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a c:' ~ I ,.>. -...J ""-l ICHTHYOFAUNAL MONITORING LARVAL FISH - DRIFT SAMPLING (COLORADO PIKE MINNOW) Larval fish drift sampling has been conducted at two locations on the San Juan River since 1992 (near Four Comers, NM and Mexican Hat, UT). The permanent upstream larval fish drift sampling monitoring site will be located about RM 128 (near Whirlpool) and the lower site will be at Mexican Hat (ca. RM 53). The latitude and longitude of each site will be determined with a GPS unit. Sampling for drifting (larval) Co\mado pikeminnow will be initiated each year by late June or early July (may vary one or two weeks depending upon anticipated spring runoff). The Moore Egg Collector (MEC) will be used for the collection of drifting larvae on the San Juan River. An advantage this device has over drift nets for the collection oflarvae is that, under low or moderate flow, drift is immediately sorted (while in the river) so there is no laboratory time necessary for picking of samples. The Moore Egg Collector (MEC) is a sluice-box-like device with a rectangular opening at its anterior end (W=43 cm, H=33 cm), parallel wooden sides (L=107 em) and an open top. The bottom is framed nylon window screen (1.6-mm-mesh) installed at a 230 angle relative to the bottom mounting bar. Mounting bars are attached near the posterior end of the mouth and perpendicular to the sides. The MEC is set just below the water's surface which prevents the colleetion of floating debris while the wedge-shaped water diverter, positioned on the top of the front flume, reduces drag under high velocity conditions. During operation, the MEC is held in place by the force of the water pushing it against steel fence-posts (T-posts) driven into the stream bottom. Electric fence insulating brackets are attached to eaeh T -post to enable vertical adjustment of the MEC. The posterior T -post and bracket support the back-end of the collecting device. Drift that enters the MEC accumulates on the screen at the water-air interface where it can be easily gathered, counted and collected with an eyedropper or larval forceps before being placed in the collection container. Capture rate of drift by the MEC will be detennined based on the volume of water (i.e., CPUE-catch per unit effort) filtered as opposed to sampling duration. This will be accomplished by mounting a mechanical flow meter in the mouth of the MEC Sampling effort will be calculated using the area of the mouth and appropriate formula for the flow meter being employed. A single MEC will be fished twice each day (morning and evening) for at least two-hours per set. Morning sampling will begin at dawn and the evening set will begin about one hour before dusk. The top of the collection device will be 5 to 10 cm below water surface and about 30 cm above the ehannel bed; flow volume will influence whether this can always be 3 Draft Long Tcnn Monitoring Plan - SJRlP Biology COffilniltCC