Date of Award:

1984

Document Type:

Thesis

Degree Name:

Master of Science (MS)

Department:

Ecology

Advisor/Chair:

Charles R. Berry

Abstract

Spottail shiner (Notropis hudsonius) and delta smelt (Hypomesus transpacificus) were introduced into Willard Reservoir to improve the forage base for walleye (Stizostedion vitreum vitreum) and black crappie (Pomoxis nigromaculatus). Spottail shiners were stocked in early spring in 1981, 1982, and 1983. Hauling mortality was generally great and an estimated 34,500 live fish were stocked in the 3-year period. Spottail shiner reproduction occurred each year of stocking. Delta smelt were introduced in 1982 with the stocking of 15,000 adult spawning fish. Stocking survival was estimated at 99%. Freshly spawned eggs were also obtained and placed in a tributary to Willard Reservoir. Shoreline seining produced 29 · young-of-the-year delta smelt during June 1982. Growth of the captured young-of-the-year spottail shiner and delta smelt in Willard Reservoir compared favorably with growth found in their respective native waters. Stomach analysis indicated food habits were similar to those in native waters. Food habit analysis of young-of-the-year walleye, black crappie, spottail shiner, and delta smelt indicated very little overlap of food organisms between the four fish species. Spottail shiners occurred in 3 of 56 walleye stomachs containing food items in 1982 and 3 of 41 stomachs containing food items in 1983. Delta smelt were not found in the 132 walleye stomachs examined. However, six adult delta smelt were angler-caught walleye in April 1983. No found in the stomachs of spottail shiners or delta smelt were found in 79 black crappie stomachs examined in 1982 or 62 stomachs examined in 1983. Low utilization of spottail shiner and delta smelt was attributed to the low relative abundance of the two species in Willard Reservoir.

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