Fago, Don / Distribution and relative abundance of fishes in Wisconsin: I. Greater Rock River basin
Methods, pp. 4-8 PDF (3.2 MB)
Turtle Creek (Rock River basin) -looking up- stream at habitat of the greater redhorse. Pecatonica River at County Trunk 0 with Mineral Point Branch coming in on the right. The average annual precipitation within the Greater Rock River basin is 80 cm (76-84 cm) according to Na- tional Weather Service data. The aver- age gradient for the Rock River above the mouth of the Crawfish River (in Jefferson Co.) is 23 cm/km. It de- creases to 18 cm/km below the mouth of the Crawfish River. The average gra- dients for the Pecatonica and Sugar rivers, however, are considerably higher at 76 and 72 cm/km, respec- tively. The discharges near where the Rock, Pecatonica, and Sugar rivers cross the state's border average 48, 19, and 9 m3/sec, respectively. The dominant land use in the Greater Rock River basin is agricul- tural, including both crop and pasture lands. The turbidity of many streams in the basin, especially in the Pecaton- ica River basin, can be traced in large measure to the activity of dairy and beef cattle in the streams and on the stream banks. The eutrophic condition of the water in many streams and lakes in the Greater Rock River basin, espe- cially in the Rock River basin, can be traced to municipal sewage treatment facilities as well as to the agricultural land practices (Wisconsin Department of Natural Resources 1971, 1971, 1971, 1976). METHODS Data Sources and Time Periods All collections except 4 are divided into 3 time periods: 1900-28, 1960-73, and 1974-81. The earlier records pro- vide the basis for assessment of changes over time in distribution of fish species within the Greater Rock River basin. If a location was sampled within a time period more than once, only 1 col- lection is used in the counts of number of stations sampled and number of sta- tions at which a species was taken. Stations were classified in one of two ways during the 1960-73 and 1974- 81 periods, depending on how the sam- ples were taken: complete (those in which all species collected were 4 recorded and identified), and partial (those in which sampling effort and/or species identification were incomplete and therefore did not yield adequate assessment of total species composition). 1900-28 Period. Collections from this period were made at 126 stations in the Greater Rock River basin (Ta- ble 2), primarily by one or more of the following individuals: Cahn (1927) and C. W. Green, L. C. Stuart, C. L. Turner, G. Wagner, Schultz, Tarzwell, E. Creaser, and J. L. Griffith (names taken from the original field notes). Most specimens were verified by Dr. Carl Hubbs or Dr. Greene. The majority of the spe- cies locations were cited by Greene (1935). The stations sampled were located on 64 streams and 18 lakes in the Greater Rock River basin (Table 2). Thoroughness of sampling effort is un- known, and therefore calculation of percent occurrence of each species was not attempted. 1960-73 Period. Complete collec- tions from this period were made at 259 sampling stations on 99 streams and 13 lakes in the Greater Rock River basin (Table 2). An additional 49 par- tial collections, which increased the number of streams sampled by 5 and lakes by 16, came from written records provided by fish management person- nel, and sport and commercial fisher- men. The data from these partial sam- ples were therefore kept separate in Tables 2 and 3, and are not included in the percentages of total stations sam- pled in Table 3. All collections (except 4 made between 1946 and 1959 from the 49 partial stations) were made be- tween 1960 and 1973.