Publications

The Steller sea lion (Eumetopias jubatus) is not considered in the main part of this report because the focus of the investigation, as stipulated in Section 120(f) of the MMPA, is Pacific harbor seals and California sea lions. However, since the term "sea lion" could apply to either Steller or California sea lions on the West Coast, this Appendix was prepared to provide the reader with relevant background information on Steller sea lions (also called northern sea lions).

The Steller sea lion is listed as threatened under the ESA throughout its range. NMFS recently proposed to reclassify the Steller sea lion population segment west of long. 144 W as endangered and maintain the remainder of the U.S. population as threatened (4 October, 1995 Federal Register Notice, 60 FR 51968). NMFS is proposing this change in classification because the western population segment, which declined by 70% between 1960 and 1989 (when the species was listed), has declined further with population decreases of 21% from 1990 to 1994. Although the eastern population has shown a stable to increasing trend for the last 15 years, NMFS is proposing to retain this population as threatened because the large decline in the overall population threatens the continued existence of the entire species.

Steller sea lions occur year­round but do not breed in Washington. The peak abundance is approximately 1,500 sea lions and appears to be stable, although not all surveys from 1988 to 1994 have been analyzed. Peak numbers occur in late summer, fall, and winter (Gearin and Scordino 1995). Steller sea lions haul­out at Split and Willoughby Rocks on the south Washington coast and at Carroll Island, Cape Alava, and Tatoosh Island on the north Washington coast. In 1992 and 1993, nursing pups were observed at Carroll Island and Cape Alava. These pups may have been born in Washington or may have migrated with their mothers from rookeries in British Columbia or Oregon.

Steller sea lions are found year­round and have breeding rookeries at several sites. At least 10 haul­out sites are used on a regular basis, with reproductive activities occurring primarily at three sites. Recent counts of Steller sea lions in Oregon (3,000­3,500) have increased from counts made in the late 1970s (2,000­2,500). Annual peak counts occur during the June and July reproductive season. Winter counts range from 1,000 to 1,500 statewide. In 1994, 2,696 adults and juveniles and 423 pups were counted at the 2 major south coast rookeries (Rogue Reef and Orford Reef). Since pup counts from aerial surveys are generally 20-25% below comparable ground counts, true pup production in Oregon is estimated at 550­600 pups per year. An additional small number of pups (4­6) are born each year at Three Arch Rocks on the north coast. Steller sea lions marked as newborn pups on Rogue Reef have been resighted at various ages (6 months-5 years) at haul­out areas from northern California through Washington, British Columbia, southeast Alaska, and the eastern and central Gulf of Alaska.

Steller sea lions are found along the coast from Monterey Bay north and are known to breed at Año Nuevo Island, the Farallon Islands, and St. George Reef (off Crescent City). They were once found as far south as San Miguel Island, but no longer occur there. Steller sea lions have been declining by 85% or more since the 1960s (LeBoeuf et al. 1991, Westlake et al. in press). They were counted during the July breeding season at Año Nuevo Island in 1993, when approximately 450 Steller sea lions were recorded. From 1990­95, Steller sea lions at St. George Reef have numbered from 400­700 animals, with just over 100 pups born per year (ODFW unpubl. data). Overall, numbers of Steller sea lions in California have decreased. Current counts for other seasonal haul­out areas in California are not available.

Food habits studies on Steller sea lions are shown below in Table A-1. In the Columbia River, Beach et al. (1985) identified prey of Steller sea lions as Pacific whiting, rockfish, eulachon, anchovy, herring, staghorn sculpin, and lamprey. In the Rogue River, surface feeding observations of Steller sea lions by Jameson and Kenyon (1977) and Roffe and Mate (1984) indicated lamprey and a small proportion (2%) of salmonids were primary prey. More recent observations of Steller sea lions foraging in the mouth of the Rogue River appear to indicate that salmonid consumption has increased (ODFW and NMFS-AFSC unpubl. data). Steller sea lion scat samples collected from the south Oregon coast from 1986 to 1993 contained primarily Pacific whiting (84%) and lamprey (39%), with salmonids identified in 19% of the samples (Riemer and Brown 1996).

* Percent of sample (scat, stomach, etc.) examined that contained the identified prey. This is not the percentage of that prey in the total diet. (n = number of samples)

Healthy Stock: A stock of fish experiencing production levels consistent with its available habitat and within the natural variations in survival for the stock.

Depressed Stock: A stock of fish whose production is below expected levels based on available habitat and natural variations in survival levels, but above the level where permanent damage to the stock is likely.

Critical Stock: A stock of fish experiencing production levels that are so low that permanent damage to the stock is likely or has already occurred.

Healthy Stock: A population is classified as healthy if the available spawning habitat has generally been fully seeded and abundance trends have remained stable or increased over the last 20 years.

Special Concern: A population is classified as special concern if either the population is probably composed of 300 or fewer spawners, or a substantial risk exists for interbreeding between the population and stray hatchery fish at a level in excess of standards established by the Oregon Wild Fish Management Policy.

Depressed Stock: A population is classified as depressed if any one of the following have occurred: available spawning habitat has generally not been fully seeded, abundance trends have declined over the last 20 years, or abundance trends in recent years have been generally below 20­year averages.

Special Concern: Populations for which: 1) relatively minor disturbances could threaten them, especially if a specific threat is known, 2) insufficient information on population trend exists, but available information suggests depletion, 3) there are relatively large ongoing releases of non­native fish, and the potential for interbreeding with the native population exists, and 4) the population is not presently at risk, but requires attention because of a unique character.

Moderate Risk of Extinction: Populations whose spawning escapements appear to be stable after previously declining more than natural variation would account for, but are above 200. Approximately one adult per spawner is returning to spawn.

High Risk of Extinction: Populations whose spawning escapements are declining. Fewer than one adult fish returns to spawn from each parent spawner. Populations having recent (within the past 1­5 years) escapements under 200, in the absence of evidence that they were historically small, also were placed in this category.

Threatened: The term "threatened species" is defined as any species which is likely to become an endangered species within the foreseeable future throughout all or a significant portion of its range.

Endangered: The ESA defines the term "endangered species" as any species which is in danger of extinction throughout all or a significant portion of its range.

NMFS considers a variety of information in evaluating the level of risk faced by salmonids of an evolutionarily significant unit. Important considerations include 1) absolute numbers of fish and their spatial and temporal distribution, 2) current abundance in relation to historical abundance and carrying capacity of the habitat, 3) trends in abundance, based on indices such as dam or redd counts or on estimates of spawner­recruit ratios, 4) natural and human influences factors that cause variability in survival and abundance, 5) possible threats to genetic integrity (e.g., selective fisheries and interactions between hatchery and natural fish), and 6) recent events (e.g., a drought or a change in management) that have predictable short­term consequences for abundance of the ESU. Additional risk factors, such as disease prevalence or changes in life history traits, may also be considered in evaluating risk to populations.

(Definitions reprinted from WDF et al. 1992)

Anadromous Fish: Species that hatch in fresh water and spend some portion of their life cycle there, migrate downstream to the ocean, mature in salt water, and return to fresh water to spawn.

Cultured Stock: A stock that depends upon spawning, incubation, hatching, or rearing in a hatchery or other artificial production facility.

Escapement: Adult fish that have survived all fisheries and will contribute to the spawning population.

Evolutionarily Significant Unit (ESU): A population (or group of populations) that 1) is reproductively isolated from other conspecific population units, and 2) represents an important component in the evolutionary legacy of the biological species.

Mixed Stock: A stock whose individuals originated from commingled native and non­native parents, and/or by mating between native and non­native fish (hybridization); or a previously native stock that has undergone substantial genetic alteration (Note: the term "mixed stock" has a different definition when used in describing commercial and sport fisheries).

Native Stock: An indigenous stock of fish that has not been substantially impacted by genetic interactions with non­native stocks or by other factors, and is still present in all or part of its original range. In limited cases, a native stock may also exist outside of its original habitat (e.g., captive broodstock programs).

Non­native Stock: A stock that has become established outside of its original range.

Salmonid: Any member of the family Salmonidae, which includes all species of salmon, trout, and char. This report addresses only Pacific salmon (chinook, chum, coho, pink, and sockeye) and steelhead and cutthroat trout in Washington, Oregon, and California.

Stock: The fish spawning in a particular lake or stream(s) at a particular season, which to a substantial degree do not interbreed with any group spawning in a different place, or in the same place at a different season.

Wild Stock: A stock that is sustained by natural spawning and rearing in the natural habitat, regardless of parentage (includes native).

Table of Contents