Using a Fish-Stocking Database to Demonstrate Temporal Changes in Stocking Patterns
George W. LaBar and Tom Frew
Abstract.—This paper describes a database of fish stocking in Idaho dating from 1913. The database contains more than 75,000 complete records on stocking since 1967 and more than 50,000 partial records prior to that date. Information contained in the complete records includes watershed and water body, species and variety, size, stocking method, number per pound, pounds stocked, rearing hatchery, haul mortality, county, and management region. In order to compare numbers of salmonids stocked at differing life stages, we converted weight of stocked salmonids to a catch equivalent index (catch equivalent [CEQ] = weight of fish stocked/0.33). Our analysis of the data from the database indicated that since the 1960s, more than 2 million CEQ of rainbow trout Oncorhynchus mykiss have been stocked annually in Idaho. These comprise 23 different stocks, including Kamloops rainbow trout, redband trout, and 16 varieties of domestic rainbow trout. Since 1970, the number of rainbow trout stocked in Yellowstone cutthroat trout O. clarkii range has decreased by more than one-third. Triploid rainbow trout stocking commenced in 2000 and now exceeds 2 million CEQ annually. Largemouth bass Micropterus salmoides and smallmouth bass M. dolomieu stocking comprises nearly 1,814.4 kg per year. Crappie species are stocked at the rate of 590 kg annually. The rate of increase in stocking by the Idaho Department of Fish and Game has been about 300% in each of the last three decades, largely due to the construction of four large anadromous mitigation hatcheries. The human population in Idaho grew 22% per decade during that same time period, suggesting increasing reliance on stocked fish.