Egg Transfer to Increase Productivity and Predictability in Bluegill Fry Production

Abstract

The traditional spawning-rearing pond method used in seed production for bluegill Lepomis macrochirus has shortcomings that inhibit meeting the demand for high numbers of uniform-size fry and fingerlings by recreational fisheries and the developing aquaculture industry. In this study, the feasibility of an egg transfer method in bluegill seed production was evaluated. For this, 30 female and 15 male broodfish were spawned in artificial nests located in 15-m2 outdoor tanks. The fish were allowed to spawn for 21 d in each of three trials conducted between June 22 and September 3. Nests with eggs were collected daily, and the eggs were either hatched in flow-through aquaria or separated from the nest using a 1.5% sodium sulfite solution and hatched in McDonald jars. Short sodium sulfite treatments were effective in separating eggs from the nest, and hatching of eggs still attached to the nests in flowing-water aquaria was reliable and required less labor. Compared with the traditional method, egg transfer improved both the number produced (mean +/- SD, 33 +/- 17 fry/g of female body weight per 21 d and 433 +/- 243 fry/m2 per day) and the efficiency of producing young. With the transfer method, high numbers of uniform-size fry can be produced in a short period using fewer brooders and less space than in the spawning-rearing pond method.