Effects of pool formation and flash flooding on relative abundance of young‐of‐year flannelmouth suckers in the Paria River, Arizona

Abstract

Flannelmouth sucker, Catostomus latipinnis, a fish endemic to the Colorado River basin in the western United States, appears to experience poor recruitment to adult size in the Colorado River, downstream of Glen Canyon Dam. Lack or impermanence of rearing areas for young-of-year (YOY) fish is hypothesized to be the problem. Knowing the importance of tributary mouths as rearing areas in other river systems, we studied use of the mouth of the Paria River, a tributary of the Colorado River, by YOY flannelmouth suckers, and the availability of rearing area in the mouth at different flow levels in the Colorado River in 1996 and 1997. We also examined the relationship between flash floods in the Paria River and catch-per-unit-effort (CPUE) of YOY in the Paria River between 1991 and 1996.Maximum mean daily discharge in the Paria River was inversely correlated with CPUE of YOY flannelmouth suckers (Spearman Rho = −0.9856, p=0.0003) during their critical rearing period (15 March-30 June). Thus, it appears that YOY flannelmouth suckers rear longer in the Paria River in years when flash flooding is minimal.Recruitment of YOY flannelmouth suckers at the Paria River may also be improved by enhancing pool formation during spring and summer rearing seasons. YOY flannelmouth sucker was captured in a pool created by high Colorado River flows ( ]336 m 3 /s) that inundated the mouth of the Paria River during spring and summer, 1996. In 1997, high flows (about 550-750 m 3 /s) in the Colorado River during winter and spring initially inundated the Paria River and formed a pool in the mouth. However, these high flows eventually caused 0.5-1.0 m of suspended sediment from the incoming Paria River to deposit in the mouth. Thus, despite higher flows than 1996, the slackwater area formed only occasionally in 1997. Differences in pool formation between 1996 and 1997 demonstrate that pool formation cannot be inferred solely from Colorado River flows.

Effects of an extreme flash flood on the native fish assemblages across a Mediterranean catchment

“…Post‐flood reductions in the abundance of small cyprinids are in line with comparable studies elsewhere (Puckridge et al. 2000; Bischoff & Wolter 2001; Thieme et al. 2001), adding to the increasing body of evidence for the role of floods in driving fish recruitment and population dynamics in Mediterranean streams (Magalhães et al.…”

“…Regular, predictable and controlled floods have little long‐term effects on species persistence and assemblage stability (Pusey, Arthington & Read 1993; Dolloff, Flebbe & Owen 1994; Halls & Welcomme 2004), given native species generally possess either life‐history, behavioural or morphological adaptations to cope with flow variability (reviewed in Lytle & Poff 2004). Conversely, severe floods occurring outside the expected temporal and hydrological range may be regarded as major stochastic events (Delong, Thorp, Greenwood & Miller 2001), the consequences of which may range from changes in density and size and age structure of populations to elimination of particular species and year‐classes, and the disruption of assemblage structure and diversity (Puckridge, Walker & Costelloe 2000; Thieme, McIvor, Brouder & Hoffnagle 2001).…”

Factors Affecting Condition of Flannelmouth Suckers in the Colorado River, Grand Canyon, Arizona

“…Mean flannelmouth sucker condition never declined below 93, despite the fact that these fish inhabit a cold, stenothermic environment in which water temperatures are typically near 10ЊC, much lower than the species' preferred temperature of 25ЊC (Deacon et al 1987). Although cold water temperatures in the main-stem Colorado River may reduce recruitment (Thieme et al 2001), swimming performance (Ward et al 2002), and possibly growth (Valdez and Ryel 1995), flannelmouth suckers can become tolerant of cold water (Chart and Bergersen 1992;McKinney et al 1999) and still increase in weight. In addition, the W s equation used to calculate W r was likely created from populations in regulated systems.…”

“…Mean September W r of flannelmouth suckers tended to increase with mean June macroinvertebrate density between RKM 0.8 and RKM 328.8 (r ϭ 0.57, P ϭ 0.08, N ϭ 10; Figure 3B). 1991-2001(Benenati et al 2002. No fish were collected in September 1994.…”

“…Although previous research has suggested that the Grand Canyon population of flannelmouth suckers is relatively stable (Douglas and Marsh 1998), there is concern that recruitment may be declining because of the effects of lower water temperature caused by hypolimnetic releases from Glen Canyon Dam (Weiss et al 1998;Clarkson and Childs 2000;Ward et al 2002), loss of suitable rearing habitat (Thieme et al 2001), blockage of spawning migrations (Chart and Bergersen 1992;McKinney et al 1999), and predation (Ward et al 2002). Therefore, continued monitoring of flannelmouth sucker populations is needed to assess changes in the status of this native fish.…”