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We designed a study to determine if Rio Grande silvery minnow Hybognathus amarus, an endangered species, would use an instream, rock channel fishway on the Rio Grande near Albuquerque, New Mexico. We implanted 6,657 Rio Grande silvery minnow with passive integrated transponders and used a passive scanning station with two antennas located within the fishway to document movements from seven release locations, up to 19.7 km upstream and 13.5 km downstream of the diversion dam. Between 11 March and 21 August 2011, 243 individuals were detected (3.7% of all fish released), with 74.1% fish being detected from upstream release sites and 25.9% from downstream release sites. We determined 14 Rio Grande silvery minnow successfully ascended the fishway, and an additional 20 fish from downstream release locations were detected on the upstream antenna only, inferring passage. We conclude Rio Grande silvery minnow can use appropriately constructed fishways. Received October 17, 2011; accepted March 21, 2012

We intensively sampled fishes from two reaches of the Rio Grande within the Albuquerque Basin (Albuquerque and Belen valleys) during 1998–2001, compared our findings with those from 1984, and compiled a list of all fishes known from the two reaches. Structure of assemblages (richness, diversity, abundance distributions–taxon dominance versus rank abundance) was similar between reaches in 1998–2001, but the faunas had low taxonomic similarity. The nonnative white sucker (Catostomus commersonii), western mosquitofish (Gambusia affinis), and native red shiner (Cyprinella lutrensis) dominated the Albuquerque Valley. Faunal change in the Albuquerque Valley between 1984 and 1998–2001 indicated all native fishes besides the red shiner declined, particularly the Rio Grande silvery minnow (Hybognathus amarus) and longnose dace (Rhinichthys cataractae). In contrast, the red shiner alone dominated the Belen Valley, nonnative fishes were less dominant, and aside from the Rio Grande silvery minnow and longnos...

We evaluated the effects of streamflow-related changes in channel shape and morphology on the quality, quantity, availability and spatial distribution of young-of-year and adult smallmouth bass Micropterus dolomieu habitat in an alluvial stream, the Baron Fork of the Illinois River, Oklahoma. We developed Habitat Suitability Criteria (HSC) for young-of-year and adult smallmouth bass to assess changes in available smallmouth bass habitat between years, and compare predicted smallmouth bass Weighted Usable Area (WUA) with observed WUA measured the following year. Following flood events between 1999 and 2000, including a record flood, changes in transect cross-sectional area ranged from 62.5% to 93.5% and channel mesohabitat overlap ranged from 29.5% to 67.0% in study three study reaches. Using Physical HABitat SIMulation (PHABSIM) system analysis, we found that both young-of-year and adult smallmouth bass habitat were differentially affected by intra- and inter-annual streamflow fluctuations. Maximum WUA for young-of-year and adults occurred at streamflows of 1.8 and 2.3 m3 s−1, respectively, and WUA declined sharply for both groups at lower streamflows. For most microhabitat variables, habitat availability was similar between years. Habitat suitability criteria developed in 1999 corresponded well with observed fish locations in 2000 for adult smallmouth bass but not for young-of-year fish. Our findings suggest that annual variation in habitat availability affects the predictive ability of habitat models for young-of-year smallmouth bass more than for adult smallmouth bass. Furthermore, our results showed that despite the dynamic nature of the gravel-dominated, alluvial Baron Fork, HSC for smallmouth bass were consistent and transferable between years. Published in 2008 by John Wiley & Sons, Ltd.

Uniquely tagged animals provide an opportunity to study changes in population demographics and movement. Passive integrated transponder (PIT) tags are used to monitor growth, movement, and survival of fishes. Laboratory studies of tag retention and mortality in small-bodied, warmwater cyprinids after insertion of PIT tags are rare. Mortality induced by two PIT tag implantation methods was compared, and tag retention after implantation was assessed. Relations between standard length and tag retention and between standard length and survival in Rio Grande silvery minnow Hybognathus amarus were examined. Fish were randomly selected and PIT-tagged with 12.5-mm tags via surgical incision or needle injection and were held in laboratory aquaria for 32 d. Mean (±SE) survival on day 32 was 99 ± 1% for control fish, 87 ± 6% for fish that received tags by incision, and 50 ± 5% for fish that received tags by injection. We also tagged 280 fish by incision and held them in aquaria for 49 d. On day 49, survival...

We collected 409 Pimephales vigilax (bullhead minnow) and 32 Percina macrolepida (bigscale logperch) from Elephant Butte Reservoir, Sierra Co., New Mexico, during a small-bodied fish survey in August and December 2005, and January and August 2006. The bullhead minnow is considered nonnative in the Rio Grande in New Mexico, but has been collected downstream of Elephant Butte Reservoir. Collections of this species document its establishment within Elephant Butte Reservoir. The bigscale logperch had not been collected previously from the Rio Grande in New Mexico and these collections represent a range extension for this species. Both species are now established in Elephant Butte Reservoir and these unnatural range extensions are related to human activities, but the exact cause remains unknown.