Abstract
Despite the high proportion of endangered species of elasmobranchs occurring in coastal areas subjected to intense fishing pressure, most of the existing habitat use information applies to pelagic species. Recent research efforts have substantially increased the information available on the habitat use of overlooked and often data deficient species. Here, we use vertebrae microchemistry data to study the habitat use patterns of four species of threatened sharks and two species of stingrays occurring in the Brazilian Amazon Coast (BAC). We obtained vertebrae samples from specimens sold in fish markets along the entire BAC area and analyze element:Ca ratios for four elements: Mg, Mn, Sr, and Ba. Our results demonstrate that most species likely complete their entire life cycle in the same region, with little to no use of freshwater habitats, and sympatric occurrence of neonates, juveniles, and adult life stages. The wingfin stingray, the only benthic-restricted species analyzed, differed substantially from all other species, with strong reliance on estuarine areas. The scalloped hammerhead has the largest variability in chemical trace elements, suggesting the use of habitats with wide variations. American cownose ray, daggernose, shovelbill, and smalleye hammerhead sharks showed strong reliance on the same type of habitat throughout their ontogenetic development. Our findings underscore the importance of the BAC as an Essential Fish Habitat for these species, a critical area for improved fisheries management given the widespread population declines and historical overfishing, and the danger of proposed oil exploration in the area can pose to its elasmobranch populations.
Published Version
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