Comparison of Diploid and Triploid Largemouth Bass Growth and Maturation in Puerto Rico

Triploid largemouth bass may have potential in sport fish management and in food fish production as a means to eliminate reproduction, which would, in turn, potentially increase somatic growth. To examine this potential, four cohorts of diploid and triploid largemouth bass were produced over a 10 &#45 yr period and tagged intramuscularly with coded wire tags. Bass were stocked into Lucchetti Reservoir, Puerto Rico, and recaptured during subsequent sampling events. Growth rates, condition (relative weight, Wr), and reproductive investment (gonadosomatic index, GSI) were compared for diploid and triploid fish. Mean daily growth rate (MDG) did not differ (P &#8805 0.050) between diploids and triploids overall (diploid MDG&#177SE=0.75 &#177 0.02 mm/d; triploid MDG&#177SE=0.74 &#177 0.03), or by age class through age 2. von Bertalanffy growth parameters were similar between ploidy groups (diploid: L&#8734 =384.5 mm, K=1.244, t0= &#45 0.237; triploid: L&#8734 =387.0 mm, K=1.231, t0= &#45 0.31). Unlike triploid largemouth bass, diploid fish exhibited advanced reproductive development following maturation at age 1; thus, mean GSI was greater for diploids versus triploids for both males and females (t &#8805 2.52, P &#8804 0.010). Relative weight was consistently greater for diploid largemouth bass (P<0.008), likely due to greater GSI. The lack of significant growth advantage in tropical environments precludes using triploid largemouth bass to enhance trophy bass potential in Puerto Rico reservoirs. However, triploid largemouth bass may have utility in systems where largemouth bass reproduction is unwanted.

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