Paper: The trophic ecology of a desert river fish assemblage: influence of season and hydrologic variability Authors: Kathrine E. Behn, Colden V. Baxter Institution associated with these data: Idaho State University, Pocatello, Idaho USA. Study Location: The Little Colorado River from approximately 2.0 – 5.4 km upstream from its confluence with the Colorado River, Coconino County, Arizona, USA. Data file: BehnBaxter_LCR_2012-2014_FishCatch.csv This README file explains the variables recorded in the process of sampling fishes in the Little Colorado River, Arizona USA during five sampling trips in 2012-2014. Site visits and sampling were performed in cooperation with the U.S. Geological Survey’s Grand Canyon Monitoring and Research Center and were permitted by the Navajo Nation, the U.S. Fish and Wildlife Service, Arizona Game and Fish Department and Idaho State University’s Internal Animal Care and Use Committee (protocol no. 702). Catch data were submitted to the Grand Canyon Monitoring and Research Center, Flagstaff, Arizona USA to be appended to the Grand Canyon fisheries database. Length-mass regression relationship are derived from the following sources: Bluehead sucker, flannelmouth sucker, and speckled dace: Our own catch from these trips as well as unpublished data collected by Baxter in the adjacent Colorado River. Humpback chub: Meretsky, V. J., Valdez, R. A., Douglas, M. E., Brouder, M. J., Gorman, O. T., & Marsh, P. C. (2000). Spatiotemporal variation in length–weight relationships of endangered humpback chub: implications for conservation and management. Transactions of the American Fisheries Society, 129(2), 419-428. Length-mass regression formulas are as follows, where W=estimated mass in grams and L=length in millimeters. Bluehead sucker: log W = (3.0491*log L) – 5.224 Flannelmouth sucker: log W = (3.1189*log L) – 5.3467 Humpback chub: log W = (2.92*log L) - 4.87 Speckled dace: low W = (2.9441*log L) - 5.0151 Description of columns: DATE = Date fish was caught in MM/DD/YYYY format GEAR = Gear type used to catch fish. Options are seine, hoop or dip net. SPECIES = Three letter species abbreviation: BBH, black bullhead (Ameiurus melas); BHS, bluehead sucker (Catostomus discobolus); BRT, brown trout (Salmo trutta); CCF, channel catfish (Ictalurus punctatus); CRP, common carp (Cyprinus carpio); FHM, fathead minnow (Pimephales promelas); FMS, flannelmouth sucker (Catostomus latipinnis); HBC, humpback chub (Gila cypha); PKF, plains killifish (Fundulus zebrinus); RBT, rainbow trout (Oncorhynchus mykiss); RSH, red shiner (Cyprinella lutrensis); SPD, speckled dace (Rhinichthys osculus); and SUC, unidentified juvenile sucker. TL_MM = Total length of fish as measured from snout to distal end of caudal fin. On a few occasions, especially during warm months, fish were only counted and not measured to reduce risk of overheating or to prioritize diet sampling. Units are millimeters. FL_MM = Fork length of fish as measured from snout to base of fork of caudal fin. Units are millimeters. WEIGHT_G = Estimate of weight. Units are grams. WEIGHT_SOURCE = Method used to estimate weight, either measured in the field directly using a balance (FIELD) or estimated using a species-specific length-to-mass regression (LM REGRESSION). SAMPLED_FOR_DIET = whether in individual was sampled for diet or simply counted and measured. FISH_ID = Individual fish label for purposes of diet analysis. Crosslisted in diet data files. NOTES = Any additional notes or caveats.