Sex differentiation of summer flounder (Paralichthys dentatesL.) raised at practical hatchery temperatures

Abstract

Female summer flounder grow considerably faster than males, and rearing temperature has been shown to influence sex differentiation in related species. The present studies were conducted to examine sex differentiation of post-metamorphic juveniles reared at temperatures conducive for commercial production. In experiments 1 and 2, offspring produced from crosses with meiogynogenetic, sex-reversed males and normal females were raised at 14, 16 or 18°C for ≥300 days or 12°C for 30, 60 or 120 days and then transferred to a male-determining temperature (21°C). In all cases, the fish developed predominantly as phenotypic males (≥74%). In a third experiment, offspring produced from crosses with normal males and females were reared at 15, 17 and 19°C for 111, 227 and 278 days and then transferred to 21°C. Most fish (≥92.1%) developed as phenotypic males irrespective of rearing temperature or length of exposure. Several hypotheses are proposed for these findings and further research is necessary to understand the sex-determining mechanisms in this species before the economic advantages associated with sexually dimorphic growth can be realized.

Effects of dietary genistein administration on growth, survival and sex determination in southern flounder,Paralichthys lethostigma

“…After 132 days (285 DPH) in culture, all fish were again anaesthetized, enumerated, measured and weighed. Flounder ≥130 mm total length (TL) were euthanized with ~200 g L −1 Tricaine‐S and dissected for morphological sex determination as described by Colburn, Breton, Nardi and Berlinsky () in summer flounder ( P. dentatus ). Gonadal tissue was collected from fish with ambiguous gender, fixed in 10% formalin and processed for routine histology with haematoxylin and eosin staining.…”

Modeling potential consequences of climate‐driven sex reversal on Southern and Summer Flounder population dynamics

“…2003, 2009; Colburn et al. 2009, 2015). We also know that the population biomass of Summer Flounder has shifted northward over time (Perretti and Thorson 2019) and, if anything, adult Southern Flounder migrate south (Craig et al.…”

“…We should not assume that the findings for Southern Flounder from Honeycutt et al (2019) could apply to juvenile estuarine populations of Summer Flounder because the two species utilize different types of habitat within estuaries (Selden Burke et al 1991) and thus will be exposed to different environmental conditions. Further, there are differences between the species in how sexual differentiation is impacted by temperature (Luckenbach et al 2003(Luckenbach et al , 2009Colburn et al 2009Colburn et al , 2015. We also know that the population biomass of Summer Flounder has shifted northward over time (Perretti and Thorson 2019) and, if anything, adult Southern Flounder migrate south (Craig et al 2015), meaning that juvenile Summer Flounder may not be exposed to consistently warming temperatures.…”