Effects of visible implant elastomer mark colour on the predation of red shiners by largemouth bass

Visible implant elastomer (VIE) marks are an effective method for marking small-bodied fishes including brown trout, Salmo trutta (Linnaeus) (Olsen & Vollestad 2001), darters, Etheostoma spp. and Percina spp. (Roberts & Angermeier 2004) and shiners, Notropis spp. (Bouska & Paukert In press). Laboratory studies have shown that Colorado pikeminnow, Ptychocheilus lucius (Girard), bluegill, Lepomis macrochirus (Rafinesque), and largemouth bass, Micropterus salmoides (Lacepède), marked with VIE have lower marking mortality and higher mark retention rates than fish marked with other methods (Haines & Modde 1996; Catalano et al. 2001; Roberts & Angermeier 2004). However, the effects VIE marks may have on the vulnerability to predation of marked fish have received limited investigation. The few experiments investigating the effect of colour and location of VIE marks on predation had conflicting results. Colorado pikeminnow marked with VIE exhibited the same vulnerability to predation as unmarked control fish (Haines & Modde 1996). Similarly, Roberts and Kilpatrick (2004) found no increase in predation by largemouth bass and rock bass, Ambloplites rupestris (Rafinesque), on fantail darters, Etheostoma flabellare (Rafinesque), marked with green and yellow VIE compared with unmarked fish. Reeves and Buckmeier (2009) found no difference in predation of orange-, red-, blueand green-marked largemouth bass, channel catfish, Ictalurus punctatus (Rafinesque), and blacktail shiners, Cyprinella venusta (Girard), by largemouth bass, flathead catfish, Pylodictis olivaris (Rafinesque) or white bass, Morone chrysops (Rafinesque). Conversely, other studies have shown that bluegills marked with blue and pink injectable phototonic dye were more susceptible to predation by largemouth bass than fish marked with cryptically coloured marks (opaque marks visible to trained observers; Catalano et al. 2001). Information is needed on the effects of VIE marking on predation so better informed decisions can be made on how to mark small-bodied fishes. Previous laboratory studies of predation on VIE-marked fish have only been conducted on a few freshwater species (Haines & Modde 1996; Roberts & Kilpatrick 2004; Reeves & Buckmeier 2009). The objectives of this study were to determine the effects of two colours of VIE marks in two body locations on the predation of a common stream fish, the red shiner, Cyprinella lutrensis (Baird & Girard), by a common predator, the largemouth bass; both species commonly coexist in lakes, streams and reservoirs throughout much their range. The effects of VIE mark colour on the predation of red shiners by largemouth bass were tested in an indoor experimental stream at Kansas State University from 9 September through 21 October 2008. The experimental stream consisted of two pools, each 130-cm diameter and 56-cm deep, connected by two J-shaped riffles 40-cm wide and 16-cm deep (Knight & Gido 2005). Pools were equipped with electric agitators for aeration and overflow drains maintained water levels. Water visibility remained >0.5 m Secchi depth throughout all experiments. Natural rock substrate was placed in the bottom of the pools and riffles