Shifts in a Fish’s Resource Holding Power during a Contact Paired Interaction: The Influence of a Copper‐Contaminated Diet in Rainbow Trout

• Published in: Physiological and biochemical zoology Vol. 78; no. 5; pp. 706 - 714
• Main Authors: Campbell, H. A., Handy, R. D., Sims, D. W.
• Format: Journal Article
• Language: English
• Published: United States The University of Chicago Press 01.09.2005
• Subjects: Analysis of Variance; Animals; Behavior, Animal - drug effects; Body size; Body Weight; Copper; Copper - toxicity; Diet; Fish; Fish feeding; Food; Glycogen; Glycogen - metabolism; Lactates; Lactic Acid - metabolism; Liver; Logistic Models; Muscle, Skeletal - metabolism; Oncorhynchus mykiss; Oncorhynchus mykiss - metabolism; Oncorhynchus mykiss - physiology; Social Dominance; Trout
• ISSN: 1522-2152; 1537-5293
• DOI: 10.1086/432146

The influence of sublethal chronic dietary copper (Cu) exposure on the dominant‐subordinate relationship between pairs of juvenile rainbow trout (Oncorhynchus mykiss) was examined. Fish were fed either a normal (11 mg Cu kg−1food) or Cu‐contaminated (721 mg Cu kg−1food) diet for 8 wk. Paired interactions were observed—control versus control, Cu‐exposed versus Cu‐exposed, and control versus Cu‐exposed fish—using a computer‐aided video tracking system to measure duration of interactions, total distance moved, and the number of encounters during each contest. In concurrence with game theory, each interaction became escalated with a lesser size disparity between contestants. However, in Cu‐exposed versus Cu‐exposed fish interactions, the dominant‐subordinate relationship was decided sooner and with less aggression than a control versus control fish interaction with fish of a similar relative body mass disparity. During control versus Cu‐exposed fish interactions, control fish would normally dominate interactions (12 out of 16 bouts) unless the Cu‐exposed fish had a 15% body mass advantage. Muscle glycogen and lactate levels after each contest reflected the duration of bouts and winners of the contests, irrespective of Cu exposure. We conclude that Cu‐contaminated fish are less able to compete and have lower resource holding power than controls and will withdraw from a contest at a lower level of interaction, unless a size advantage in the Cu‐exposed fish increases the probability of winning.