Options for Selectively Controlling Non-Indigenous Fish in the Upper Colorado River Basin Draft Report June 1995 Leo D. Lentsch Native Fish and Herptile Coordinator Utah Division of Wildlife Resources Robert Muth Larval Fish Lab Colorado State University Paul D. Thompson Native Fish Biologist Utah Division of Wildlife Resources Dr. Todd A. Crowl Utah State University and Brian G. Hoskins Native Fish Technician Utah Division of Wildlife Resources Utah Division of Wildlife Resources Colorado River Fishery Project Salt Lake City, Utah TABLE OP CONTENTS PAGE ABSTRACT .......................... INTRODUCTION ...................... Non-Indigenous Problems ..... Objectives ................... Control Options ............. Mechanical Control ..... Chemical Control ....... Biological Control ..... Physicochemical Control METHODS .......................................................... Literature Review .......................................... Species Accounts ........................................... RESULTS .......................................................... Species Accounts ........................................... Clupeidae-Herrings ................................... Threadfin Shad .................................. Cyprinidae-Carps and Minnows ........................ Red Shiner ...................................... Common Carp ..................................... Utah Chub ........................................ Leathers ide Chub ................................ Brassy Minnow ................................... Plains Minnow ................................... Sand Shiner ..................................... Fathead Minnow .................................. Longnose Dace ................................... Redside Shiner .................................. Creek Chub ...................................... Catostomidae-Suckers ................................. Utah Sucker ..................................... Longnose Sucker ................................. White Sucker .................................... Ictaluridae-Bullhead Catfishes ...................... Black Bullhead .................................. Yellow Bullhead ................................. Channel Catfish ................................. Esocidae-Pikes ....................................... Northern Pike ................................... Cyprinodontidae-Killifishes ......................... Plains Topminnow ................................ Plains Killifish ................................ Poeciliidae-Livebearers .............................. Western Mosquitofish ............................ i PAGE Percichthyidae-Temperate Basses ..................... White Bass ...................................... Striped Bass .................................... Centrarchidae-Sunfishes .............................. Green Sunfish ................................... Bluegill ......................................... Smallmouth Bass ................................. Largemouth Bass ................................. White Crappie ................................... Black Crappie ................................... Percidae-Perches ..................................... Iowa Darter ..................................... Johnny Darter ................................... Yellow Perch .................................... Walleye .......................................... DISCUSSION ....................................................... Clupeidae .................................................. Cyprinidae ................................................. Catostomidae ............................................... Ictaluridae ................................................ Esocidae ................................................... Cyprinodontidae ............................................ Poeciliidae ................................................ Percichthyidae ............................................. Centrarchidae .............................................. Percidae ................................................... RECOMMENDATIONS ................................................. Mechanical Control ........................................ Chemical Control ........................................... Biological Control ........................................ Physicochemical Control ................................... LITERATURE CITED ................................................ 11 LIST OF TABLES PAGE Table 1. Non-native, non-salmonid fishes in the UCRB ....... Table 2. Status of non-native, non-salmonid fishes in the UCRB (from Tyus et al. 1982) ...................... Table 3. Control options for non-native, non-salmonid fishes in the UCRB ......................... iii ABSTRACT The introduction of non-indigenous fish in the Upper Colorado River Basin (UCRB) has been contributed to the decline of the native fish fauna. There is a need to control the interactions between native and nonnative species throughout the upper basin to insure the preservation and possible recovery of the endangered fishes. We referenced >10,000 journal articles, unpublished reports, regional fisheries guides, and general fishery biology textbooks to obtain pertinent information about the life history and control options for the nonnative fish in the UCRB. The nonnative fish families of concern in the UCRB are: cyprinidae, catostomidae, ictaluridae, esocidae, centrarchidae, and percidae. Physicochemical approaches are the most promising control option for most nonnative cyprinids. Correlative evidence has demonstrated that relative abundance of red shiner, sand shiner, fathead minnow, and redside shiner is negatively affected by high river discharges and associated lower water temperatures. Selective control of carp and white sucker, however, will probably require the combination of the physiochemical approach and mechanical or chemical control. These cyprinids are generally tolerant to a wide range of environmental conditions. The most promising method to selectively control channel catfish and black bullhead is mechanical removal. Further expansion of northern pike can be prevented with increased fishing pressure, the installation of barriers to prevent downstream movement from reservoirs, and netting and/or electrofishing areas of high concentration. Control measures directed towards centrarchids should begin by preventing the downstream movement from impoundments. Eliminating stocking in and isolating off-channel habitats from river channels would reduce their abundance. Targeting spawning aggregations for netting, electrofishing, and/or chemical treatment also are viable mechanical control options for centrarchids. Further walleye expansion in the upper basin can be prevented by eliminating reservoir stockings and installing fish barriers to prevent downstream movement from reservoirs. INTRODUCTION The introduction of non-indigenous fish in the Upper Colorado River Basin (UCRB) began over 100 years ago. The first introductions were made primarily for the purpose of increasing the food supply (Popov and Low 1950) and for sport. These introductions were made primarily because European settlers saw little tangible value in the native fish assemblage (Hawkins and Nesler 1991). Since 1900, most introductions have been made in the interest of anglers (Popov and Low 1950). Introduced species included members of the centrarchid, percid, ictalurid, cyprinid (carp), and salmonid families (Behnke and Benson 1983). Consequently, game fish species and bait fish have become established and in some cases expanded their range in the upper basin. The ichthyofauna of the UCRB is now dominated by non- indigenous species. In 1982, Tyus et al. reported that 42 of the 55 fish species (76%) in the upper basin have been introduced. Thirty-four of these 42 introduced species are non-salmonid (Table 1). These introduced species account for over 90% of the fish sampled during standardized efforts in the basin (McAda et. al. 1994). Behnke and Benson (1983) attributed the dominance of non-indigenous fish species in the basin to dramatic alterations in flow regimes, water quality, temperature, and habitat characteristics. They noted that water development had converted a turbulent, highly variable river system into a relatively 1 2 stable system with flows and temperature patterns that allowed the indiscriminate introductions of non-indigenous fish to flourish. Hawkins and Resler (1991) identified six species on a list of 28 non-native species, which were considered by CRB researchers to be of greatest or widespread concern and adversely impact native fishes of the CRB and the southwestern United States. These species are channel catfish, red shiner, northern pike, common carp, green sunfish, and fathead minnow. Other species of increasing concern are sand shiner, white sucker, black bullhead, and largemouth bass. The four cyprinids and channel catfish are considered to be either abundant or common in the upper basin (Table 2) and sympatric with native fishes. The remaining species, although not as common, are primarily considered threats to native fishes due to their increasing abundance, habitat preference, and/or piscivorous nature. Selective Control Options By the 1930's, strategies for the manipulation (e.g. control) of fish populations had been developed to improve sport fishing (Wiley and Wydoski 1993). Since the 1930's, additional techniques have been developed to manipulate/control fish communities. Three control options have generally been recognized to reduce undesirable