Date:

2019 - 2022

Abstract:

In Pyramid Lake, Nevada the fish community is comprised largely of native fishes, and the population of Lahontan cutthroat trout (LCT) is thriving based largely on intensive and effective management. The population is sustained by large-scale stocking and provides a world-class fishery and an extremely important source of income for the Pyramid Lake Paiute Tribe. Management of a fishery requires adequate monitoring and annual “adaptive” decision-making. Based on gill netting, the adult population of LCT appears to be relatively stable. In autumn, we estimated there were 1.08 million large LCT in 2019 yet only 524,200 large LCT in 2020. Nonetheless, the 2019 acoustic estimate compares well to the range of abundance estimated from the 2019 cohort analysis, based on stocking, apparent survival, and harvest. One goal of this monitoring program is to evaluate and develop relationships between different complimentary metrics of health and abundance of the fish populations. Managing for LCT means managing carefully for tui chub, their primary food source. Tui chub continue to comprise over 50% of the gill-net catch, and across time we observed a strong and significant declining trend in tui chub CPUE, concordant with declines in lake elevation. The condition of tui chub remains high and varies little across time to date. Collectively these observations suggest the fishery is healthy although the LCT abundance may have declined some in 2020 based only on hydroacoustics. All metrics of performance come with some uncertainty, thus it is best to consider them collectively.

Funding:

• Lahontan National Fish Hatchery Complex, US Fish and Wildlife Service
• Pyramid Lake Fisheries and the Paiute Tribe (In-kind)
• US Geological Survey – Utah Cooperative Fish and Wildlife Research Unit (In-kind)
• The Ecology Center at Utah State University

Investigators:

• Gary P. Thiede, Researcher, USU - Dept. of Watershed Sciences
• Dr. Phaedra Budy, USGS UCFWRU, USU

Other Collaborators:

• Dr. Robert Al-Chokhachy, USGS, N. Rocky Mountain Science Center, Bozeman, MT