There is an expectation that female largemouth bass (LMB) will grow faster than male LMB in aquaculture. In the sport fishery, trophy largemouth bass are often observed to be female. It has also been documented that female LMB tend to live longer than male LMB and that females are larger than males among older fish of the same age. Whether there is significant difference in growth rate among male and female largemouth bass in commercial aquaculture over a two-year production cycle is not clear. If so, culture of a single sex may be a useful strategy. In this study, observations were made on growth rate of feed trained male and female largemouth bass (Micropterus nigricans) during the second year of growth in small experimental ponds (P) and floating raceways (RW).
One-year-old stocker size largemouth bass were grown out in two formats (P and RW) in 2022 and in a single RW in 2023 and 2024. In all three seasons, fish were fed a 45% protein 20% lipid diet once daily to apparent satiation. In 2022, fish were stocked into three 0.04ha ponds and two 41m3 floating pond raceways. 50 fish in each pond and 100 fish in each raceway were inserted with a Passive Integrated Transponder (PIT) tag. In 2023 and 2024, fish were stocked into a single 41m3 raceway. In all seasons, weekly water quality was performed to determine total ammonia nitrogen, nitrite, nitrate, alkalinity, and pH, in addition to daily water parameters including dissolved oxygen and temperature. At stocking fish tag number, weight, and length were recorded. At harvest recovered tagged fish were euthanized and measured for individual weight and length. Visual examination of internal gonads was the basis for determination of sex at harvest.
No difference in growth rate with regard to sex was observed among LMB in any format or season.