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Fish Schooling “Never let schooling interfere with your education….” (apologies to Mark Twain) Schooling not all fish aggregations are schools aggregation: group created by the attractiveness of some feature of the environment. www.seafriends.org.nz www.blackchampagne.com www.blackchampagne.com Schooling not all fish aggregations are schools aggregation: group created by the attractiveness of some feature of the environment. shoal: group of fish remaining together for social reasons www.seafriends.org.nz www.blackchampagne.com Schooling not all fish aggregations are schools www.seafriends.org.nz aggregation: group created by the attractiveness of some feature of the environment. shoal: group of fish remaining together for social reasons school: polarized, synchronized shoal of fish that swim together in the same direction, at a similar speed, with a similar distance between one another school shoal Schooling who? 25% of fish shoal throughout lives 50% shoal at some point in lives Schooling shape ( highly variable) fast-traveling schools = wedge-shaped feeding schools = circular minimum size for effectiveness as predation defense maximum limit for effective coordinated movement Schooling how? primarily visual cues, as schools often break up at night optomotor reaction - explains prevalence of vertical bars Schooling how? primarily visual cues, as schools often break up at night optomotor reaction - explains prevalence of vertical bars Tank exps. with vertical bars…. Schooling why? reduced risk of predation “dilution” effect - predators only get strays Schooling why? reduced risk of predation “dilution” effect - predators only get strays “confusion” effect - flash expansion Schooling why? reduced risk of predation “dilution” effect - predators only get strays “confusion effect" for predators “flash expansion” traveling: increased hydrodynamic efficiency? usually similar in size Schooling why? reduced risk of predation “dilution” effect - predators only get strays “confusion effect" for predators “flash expansion” traveling: increased hydrodynamic efficiency? usually similar in size increased efficiency of food finding schooling to round up prey shoaling to optimize finding food - fish follow those that are most successful Schooling why? reduced risk of predation “dilution” effect - predators only get strays “confusion effect" for predators “flash expansion” traveling: increased hydrodynamic efficiency? usually similar in size increased efficiency of food finding increased reproductive success minimal sexual segregation in schooling species consensus on where to go for spawning Schooling Why not? group feeding dictated by productivity of environment when food is scarce, feeding is solitary when risk of disease/parasite transmission is high Pitcher 1983