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MAXIMIZING GROWTH AND SEXUAL MATURATION OF SHEEPSHEAD MINNOWS IN SUPPORT OF MULTI-GENERATION TEST DEVELOPMENT
Citation:
Hemmer, B. L., G M. Cripe, AND L R. Goodman. MAXIMIZING GROWTH AND SEXUAL MATURATION OF SHEEPSHEAD MINNOWS IN SUPPORT OF MULTI-GENERATION TEST DEVELOPMENT. Presented at SETAC World Congress, Portland, OR, November 14 - 18, 2004.
Impact/Purpose:
Conference abstract
Description:
Hemmer, R.L., G.M. Cripe and L.R. Goodman. In press. Maximizing Growth and Sexual Maturation of Sheepshead Minnows (Cyprinodon variegatus) in Support of Multi-Generation Test Development (Abstract). To be presented at the SETAC Fourth World Congress, 14-18 November 2004, Portland, OR. 1 p. (ERL,GB R1016).
Chemical exposures spanning multiple generations are essential for identifying and characterizing possible cumulative long-term adverse effects on aquatic organisms. Because life-cycle exposures are time consuming and expensive to conduct, it is important to determine ways to minimize the duration of these tests. The longest critical development period for most fish species is transformation from a juvenile to sexually mature adult. Critical elements which typically affect growth are space, temperature and nutrition factors. In established life-cycle guidelines for sheepshead minnows (SHM), the age for spawning adults ranges from 70 to 150 days. Other studies indicate size (total length greater than or equal to 27 mm) rather than age is a better discriminator of sexual maturity. In a preliminary study, we observed that SHM reached 27.7 mm at 25?C in as early as 50 days. In the present study, three different feeding regimens were examined for their effect on growth and time to maturation of juvenile SHM. Viable embryos were collected from adult SHM and held under intermittent flow-through conditions until hatching. Spawning, hatching and feeding regimens were maintained under identical flow-through conditions of 27 ? 2?C, 20 ? 2 ppt salinity, photoperiod of 14L:10D. Larval SHM were fed high quality 48 hr. old Artemia nauplii through 14 days post-hatch. Twenty-five larval fish were randomly assigned to one of three feeding regimens: Tetramina Tropical Flakes (morning) and frozen adult brine shrimp (afternoon). Feeding was accomplished by supplying small aliquots of food over a period of 10 minutes until satiation was observed. Survival and growth (total length) was monitored at ten day intervals throughout the test. At test termination, growth parameters were analyzed for significant difference between feeding treatments. The results of this research will support the development and evaluation of multi-generational tests with estuarine fish.