Theses and Dissertations


Title: The effects of water hardness and age at stocking on the survival of striped bass, Morone saxatilis (Walbaum), fry

Name: Powell, Madison Ray

Degree: MS

Chair: Dr. E.W. Shell

Resides: FAA Library

University: Auburn

Location: Auburn, Alabama

Date: 1971

Pages: 61

Keywords: Water Hardness,Age,Stocking,Survival,Striped Bass,Fry.

Abstract:

In several states efforts are being directed toward the hatchery rearing of striped bass, Morone saxatilis, fry to fingerlings. Further knowledge is needed concerning factors affecting survival of the fry. The effects of increased water hardness and age at stocking on the survival of striped bass fry from two river systems (Upper Roanoke River, Virginia, and Cooper River, South Carolina) were studied at the Fisheries Research Unit, Auburn University Agricultural Experiment Station during the period May 11 to July 17, 1970. The effects of the two factors were studied utilizing two cultural methods, intensive (in hatching jars) and extensive (in earthen ponds). Th effectiveness of a water recirculating rearing system during intensive culture was evaluated. Fry from both strains were stocked into 7.6-liter hatching jars on each of two recirculating systems. One system contained untreated water (39 ppm total hardness as CaCO3) and the other contained water treated with calcium sulfate (CaSO4) to increase total hardness to 150 ppm. In the hard water, some of the Roanoke fry and a mixed culture of Roanoke and Cooper fry survived for 92 and 47 days, respectively. The maximum survival period for any fry in the soft water treatment was 21 days. The recirculating systems were effective in maintaining water quality parameters closer to favorable ranges. Roanoke and Cooper River Fry, ranging in age from 3 to 19 days, were stocked into twenty, 0.1-acre earthen ponds containing soft or hard water. Total hardness ranged from 15 to 39 and 77 to 170 ppm in the soft and hard water, respectively. The mean survival rate among fry was 4.5 per cent in the soft water as compared to 2.2 per cent in the hard water. Increasing age at stocking beyond 7 days decreased survival among fry from both strains. Causes of high mortalities are discussed.

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