Cognitive aspects of food searching behavior in free-ranging wild Common Carp

Abstract

Although laboratory experiments have shown that many fishes, Goldfish (Carassius auratus) in particular, employ relatively sophisticated orientation strategies to learn the location of food in laboratory arenas, this ability has not been rigorously tested in the natural environment. In this study we documented the ability of Common Carp (Cyprinus carpio), a close relative of Goldfish, to learn the location of newly introduced food in a lake. Two experiments were conducted, the first of which determined that carp feed largely at night. The second used this information and tracked the day-and nighttime locations of 34 radio-tagged carp before and then while a food reward was introduced at a specific location in the lake for 10 days. Before the introduction of the reward, carp maintained small (∼100 m× 70 m), isolated home ranges which expanded slightly at night. This movement pattern changed after the reward was added when on the fourth night six radiotagged carp visited and exploited the reward and then returned to their home areas after sunrise. This pattern persisted for the rest of the experiment with increasing numbers of carp visiting the reward each night (21 of 34 carp visited on the tenth night) and returning to their home ranges each day. The speed and precision with which wild carp learned to exploit this reward is consistent with the social learning and spatial memory skills that they and their relatives have shown in laboratory arenas. This is particularly impressive given the turbid conditions in the lake and the lack of obvious visual landmarks.

Attracting Common Carp to a bait site with food reveals strong positive relationships between fish density, feeding activity, environmental DNA, and sex pheromone release that could be used in invasive fish management

“…Indeed, many fish, including the Common Carp and Bigheaded Carps, can be trained to come to particular locations in lakes using food, and this trait has proven to be exploitable for removal in areas they are otherwise hard to measure or catch (Bajer et al., 2010; P. W. Sorensen, unpublished results; Robin Calfee, USGS, Columbia Environmental Research Center, MO, USA). Interestingly, feeding activity in many fish, including the Carps follows circadian patterns, which might also influence eDNA distribution but this too has not yet been considered (Bajer et al., 2010; Helfman, 1986). Of course, fishers also employ an understanding of fish behavioral ecology to locate and catch fish (Jones, 1992); however, to our knowledge, basic ecological tenants that determine fish distribution have not yet been tested to determine whether they could be paired with eDNA measurement to enhance its value to fishery managers.…”

“…Carp were located once each night (21:00–02:00 hours) and once each day (9:00–14:00 hours), and their positions calculated using LOAS ® 4.0 (Ecological Software Solutions, CA, USA) as our previous studies have suggested that they are nocturnal feeders (Bajer et al., 2010). During this time, empty mesh food bags were also placed as a control at the bait site which we lifted every 6‐hr while monitoring the presence of Carp within a distance of 150 m every hour using our automated receiver.…”

“…First, evidence from a laboratory study of Asian Carp suggests that feeding increases eDNA release rates (Klymus, Richter, Chapman, & Paukert, 2015). Second, wild fishes are typically food limited and food distribution (and its addition) can attract fish causing them to aggregate (Bajer, Lim, Travaline, Miller, & Sorensen, 2010; Ferno, Huse, Jackobsen, & Kristiansen, 2006; Ryer & Olla, 1995; Schmidt, Reis‐Filho, Harvey, & Girrizo, 2017), likely enhancing eDNA concentrations. Third, many fish have an inherent ability to locate and remember food patches, an understanding of which might be used by fishery biologists to both predict and perhaps create aggregations, which might then be measured as an enhanced index of fish presence using eDNA (Bajer et al., 2010; Broglio, Rodriguez, & Salas, 2003; Hughes & Blight, 2000; Odling‐Smee & Braithwaite, 2003; Vargas, López, Salas, & Thinus‐Blanc, 2004).…”

“…Second, wild fishes are typically food limited and food distribution (and its addition) can attract fish causing them to aggregate (Bajer, Lim, Travaline, Miller, & Sorensen, 2010; Ferno, Huse, Jackobsen, & Kristiansen, 2006; Ryer & Olla, 1995; Schmidt, Reis‐Filho, Harvey, & Girrizo, 2017), likely enhancing eDNA concentrations. Third, many fish have an inherent ability to locate and remember food patches, an understanding of which might be used by fishery biologists to both predict and perhaps create aggregations, which might then be measured as an enhanced index of fish presence using eDNA (Bajer et al., 2010; Broglio, Rodriguez, & Salas, 2003; Hughes & Blight, 2000; Odling‐Smee & Braithwaite, 2003; Vargas, López, Salas, & Thinus‐Blanc, 2004). Indeed, many fish, including the Common Carp and Bigheaded Carps, can be trained to come to particular locations in lakes using food, and this trait has proven to be exploitable for removal in areas they are otherwise hard to measure or catch (Bajer et al., 2010; P. W. Sorensen, unpublished results; Robin Calfee, USGS, Columbia Environmental Research Center, MO, USA).…”

“…Third, many fish have an inherent ability to locate and remember food patches, an understanding of which might be used by fishery biologists to both predict and perhaps create aggregations, which might then be measured as an enhanced index of fish presence using eDNA (Bajer et al., 2010; Broglio, Rodriguez, & Salas, 2003; Hughes & Blight, 2000; Odling‐Smee & Braithwaite, 2003; Vargas, López, Salas, & Thinus‐Blanc, 2004). Indeed, many fish, including the Common Carp and Bigheaded Carps, can be trained to come to particular locations in lakes using food, and this trait has proven to be exploitable for removal in areas they are otherwise hard to measure or catch (Bajer et al., 2010; P. W. Sorensen, unpublished results; Robin Calfee, USGS, Columbia Environmental Research Center, MO, USA). Interestingly, feeding activity in many fish, including the Carps follows circadian patterns, which might also influence eDNA distribution but this too has not yet been considered (Bajer et al., 2010; Helfman, 1986).…”