Razorback sucker studies on Lake Mead, Nevada, 1997-1998 annual report

Holden, Paul; Abate, Paul; Ruppert, Jack

This is a report on the studies done on the razorback sucker (Xyrauchen texanus) in Lake Mead from 1997-1998, including study areas, spawning areas, fish distribution numbers, and tagged fish locations.... INTRODUCTION In 1996 the Southern Nevada Water Authority (SNWA) and the Colorado River Commission of Nevada, in cooperation with the Nevada Division of Wildlife (NDOW), initiated a cooperative study to develop information about the Lake Mead razorback sucker population. BIO/WEST Inc. (BIO/WEST), under contract with the SNW A, developed the study design in conjunction with the NDOW and the SNW A, and had primary responsibility for conducting the study. The NDOW provided equipment, technical support, and field support for the project. Other agencies that joined as cooperators at the beginning of the study included the Bureau of Reclamation (BOR), which provided funding for equipment, storage facilities, and technical support; the National Park Service, which provided residence facilities in their campgrounds; and the U.S. Fish and Wildlife Service (USFWS). An annual report (Holden et al. 1997) summarized the methods and results of the first year of the study (October 1996 to July 1997). Trammel netting was the primary gear used to collect adult razorback suckers, and 21 were surgically implanted with sonic transmitters. Relatively small razorback sucker populations totaling a few hundred fish were identified at Las Vegas Bay and Echo Bay. The fish used the Las Vegas Bay and Echo Bay areas during winter and spring for spawning, but they also moved into other adjacent parts of the Jake. The two populations did not intermix. Larval razorback suckers were found at both sites, but they were found in much greater abundance at Echo Bay. Growth rates of recaptured fish indicated that growth of razorback sucker in Lake Mead was considerably higher than in any other known location. This suggested that recruitment may be occurring in Lake Mead. This report presents findings from the second year of the razorback sucker study conducted on Lake Mead. Information contained in this report was collected from July 1997 through June 1998, although information from the previous year of research (October 1996 through June 1997) has been included where appropriate.

Razorback sucker studies on Lake Mead, Nevada, 1997-1998 annual report

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