SWFSC juvenile loggerhead sea turtle tracking 2002-2005

Original provider: NOAA Southwest Fisheries Science Center (SWFSC) Dataset credits: NOAA Southwest Fisheries Science Center (SWFSC) Abstract: Satellite telemetry data from 17 juvenile loggerhead turtles (43.5-66.5 cm straight carapace length) were used in conjunction with oceanographic data to analyze the influence of regional and seasonal oceanography on dive behavior in the North Pacific Ocean. Combined dive behavior for all individuals showed that turtles spent more than 80% of their time at 0-5 m depths, and more than 90% of their time at 0-15 m depths. Multivariate classifications of dive data revealed four major dive types, three representing deeper, longer dives, and one representing shallower dives shorter in duration. Turtles exhibited variability in these dive types across oceanographic regions, with deeper, longer dives in the Hawaii longline swordfish fishing grounds during the first quarter of the year, as well as in the Kuroshio Extension Bifurcation Region and the region near the Baja California Peninsula, Mexico. Turtles in the Kuroshio Extension Bifurcation Region also exhibited dive variability associated with mesoscale eddy features, with turtles making deeper, longer dives while associated with the strongest total kinetic energy. Turtles in the central North Pacific exhibited seasonality in dive behavior that appeared to reflect synchronous latitudinal movements with the North Pacific Subtropical Front and the associated seasonal, large-scale oceanography. Turtles made deeper, longer dives during the first quarter of the year within this region, the reported time and area where the highest loggerhead bycatch occurs by the longline fishery. These results represent the first comprehensive study of dive data for this species in this region. The increased understanding of juvenile loggerhead dive behavior and the influences of oceanography on dive variability should provide further insight into why interactions with longline fisheries occur and suggest methods for reducing the bycatch of this threatened species.原始提供者： 美国国家海洋和大气管理局（National Oceanic and Atmospheric Administration，NOAA）西南渔业科学中心（Southwest Fisheries Science Center，SWFSC） 数据集贡献： 美国国家海洋和大气管理局（NOAA）西南渔业科学中心（SWFSC） 摘要： 本研究采用17只幼蠵龟（juvenile loggerhead turtles，背甲直线长度（straight carapace length）43.5~66.5 cm）的卫星遥测数据（satellite telemetry data），结合海洋学数据（oceanographic data），分析了北太平洋区域与季节尺度的海洋学特征对其潜水行为（dive behavior）的影响。所有受试个体的综合潜水行为数据显示，蠵龟80%以上的活动时间处于0~5米水深，90%以上的活动时间处于0~15米水深。对潜水数据的多变量分类（multivariate classifications）结果表明，可划分为4种主要潜水类型：其中3种为深潜长时型，1种为浅潜短时型。 受试蠵龟的潜水类型在不同海洋学区域存在显著差异：每年第一季度（first quarter），夏威夷延绳钓剑鱼渔场（Hawaii longline swordfish fishing grounds）、黑潮延伸体分叉区（Kuroshio Extension Bifurcation Region）以及墨西哥下加利福尼亚半岛（Baja California Peninsula）附近海域的蠵龟，会进行更深、更长时的潜水。在黑潮延伸体分叉区的蠵龟，其潜水行为变异还与中尺度涡旋特征（mesoscale eddy features）相关：当处于总动能（total kinetic energy）最高的区域时，蠵龟会实施更深、更长时的潜水。 北太平洋中部海域的蠵龟，其潜水行为呈现季节性特征，这似乎与北太平洋副热带锋面（North Pacific Subtropical Front）的纬向同步移动以及伴随的季节性大尺度海洋学变化相契合。在该区域，蠵龟会在第一季度开展更深、更长时的潜水——而这一时间段与海域正是现有报道中延绳钓渔业（longline fishery）蠵龟兼捕（bycatch）发生率最高的区域。 本研究是该区域首个针对该物种潜水数据的综合性研究。对幼蠵龟潜水行为及海洋学因素对潜水变异的影响的深入认知，将有助于进一步揭示其与延绳钓渔业产生交互作用的机制，并为降低这一受威胁物种（threatened species）的兼捕损失提供可行思路。