Biocomplexity at North Temperate Lakes LTER; Coordinated Field Studies: Predation Study Data 2000 - 2004

These data were collected to track changes in dietary composition, changes in age and growth structure, and changes in species and size of prey of fish predators in Sparkling Lake, Vilas County, WI, USA. Sampling began in May of 2000 and ended in September of 2004. Fish were collected with a boat-mounted electrofishing system, usually by conducting a complete lap around Sparkling Lake shortly after dark. Commonly captured species were rock bass, smallmouth bass, and walleye. Less common species were pumpkinseed sunfish and yellow perch. Dietary Composition: Fish stomach contents were collected by gastric lavage, and fish were released after capture. Stomach contents were sorted and counted by major taxonomic groups, dried in polystyrene weighboats at 57 deg C for 48hrs, and then weighed to 0.001g. The count under a taxonomic group heading indicates how many individuals of that group were found in that diet sample. The mass of that group is given in the adjacent ''net wt'' column. Diets varied across sampling dates and years, with a trend towards decreased abundance of the exotics rusty crayfish and rainbow smelt and increased reliance on native minnows. Prey Data: Fish stomach contents were collected by gastric lavage, and fish were released after capture. Once collected, crayfish and fish prey were measured unless advanced digestion had occurred. If possible, the carapace, right chela and left chela of crayfish prey were measured . Due to digestion, it was usually not possible to get all three measurements. The total length of prey fish was recorded. Young-of-year smelt and crayfish were often too small or digested to measure; these were often just counted. Gut labels on each sampling date correspond with the same gut labels in other datasets. Prey fish and crayfish size and composition varied across sampling dates and years, with a trend towards decreased abundance of rusty crayfish and rainbow smelt and increased reliance on native minnows. Age Growth Data: Scale samples were taken from captured predator fish in the summers of 2000, 2001, 2002, and 2004. Number of sites: 1 - Sparkling Lake Sampling Frequency: 2000: twice; 2001-2004 weekly or biweekly

这些数据采集自美国威斯康星州维拉斯县的闪光湖（Sparkling Lake），旨在追踪捕食性鱼类的日粮组成、年龄与生长结构，以及猎物的物种和体型变化。采样工作始于2000年5月，至2004年9月结束。
研究人员通常在入夜后，驾驶搭载船载电捕鱼系统的船只环绕闪光湖开展完整采样，以此收集鱼类样本。常见捕获物种包括岩鲈（rock bass）、小口黑鲈（smallmouth bass）和大眼梭鲈（walleye）；较稀见的物种为南瓜籽太阳鱼（pumpkinseed sunfish）和黄鲈（yellow perch）。
日粮组成：研究人员通过胃灌洗法采集鱼类胃容物，采样完成后将捕获的鱼类放归自然。胃容物按主要分类类群进行分拣与计数，随后置于聚苯乙烯称量皿中，在57摄氏度环境下烘干48小时，再以精度达0.001克的天平称重。分类类群下的数值代表该类群在当日日粮样本中的个体数量，相邻的“净重（net wt）”列则标注该类群的总质量。不同采样日期与年份的日粮组成存在显著差异，整体呈现出外来物种锈色小龙虾（rusty crayfish）和胡瓜鱼（rainbow smelt）丰度下降，而对本土鲦鱼（minnows）的依赖程度逐步上升的趋势。
猎物数据：同样通过胃灌洗法采集胃容物并放归捕获的鱼类。对于采集到的小龙虾与鱼类猎物，除非已发生严重消化，均会开展体型测量工作。针对小龙虾猎物，研究人员尽可能测量其甲壳、右螯与左螯的尺寸；但受消化作用影响，通常无法完成全部三项测量。猎物鱼类则记录其总长度。当年生的胡瓜鱼与小龙虾往往体型过小或消化程度过高，无法进行准确测量，通常仅对其进行计数。每个采样日期的胃样本编号与其他数据集的对应编号保持一致。不同采样日期与年份的猎物鱼类与小龙虾的体型及组成存在差异，整体趋势同样为锈色小龙虾与胡瓜鱼丰度下降，本土鲦鱼的取食占比逐步提升。
年龄与生长数据：2000、2001、2002与2004年的夏季，研究人员从捕获的捕食性鱼类身上采集鳞片样本。
采样点位数量：1个——闪光湖。
采样频率：2000年：每年两次；2001年至2004年：每周或每两周一次。