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<br />( <br /> <br />(:J <br />o <br />G <br />,,~~ <br />Co:l <br />~ <br /> <br />San Juan Seven Year ~esearcb Plan <br /> <br />WORK STATEMENT/PR.OTOCOL <br /> <br />EARLY LIFE STAGE ~ESSAR.CH - UDWR. <br /> <br />Background: <br />This component of the research has been designed to characterize the early life <br />stage of the ichthyofaunal community in the San Juan system. It is directed at <br />specifically determining the annual relative abundance and distribution patterns <br />of the larval stage of the target species over a seven year period. Research <br />efforts have been divided into three major areas: 1) Larval Drift, 2) Larval <br />Distribution, and 3) Over-winter Survival. Sampling begins in mid-June with <br />simultaneous larval drift netting and intensive sampling of low velocity <br />habitats. Platania (1990) estimated that Colorado squawfish spawned in the San <br />Juan River during the months of July and August. Larval drift sampling and <br />intensive sampling low velocity habitats concludes in mid-August. Fall <br />(September) sampling characterizes the fish community in the low velocity <br />habitats and represents the faunal conditions as the fish community prepares to <br />over-winter. Those fish that over winter are sampled during the March sampling <br />period. <br /> <br />Although these protocol have been -written to answer specific questions on the san <br />Juan River, much of the standardized sampling procedures draw heavily from <br />existing protocols used currently on other Upper Basin rivers. The design is not <br />intended to mimic those efforts, but rather to provide a method for comparison <br />of data collected in the two areas. <br /> <br />( <br /> <br />Objectives: <br />1) To determine annual Colorado squawfish yay recruitment (i.e., reproductive <br />success) in relation to flow patterns in the San Juan River. <br /> <br />2) To identify timing and location of Colorado squawfish spawning in the San <br />Juan River utilizing size and distribution of drifting larvae. <br /> <br />3) To characterize the early life stage ichthyofaunal community in low <br />velocity habitats. <br /> <br />4) To estimate the relative influence of larval emigration on the squawfish <br />population in the San Juan drainage. <br /> <br />5) To determine the relationship between over-winter survival and flow <br />patterns in the San Juan River. <br /> <br />Methods: <br /> <br />Larval Drift <br /> <br />Samnlina Protocol <br />Drifting larval fishes will be sampled with stationery nets at two locations on <br />the San Juan River: 1. Below the Mancos/San Juan confluence in New Mexico <br />(approx. RM 139) and 2. Mexican Hat, Utah (approx. RM 56). Drift nets will be <br />similar to those used in the. Upper Basin (O.Smm mesh equipped with flow meters). <br />Drift net stations will be operated for six weeks from June 17 - July 26. At <br />each of the two stations three nets will be fished' on a daily basis'during the <br />pre-dawn/dawn hours with a target diel effort of three net-hours per station. <br />Depending on the San Juan sediment/debris load it may 'be necessary to run the <br />nets'for two consecutive O.S-hour runs to accrue this effort. <br /> <br />Nets should be set along an axis perpendicular to the shore, preferably on the <br />margin of quiet shorel'ine habitats and a flowing' channel. The drift nets <br />equipped with steel rings attached to the mouth frame slide over steel posts <br /> <br />'- <br /> <br />AS <br />