Annual Report, FIS 05-403

Life history and essential habitats of humpback whitefish in Lake Clark National Park, Kvichak River watershed, Alaska

Principal Investigators:
Carol Ann Woody, Fisheries Research Biologist, U.S. Geological Survey, Alaska Science Center, 4230 University Dr, Suite 201, Anchorage, AK 99508;
(907)786-7124, carol_woody@usgs.gov

Dan Young, Fisheries Biologist, National Park Service, Lake Clark National Park and Preserve, Port Alsworth, AK 99543; (907)781-2113, dan_young@nps.gov

June Tracey of Nondalton fishes through the ice for humpback whitefish using a traditional hook and line.  Whitefish are the second most important subsistence fish in the region.

December 2006

Rationale

Figure 1.  Kvichak River watershed, Alaska; communities are indicated by dots.

In contrast to the sockeye salmon resource, which is available July – August, non-salmon fish provide year-round local subsistence opportunities; 70 – 100% of Kvichak River watershed households annually harvest 18,000 to 50,000 usable pounds of non-salmon fish (Table 74; Krieg et al. 2005) with humpback whitefish (Coregonus pidschian) being their  primary target (Figure 2).  About 75% of households in the community of Nondalton (Figure 1) participate in the harvest of humpback whitefish in areas within and adjacent to Lake Clark National Park and Preserve (Morris 1986, Stickman et al. 2003), a federal subsistence conservation unit.  Humpback whitefish are also important in the Lake Iliamna area, supplying the largest freshwater fish harvest in the community of Igiugig (Figure 1) and providing food for residents of the region through a resource exchange network among villages (Morris 1986, Fall et al. 1996).

Figure 2.  George Koktelash Sr. of Nondalton displays a humpback whitefish he harvested spring of 2005.

Subsistence fishers in the Kvichak River watershed began reporting declines in their annual fall harvests of humpback whitefish in 1999 (D. Salmon, Igiugig, personal communication).  Recent surveys show total whitefish subsistence harvests in the Kvichak River watershed dropped from about 13,000 fish per year in the mid-1990s to 1,000 fish per year in the early 2000s (Figure 3; Krieg et al. 2005).  The reasons for the reduced harvest remain unclear as catch-per-unit-effort data are lacking.

A lack of basic biological information on humpback whitefish in Lake Clark, as well as in the greater Kvichak River watershed, hinders assessment of this species’ status and their reported decline.  The importance of this species to subsistence users in the region led the Bristol Bay Regional Advisory Council, the Federal Office of Subsistence Management, and the National Park Service to prioritize humpback whitefish in Lake Clark National Park and Preserve as a study topic for the Fisheries Resource Monitoring Program.

Figure 3.  Percent composition of the total non-salmon freshwater fish subsistence harvest in the Kvichak River watershed (graph from Krieg et al. 2005).  Note the large decline in whitefish harvest from the mid-1990s to early 2000s.

Related Life History Studies

Recorded age at maturity in Alaskan humpback whitefish populations ranges from 4 – 10 years, depending on geographic location (Alt and Kogl 1973, Alt 1979), although this information is lacking for populations in the Bristol Bay area.  Humpback whitefish spawn during fall in littoral areas of lakes and rivers (Anras et al. 1999, Brown et al. 2002).  They are broadcast spawners, casting gametes into the water where embryos eventually settle in the gravel to develop and hatch the following spring.

Lacustrine (lake resident), river resident, allacustrine (move between lakes and rivers), and anadromous (move between salt- and freshwater; spawn in freshwater) ecotypes of adult humpback whitefish are found in Alaska and Canada (Alt 1979, Morrow 1980, Bond and Erickson 1985, Reist and Bond 1988, Fleming 1996 and 1999).  Multiple ecotypes of humpback whitefish may exist in the same watershed, indicating wide plasticity in life history behavior.  For example, in the Chatanika River, humpback whitefish either reside exclusively in riverine habitats or migrate between lake and river habitats (Fleming 1996).  Brown et al. (2002) observed that upper Tanana River humpback whitefish reside in lakes during spring and early summer (feeding habitat), riverine habitats during mid summer to late fall (spawning habitat), and either lake or river habitats during winter (overwintering habitat).

Based on strontium distribution in otoliths, Brown (2006) documented the presence of anadromous humpback whitefish in the Yukon, Koyukuk, and Tanana Rivers up to 1,700 km from the ocean. The Kvichak River watershed, which includes Lake Clark, contains an extensive system of lakes, rivers, ponds, and streams with waters ranging from glacially influenced and turbid to clear.  Such habitat diversity may support multiple ecotypes of humpback whitefish, including anadromous forms, although this remains unverified.  Two studies in the Lake Clark watershed, a field survey by Russell (1980) and a subsistence user survey by Stickman et al. (2003), documented the presence of humpback whitefish in Lake Clark, the Chulitna River, Pickerel Lakes, and Little Lake Clark, although some confusion was apparent in differentiating among whitefish species (Stickman et al. 2003).

In our study, we provide information on Lake Clark humpback whitefish biology that will both allow resource managers to better understand this species and help in developing stock status and trends projects.

(continued to Objectives)