9714 - Laserfiche WebLink

Home Browse Search

\// All fish caught (3,401) were handled following protocols in Ward (2002). All fish collected were identified to species and measured for total length (TL; nearest mm). Fork length was also measured for humpback chub, flannelmouth sucker, and bluehead sucker. Weights were not measured because scales did not yield accurate weights in high winds common during the study period. Native fish were sexed when possible based on manual extrusion of gametes and sexual condition (not ripe, ripe, spent) was recorded. Examination of sexual characteristics (none, color, tuberculate) was also noted. Number and type of external parasites were recorded. Native fish ~ 100 mm TL were scanned for the presence of a PIT tag with both new 134.2 KHz tag reader and an old 400 KHz tag reader to verify that no tags were missed. If a tag was not found and the fish was ~ 150 mm TL, a 134.2 KHz PIT tag was inserted into the abdominal cavity. Tag presence or absence and PIT tag number were recorded. Fish were also checked for fin clips or elastomer dye (marks used in previous years to identify tag loss or fish translocated above Chute Falls). PIT tag information was downloaded electronically and checked for errors. Catch-per-unit-effort trends presented in this report may appear slightly different than trends reported in previous years. Differences in collection methodology among years created the necessity to refine and standardize the data so that only comparable data was included in the catch trend analysis. We took the following steps to refine the data prior to analysis. 1. Fixed Trip ID's within the GCMRC 14.5 database so that the data for any given of year of Little Colorado River sampling since 1987 could be obtained by the trip ID. (Table 2). 2. Queried out all Lower 1200 meter Little Colorado River sampling by trip ID and verified that each year was accounted for. 3. Added the 2004 Lower 1200 meter data. 4. Removed all D-Hoop nets and Fyke nets from the analysis so that only Gear types, HN, MH, and GFH were included. 5. Standardized effort. Many records were missing effort. In some cases effort could be calculated from start and end times and in other cases effort was extrapolated from other data collected within the same trip. In most cases nets were set for either 12 (1993-1997) or 24 hours. 6