Abstract

The Chandeleur Island chain is a natural barrier island formation off the east coast of Louisiana. Due to the north-south orientation of the Chandeleur Island chain, an estuary is formed between the eastern coast of Louisiana and the western boundary of the islands. Though the Chandeleur Island chain is known to support shark populations, there is considerable environmental variability associated with the area, thereby obscuring the specific usage by various species and life stages. The western, estuarine area, the Chandeleur Sound, is relatively shallow, and more subject to freshwater runoff from terrestrial sources creating an environment with generally lower salinity and higher nutrients. This is evidenced by the rich seagrass beds present on the west side of the islands. In contrast, the east side of the island chain does not support seagrass beds, generally has a higher salinity, and drops off to depths greater than 20 feet within a couple of nautical miles. The southern end of the island chain (south of Curlew Island) supports smaller seagrass beds on the western side of the islands, receives terrestrial runoff, but is not as insulated, as the islands become smaller and less contiguous, thus more exposed to the open Gulf. Understanding the specific utilization of the island chain by multiple species and life stages of sharks, especially in regards to the area serving as a potential nursery ground, is imperative. The island chain regularly experiences hurricanes, freshwater runoff, and land mass loss, all of which are expected to increase in coming years and contribute to a vastly fluctuating environment.

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