Principal Investigator: Dr. James E. Wetzel
Our goal is develop, using family selection, a bluegill cultigen for use as a food-fish that can reach consistently a harvest weight of 1.5 pounds in 18 months (approximately 2 summer growing seasons). Results of a preliminary trial indicate hereditability of growth within northern bluegill sunfish appears to be extremely high approaching 91% justifying our efforts with broader genetic base.
We have founded two lineages using combinations of northern, coppernose, southwestern and hand-paint bluegill subspecies. The first lineage (Lineage-1 Generation-1) based only on northern and coppernose bluegill was composed of 69 surviving broods has been intensively reared through a 4 month indoor water reuse system trial and a 6 month outdoor pond trial with evaluation based on a 14 month lifetime growth performance. Fourteen of broods where chosen as sources for potential sires and dams to found Lineage-1 Generation-2 in January 2009. Lineage-2 Generation-1 represented by 52 broods was founded in August 2008 and will follow a similar production cycle with evaluation after at 14 months.
Generation of multiple half-sibling broods has proven to be a challenge, especially in respect to the dam’s breeding efficiency and handling of nest with embryos and pro-larvae. Teaser males and females are being used routinely to reduce stress associated agonistic encounters on broodfish. A student project underway is determining whether use of the hormone “human chorionic gonadotropin” improves our ability to synchronize the females becoming ripe. We have a identified a cheap, commercially available plastic bowl with the ideal dimensions and rigidity for production of large numbers of broods that must be moved and monitored. The nest may also enhance our ability to control the number of fry reared reducing variations associated with stocking density.
Several novel bluegill crosses have been created with considerable variation in terms of their performance. The generation of hatchery lineages has reduced variability in growth and reproductive performance exhibited by wild funding stocks which will improve breeding efficiency of subsequent generations. Sex ratio of broods generated by crosses between subspecies are consistent with those involving only northern bluegill in that sex ratios appear not to be determined by a simple XX / XY or WZ / ZZ system.
Our lineages will provide a broad genetic base from which further genetic improvement can be realized, especially as diet formulations are increasingly based on plant derived feedstuffs.