Meeting Abstract

76.1  Tuesday, Jan. 6  What’s for Dinner? Feeding Ecology of Two Native Fish in Fossil Creek, AZ ARENA, A.J.*; GIBB, A.C.; Northern Arizona University; Northern Arizona University aja75@nau.edu

Understanding how native fishes obtain food from their environment is critical to understanding current and future threats to their existence. This study examines two native fish representing different trophic levels in the restored Colorado river tributary of Fossil Creek: roundtail chub (Gila robusta), a mid-water omnivore, and Sonora sucker (Catostomus insignis), a benthic feeder. Here, we examine the feeding behaviors employed by these fish and assess their potential efficacy as biological control agents for invasive crayfish. In laboratory trials, we offered different items representing ecologically-relevant food types (e.g. algae, insect larvae, feeder fish) and noted each species feeding behavior, preferences, and success on each item. Trials were recorded using high-speed video, and feeding kinematics were analyzed to determine which items were aggressively pursued and effectively captured and consumed. Roundtail chub were consistently aggressive feeders: attacking and consuming all food items with the exception of algae. Roundtail chub exhibited no aversion to crayfish; however, crayfish are most susceptible to predation by roundtail chub when crayfish body-depth is >0.5 the fishs gape. Sonora suckers were less aggressive in feeding, preferring to consume only food items on or just above the substrate. In addition, they were sometimes unsuccessful in removing attached food, and generally avoided crayfish. Based on this, we predict that Roundtail chub could be an effective biological control agent for invasive crayfish in Fossil Creek, but that crayfish will grow into a size refuge that will make them difficult or impossible for chub to consume.