Snake River Sockeye Salmon Habitat and Limnological Research; 2003 Annual Report.

Taki, Doug; Kohler, Andre E.; Griswold, Robert G.

doi:10.2172/897659

Cited by 1 publication

(6 citation statements)

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“…In addition, kokanee grew more (in TL and WW) and their predicted November-May consumption was greater for 1994-1995, when mean zooplankton biomass was five times greater, than it was in 1993-1994. These results suggest that zooplankton abundance can limit the growth of Stanley Lake kokanee in winter and that competition with abundant O. nerka may further limit growth (Taki and Mikkelsen 1997).…”

Section: Kokanee Growth During Wintermentioning

confidence: 81%

“…In 1994, kokanee condition factor and lipid content in November were higher than in 1993, which may have been the combined result of 25% more zooplankton and 75% fewer kokanee during ice-free periods in 1994 (Taki and Mikkelsen 1997). In addition, kokanee grew more (in TL and WW) and their predicted November-May consumption was greater for 1994-1995, when mean zooplankton biomass was five times greater, than it was in 1993-1994.…”

Section: Kokanee Growth During Wintermentioning

confidence: 91%

“…It covers 81 ha and has mean and maximum depths of 13 and 26 m. During our study, the fish community of Stanley Lake was predominated by kokanee and lake trout Salvelinus namaycush but also included cutthroat trout O. clarki, rainbow trout O. mykiss, brook trout S. fontinalis, mountain whitefish Prosopium williamsoni, northern pikeminnow P. oregonensis, suckers Catostomus spp., redside shiner Richardsonius balteatus, dace Rhinichthys spp., and sculpin Cottus spp. (Taki and Mikkelsen 1997). We sampled limnological characteristics and the kokanee population monthly during October-May and every 2 weeks during June-September 1993-1995 Limnological sampling.-On each sampling date, we sampled three stations near the center of Stanley Lake, where depth exceeded 23 m. During ice cover, we cut holes with an ice auger or a chainsaw.…”

Section: Methodsmentioning

confidence: 99%

“…This result could have important implications for endangered Snake River sockeye salmon recovery efforts. Smolts leaving the Sawtooth Valley are some of the largest of any sockeye salmon system (Bjornn et al 1968;Taki and Mikkelsen 1997), and they must undergo a 1,400-km migration. This arduous migration may explain why smolts traditionally left the Sawtooth Valley lakes at such a large size.…”

Section: Implications For Snake River Sockeye Managementmentioning

confidence: 99%

“…Monitoring programs in the Sawtooth Valley lakes have documented an inverse relationship between O. nerka abundance and zooplankton biomass (Taki and Mikkelsen 1997). Food limitation may be exacerbated during winter, when low under-ice temperatures and light intensities limit phytoplankton and zooplankton production (Steinhart 1997;Steinhart and Wurtsbaugh 1999).…”

Section: Implications For Snake River Sockeye Managementmentioning

confidence: 99%

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Winter Ecology of Kokanee: Implications for Salmon Management

Steinhart

Wurtsbaugh

2003

Trans Am Fish Soc

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Abstract.-We sampled various limnological parameters and measured growth and diet of age-0 kokanee Oncorhynchus nerka (lacustrine sockeye salmon) during two winters in a high-mountain lake of the Sawtooth Valley, Idaho. Although winter has been recognized as an important period for many warmwater fishes and for stream-dwelling salmonids, winter limitations have only recently been studied for coolwater and coldwater species. Ice and snow cover in winter limited light penetration. As a result, chlorophyll-a and zooplankton density were lower in ice-covered periods than during ice-free periods. The weight of stomach contents was often below a maintenance ration, yet the incidence of empty stomachs was extremely low (1 of 63) and the weight of stomach contents increased as energy reserves declined, indicating that kokanee were actively foraging during winter. Kokanee length and weight remained constant during the winter of 1993-1994 but increased from November through May in 1994-1995. Condition factors, however, declined significantly over the winter in both years, and lipid content approached levels associated with mortality. Differences in growth patterns may have been caused by a combination of changes in zooplankton density and kokanee abundance and in kokanee behavior to defend energy reserves or avoid predation. Results demonstrated the ambiguity of some growth measurements and the importance of choosing the correct metric for measuring growth in fishes. Because juvenile kokanee and sockeye salmon are ecologically similar, management efforts to restore the endangered Snake River sockeye salmon to the Sawtooth Valley lakes should recognize that winter conditions might be a bottleneck for this species.

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Section: Kokanee Growth During Wintermentioning

confidence: 81%

Section: Kokanee Growth During Wintermentioning

confidence: 91%