USGS Lake Erie East Harbor bottom trawl data series, 1961-2011

The USGS Lake Erie Biological Station’s East Harbor sampling program began in 1961 with the commissioning of the research vessel Musky II. It is the longest known continuous trawl survey in Lake Erie. In addition to spanning over 50 years, the data series is unique for three prominent design elements: 1) sampling was conducted at three depth strata; 2) replicate trawl samples were collected at each depth stratum; and 3) sampling was conducted during both day and night. Unlike other trawl series collected in Lake Erie, and throughout the Great Lakes, the East Harbor program is the only one to combine these sampling practices in a single survey. In 2012, the original vessel used since the inception of the East Harbor program, the research vessel Musky II, was retired and replaced with a larger research vessel, Muskie. The change in vessel necessitated change in the trawl net and all of the rigging and hardware needed to tow it (LEBS, 2013). This effectively ended the time series of data, which were collected with the exact same vessel and sampling gear for 51 years. This historical data set has proven valuable for testing hypotheses about long-term ecological change and the impacts of non-native species invasions in the Great Lakes. Further, at various times through history it provided accurate predictions of recruitment for species, such as Yellow Perch, that support some of the most valuable fisheries in the Great Lakes. For future scientific endeavors, and to ensure this work is available to the public, we present here the entire data set from 1961 through 2011.美国地质调查局（USGS）伊利湖生物站的东港采样项目于1961年启动，伴随研究船马斯基二世号（Musky II）的正式启用。该项目是目前已知的伊利湖持续时间最长的连续拖网调查。该数据集序列不仅拥有50余年的时间跨度，其独特性还体现在三大突出设计要素：1）采样覆盖三个水深分层；2）每个水深分层均采集重复拖网样本；3）采样在昼夜两个时段均开展。不同于伊利湖乃至整个五大湖区域的其他拖网调查序列，东港采样项目是唯一一项将上述采样方案整合至同一调查中的项目。 2012年，该项目自启动以来一直使用的研究船马斯基二世号退役，替换为更大吨位的研究船马斯基号（Muskie）。船只更换导致拖网及所有用于拖拽的索具与硬件设施的更新（LEBS, 2013）。这一变更实质上终结了使用完全相同船只与采样设备开展的长达51年的时间序列数据采集工作。 这套历史数据集已被证实对检验五大湖长期生态变化及外来物种入侵影响的相关假说极具价值。此外，在历史的不同阶段，它还为支撑五大湖部分最具经济价值渔业的物种（如黄鲈（Yellow Perch））的种群补充量提供了精准预测。为支撑未来科研工作，并确保该数据集可面向公众开放，本文现公开1961年至2011年的完整数据集。