WWW.WAS.ORG • WORLD AQUACULTURE • DECEMBER 2012 27 Bluegill and other sunfish are an important and abundant fish in the US. Traditionally private lakes and ponds are stocked with bluegill in combination with largemouth bass and channel catfish. There are over 200 farms in the US that produce sunfish for a variety of markets (USDA 2006). Bluegill are produced and sold as 1-2 inch fingerlings for initial pond stocking and as 6-8 inch sub-adults for corrective stocking and to accelerate the availability of fish suitable for angling in a sportfish pond. In addition, bluegill and other sunfish are grown to larger sizes (1/2-pound and larger) for corrective sportfish pond stocking, as bait for angling for trophy-size fish, and for food-fish markets. Total sales are in excess of $5.3 million (USDA 2006). In the north-central US, bluegill and their hybrids with other sunfish have been identified as a priority for development of food-fish production. Hybrids of some sunfish crosses have increased growth rates, are more readily trained to consume prepared diets, and have efficient feed conversion. Bluegill Spawning The bluegill is a reproductive machine that, once water temperature reaches 70 F (21 C), spawns multiple times through summer. Male bluegill excavate a shallow nest and court a female for spawning. One male will often spawn with multiple females. Females release about one-third of the eggs at each spawning site. The male guards fertilized eggs and defends hatched fry for about three days until they swim up, start feeding, and leave the nest. Although the male bluegill is a fierce competitor, spawning occurs in close proximity to other males, which are part of a large group or colony of spawning adults. Growing Hybrid Sunfish Culturing hybrid sunfish adds product diversity in markets and solves the problem of multiple spawns that are characteristic of bluegill. Hybrid sunfish are often stocked in recreational fishing ponds to provide another species of “panfish” for anglers to catch and consume. Usually hybrids are stocked in combination with bluegill so that the reproductive potential will not be reduced excessively by stocking hybrids. Some advantages of stocking hybrids include providing another angling opportunity, reducing the overall reproductive rate, and adding a fish that grows faster due to hybrid vigor. The most popular hybrids are crosses between green sunfish or redear sunfish females and bluegill males. The common green sunfish × bluegill hybrid results in populations dominated by fast-growing males, often as high as 90 to 97 percent of the population, that limit reproduction and reduce overcrowding and stunting. The redear × bluegill hybrid is also desirable, with rapid growth and limited reproductive capacity. The potential for rapid growth is a desirable characteristic to growers targeting food-fish markets. Redear sunfish will spawn only once during the reproductive season and hybrids retain this trait. Limited reproduction can be expected and excellent growth provides a harvestable fish for the food-fish market or stocking in recreational sportfish ponds. (CONTINUED ON PAGE 26) Two-Year Growth of Sunfish Hybrids in Missouri Charles E. Hicks1 FIGURE 1. Structures placed in ponds for spawning bluegill and sunfish hybrids. FIGURE 2. Nests consisting of a plastic basin with gravel were placed in spawning structures for bluegill and hybrid sunfish production. FIGURE 3. Indoor recirculating system for overwintering sunfish hybrids.
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