This paper was written as part of the 2003 Alaska Ocean Sciences Bowl high school competition. The conclusions in this report are solely those of the student authors.
At All Costs: The Effort to Protect Steller Sea Lions and its Possible Outcome for the Salmon Industry and Kodiak's Economy
Steller sea lion populations have undergone a severe decline (Alaska Fisheries Science Center, 2001) since scientific counts began. The western stocks decreased by 86% from 1956 to 1998. Recently, an attempt was made to counteract the decline by banning pollock trawling near Steller sea lion haulouts and rookeries. This report will explore these efforts, similar efforts, and their effects on Kodiak's economy.
Sea Lion Biology
Steller sea lions (Eumetopias jubatus) are a large marine mammal common in Kodiak waters. Large males may reach 3.25 m in length and can weigh over 1000 kg. Females reach lengths of 2.5 m and weigh up to 350 kg. Pups are 1 m in length and between 16 kg and 32 kg (National Marine Mammal Laboratory, 2002). Steller sea lions are found across the North Pacific Ocean from northern Japan to southern California in inshore and offshore waters (Fig. 1). Steller sea lions, like most marine mammals, reproduce relatively slowly. Females give birth to a maximum of a single pup per year. These pups are generally born in early summer (National Marine Mammal Laboratory).
The Steller sea lion population is divided into two stocks due to minor biological differences and differing population trends. The eastern stock, found east of 144° W longitude, is currently at healthy levels with no sign of declining (National Marine Mammal Laboratory, 2002). In contrast, western stocks have undergone a massive decrease since efforts were first made to monitor the population (Fig. 2).
Early eyewitness accounts pre-dating scientific surveys state that there were few Steller sea lions on Marmot Island, a major rookery off Kodiak Island, during the 1940s. The population reached at least 140,000 sea lions during the period of 1956-1960. During the 1970s, the Steller sea lion population crashed. By 1989, the population had reached roughly 30,000 animals. In 1989, the adult and juvenile Steller sea lion populations began to decline steadily, with an average annual decrease of 3.1% between 1991 and 2001 (Alaska Fisheries Science Center, 2001; Fig. 3).
Steller sea lions are opportunistic predators with a wide range of reported food sources. Steller sea lions feed primarily on fish and cephalopods. Their prey, which varies depending on season and location, includes walleye pollock (Theragra chalcogramma), salmon (Oncorhynchus spp.), Atka mackerel (Pleurogrammus monopterygius), Pacific herring (Clupea pallasi), Capelin (Mallotus villosus), Pacific sand lance (Ammodytes hexapterus), and Pacific cod (Gadus macrocephalus). In some circumstances, Steller sea lions have been known to eat other marine mammals such as harbor seals (National Marine Mammal Laboratory, 2002).
Pollock and salmon are both important parts of a Steller sea lion's diet. According to a study of Steller sea lion stomachs and scats conducted by Merrick et al. (1997), Steller sea lion diets in the Gulf of Alaska are composed of about 20% salmon, an amount superceded only by pollock and cod consumption. During the summer, salmon can rise to consist of up to 40% of their diet (Loshbaugh, 2000). This unfortunately corresponds with Kodiak's fishing season. Clearly, salmon are a significant part of the diet of the Steller sea lions that surround the Kodiak Archipelago.
One of the main gadid species consumed is walleye pollock. Pollock have had an increasing biomass in the last few decades, and have become an increasing part of western Steller sea lion's diet (Marine Mammal Research Consortium, n.d.). In a 2001 study by Wynne and Foy, pollock were found in 31 percent of sea lion scats containing prey. Another study also found that walleye pollock were the most commonly occurring prey in sea lion scats (Sinclair and Zeppelin, 2001).
Previous Protection Efforts
In a 2000 effort to protect Steller sea lions under the Endangered Species Act (ESA), the National Marine Fisheries Service (NMFS) closed all pollock trawling in certain areas. Pollock trawling was banned within a twenty nautical mile radius of all Steller sea lion rookeries, haulouts, and foraging areas in the Aleutian. In the central Gulf of Alaska, including the Kodiak Archipelago, the trawl ban extended 10 nautical miles from haulouts, rookeries, and foraging areas islands (National Marine Fisheries Service, 2000; Fig. 4). The ESA is written to err on the side of caution. Little proof is required to enact ESA based policy, and a decision cannot consider economical effects. In the case of pollock, the decision to close the trawl fishery by Judge Thomas Zilly was based upon the theory that although there was inadequate research to show a distinct cause to the Steller sea lion decline, over-harvesting of pollock could play a role. As a result, closures that were deemed drastic by local fishermen were implemented (At-Sea Processor Association, n.d.).
As a possible outcome of this logic, Kodiak's salmon industry is under threat. A NMFS press release issued April 30, 1997 says, "Commercial fishing operations in the western population area that are likely to affect Steller sea lions may have to reconsult with the fisheries service under section 7 of the Endangered Species Act." If environmental groups such as those that initiated the lawsuit to close down pollock trawling conclude that salmon fishing also influences the Steller sea lion population, salmon fishing around Kodiak could be halted. Although there is no current legal action against the Kodiak salmon industry pending, it is possible the ban on pollock will be extended to salmon (Loshbaugh, 2000).
Despite the poor market for Alaskan salmon, the salmon industry remains a crucial part of Kodiak's economy. According to the Kodiak Chamber of Commerce (2001), salmon fishing is 25.3% of the total value of Kodiak's fisheries, the highest of all fisheries (Fig. 5). In 2001, the salmon industry infused 18.8 million dollars into the Kodiak economy.
In the event that closures are necessary to protect the endangered Steller sea lions, the Kodiak community will suffer major economic consequences. Both law and common sense dictate that environmental protection has precedence over immediate economic problems. However, there have been no scientific studies to determine if fishery closures are effective at protecting Steller sea lions (Wynne, pers. comm.). A limited closure should be designed to allow a scientific analysis of the impacts of fishery closures on Steller sea lions. These closures could be implemented on multiple fisheries that may interfere with Steller sea lions. A scientific effort to research the effects closures have on Steller sea lions, whether it be negative, positive, or negligible, would allow for more educated decisions in the future.
It is possible that the Steller sea lion population was artificially inflated when the population surveys began in 1956. Eyewitness accounts that predate scientific research state that Marmot Island, one of the largest rookeries in Alaska, had very few Steller sea lions living on it (Wynn, pers. comm.). If the population was unstably high in the 1950s and 1960s, the current decline would be a natural change back to a population that can be supported by the environment. The eastern stock of Steller sea lions has maintained a steady population of 15,000 to 20,000 (Alaska Fisheries Science Center, 2000) in a range that is, according to Robert Foy (pers. comm.), roughly comparable. Therefore, attempts to ensure that Steller sea lion populations remain what they were in the late 1960s may be unnecessary. The decline in Steller sea lions will end once the population reaches a stable number.
Whaling could be a cause for an artificially high population and resulting plummeting numbers. During the 20th century, around 28,000 humpback whales were harvested from the waters around Kodiak Island (Rice, 1978). This harvest would have had an extreme change to the ecosystem (Wynne, pers. comm.). Logic would link the whaling to an increase in the food supply of Steller sea lions. A fully-grown humpback whale can consume massive amounts of food. With whales gone, many species low on the food chain should increase in number, followed by species high in the food chain. All of this would be followed by species low on the food chain plummeting in numbers, followed by species high on the food chain plummeting on numbers. If whaling was the cause of a food increase for Steller sea lions, human impact has already been curtailed with the end of commercial whaling in the United States and the Steller sea lion population will return to a sustainable level naturally.
Knowledge is power, and Kodiak's community should understand the important issue of Steller sea lions. First, this would alleviate the political backlash that results from fishery regulations that hurt Kodiak. If everyone understood why a decision was being made, it could be accepted or challenged on scientific grounds instead of emotional. Furthermore, education will decrease the number of sea lions taken illegally. Although this is not a big factor, illegal killing of sea lions is still an occurrence in Kodiak waters. At a recent panel put on by the National Research Council, an Orthodox priest reported that through confessionals he knows there are a number of sea lions being killed illegally (Bishop, 2002). Education about the current plight of the Steller sea lions will decrease the number killed in frustration by fishermen. Fishermen will realize that their right to fish is tied to the fate of the sea lions, and will protect the sea lions just as vigilantly as they do their right to fish.
Leading scientists on marine mammals are still debating what is contributing to the decline of Steller sea lions. It is quite likely that many factors are contributing to the decline, and no single panacea will solve the problem. When creating policies that affect so many people, officials should be careful to ensure that their decisions are as based on scientific evidence as possible. Although the ESA restricts the decision-making process, Kodiak's economy should remain under consideration.
We would like to thank the following people for their indispensable help and support on this project: Craig Baker, Quentin Fong, Robert Foy, Susan Sugai, Clayton Wallace, Kate Wynne, and all of our other contributors.
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