New England Fishery Management Council responded to scientists' warnings by "imposing reasonable restraints, it could have prevented the whole mess with much less sacrifice by those who fished." However, scientists must also take some of the blame, for failing to make proper use of the "vast knowledge held by the fishing community." Science that respected that knowledge "would have stood a far better chance of persuading fishermen to restrain their fishing."

Sources: T. Hennessey and M. Healey. 2000. Ludwig's Ratchet and the collapse of New England groundfish stocks. Coastal Management 28: 187-213.

D. Dobbs. 2000. The Great Gulf: Fishermen, Scientists, and the Stuggle to Revive the World's Greatest Fishery. Washington, D.C.: Island Press, xv+206pp. Contact: M. Healey, Institute for Resources and Environment, and Department of Earth and Sciences, University of British Columbia, Vancouver, BC, Canada V6T IZ3.
E-mail: healey@ocgy.ubc.ca

Lea Kleinschmidt, Island Press.
E-mail: lkleinschmidt@islandpress.org.

Although there is a popular perception that marine fish populations are generally highly resilient and able to recover substantially from severe depletions, there is in fact "very little evidence for rapid recovery from prolonged declines." This according to a paper in the journal Nature.

The paper analyzes 90 populations which had experienced declines of 13 to 99% over a 15-year period. An additional 15 years after the end of that period, 12% of the marine populations for which data was available had exhibited full recovery, whereas 40% had experienced no recovery at all. All of the species which had fully recovered were clupeids: herring, sprat, and their relatives; the species which showed no recovery at all after 15 years were primarily gadids ? for example, cod and haddock.

The data suggest, notes the paper's author, "that, after prolonged decline, clupeids are more likely to recover to previously experienced population sizes and are more resilient than other marine fishes." Such an increased rate of recovery may, he suggests, be attributable to the younger age at which clupeids mature relative to other fish, and the "higher intrinsic rate of increase that earlier maturity generally effects." In addition, "being at a lower trophic level than other families considered here, clupeids may be better able to 'track' temporal and spatial fluctuations in primary and secondary productivity."

Regardless of the relative robustness of clupeids and other fish species, the fundamental point remains, however: "5-15 years after 15-year declines of 50 and 80% … gadid and other non-clupeid populations, on average, have increased marginally or not at all. Thus, although the effects of overfishing may indeed be generally reversible, the time required for population recovery in many marine fishes appears to be considerably longer than previously believed."

Source: J.A. Hutchings. 2000. Collapse and recovery of marine fishes. Nature 406: 882-885.

Contact: Jeffrey A. Hutchings, Department of Biology, Dalhousie University, Halifax, Nova Scotia B3H 4JI, Canada.
E-mail: jhutch@mscs.dal.ca.

The western population of Steller sea lions, from Alaska's Prince William Sound west to the far Aleutian Islands, has been declining since the mid-1970s, and in 1997 was accorded endangered status. Most researchers believe that changes in the available food base are the most likely cause of this decline, and a recent paper argues that there is growing evidence "that the population declines might be related to the quality and diversity of prey available to sea lions in the wild."

The paper, published in the Canadian Journal of Zoology, notes that there was an apparent switch in the diet of Steller sea lions in the Gulf of Alaska from mostly small schooling fatty fishes (such as herring, sandlance, capelin, and smelt) in the 1950s and 1960s to mostly gadid species (such as pollock) in the 1980s and 1990s. It notes, also, that the sharpest declines in Steller populations have been in areas with the lowest diversity of diet and particularly where diet is dominated by pollock.

However, although "researchers have suggested that Steller sea lion populations are declining because they eat too much pollock, which contain fewer calories, and not enough of the fatter high energy fishes" ? a theory known as the junk-food hypothesis ? "there have been no empirical data on the whole-animal response to different types of prey." The paper's authors therefore sought to test the junk-food hypothesis by switching the diet of captive Steller sea lions between pollock and herring.

Six juvenile sea lions (three male and three female) were each fed herring for a two-week control period and then switched to a pollock diet for an 11-24 day experimental period, before being returned to herring for a two-week recovery period. During each feeding, the sea lions were allowed to eat as much as they wanted. The most noticeable effects during the experimental period were significant declines in body mass, and also decreases in resting metabolism that are usually associated with fasting or decreased prey availability.

The findings underline, say the paper's authors, the significantly lower energy intake from pollock compared to the same amount of herring, and have considerable ecological implications especially for young and juvenile sea lions, which have smaller stomachs and are thus less able to increase their total food intake to compensate for the lower energy potential of pollock.

Although the papers' authors do not themselves make such a connection, their findings could also provide support for environmentalists' assertions that fishing for pollock by factory fleets in so-called critical habitat for sea lions ? such as haul-outs and nursery areas ? may, by placing further pressure on the sea lions' food source, be making it still more difficult for the animals to get the nourishment they need, thus preventing any chance of a recovery by the population. A recent court ruling imposed restrictions on fisheries in such critical habitat, and the National Marine Fisheries Service (NMFS) was scheduled

The U.S. House of Representatives Committee on Resources has expressed its concern over the U.S. Navy's development and planned deployment of the Surveillance Towed Array Low Frequency Active (LFA) sonar system. LFA sonar is designed to take advantage of the special acoustic properties of high-decibel, low-frequency sound in sea water to detect hostile submarines.

In a letter to Secretary of Defense William Cohen, the committee notes that, because "sound produced by the LFA sonar system is designed to travel over vast distances, and because the sound produced by the system is so powerful, there is a growing scientific concern that the use of LFA sonar will interfere with the natural behavior of many marine species, especially marine mammals." As has been reported in previous issues of Ocean Update, LFA sonar has been linked to at least two mass strandings of cetaceans: in the Bahamas in March 15 and 16, 2000, and on the Greek Mediterranean coast in 1996, the latter taking place during NATO exercises which employed LFA sonar.

Because of such concern, the committee believes that "the research program on LFA sonar conducted by the Navy has been inadequate," and is "particularly concerned by the Navy's application to the National Marine Fisheries Service (NMFS) for a permit to harass marine mammals while operating LFA sonar worldwide even though there is significant scientific uncertainty surrounding the technology."

The committee's letter concludes by urgently requesting Secretary Cohen to "withdraw the DEIS [Draft Environmental Impact Assessment] and reassess your assumptions that LFA sonar poses no threat to the marine environment." The letter's signatories also "request that you postpone proceeding with the NMFS to obtain a Letter of Authorization for incidental take under the Marine Mammal Protection Act to operate LFA sonar worldwide until such time that NMFS can properly establish scientifically-based noise standards for marine animals."

For further information: http://www.house.gov/resources

Both houses of Congress have passed the Beaches Environmental Assessment and Coastal Health Act (the BEACH Bill), a step which Ted Danson, founder of the American Oceans Campaign (AOC), described as "a critical step toward ensuring that future trips to the beach are healthy ones for millions of Americans."

The BEACH bill amends the Clean Water Act to require ocean, bay and Great Lakes states to adopt minimum, health-based criteria for water quality, comprehensively test recreational beach waters for pathogens and notify the public when contamination levels make beach water unsafe for swimming, surfing and similar activities. The bill also authorizes $30 million annually in federal grants to help coastal states develop and implement effective water quality monitoring and public notification programs.

Currently, only eleven states comprehensively test their beach waters and notify the public when contamination occurs. States and localities that tested their beach waters in 1999 posted 6,100 beach closings and advisories due to the presence of bacteria and viruses from polluted stormwater and runoff, overburdened sewage treatment facilities and malfunctioning septic systems. Contact with contaminated beach water can result in a variety of illnesses, ranging from gastroenteritis and hepatitis to various ear, nose and throat infections.

The bill's passage was welcomed by environmentalists. "Everyone who depends on healthy beaches for recreation and economic well-being wins with the BEACH bill," said Kelli McGee, AOC's California Director. "The BEACH bill will also help local communities target their water pollution cleanup efforts and give coastal citizens and beach-goers across America a fighting chance against beach water pollution."

Contact: David Hall, American Oceans Campaign.
Tel: (202) 544-3526, ext. 15

Natural landscapes in the United States have been altered significantly, and the wetlands, shoreline habitats and grasslands used by shorebirds have been particularly disturbed. For many shorebird species, existing information is insufficient to determine how these alterations have affected populations. However, it is known that many shorebird species face significant threats from habitat loss, human disturbance and from different forms of habitat degradation such as pollution, prey resource depletion and increasing threats from predators. Despite ongoing conservation efforts, many shorebird populations are declining, in some cases at alarming rates.

This is the conclusion of the recently-released United States Shorebird Conservation Plan, a "partnership effort of state and federal agencies, non-governmental conservation organizations, academic institutions, and individuals from across the country committed to restoring and maintaining stable and self-sustaining populations of shorebirds in the U.S. and throughout the Western Hemisphere."

A Comprehensive Assessment undertaken for the conservation plan reported "significant causes for concern related to many different aspects of shorebird biology and conservation." Twelve of the fifty species considered (24%) have undergone a significant decline in breeding range, and there is insufficient information to evaluate 15 more. Significant threats were documented for 27 species (54%) during the breeding season, 36 species (72%) during migration, and 40 species (80%) on their wintering grounds. In addition, almost half of the shorebird species considered have significant or apparent population declines. Overall, however, there is "not enough information available to thoroughly assess the status of most, if not all, North American shorebirds."

The Plan recommends a series of specific research needs to address this shortcoming, and also stresses the need to "protect and restore necessary habitats and address other threats to prevent additional shorebird species from becoming threatened or endangered."

Source: Brown, S., C. Hickey, and B. Harrington, eds. 2000. The U.S. Shorebird Conservation Plan. Manomet Center for Conservation Sciences, Manomet, MA.

For Further Information: Copies of the Conservation Plan should be requested from the U.S. Fish and Wildlife Service, Division of Migratory Bird Management, 4401 North Fairfax Drive, Room 634, Arlington, VA 22203,
or
from Manomet Center for Conservation Sciences, P.O. Box 1770, Manomet, MA 02345.

The document is also available online at http://www.manomet.org/USSCP/files.htm.

A recent study in the Journal of Plankton Research examined the survival of tropical plankton organisms in ballast water, as part of an ongoing assessment of non-indigenous species transported by international ship traffic. Two tanks on board one vessel ? one tank filled off Singapore and the other filled nine days later off Colombo, Sri Lanka ? were monitored for their phyto- and zooplankton content by daily sampling.

The tank which was filled off Singapore showed a "very low concentration of larger phytoplankton"; their abundance dropped rapidly by a factor of around 10 during the first 10 days, and remained more or less constant at a very low level until the end of the 23-day cruise. The decrease in abundance of zooplankton, which was dominated by juvenile and adult copepods, was even more pronounced than for phytoplankton, with a 90% drop during the first four days.

The story was similar with phytoplankton in the tank filled off Colombo. Although the initial phytoplankton abundance was higher than in the tank filled off Singapore, in absolute terms it was still relatively low. The last dinoflagellates were recorded on day 10, and the last diatoms on day 13, one day before arrival in the German port of Bremerhaven.

With zooplankton, however, it was a different picture. The initial concentration was "considerably lower" than in the Singapore tank, and "exhibited only a slight decrease until day 5 when it dropped by about 70% and then remained constant until [Day 9]." From that point, there was an "almost exponential" increase in concentrations of one particular form of zooplankton, the copepod Tisbe graciloides.

The study's authors argue that "the environmental conditions in the tanks were apparently not responsible" for the decline in abundance of those organisms which declined in number shortly after the tanks were filled. Instead, they offer, "the only plausible explanation is that the generally delicate plankton organisms suffered damage during the filling of the tanks through contact with the impellers of the pump and tank walls and died within a few days." Wave action, they suggest, may have further damaged the organisms; the steady drop in temperature during the journey north may have affected some warm-water species; and darkness inside the tanks may have affected phytoplankton by inhibiting photosynthesis.

The increase in Tisbe graciloides in the tank from Colombo, the authors suggest, may also have been at least partly a function of darkness. They note that studies of other species in the genus have indicated that mating behavior may increase during nighttime. In addition, they propose that the Colombo tank, which unlike the Singapore tank was constructed with several partition floors, may have favored sedimentation of phytoplankton and provided better living conditions for the predatory Tisbe. "It therefore seems reasonable to assume that we were observing a bloom phase of the population as a result of a strong propagation due to optimal feeding conditions in the tank."

The study shows, conclude the authors, that at least some organisms "are able to thrive and reproduce in ballast water tanks. A ballast water tank can thus function as an incubator during the cruise for some species." They emphasize that this may have significant impact on the release and spread of non-indigenous aquatic organisms and urge that further studies be conducted to determine if such incubation was a one-off happening or is a regular occurrence.

Source: Gollasch, S. et al. 2000. Survival of tropical ballast water organisms during a cruise from the Indian Ocean to the North Sea. Journal of Plankton Research 22(5): 923-937.

Contact: Jürgen Lenz, Institut für Meereskunde, Düsternbroker Weg 20, 24105 Kiel, Germany.

Those non-indigenous species which do survive transport in ballast water frequently cause profound change in the ecosystems into which they are released. According to a recent paper in the journal Ecology, many "coastal estuarine and marine systems have proven particularly vulnerable to invasion, and literally hundreds of non-indigenous species have been reported from the most heavily invaded systems." However, relative to scientific understanding of the effects of invasions in terrestrial and freshwater communities, "our knowledge of the impacts of introduced species in marine systems is comparatively limited. Therefore, we are currently unable to compare impacts among invasions in marine habitats, or to predict changes in these systems that might result from future invasions."

As a step toward addressing this shortcoming, the authors of the Ecology paper examined the impacts of the invasion of the European green crab Carcinus maenas on the ecosystem of Bodega Bay Harbor, California. The green crab first became established along the western United States around 1989, and first invaded Bodega Bay Harbor in 1993.

Among the most noticeable impacts of the green crab's establishment in the bay was significant declines in several benthic invertebrate species, including the small native clams Nutricola confusa and N. tantilla. In the first three years after the green crab invasion, the clam species declined nearly five-fold relative to the years before 1993. Those declines were almost certainly the result of predation by the green crabs; the same cause was behind the decline of the native shore crab Hemigrapsus oregonensis. Conversely, some non-prey invertebrate taxa increased, which the authors suggest may be the result of the green crab reducing numbers of these taxa's predators. Additionally, the authors found no evidence of impacts on higher trophic levels; numbers of seabirds, which subsist on benthic invertebrate prey, did not decline.

The lack of impact on seabirds is probably, say the authors, because the decline in the birds' prey as a result of green crab predation took place over a sufficient length of time for the birds to adapt their feeding habits. However, they caution, it may be that, as the green crab expands along the coast of western North America, prey resources may be reduced over a larger geographic area, "thereby increasing the chances of both local and regional effects on shorebird populations."

Source: Grosholz, E.D., et al. 2000. The impacts of a nonindigenous marine predator in a California bay. Ecology 81(5): 1206-1224.

Contact: Edwin D. Grosholz, Department of Environmental Science and Policy, University of California, One Shields Avenue, Davis, CA 95616.

Each year polluted runoff devastates coastal communities and economies by, among other things, closing beaches, contaminating fish and shellfish, and stimulating outbreaks of parasite-induced illnesses and harmful algae. This pollution continues unabated due in part to a lack of targeted federal funding to control it, even though "a small investment in pollution prevention today can prevent continued losses in pollution related damages." So says a new report by the Washington, D.C.-based Coast Alliance.

The report, Mission Possible, calls for funding of the Coastal Nonpoint Pollution Control Program, which gives federal grants to states which have enacted enforceable plans to control runoff as part of their Coastal Zone Management Programs. The program, says the Coast Alliance "represents the most meaningful opportunity to address the pervasive problem of runoff pollution because it requires enforcement of management measures where voluntary measures fail, while emphasizing a cooperative approach among federal, state and local planners." Twenty-nine of the thirty-five eligible states and territories are participating in the program.

However, argues the Coast Alliance, "the program is threatened. While states and local communities continue to suffer runoff-related losses, Congress has yet to reauthorize the Coastal Zone Management Act. In the meantime, hundreds of millions of dollars are pumped into states for voluntary programs which have yet to demonstrate real environmental gains. If a fraction of this amount were invested in the Coastal Nonpoint Program, local communities across the nation would soon see real results."

Mission Possible includes an in-depth analysis of five states, Wisconsin, Louisiana, Maine, California, and New Jersey, to assess the progress of the states in controlling runoff. These five states collectively demonstrate "tremendous geographic, economic, environmental and regulatory diversity." Succinct summaries of other state programs are also included in the report. The analysis identifies innovative approaches to solving runoff problems as well as obstacles encountered by states in doing so.

Contact: Jennifer leMat, Coast Alliance.
Tel: (202) 546 9554.
Fax: (202) 546 9609.
E-mail: coast@coastalliance.org.

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