Telemetric and Genetic Analyses of Habitat Use, Philopatry and Natal Homing of a Coastal Shark Species in Continental Nursery Areas

海洋的洄游脊椎动物，包括海洋鱼类、海龟、海鸟和海洋哺乳动物，与海洋边缘的联系方式尚不完全清楚。这些海洋动物在其生命史的关键阶段往往依赖近海地区进行繁殖、进食和其他基本活动。人们对如何将沿海地区与其他地区区分为这些移栖物种的首选栖息地知之甚少，特别是在适宜栖息地似乎分布广泛的广阔大陆地区。一个物种如何以及为什么选择一个特定的大陆沿海地区进行繁殖和早期生活阶段--以及同一地理位置是否被个别动物以进化上固定的方式利用--仍然是一个谜，特别是在鲨鱼的情况下，鲨鱼是海洋中占主导地位的顶级捕食者。莫特海洋实验室自1991年以来对鲨鱼育苗区进行的研究表明，至少有14种沿海鲨鱼利用佛罗里达墨西哥湾沿岸地区作为幼鲨和/或育苗区。这项研究表明，新生黑鳍鲨（Carcharhinus limbatus）在5月至9月期间大量出现在佛罗里达湾沿岸的沿海海湾和河口，然后向南迁徙过冬。该项目将研究使用海湾作为新生儿和青少年C limbatus的苗圃区，试图确定这一地区的年轻鲨鱼的生活史中的生态作用，如果使用这些地区导致了philopatry的演变。本研究的目的是：1）描述保育区内的缘纹石首鱼幼鱼的活动模式、活动范围和栖息地偏好，并确定它们在保育区内的栖息时间; 2）估计返回率（philopatry）一岁的动物到纳塔尔托儿所和defiiie他们继续使用托儿所区;以及3）通过分析种群内的遗传变异来确定成年雌性鲨鱼是否返回其纳塔尔育儿区分娩（纳塔尔）。这项研究将在Terra Ceia湾进行，Terra Ceia湾是沿着佛罗里达墨西哥湾中部海岸的大陆苗圃区。在春季、夏季和秋季，将在保育区内部署一个最先进的远程声学水听器系统，不断监测装有超声波发射器的鲨鱼的位置和移动。从水听器站收集的数据将用于确定幼鲨在保育区的停留时间、活动模式、活动范围和栖息地利用。一旦使用泰拉塞亚湾作为新生儿C的托儿所。limbatus的定义，重要的是要审查特定的托儿所区是否继续是幼鲨生活史的组成部分。将利用水听器系统并通过在三个相邻的沿海保育区（松岛湾、扬基敦、万岛）进行取样，检查幼鲨返回其纳塔尔保育区的比率。继续监测Terra Ceia湾将提供关于非新生幼鱼的同一个体的停留时间、活动模式、活动范围和栖息地利用的信息。远程声学系统的使用将为完成本研究的前两个目标提供主要数据。遗传分析将测试亲视行为的发生，以支持水听器结果，并测试成年雌性的纳塔尔归巢。这些分析将提供必要的数据，以评估雌性鲨鱼纳塔尔归巢的假设。虽然philopatry和纳塔尔是众所周知的其他动物物种，这项研究将提供第一个直接的努力，以阐明这些行为的板鳃类种群，特别是一个居住在大陆地区，合适的托儿所栖息地是广泛的，而不是孤立的。这项研究的结果将提供有关幼鲨习性的连续数据，在跟踪过程中不受科学家的干扰。总的来说，该项目将研究沿海育苗区在栖息于大陆架沃茨的鲨鱼物种生活史中的更大作用。

The ocean's migratory vertebrates, including marine fishes, sea turtles, sea birds and marine mammals, are tied to the sea's margins in ways that are not completely understood. These marine animals often depend on inshore regions for reproduction, feeding and other essential activities during critical stages of their life histories. What delineates one coastal area from another as preferred habitat for these migratory species is poorly known, particularly for broad continental regions where suitable habitat appears to be widespread. How and why a species selects a specific continental coastal area for reproduction and early life stages -and whether the same geographic site is utilized by individual animals in an evolutionarily fixed way- remain somewhat of a mystery, particularly in the case of sharks, the predominant apex predators in the sea. Previous research on shark nursery areas conducted by Mote Marine Laboratory since 1991 has shown that at least 14 coastal shark species utilize inshore regions of the Gulf of Mexico coast of Florida as pupping and/or nursery areas. This research has shown that neonate blacktip sharks (Carcharhinus limbatus) are abundant in coastal bays and estuaries of the Florida Gulf coast from May through September before migrating south for the winter. This project will examine the use of a bay as a nursery area for neonate and juvenile C limbatus, attempt to define the ecological role of this area in the life history of young sharks and if use of these areas has resulted in evolution of philopatry. The research objectives are to: 1) delineate the activity patterns, home range and habitat preferences of young C limbatus in a nursery area and ascertain how long these animals reside within a specific continental nursery area; 2) estimate the return rate (philopatry) of one year-old animals to the natal nursery and defiiie their continued use of the nursery area; and 3) determine if adult female sharks return fo their natal nursery area to give birth (natal homing) through analysis of genetic variation within the population. This research will be conducted in Terra Ceia Bay, a continental nursery area along the central Gulf coast of Florida. A state-of-the-art system of remote acoustic hydrophones will be deployed within the nursery area during spring, summer and fall months to continuously monitor the location and movement of sharks fitted with ultrasonic transmitters. Data collected from hydrophone stations will be used to determine the residence time, activity patterns, home range and habitat use of young sharks in the nursery area. Once the use of Terra Ceia Bay as a nursery area for neonate C. limbatus has been defined it will be important to examine whether specific nursery areas continue to be integral in the life history of juvenile sharks. The return rate of young sharks to their natal nursery will be examined using the hydrophone system and by conducting sampling in three adjacent coastal nursery areas (Pine Island Sound, Yankeetown, Ten Thousand Islands). Continued monitoring of Terra Ceia Bay will provide information on residence time, activity patterns, home range and habitat use for the same individuals as non-neonate juveniles. Use of the remote acoustic system will provide the primary data to accomplish the first two objectives of this study. Genetic analyses will test for the occurrence of philopatry to support hydrophone results and test for natal homing by adult females. These analyses will provide the data necessary to evaluate the hypothesis of natal homing by female sharks. Although philopatry and natal homing are widely known in other animal species, this study will provide the first directed effort to elucidate these behaviors within an elasmobranch population, particularly one inhabiting a continental region where suitable nursery habitat is widespread and not insular. Results of this study will present continuous data concerning the habits of young sharks without disturbance by scientists during tracking. Overall, this project will examine the larger role of the coastal nursery area in the life history of shark species inhabiting continental shelf waters.