Burger brought up the research first and I went and found it. There are hybrid crappie with lower fecundity and some (?) triploid ( research). TPW has some triploid LMB that they won't share. Also many fish species can be sex reversed to all male or all female including some tilapia. From
http://www.pondboss.com/ubb/ultimatebb.php?ubb=get_topic;f=5;t=000402#000002 Lusk and Burger's comments are there.
Comparisons of Triploid and Diploid White Crappies
GLENN R. PARSONS
Freshwater Biology Program, Department of Biology, The University of Mississippi, University, Mississippi 38677, USA
Abstract.—I produced triploid white crappies Pomoxis annularis in the laboratory by subjecting stripped eggs to 5°C for 90 min. This treatment produced triploids on three out of seven attempts, yielding 92%, 93%, and 100% triploids. I compared several hematological characteristics of adult triploid and diploid white crappies. Triploids had significantly lower concentrations of circulating red blood cells and hemoglobin than diploids but their red blood cells had significantly greater volumes and hemoglobin contents. Diploids had significantly higher gonadosomatic indices. Diploids and triploids did not differ significantly in heart weight as a percentage of body weight or in standard metabolic rate, active metabolic rate, or critical swimming speeds. Despite the hematological differences, nonreproductive triploid white crappie adults appear to be as fit for survival as normal diploid fish.
Comparison of Triploid Hybrid Crappie and Diploid White Crappie in Experimental Ponds
GLENN R. PARSONS
Department of Biology, The University of Mississippi, University, Mississippi 38677, USA
KEITH MEALS
Mississippi Department of Wildlife, Fisheries and Parks, 310 Shoemaker Hall, University, Mississippi 38677, USA
Abstract.—We crossed female white crappies Pomoxis annularis with male "black-stripe" black crappies P. nigromaculatus to yield hybrids possessing a distinct coloration that may serve as a natural tag when fish are introduced into existing crappie populations. Eggs of these hybrids were cold shocked to produce triploid hybrid crappies. In three spawns, the black stripe was expressed in 100% of hybrids that were not cold shocked and 85% of hybrids that were cold shocked. Coldshocked hybrids were 95% triploid and 5% diploid. Triploid hybrids bearing the black stripe and diploid white crappies without the black stripe were stocked into experimental ponds for growth and survival comparisons. There were inconsistent differences in growth, body condition, and survival of triploid hybrids and diploid white crappies after 1,151 d in ponds, but the gonads of triploid hybrids were consistently smaller than those of diploid white crappies for each sex. No reproduction was observed in ponds with triploid hybrids, whereas reproduction occurred in ponds with diploid white crappies. Although better growth and survival were not consistently observed among triploid hybrids, the lack of reproduction may be an advantage over diploid white crappies in the management of small impoundments.
Evaluation of F1 Hybrid Crappies as Sport Fish in Small Impoundments
MICHAEL L. HOOE and D. HOMER BUCK
Illinois Natural History Survey, Sam Parr Biological Station, Rural Route 1, Box 174, Kinmundy, Illinois 62854, USA
Abstract.—Growth and reproductive characteristics of reciprocal F1 and F2 hybrid crappies–white crappies Pomoxis annularis × black crappies P. nigromaculatus–were examined to determine if hybrids are better suited for stocking in small impoundments than their parent species. Relative weight gains of the reciprocal age-0 F1 and F2 hybrid crappies were not significantly different (P = 0.55), but the relationship may have been masked by differences in initial sizes of the test fish. Second-year relative growth rates of both reciprocal F1 hybrids were significantly greater than growth of either of the parent species and, with one exception, than growth of the reciprocal F2 hybrids. The reciprocal F1 hybrid crappies were capable of backcrossing with their parent species, and both reciprocal F1 hybrid male crappies had viabilities equal to those of their parent species. Egg viability for the F1 hybrid black crappie female × white crappie male appeared equal to that of the parent species and greater than that of its reciprocal hybrid. Recruitment in ponds was highest for the pure species, intermediate for the F1 hybrids, and lowest for the F2 hybrids. This study confirmed that F1 hybrid crappies may offer a viable alternative to stocking parent species in small impoundments, the F1 hybrid white crappie female × black crappie male being preferable to its reciprocal hybrid. We recommend that hybrid crappies be used only on an experimental basis pending a more thorough evaluation of the incidence and effects of backcrossing with parent species.
