North Temperate Lakes LTER: Fish Species Richness 1981 - current

This data set is a derived data set based on fish catch data. Data are collected annually to enable us to track the fish assemblages of eleven primary lakes (Allequash, Big Muskellunge, Crystal, Sparkling, Trout, bog lakes 27-02 [Crystal Bog] and 12-15 [Trout Bog], Mendota, Monona, Wingra and Fish). Sampling on Lakes Monona, Wingra, and Fish started in 1995; sampling on other lakes started in 1981. Sampling is done at six littoral zone sites per lake with seine, minnow, or crayfish traps, and fyke nets; a boat-mounted electrofishing system samples four littoral transects. Vertically hung gill nets are used to obtain two pelagic samples per lake from the deepest point. A trammel net samples across the thermocline at two sites per lake. In the bog lakes only fyke nets and minnow traps are deployed. Parameters measured include species-level identification and lengths for all fish caught, and weight and scale samples from a subset. Derived data sets include species richness, catch per unit effort, and size distribution by species, lake, and year. Species richness for a lake is the number of fish species caught in that lake during the annual fish sampling. Hybrids captured are only included in the richness value if neither of the two hybridized species are caught in the lake that year. Fish idenitified only to genus or higher taxonomic level are not included if any fish identified to species within that genus or higher taxonomic level are caught. E.g., Unidentified Chub would be only included in the richness value if no other chub is caught in that lake that year. Sampling Frequency: annually Number of sites: 11

本数据集为基于渔获数据衍生而来的数据集。数据按年度采集，用于追踪11处主要湖泊的鱼类群落组成，涉及湖泊包括Allequash湖、Big Muskellunge湖、Crystal湖、Sparkling湖、Trout湖、27-02号沼泽湖[Crystal Bog（水晶沼泽湖）]与12-15号沼泽湖[Trout Bog（鳟鱼沼泽湖）]、Mendota湖、Monona湖、Wingra湖以及Fish湖。其中，Monona湖、Wingra湖与Fish湖的采样工作始于1995年，其余湖泊的采样始于1981年。

采样实施方式为：每个湖泊设置6个沿岸带（littoral zone）采样点，采用围网（seine）、小型鱼类诱捕笼（minnow trap）、螯虾诱捕笼（crayfish trap）以及翼网（fyke net）进行采样；同时搭载于作业船只的电捕鱼系统（electrofishing system）会对4条沿岸样带开展采样。此外，垂直悬挂刺网（gill net）会在每个湖泊的最深点位采集2份远洋带（pelagic zone）样本；三层刺网（trammel net）则会在每个湖泊的2个采样点沿温跃层（thermocline）布设采样。需说明的是，仅沼泽湖会布设翼网与小型鱼类诱捕笼。

本次采样的测量参数包括：所有捕获鱼类的物种级鉴定信息与体长数据，同时从部分捕获样本中采集体重数据与鳞片样品。衍生数据集包含物种丰富度（species richness）、单位捕捞努力量渔获量（catch per unit effort）以及按物种、湖泊与年份划分的体长分布。

关于物种丰富度的定义：某湖泊的物种丰富度为该湖泊年度鱼类采样中捕获的鱼类物种总数。仅当当年该湖泊未捕获某杂交组合的两个亲本物种时，该年度捕获的杂交个体方可计入物种丰富度值。若某属或更高分类阶元内存在鉴定至物种级的鱼类被捕获，则仅鉴定至该属或更高分类阶元的鱼类不计入物种丰富度统计。例如：若当年该湖泊未捕获其他雅罗鱼（chub）类群，则未鉴定雅罗鱼方可被计入物种丰富度值。

本次采样的频率为年度采样，总采样点位数量为11处。