Distribution and abundance of pelagic fish in Lake Powell, Utah, and Lake Mead, Arizona–Nevada

Authors

Gordon A. Mueller, U.S. Geological Survey, Denver, Coloardo
Michael J. Horn, United States Bureau of Reclamation, Denver, Colorado

Abstract

Pelagic fish communities (waters with depths > 20 m) of Lakes Powell and Mead were examined quarterly from 1995 to1998 using vertical gill nets and a scientific echosounder. Nets captured a total of 449 fish consisting of striped bass (57%/45% [Lake Powell/Lake Mead]), threadfin shad (24%/50%), common carp (15%/4%), walleye (3%), channel catfish (2%), and rainbow trout (<1%). Each reservoir contained concentrations of pelagic species separated by expanses of habitat with few fish (<10 kg · ha⁻¹). Reservoirs experienced dramatic seasonal and annual fluctuations in pelagic biomass. Lake Powell's biomass peaked at the Colorado River at 709.7 (±46.5) kg · ha⁻¹ and Lake Mead's reached 291.9 (±58.2) kg · ha⁻¹ at Las Vegas Wash. These locations supported estimated fish densities of 124,668 fish · ha⁻¹ and 15,131 fish · ha⁻¹, respectively. Maximum reservoir biomass peaked in August 1996, with Lake Powell supporting 10,852,738 ± 5,195,556 kg (27.6 × 10⁷ fish) and Lake Mead 1,926,697 ± 892.994 kg (10.8 × 10⁷ fish). Biomass ebbed in May (1996 and 1997), when Lake Mead supported 65% (296,736 kg vs. 453,097 kg) and 62% (101,016 kg vs. 162,262 kg) of biomass levels found in Lake Powell.

Recommended Citation

Mueller, Gordon A. and Horn, Michael J. (2004) "Distribution and abundance of pelagic fish in Lake Powell, Utah, and Lake Mead, Arizona–Nevada," Western North American Naturalist: Vol. 64: No. 3, Article 3.
Available at: https://scholarsarchive.byu.edu/wnan/vol64/iss3/3