Dispersal Patterns of Subadult and Adult Colorado Squawfish in the Upper Colorado River

Abstract

We investigated distribution and dispersal patterns of subadult and adult Colorado squawfish Ptychocheilus lucius (recently renamed the Colorado pikeminnow) throughout their range in the upper Colorado River. Annual, river-wide, capture-recapture data were used to document movements during a 5-year period (1991-1995). Average total length of Colorado squawfish progressively increased upstream: juveniles and subadults occurred almost exclusively in the lowermost 105 km of the 298-km study area, whereas most adults were concentrated in the uppermost 98 km. This was most pronounced early in the study and less so later due to the effect of two or three strong year-classes that dispersed through the system. Only 16% of subadult and adult fish initially captured and tagged in the upper reach were later located more than 10 km from the previous capture site; of those tagged in the lower reach, 58% were later located more than 10 km from the previous site. Most movements greater than 10 km were directed upstream, and many fish tagged in the lower reach moved to the upper reach; the smallest of these fish was between 421 and 449 mm in total length (TL) when it moved. No movement was detected from the upper reach to the lower. Distance moved was inversely related to fish size: displacement of fish shorter than 550 mm TL averaged 33.6 km; for those longer than 550 mm, average displacement was only 7.5 km. Movement of young adults may have been a response to changing food needs. Upstream movements placed fish into areas with greater availability of larger prey, and body condition of large adults during spring was significantly higher in the upper reach than in the lower reach. Water temperatures, however, were inversely related to adult distribution despite a preference for warmer water. We suggest that portions of the upper reach offer adults the best balance between food and water temperature.

Geomorphology and endangered fish habitats of the upper Colorado River: 1. Historic changes in streamflow, sediment load, and channel morphology

“…Colorado squawfish can migrate long distances (>300 km [Miller et al, 1983]), but adults in the upper Colorado River typically move less than 10 km [McAda and Kaeding, 1991; Osmundson et al, 1997]. Presumably, these fish do not need to travel such long distances because forage fish are more abundant in the Grand Junction area than elsewhere.…”

A Tribute to Tributaries: Endangered Fish Distributions within Critical Habitat of the San Juan River, USA

“…The general patterns of smaller Colorado Pikeminnows using downstream reaches and larger ones using upstream reaches was also seen in the upper Colorado River basin (Osmundson et al. ). Even though Chaco Wash is near barriers that limit upstream movements, recovery actions could benefit by determining how these older individuals persist in upstream reaches without meeting a similar fate as subadult fish that largely disappear from the system after age 3 (Durst and Franssen ).…”

Prey and non‐native fish predict the distribution of Colorado pikeminnow (Ptychocheilus lucius) in a south‐western river in North America

“…Gape-limited age 1 P. lucius individuals may occur in reaches with high numbers of native small-bodied fishes because these prey may be more susceptible to predation due to their more fusiform body shapes compared with the more laterally compressed non-native C. lutrensis (Franssen et al 2007). This suggests that the different size classes of P. lucius are potentially tracking prey resources, a pattern similar to P. lucius in the Upper Colorado River, UT and CO, where adults often reside in reaches with higher prey numbers (Osmundson et al 1998). Indeed, all three native small-bodied fishes and age 1 P. lucius feed on invertebrates when available (Sublette et al 1990).…”

“…Indeed, the mobile nature of P. lucius (Osmundson et al 1998;Fresques et al 2013) and I. punctatus (Wendel & Kelsch 1999) likely provides the potential for more spatial and temporal interactions between these species. Ictalurus punctatus individuals become increasingly piscivorous when they reach 300 mm TL, which suggests that they could potentially prey on age 1 and age 2 P. lucius.…”

“…Age 0 P. lucius often use low-velocity habitats in lower portions of large rivers (Haynes et al 1984;Osmundson et al 1998), whereas adults can be highly mobile and often use mainstem river habitats (Osmundson et al 1998). Information on subadult habitat use is limited, but they also appear to be highly mobile and can use mainstem as well as small tributary habitats (Fresques et al 2013).…”