Vital Statistics of the Fish Population of Gordy Lake, Indiana

Abstract

The fishing, populations, and mortality rates of fishes in Gordy Lake, Indiana, were studied in 1950 by creel-census and mark-and-recapture techniques. Gordy Lake has an area of 28.5 acres and a maximum depth of 35 feet. The total number of fish caught by all methods of fishing from June 2 to September 4 was 4,012 which weighed 722.5 pounds. Bluegills (Lepomis macrochirus) constituted 81.5 percent of the total yield which amounted to 25.4 pounds per acre of water surface. Cane-pole fishermen caught 15.2 fish (2.72 pounds) per 10 pole-hours. Populations of the most important species were measured by at least two of the following independent methods of estimation: (1) Schnabel estimate based on trap-caught fish; (2) Schnabel estimate based on fish caught by fishermen; (3) Petersen estimate based on the fish caught by fishermen after trapping ceased; (4) DeLury estimate based on catch-effort statistics of traps. The total standing crop of legal-sized (5 inches or longer, total length) bluegills was 7,900 or 1,320 pounds. Legal-sized redear sunfish (Lepomis microlophus) numbered about 600 individuals weighing 105 pounds. Legal (10 inches or longer) largemouth bass (Micropterus salmoides) were estimated at about 100–300 fish, or 88–270 pounds. Warmouth (Chaenobryttus coronarius), pumpkinseeds (Lepomis gibbosus), and green sunfish (Lepomis cyanellus) of legal size numbered about 550 fish weighing 63 pounds. The total standing crop of all species, including those not mentioned, was estimated to be 78 pounds per acre. The total annual mortality of bluegills was judged to be 82 percent of which exploitation by anglers accounted for 35 percent. The yearly rate of exploitation of redear sunfish was estimated as 29 percent and the total annual mortality rate 69 percent. Largemouth bass were exploited at a rate of about 36 percent per year and the total annual mortality rate was estimated to be 60 percent. Some mortality rates of the minor species are given. As nearly as can be judged by published information, Gordy Lake represents about the average condition with respect to yield, catch per unit effort, and standing crop to be expected on Indiana lakes of this type.