Shelby D. Gerking

Evidence for the Concepts of Home Range and Territory in Stream Fishes

The size and structure of fish populations have received much attention in recent years. Contributions in this field have provided ideas concerning the theory of animal populations as well as a sound basis for the management of sport and commercial fishing. Among the factors influencing fish populations, most study has been accorded food, feeding habits, reproductive behavior, reproductive potential, growth, and mortality. The fish population has been considered an aggregate of animals in most studies of this sort. Very little attention has been given to the interaction between individuals of a fish population and to the effect such interaction might have on the size and structure of the group. The present work attempts to interpret a population of stream fishes as the result of competition among the individuals of which it is composed. The movements of the fish have been followed in detail and the possible importance of these activities is discussed. Evidence will be presented to show that many stream fishes live in very restricted areas during most, if not all, of their lifetime. The movements of fish will be considered from two viewpoints: (1) home range, and (2) territory. Home range is a term borrowed from the mammalogists who have found that many mammals live within rather narrowly circumscribed limits. Such small mammals as the meadow vole, woodland deer mouse, woodmouse, and chipmunk

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 ...

The Survival of Fin-Clipped and Latex-Injected Redear Sunfish

Abstract Redear sunfish (Lepomis microlophus) were marked by latex injection and by fin-clipping in Wyland Lake, Indiana, to determine immediate and delayed effects of these techniques on survival. A variety of fin-clips were used and latex was injected subdermally with a hypodermic syringe in the occiput region and posterior dorsal region. From recaptures made during the year of marking and in the next year the following conclusions were drawn. (1) Survival of fin-clipped fish below and above 123 millimeters fork length was similar two weeks following marking and proportionate recaptures from these two size groups were also made a year subsequent to marking for fish carrying either a single fin-clip or a double fin-clip. (2) There was no immediate mortality from subdermal injection of latex; and survival of fish of different sizes was the same with no difference noted between the two sites of injection. (3) Survival of fish marked with posterior-dorsal latex injections was similar to that of fin-clipped ...