Rearing Male Bluegills Indoors May Be Advantageous for Producing Food‐size Sunfish

Abstract

Abstract.— An indicated demand for sunfish (Lepomis spp.) as a food fish remains untested because of continuing inability to efficiently rear these fishes to required large sizes (≥227 g; 0.5 lbs). A recent study involving parallel, indoor rearing of two sunfishes under favorable conditions showed that bluegills Lepomis macrochirus possessed markedly higher growth capacity than B × G hybrids (F1: male bluegill × female green sunfish, Lepomis cyanellus). B × G hybrids had been thought to possess superior growth capacity and so have received more attention than bluegills as a food‐fish candidate in many areas of the USA. Reanalysis of data from the recent study with emphasis on gender differences revealed that the male bluegills possessed much higher growth capacity than male B × G hybrids, at least from May to March as Age 1 and then early Age 2 fish. Male bluegills reached 67% of food‐market weight within the 10‐mo period from a starting weight of 7 g; male B × G hybrids reached only 24% of this weight. Male bluegills’ more rapid growth versus male B × G hybrids’ apparently involved less growth energy allocation to gonad development. Female bluegills grew slower than male bluegills but also outgrew male and female B × G hybrids whose growth trajectories declined in midsummer (June) and remained largely flat through March. The previous view that B × G hybrids possess higher growth capacity than bluegills was fostered by studies in ponds where bluegill growth can be impeded by high reproduction rates and, as this study reveals, by high densities and exposure to suboptimal temperatures when their growth potential is high. Indoor rearing of male bluegills should ameliorate most pond‐related growth impediments and take fuller advantage of their rapid growth capacity.