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CUNNER(TAUTOGOLABRUS ADSPERSUS) AS A MODEL FISH FOR REPRODUCTIVE STUDIES IN THE LABORATORY
Citation:
GutjahrGobell, R, M Huber, D Borsay, G Zaroogian, AND L J. Mills. CUNNER(TAUTOGOLABRUS ADSPERSUS) AS A MODEL FISH FOR REPRODUCTIVE STUDIES IN THE LABORATORY. Presented at 1st Biennial Conference on the Biology of Tautog and Cunner,sponsored by NOAA/NMFS and CT Department of Environmental Protection, Mystic, CT, November 30-December 1, 1999.
Description:
Cunner (Tautogolabrus adspersus) are being studied at our laboratory as a model species to determine the effects of endocrine disrupting chemicals (EDCs) on estuarine fish populations. Cunner was selected because this species is common in estuarine areas, is easily obtainable, and is amenable to laboratory holding. In addition, the fish are daily spawners and are large enough to sample blood repeatedly for measuring plasma steroid hormone levels. Because few laboratory reproductive studies with cunner are reported, background data from laboratory observations and field measurements were collected prior to exposure studies. We developed a laboratory holding system to accommodate the spawning behavior of cunner, as well as methodology to collect and enumerate viable, non-viable and fertile eggs produced by cunner in the laboratory. Results of egg production studies indicated that sex ratio and fish density affect cunner reproduction. Both low (1 male: 1 female) and high (3 males: 4 females) fish densities resulted in lower egg production per female than medium fish densities (2 males: 2 females), (3 males: 2 females) and (2 males: 3 females). We also studied various nondestructive methods to distinguish the sex of ripe fish. Coloration of ripe male and female fish, mandible length and gonad biopsy methods did not distinguish the sex of individual fish in our Narragansett Bay population. The only reliable nondestructive method to separate male and female fish was to strip gametes from ripe fish. No evidence that these fish change sex was found. In addition, we sampled cunner from a field reference site weekly for a full reproductive season (April -October 1999) and measured the gonadosomatic (GSI) and hepatosomatic (HSI) indices in male and female fish. Field observations indicated an increase in GSI from mid-April to late-May in male fish and mid-April to early-June in female fish. GSI decreased in both males and females (indicating release of gametes) during June and July. HSI increased in females and decreased in males as fish approached reproduction. In this study, considerable laboratory and field data were collected to characterize both the culture and reproduction of cunner in order to determine if cunner could be a useful sentinel species for environmental EDCs.