Bradford G. Parsons

Plasma Cortisol and Chloride Stress Responses in Juvenile Walleyes during Capture, Transport, and Stocking Procedures

Abstract Extensively reared juvenile walleyes Stizostedion vitreum subjected to capture and transport stressors associated with stocking procedures in South Dakota and Minnesota displayed acute increases in plasma cortisol and extended declines in concentrations of plasma chloride. In four separate South Dakota transport hauls, mean plasma cortisol in walleyes rose from 12–49 ng/mL at the time of trap-net capture to 138–174 ng/mL after 1 h of transport; these concentrations remained increased at 3 h. Plasma chloride decreased by about 19% during this period; by 3 h, mean values had dropped about 30%, to 53–61 meq/L. Similarly, in Minnesota mean plasma cortisol in captured and transported walleyes increased from 13–26 ng/mL during trap-net capture to 154–214 ng/mL by 1 h after transport in three separate trials and remained at the higher values at 3 h posttransport. Mean plasma chloride concentrations dropped about 28%, to 65–72 meq/L, by 3 h after transport and remained significantly decreased at 68–82 me...

Angler Opinions of Bluegill Management and Related Hypothetical Effects on Bluegill Fisheries in Four Minnesota Lakes

Abstract We surveyed anglers on four Minnesotta lakes who fish for bluegill Lepomis macrochirus to determine (1) if they would support regulation changes designed to increase bluegill size structure, (2) if their behavior would allow increases in bluegill size structure to be sustainable, and (3) what they viewed as the causes and remedies for declining bluegill fisheries. The majority of anglers surveyed would not support regulation changes on bluegill fisheries. However, most said they would increase the number of fishing trips they took if increased bluegill size structure could be reestablished. We estimated that a modest increase of two trips annually would result in a 16–34% increase in the rate of exploitation on the four lakes. On certain lakes this could jeopardize the sustainability of a quality fishery. The majority of anglers believed that stunting was the cause of the decline in bluegill populations and that removal by managers and anglers was the most important management tool available.

Yellow Perch Piscivory and Its Possible Role in Structuring Littoral Zone Fish Communities in Small Minnesota Lakes

ABSTRACT We monitored the seasonal food habits of juvenile and adult yellow perch (Perca flavescens) in four west-central Minnesota lakes, focusing on consumption of fishes by perch. Macroinveretebrates were usually the primary (% by number) prey item selected by yellow perch <200 mm, while prey fishes were commonly the primary (% by weight) prey source for yellow perch ≥130 mm, and fish consumption was observed in yellow perch as small as 65 mm. Yellow perch that exceeded 130 mm regularly consumed fish, and prey fish selection varied considerably by season. During the spring, the two primary prey fishes were brook stickleback (Culae inconstans) and johnny darter (Etheostoma nigrum). During the early summer months, larval fishes appeared in yellow perch diets. Lepomids were the primary fishes consumed during late summer, fall, and winter months.

Relationship between Electrofishing Catch Rates of Age-0 Walleyes and Water Temperature in Minnesota Lakes

Abstract We compared catch data for age-0 walleyes Stizostedion vitreum captured by night electrofishing 18 Minnesota lakes sampled over a wide range of water temperatures (4–25°C) throughout the fall 1996. The relationship between electrofishing catch per hour (CPE) of age-0 walleyes and temperature showed a curvilinear pattern, CPE rising and peaking at 18.6°C and declining thereafter, as water temperature cooled throughout the fall. Three different patterns of CPE were observed within subsets of the data, but peak CPE generally occurred at intermediate water temperatures, and declines in CPE generally occurred when water temperature dropped below 10°C. Mean lengths differed significantly between August and September in all but three lakes, but did not differ significantly between September and October, except in two lakes. For managers needing to assess age-0 walleye abundance before stocking advanced fall fingerlings, our data suggest that fall assessments should target water temperatures between 20°C...

Movement of Black Crappies and Bluegills among Interconnected Lakes in Minnesota

Abstract The movement of fish among interconnected lakes has been documented for highly mobile species; however, little information is available for black crappie Pomoxis nigromaculatus and bluegill Lepomis macrochirus. We assessed emigration of black crappies from 4 lakes and bluegills from 2 lakes within a chain of 16 lakes in west-central Minnesota by comparing the proportion of angler returns of T-bar anchor tags reported from lakes other than the one in which the fish were tagged. Over a 3-year period, black crappie angler tag returns from nonorigin lakes ranged from 6% to 23% in the four lakes. Annual emigration rates of black crappies ranged from 0% to 92%. For bluegills, the 3-year emigration rate was 9% from Le Homme Dieu Lake and 14% from Victoria Lake, with annual rates ranging from 3% to 36%. We found no evidence that the size of bluegills or black crappies at tagging affected the likelihood of emigration and no evidence that movement upstream or downstream was preferred. Fisheries managers sh...

Dispersal of Walleye Fingerlings after Stocking

Abstract Lake size and morphometry affected dispersal of fingerlings of walleyes Stizostedion vitreum following stocking in three Minnesota lakes. A portion of stocked fingerlings were marked with coded wire tags and released in September and October of 1986, 1987, and 1988. Walleyes were collected in subsequent years by spring electrofishing. Most tagged walleyes remained near the release site through their first spring, but this effect was inconsistent among lakes. Tagged fish dispersed by their first spring in Lake Mary (960 ha), which is the smallest of the three lakes and has little underwater structure. In Lake Miltona (2,363 ha), the largest lake in the study, fish were dispersed only marginally at age 3, likely due to the lakes size and its division into two basins. Walleyes in Lake Ida (1,736 ha), which is intermediate in size and habitat complexity, generally were dispersed by age 2. These results have important implications for release–recapture experiments. Failure to evaluate dispersal may b...

Effect of T-Bar Anchor Tags on Growth of Black Crappies

Abstract T-bar anchor tags provide a means for identifying individual fish in tagging experiments. Despite prior use, no information is available regarding the effect of these tags on the growth of black crappies Pomoxis nigromaculatus. We compared the growth of black crappies larger than 180 mm total length that were tagged with t-bar anchor tags with the growth of untagged members of the same cohort over 1-year periods in four Minnesota lakes. We found no difference in the growth of tagged and untagged black crappies in three of the lakes, but in the fourth lake growth of tagged fish averaged 3.7 mm less than that of untagged fish. While the effect on the growth of individual fish may be substantial, the overall effect on the population of tagged black crappies was minor. Therefore, concerns about effects on growth should not deter the use of t-bar anchor tags for tagging black crappies.