Surface feeding and aggressive behaviour of diploid and triploid brown trout Salmo trutta during allopatric pair‐wise matchings. Issue 3 (31st July 2014)

• Record Type: Journal Article
• Authors: Preston, A. C.; Taylor, J. F.; Adams, C. E.; Migaud, H.
• Is Part Of: Journal of fish biology. Volume 85:Issue 3(2014)
• Page Start: 882
• Page End: 900
• Publication Date: 2014-07-31
• Subjects: Fishes -- Periodicals; Fishes -- Great Britain -- Periodicals; 597
• DOI: 10.1111/jfb.12478
• Languages: English
• ISSNs: 0022-1112

Abstract

<abstract abstract-type="main" id="jfb12478-abs-0001"> <title> <x xml:space="preserve">Abstract</x> </title> <p id="jfb12478-para-0001">Diploid and triploid brown trout <italic>Salmo trutta</italic> were acclimated for 6 weeks on two feeding regimes (floating and sinking). Thereafter, aggression and surface feeding response were compared between pairs of all diploid, all triploid and diploid and triploid <italic>S. trutta</italic> in an experimental stream. In each pair‐wise matching, fish of similar size were placed in allopatry and rank was determined by the total number of aggressive interactions recorded. Dominant individuals initiated more aggression than subordinates, spent more time defending a territory and positioned themselves closer to the surface food source (<italic>Gammarus pulex</italic>), whereas subordinates occupied the peripheries. In cross ploidy trials, diploid <italic>S. trutta</italic> were more aggressive than triploid, and dominated their sibling when placed in pair‐wise matchings. Surface feeding, however, did not differ statistically between ploidy irrespective of feeding regime. Triploids adopted a sneak feeding strategy while diploids expended more time defending a territory. In addition, we also tested whether triploids exhibit a similar social dominance to diploids when placed in allopatry. Although aggression was lower in triploid pairs than in the diploid and triploid pairs, a dominance hierarchy was also observed between individuals of the same ploidy. Dominant triploid fish were more aggressive and consumed more feed items than subordinate individuals. Subordinate fish displayed a darker colour index than dominant fish suggesting increased stress levels. Dominant triploid fish, however, appeared to be more tolerant of subordinate individuals and did not display the same degree of invasive aggression as seen in the diploid and diploid or diploid and triploid matchings. These novel findings suggest that sterile triploid <italic>S. trutta</italic> feed similarly but are less aggressive than diploid trout. Future studies should determine the habitat choice of triploid <italic>S. trutta</italic> after release and the interaction between wild fish and triploids during the breeding season prior to utilization of triploids as an alternative management strategy within freshwater fisheries.</p> </abstract>