California Cooperative Oceanic Fisheries Investigations (CalCOFI): Acoustic and Trawl Data . In California Cooperative Oceanic Fisheries Investigations (CalCOFI) Collection

The California Cooperative Oceanic Fisheries Investigations (CalCOFI) are a unique partnership of the California Department of Fish & Wildlife, NOAA Fisheries Service and Scripps Institution of Oceanography. The organization was formed in 1949 to study the ecological aspects of the sardine population collapse off California. Today the focus has shifted to the study of the marine environment off the coast of California, the management of its living resources, and monitoring the effects of climate variability and climate change. CalCOFI conducts quarterly cruises off southern & central California, collecting a suite of hydrographic and biological data on station and underway. Data collected at depths down to 500 m include: temperature, salinity, oxygen, phosphate, silicate, nitrate and nitrite, chlorophyll, transmissometer, PAR, C14 primary productivity, and zooplankton biomass. A combination of multi-frequency acoustics and midwater trawl samples were used to estimate the biomass and distribution of mesopelagic and epipelagic (sardine and anchovy) fishes as well as macrozooplankon and identify areas of enhanced productivity and concentration in the southern California Current. Acoustic has been used to remotely detect aquatic organisms for more than half a century. As a non-invasive technique, the use of sound provides a real-time high resolution technique to study aquatic organisms, both quantitatively and qualitatively, with the capacity to reveal complex dynamics of the local biology that include their response to micro- and meso-scale oceanographic features, such as fronts. The methods and potential to identify different groups remotely have improved as the technology has evolved, with the addition of correction factors, development of calibration procedures, and studies of the relationship between echo amplitude and size, material properties of organisms and orientation with respect to the acoustic beam. A multi-frequency acoustic system takes advantage of the differential response of targets of different sizes and composition to different wave lengths, thus enabling discrimination of small organisms (i.e. zooplankton) from large ones (i.e. fish) and fish with air-filled swimbladders from those without. Tony Koslow, now emeritus, led the acoustics group at Scripps, which collected acoustic data on the CalCOFI and California Current Ecosystem Long-term Ecological Research (CCE-LTER) cruises. This acoustic data are the primary subject of the collection here. The data come from up to 4 cruises per year from 2009 – 2015. Each cruise covers 6 or more transects (each 500 km or more) from San Diego to north of Pt Conception (Map of transects). Each cruise is ~16 days duration, with the 5-frequency echo sounder collecting data on each frequency from the surface to 1000 m depth continuously. For these CalCOFI cruises the primary focus of the Koslow lab was to generate acoustic data that can be used to obtain snapshots of ecological populations and monitor changes. Trawl nets were also used to sample species directly, and to help model the acoustic backscatter in relation to the actual species in the water. These data are also included in the collection. In 2004, the CalCOFI surveys became part of the LTER (Long Term Ecological Research) ecological studies network as a site to understand the pelagic ecosystem of the California Current. The CCE-LTER project has expanded CalCOFI objectives, including the addition of midwater trawl and acoustic sampling. LTER also conducts quasi-annual process cruises in the CalCOFI region and operates autonomous gliders along lines 80 and 90 (http://spray.ucsd.edu/).

加州合作海洋渔业调查（California Cooperative Oceanic Fisheries Investigations, CalCOFI）是由加州鱼类与野生动物部、NOAA渔业服务处与斯克里普斯海洋研究所共同组建的独特合作机构。该机构成立于1949年，旨在研究加州外海沙丁鱼种群崩溃的生态学特征。如今其研究重心已转向加州沿岸海洋环境、海洋生物资源管理，以及监测气候变率与气候变化的影响。
CalCOFI每季度会在加州南部与中部外海开展科考巡航，通过定点与走航方式采集一系列水文与生物数据。采集深度可达500米的指标包括：海水温度、海水盐度、溶解氧、磷酸盐、硅酸盐、硝酸盐与亚硝酸盐、叶绿素浓度、透射仪数据、光合有效辐射（PAR）、碳14（C14）初级生产力数据，以及浮游动物生物量。
研究团队结合多频声学技术与中层拖网采样数据，对中层浮游（mesopelagic）和近表层浮游（epipelagic，即沙丁鱼与鳀鱼）鱼类的生物量与分布进行估算，同时针对大型浮游动物开展调查，并识别加州海流系统中生产力与生物聚集增强的区域。
声学技术用于远程探测水生生物已有逾半个世纪的历史。作为一种非侵入式手段，声学探测可实时提供高分辨率数据，实现水生生物的定量与定性研究，能够揭示当地生态系统的复杂动态——包括生物对锋面等微尺度与中尺度海洋学特征的响应。随着技术迭代，远程识别不同生物类群的方法与潜力不断提升，这得益于校正因子的完善、校准流程的开发，以及对回声振幅与生物尺寸、机体材质属性、相对于声束朝向之间关系的研究。多频声学系统可利用不同尺寸与组成的目标对不同波长声波的差异化响应，从而实现区分小型生物（如浮游动物）与大型生物（如鱼类），以及有充气鱼鳔鱼类与无鳔鱼类的目的。
现已荣休的托尼·科斯洛（Tony Koslow）曾领导斯克里普斯研究所的声学研究团队，该团队在CalCOFI与加州海流生态系统长期生态研究（California Current Ecosystem Long-term Ecological Research, CCE-LTER）科考巡航中采集了声学数据。本次数据集的核心内容正是这批声学数据。数据采集时段为2009年至2015年，每年最多开展4次巡航。每次巡航覆盖6条及以上断面（单条断面长度达500千米及以上），航行范围从圣迭戈延伸至康塞普申角以北（断面分布地图可参见http://spray.ucsd.edu/）。单次巡航时长约16天，搭载的5频回声测深仪会连续采集从海面至1000米深度的各频段声学数据。在这些CalCOFI巡航中，科斯洛实验室的核心目标是获取可用于描绘生态种群快照并监测种群变化的声学数据。
研究团队同时使用拖网开展直接物种采样，以辅助构建与水体中实际物种对应的声学背散射模型，相关数据也被纳入本数据集。
2004年，CalCOFI调查项目加入长期生态研究（Long Term Ecological Research, LTER）生态研究网络，成为研究加州海流上层浮游生态系统的核心站点。CCE-LTER项目拓展了CalCOFI的研究目标，新增了中层拖网与声学采样内容。LTER还会在CalCOFI研究区域开展准年度的过程科考巡航，并在80号与90号断面沿线部署自主滑翔机（相关信息可参见http://spray.ucsd.edu/）。