| The habitat use and movements of the round stingray, Urobatis halleri, were compared between natural and mitigation habitats of the Anaheim Bay Estuary, California, U.S.A., from 2006--2008 to determine whether rays use warm water habitats and if pregnant females are present in mitigated areas during months of warm water temperatures. Rays were uncommon in the estuary from late fall through early spring, but abundant in mitigated areas during summer. From July--September, only female rays were present in mitigated areas, but sex ratios in natural areas were only slightly female-biased. Pregnant female rays were present in mitigated areas during summer and early fall. Female rays spent less time in mitigated areas as seasonal water temperatures decreased and typically emigrated from the estuary by mid-August. Pregnant female rays that aggregate in mitigated areas may attain a thermally-derived reproductive benefit by using warmer water habitats during gestation. Understanding these behavioral patterns is necessary in order to recognize the potential effects of sex-biased fishing exploitation and modified thermal environments on elasmobranch populations that show a seasonal habitat preference for inshore and nearshore marine environments. |
