8142

• UCREFRP Catalog Number: 8142
• Author: Horn, M. J.
• Title: Nutritional Limitation of Recruitment in the Razorback Sucker ‎(
• USFW Year: 1996.
• Copyright Material: NO

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Papoulias (1989) were unable to provide support for this. There also exists the

probability that larvae are moved by longshore currents into less or more productive

habitats, or into areas frequented by predators.
Of these three general hypotheses, it has been generally accepted that predation is

the ultimate end to any razorback suckers in the wild; however, anything influencing

predation influences survival. The faster a larvae grows the quicker it exceeds the

predation threshold (Werner et al. 1983). Quantifying the impacts of nutrition on larval

survival will allow a better separation of impacts affecting recruitment that have arisen as

a result of introduced or native predators and those associated with food-related changes

in system productivity.

II. Description of the Study Area

My study focused on Lake Mohave, AZ-NY, because: 1) the existing population

of razorback suckers is the largest known; 2) a current management focus is to replace the

aging, non-recruiting adult population as part of an effort to recover the species; and 3)

Yuma cove, a detached "backwater" different in environmental conditions than the

adjacent reservoir provided an opportunity for comparative research.

Lake Mohave is a north-south oriented, mainstem reservoir impounded by Davis

Dam on the Colorado River just upstream from Laughlin, NY (Figure 3). It was built in
the period 1942-1951 and finally closed in 1954 (Allan and Roden 1978). Lake Mohave
at full pool is 108 kIn long and extends upstream essentially to the base of Hoover Dam.
The maximum width is 6.4 lan, maximum depth at the time of impoundment was 54 m