Population dynamics and movements of the Kemp's ridley sea turtle, lepidochelys kempii, in the northwestern Gulf of Mexico

摘要

The Kemp?s ridley sea turtle, Lepidochelys kempii, is recovering fromdevastating declines that reduced nesting activity from a single-day estimate of 10,000-40,000 females in 1947 to fewer than 300 during all of 1985. Nesting beach monitoringis crucial to estimating population size and reproductive activity, but in-water data areessential for understanding population dynamics and evaluating management strategies.Hook-and-line, stranding, and nesting records, satellite telemetry, and dietanalyses were used to characterize ridley population dynamics and movements in thenorthwestern Gulf of Mexico during 2003-2007. Recreational hook-and-line capturescomprised approximately one third of non-nesting encounters along Galveston andJefferson Counties, Texas. The hook-and-line dataset displayed similar geographical andmonthly trends to that of strandings, but was devoid of pelagic-stage, subadult, and adultridleys.Coastal and bay waters along the upper Texas and western Louisiana coasts wereutilized by immature ridleys during warmer months. Nesting occurred along GalvestonIsland on both armored and unarmored beaches. Inter-nesting females exhibited fidelityto Galveston during nesting season and subsequently migrated to federal waters offshoreLouisiana. Crabs were important components of benthic-stage (>25 cm SCL) ridley diet,while worm tubes were targeted by some individuals. Short satellite track durations for immature ridleys precipitated examinations ofbiofouling, attachment protocols, and turtle excluder device (TED) interactions.Antifouling paints drastically reduced fouling of transmitters. A less-rigid neopreneattachment method was developed to increase transmitter retention on fast-growingjuveniles, but further trials are necessary. Transmitters were not damaged or lost duringTED trials, but turtle escape times increased when transmitters wedged between TEDbars.Projected population growth will increase numbers of Kemp?s ridleys utilizingthe Gulf of Mexico and interacting with human activities. Future research shouldexamine year-round distribution and abundance of all life history stages and furthercharacterize recreational hook-and-line capture, nesting activity, movements, and diet.Education efforts targeting the beach-going public, beach residents and workers, and therecreational fishing sector should be employed to promote sea turtle reporting andminimize negative interactions. State and federal managers should examineanthropogenic impacts within the region and determine the need for mitigation and/orregulations to promote continued species recovery.