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,~:Ji (~ ),17 . .~ J-{aAlti:: ~ Physiological Effects of Electrofishing on Largemouth Bass ... Thomas A. Burns Northwestern State University, Department of Biological Sciences Natchitoches, Louisiana 71457 and Kenneth Lantz Louisiana Department of Wildlife and Fisheries P.o. Box 444, Natchitoches, Louisiana 71457 ABSTRACT: Blood and tissue samples of adult largemouth bass (Micropterus salmoides) were taken from control fish and from fish that were electroshocked and allowed recovery times of 0, 1,3, 5.5, and 19 h. Shocking had no significant effect tp > 0.05) on hemoglobin, hematocrit, plasma protein. or percentage water content oftissue. No sexual differences in these factors were noted. Blood lactate increased signifi- cantly (P < 0.01) 1 h after electroshocking, returned to pre-shocked levels within a 3-h period, and then continued to decline. .. The objectives of this study were to establish certain blood and tissue values for largemouth bass (Microp- terus salmoides), to determine whether electroshock had a significant effect on these values, and to ascertain the period of time necessary for recovery to pre-shocked conditions. Materials and Methods In February 1977 we obtained 100 largemouth bass ranging from 30 to 46 em in total length from the Bass Anglers Sportsman's Society fishing tournament held at Toledo Bend Reservoir, Louisiana. The fish were trans- ported in aerated tanks to the National Fish Hatchery at Natchitoches, Louisiana, and placed in a 0.2-ha pond containing forage fish. No mortality occurred either dur- ing transport or while the fish were held in the pond. Fish were allowed to remain in the pond 1 week before being seined and transferred a short distance to a build- ing equipped with aerated cement holding tanks (about 0,8 x 0.8 x 2.7 m). Fish were held in these tanks at 160C for 3 days without food before treatment. A Smith-Root Type VI Electrofisher was used to shock the fish with 400 V at 5 A pulsating DC for 13 s. At the time of sampling a single fish was netted and removed from the holding tank, stunned with a blow to the head, and 3-4 ml of blood collected from a severed caudal peduncle in a pre-dried test tube containing ammonium heparin. Immediately after sampling, 0.5 ml was with- drawn from the tube and transferred to a tube contain- 148 ing 1.0 ml of cold 30% perchloric acid for determination of plasma lactate. Both blood samples were then placed on ice for 2 h before analysis. The fish was then measured and weighed, whole gonad samples were taken, and a piece of muscle was removed from the lateral region of the caudal peduncle, wrapped in foil, and stored frozen. Hemoglobin determinations were made by using the cyanmethemoglobin technique (Medi Chem Inc., Santa Monica, California). Hematocrit measurements were made by the microhematocrit method. After sampling for hemoglobin and hematocrit, plasma was obtained by centrifugation. Plasma proteins were determined by the Lowrey technique (Sterling 1966). We determined plasma lactate in the deproteinized sample, using an enzyme kit (Boehringer Mannehim Co., Dallas, Texas). The frozen muscle tissue was thawed and weighed on an electronic balance and dried in a vacuum desiccator until a constant weight was reached. The difference between the initial weight and the dried weight was used to calculate the percent tissue water. When enough females and males had been sampled in a particular treatment group, a Student's t-distribution was used to test for siginficant differences between sexes. If no significant difference (p ~ 0.05) was present, data from males and females were combined for that treatment group and compared with other treatment groups by analysis of variance. If a significant difference was observed, a Newman-Keuls test was used for dif- ferentiation (Zar 1974). THE PROGRESSIVE FISH-CULTURIST