No abstract

Management and conservation have begun to rely on supplemental information to make appropriate decisions. In organisms with little available information, preserved specimens may be particularly important for researchers to continue their role in the management process. Bluenose Shiners are a minnow species that can benefit from such analyses as they are of conservation concern across their native range in the Southeastern United States. To supplement conservation, the objectives were to: (a) quantify sexual dimorphism through a comprehensive morphological analysis, (b) approximate peak spawning condition of males and females through GSI measurements over the anticipated spawning season, and (c) utilize female gonad histology to refine conclusions regarding spawning condition from GSI. Historical collections of Bluenose Shiners obtained from the Tulane University Biodiversity Research Institute were used to conduct morphological and gonadal analyses. While males expressed all morphometrics to a greater degree, male dorsal and anal fin length appears to be the most distinguished characteristic beginning at a total length of approximately 45 mm. GSI displayed peaks in the samples from April 21, 1957 and June 1, 1968; female GSI from Black Creek, MS in April, May, and June of 1986 suggested a peak in late May. Gonad histology showed a progression towards final oocyte maturation through May to early June, via relative prevalence of stage IV and absence of stage I oocytes. This information can be used to supplement future morphometric analyses and reproductive studies performed on Bluenose Shiners or other fish species.

A culture demand has developed within the ornamental and baitfish industries for fishes of the genus Fundulus. Refining reproductive methods may not only benefit important industries, but related species of conservation concern as well. Golden Topminnows Fundulus chrysotus are a common fish species across their native range and they have their own ornamental demand. Low fecundity observed in species of Fundulus has been the main obstacle to their efficient culture. Therefore, the objective of this study was to determine the optimal female broodfish size for increasing certain reproductive parameters (fecundity, embryo, and larval morphometrics), which ultimately contributes to better survival from embryo to larva. Outdoor and indoor studies were conducted between April 2018 and July 2018. Three distinct female size‐classes were stocked in an indoor recirculating aquaculture system and outdoor mesocosms. The indoor study involved palpating females once every 3–4 d for 2.5 weeks, and the outdoor study utilized mesocosms to assess natural embryo and larval metrics over a 10‐week period. In indoor laboratory experiments, large females ovulated the greatest numbers of eggs; however, the number of eggs per gram (female weight; mean ± standard error of the mean) was proportional across all three size‐classes (small: 2.8 ± 0.64; medium: 2.3 ± 0.51; large: 3.1 ± 0.51). In outdoor mesocosm experiments, larval TL and percentage of embryos surviving to hatch were lowest for large size‐class progeny, which may have resulted from their relatively larger chorion size and nonstandardized incubation density contributing to inhibited development. Female Golden Topminnows proportionally invest in yolk production, and thus produce greater numbers of eggs.