Elasmobranquios de la Isla Cayo Serranilla durante la Expedición Seaflower 2017 - Proyecto Colombia BIO

In response to population declines noted for many sharks and other elasmobranch species around the world, protecting them from overexploitation has become a global priority. However, the necessary data to assess the diversity and abundance of elasmobranchs has often hindered efforts to effectively restore and protect such species. Many reef surveys around the world have been conducted by scuba divers, although many studies have exposed the flaws and biases of this type of surveys for species such as elasmobranchs. Sampling of these species has traditionally been resource and time intensive due to the need to capture sharks or rays on lines. Recently, advances in video technology have allowed the deployment BRUVs. This technique involves positioning a bait source in front of an underwater video camera and quantifying the fish that are observed in the field of view over a standard sampling period and are an ideal way to quickly, and inexpensively, sample populations of relatively low-density predators like sharks and rays. Due to the remote location of Isla Cayo Serranilla, in the northernmost region of the Seaflower Biosphere Reserve, there is a lack of knowledge of elasmobranch species and their abundance in the area. In order to estimate reef elasmobranch diversity and relative abundance in the Colombian Caribbean at Isla Cayo Serranilla and detect possible bright spots in the region, 52 BRUVs were deployed on the fore-reef and the inner lagoon. Depth was standardized between 8 and 30 m and deployments were performed using standardized pre-weighted bait. Videos will be watched, and species and the maximum number of reef species observed in a single frame (Nmax) will be recorded. This estimate (Nmax) is similar to the Catch per Unit of Effort (CPUE) and will be used to assess the relative abundance of reef shark at Isla Cayo Serranilla. Conduct a 2-week Baited Remote Underwater Video Survey (BRUV) of reef elasmobranch diversity and relative abundance in the Colombian Caribbean at Isla Cayo Serranilla (San Andrés Archipelago) and detect possible bright spots in the region. These key baseline data will support future studies on elasmobranchs in other areas of the Seaflower Biosphere Reserve and fill in gaps on the status of elasmobranch populations in the region. This will be combined with large existing BRUV datasets collected in other key locations around the world for a global analysis through the Global FinPrint project (www.globalfinprint.org).针对全球范围内多种鲨鱼及其他板鳃类（elasmobranch）物种种群衰减的现状，对其实施保护以规避过度捕捞已成为全球优先议题。然而，评估板鳃类物种多样性与种群丰度所需的基础数据往往匮乏，这严重阻碍了针对该类群开展有效保护与种群恢复的工作。目前全球诸多珊瑚礁调查多由水肺潜水员完成，但已有多项研究指出，针对板鳃类等物种而言，此类调查方法存在显著缺陷与采样偏差。传统采样方式需通过延绳钓捕获鲨鱼或鳐鱼，因此往往耗费大量人力、物力与时间成本。近年来，视频技术的进步推动了诱饵式远程水下视频采样（Baited Remote Underwater Video Survey, BRUV）技术的应用部署。该技术的核心操作是将诱饵布设至水下摄像机前方，在标准采样时段内统计视野范围内出现的鱼类个体数量，是一种能够快速且低成本地对鲨鱼、鳐鱼等低密度捕食者种群开展采样的理想方案。塞拉尼拉礁岛（Isla Cayo Serranilla）坐落于海花生物圈保护区（Seaflower Biosphere Reserve）最北端，地理位置偏远，目前学界对该区域内的板鳃类物种及其种群丰度的认知极为有限。为评估哥伦比亚加勒比海海域塞拉尼拉礁岛的珊瑚礁板鳃类物种多样性与相对丰度，并探寻该区域的潜在种群热点，研究团队在前礁礁坡与潟湖内部共布设了52台诱饵式远程水下视频采样设备。本次采样统一将布设深度控制在8至30米区间，并采用标准化预配重诱饵开展设备部署。后续将对采集到的视频进行人工标注，记录观测到的物种信息，以及单帧画面中出现的珊瑚礁鱼类最大个体数量（Nmax）。该统计指标（Nmax）与单位捕捞努力量渔获量（Catch per Unit of Effort, CPUE）具有相似的生态学意义，将被用于评估塞拉尼拉礁岛的珊瑚礁鲨鱼相对种群丰度。 本次研究将在哥伦比亚加勒比海海域圣安德烈斯群岛（San Andrés Archipelago）辖下的塞拉尼拉礁岛开展为期两周的诱饵式远程水下视频采样（BRUV），以调查该区域的珊瑚礁板鳃类物种多样性与相对丰度，并探寻区域内的潜在种群热点。本次研究获取的核心基线数据，将为海花生物圈保护区其他区域的板鳃类相关研究提供支撑，并填补该区域板鳃类种群现状相关研究的空白。研究团队将结合全球其他关键区域已收集的大型诱饵式远程水下视频采样数据集，通过全球鳍印项目（Global FinPrint, www.globalfinprint.org）开展全球性综合分析。