NOSB paper

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

Authors

Devin Boyer
Andrea Cooney
Justin Leedy
Matt Reppond
John Van Atta

 

Team Perspicacious Pinnipeds
Kodiak High School
722 Mill Bay Road
Kodiak, AK 99615


Kodiak team photo

Introduction

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).

Population History

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).

Diet

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.

Protection Plan

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.

Conclusion

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.

Acknowledgments

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.

Literature Cited

Alaska Fisheries Science Center. (September 23, 2000). Steller Sea Lion (Eumetopias jubatus): Eastern U.S. stock. National Marine Fisheries Center.

Alaska Fisheries Science Center. (April 21, 2001). Steller Sea Lion (Eumetopias jubatus): Western U.S. stock. National Marine Fisheries Center.

At-Sea Processor Association. (n.d.). Steller Sea Lion Chronology. Retrieved December 14, 2002 from http://www.atsea.org/concerns/steller_chronology.html

Bishop, S. (Wednesday, December 4, 2002). Scientists: Fishing not cause of sea lion decline. Kodiak Daily Mirror, Vol. 62, 10 pgs.

Kodiak Chamber of Commerce. (2001). Business and Community Profile. Retrieved December 14, 2002 from http://www.kodiak.org/seafood.html

Loshbaugh, D. (Thursday, December 14, 2000). Concern Mounting Over Sea Lion Plan. Peninsula Clarion.

Marine Mammal Research Consortium. (n.d.) Steller Sea Lion Diet Changes. Retrieved December 14, 2002 from http://www.marinemammal.org/research/dietchangebody.html

Merrick, R. L., Chumbley, M. K., Byrd, G. V. (1997). Diet Diversity of Steller Sea Lions (Eumetopias jubatus) and Their Population Decline in Alaska: A potential relationship. Canada. Canadian Journal of Fisheries and Aquatic Sciences.

National Marine Fisheries Service. (April 30, 1997). Decline of Steller Sea Lion Continues - Species reclassified as two populations endangered in most of Alaska current fishing operations may continue. National Marine Fisheries Service press release.

National Marine Fisheries Service. (January 2002). Environmental Assessment/Regulatory Impact Review for Emergency Rule to Implement Reasonable and Prudent Steller Sea Lion Protection Measures in the Pollock Fisheries of the Bering Sea and Aleutian Islands Area and the Gulf of Alaska. National Marine Fisheries Service Alaska Regional Office.

National Marine Mammal Laboratory. (Wednesday, November 6, 2002). Steller Sea Lion Biology. Retrieved December 14, 2002 from http://nmml.afsc.noaa.gov/AlaskaEcosystems/sslhome/StellerDescription.html

National Marine Mammal Laboratory. (n.d.). Steller Sea Lion Range. Retrieved December 14, 2002 from http://nmml.afsc.noaa.gov/gallery/pinnipeds/stellerrange.jpg

National Marine Mammal Laboratory. (n.d.). Steller Sea Lion Research. Retrieved December 14, 2002 from http://nmml.afsc.noaa.gov/alaskaecosystems/sslhome/stellerhome.html

National Oceanic and Atmospheric Administration. (n.d.). Steller Sea Lion Critical Habitat and No-Entry Zones. Retrieved December 14, 2002 from http://www.fakr.noaa.gov/protectedresources/stellers/habitat.htm

Rice, D. W. (1978). The Humpback whale in the North Pacific: Distribution, exploitation, and numbers. Appendix 4. Pp. 29-44, in K. S. Norris and R. R. Reeves (eds), Report on a workshop on problems related to humpback whales (Megaptera novaeangliae) in Hawaii U.S. Department of Commerce, Nat. Tech. Info. Serv. Pb-280 794. Springfield, VA. in National Marine Fisheries Service (September 24, 2000). Humpback Whale (Megaptera novaeangliae): Western Pacific stock.

Sinclair, E., and Zeppelin, T. (May 2001). Seasonal Diet Trends Among the Western Stock of Steller Sea Lions (Eumetopias jubatus). Seattle Washington. National Marine Fisheries Service.

Wynne, K., and Foy, R. (May 2001). Is It Food Now? Gulf Apex Predator-Prey Study. Kodiak, Alaska. University of Alaska.

Figures

Figure 1. Steller sea lion range

Fig. 1, steller sea lion range

Figure originally appeared in the National Marine Mammal Laboratory's Pinniped Gallery (http://nmml.afsc.noaa.gov/gallery/pinnipeds/stellerrange.jpg).


Figure 2. Time-lapse photos of Ugamak Island rookery

Fig. 2, photos of rookery

Pictures originally appeared in National Oceanic and Atmospheric Administration National Marine Mammal Laboratory website (http://nmml.afsc.noaa.gov/alaskaecosystems/sslhome/stellerhome.html).


Figure 3. Decline in population of Steller sea lions

Fig. 3, sea lion population decline

Data taken from the Alaska Fisheries Science Center's report "Steller Sea Lion (Eumetopias jubatus): Western U.S. stock" dated April 21, 2001.


Figure 4. Steller sea lion designated critical habitat

Fig. 4, sea lion critical habitat

Figure originally appears in National Oceanic and Atmospheric Administration's report "Steller Sea Lion Critical Habitat and No-Entry Zones."


Figure 5. Exvessel value of Kodiak's fisheries by fishery in millions of dollars

Fig. 5, fishery exvessel value

Chart based on information from the Kodiak Chamber of Commerce's "Business and Community Profile."



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