Schooling of Fish: Advantages and Disadvantages of the Buddy System

1. Schooling of Fish: Advantages and Disadvantages of the Buddy System Taylor Drexinger Lena Finkel David Quinn Caroline Wilkinson

2. Background • Schooling vs. Shoaling • How fish school • Both advantages and disadvantages

3. Relevance • Impact on surrounding species • Impact on surrounding environment

4. What Fish School • Clupeomorpha • Barracuda • Larvae • Some sharks (hammerheads) • Ostariophysi

5. Advantage-Social • When separated from the school, the individuals become skittish and aggressive • Lower respirationrate when fish in groups • Synchronized actions

6. Advantage-Reproductive • Easier to find mate • Decreases chance of larval predation • Initiation of schooling from environmental factors after morphological evolution

7. Advantage-Foraging • More eyes to seek prey • Copepods and herring

8. Advantage-Hydrodynamic • Schooling placement is not random • Draft off of each other • Back and forth tail movement “wagging”

9. Advantage-Predator avoidance • Reduce probability of capture • Reduced ease of capture • Improved detection of predatory threats

10. How does schooling decrease risk of predation? • 1/N Hypothesis • Confusion Hypothesis • Predator Satiation Hypothesis • Predator Detection

11. 1/n Hypothesis • Based on a simple mathematical model P = 1/n Where a schooling fish’s probability of being consumed by a predator (P) is function of the size of the school (n) • Obviously a gross simplification (basic form assumes predators only consume one prey item per feeding) • Nevertheless, useful in describing the basic theoretical relationship between school size and risk of predation.

12. Confusion Hypothesis • Schooling may allow fish to exploit perceptual bottlenecks within a predator’s nervous system, by overwhelming its ability to process visual and auditory signals. • Predators unable to isolate/maintain focus on individual prey • results in “relay race” effect, in which predator follows a prey target for a short time before diverting its attention to a different target… overall predation reduced as attacker constantly pursues new prey targets with little success. • In theory the confusion effect on predator should increase with relative school size of the prey

13. Confusion Hypothesis Vs. Works on humans too!

14. Predator Satiation Hypothesis • There is a maximum amount of prey an individual predator can consume during an individual feeding • By synchronizing behaviors amoung large groups of individuals, prey fishes can exploit the inability of predators to consume more than a set amount of prey… ensures the survival of the remaining fish • The Predator Satiation Hypothesis may explain the synchronized and social behavior of wide range of other organisms throughout the biological world

15. Synchronous Emergence of Adult Mayflies from Larval Stage

16. Synchronous Acorn Production Among Adjacent Oak Trees

17. Mass Nesting in Sea Turtles

18. Predator Detection Hypothesis • Larger schools… wider collective field of vision • One hole: schooling obscures vision of individuals located near the interior of the group • Possible association with alarm substances to provide net advantage…. See Ostariophysi

19. Disadvantages – Ease of Predation • Easy for underwater predators to spot because of size • Birds can easily spot large bait balls near the surface • Normally attracts a lot of birds, not just one • Cannot effectively hide in reefs or underwater structures • Move around constantly due to resource demands • More chances to run into prey • Whale’s size negate most anti-predator measures

20. Disadvantages – Concentration of Pollution • Very similar to aquaculture disadvantages • Disease spread quick due to proximity • Waste is concentrated • One sick fish can put the entire school at risk • One fish gets out of rhythm • Loses main anti-predator behavior caused by synchronous movements • Predators can begin to pick off the school

21. Disadvantages – Use of Resources • Must move on quickly to new food sources • Food found during foraging used up quickly due to sheer number of fish • Can get very little food depending on orientation in the school • Use large amounts of dissolved oxygen

22. Predator Adaptations • Adopted their own schooling behavior • Will yield very high returns especially for predators in front of the pack • Sailfish, Dolphins • Force schools into shallow or cluttered waters • Mass synchronous movement greatly hindered • Specific adaptations • Spinner Shark, Sailfish, Swordfish, Thresher Shark

23. Still, certain questions remain unanswered… …What aspects of a predatory stimulus actually elicit a behavioral/defensive response? …How do schooling patterns change in response to a predatory attack? …Who shot Biggie Smalls?

24. Conservation • Quantitative analysis of fish schooling can lead to • better commercial fishing practices • information on environmental demands for large schools • Better understanding for efficient aquaculture of schooling fishes • Resources demand (ex. Oxygen levels) • Need for Waste Removal • Combating diseases

25. Future Research Windmills!

26. Summary • Advantages • Disadvantages • Hypotheses

27. Evaluation of Sources • Valid conclusions • Experimental data • Dated in some cases

28. References • Barber, I., & Huntingford, F. A. (1996). Parasite infection alters schooling behaviour: deviant positioning of helminth-infected minnows in conspecific groups. Proceedings of the Royal Society of London. Series B: Biological Sciences, 263(1374), 1095-1102. • Bertrand, A., Barbieri, M. A., Gerlotto, F., Leiva, F., & Córdova, J. (2006). Determinism and plasticity of fish schooling behaviour as exemplified by the South Pacific jack mackerel Trachurus murphyi. Marine Ecology Progress Series, 311, 145-156. • Eggers, D. M. (1976). Theoretical effect of schooling by planktivorous fish predators on rate of prey consumption. Journal of the Fisheries Board of Canada, 33(9), 1964-1971. • Major, P. F. (1978). Predator-prey interactions in two schooling fishes,< i> Caranx ignobilis</i> and< i> Stolephorus purpureus</i>. Animal Behaviour, 26, 760-777. • Ryer, C.H., and B.L. Olla. 1991. Information transfer and the facilitation and inhibition of feeding in a schooling fish. Environmental Biology of Fishes 30.3: 317-323. • Abrahams, M., Colgan, P. 1985. Risk of predation, hydrodynamic efficiency, and their influence on school structure. Environmental Biology of Fishes. 13.3: 195-202. •  Partridge, B., Pitcher, T., Culler, M., Wilson, J. 1980. The three-dimensional structure of fish schools. Behavioral Ecology and Sociobiology. 6.4:277-288.

29. References •  Kils, U. 1992. The esSCOPE and dynIMAGE: Microscale tools for in situ studies of predator-prey interactions. Arch Hydrobiol Beih 36: 83-96. •  Moyle, P.B., Cech, J.J. 2003. Fishes, An introduction to Ichthyology. 5th Ed. Benjamin Cummings. • Hunter, J.R., Coyne, K.M. 1982. The onset of schooling in northern anchovy larvae, Engraulis mordax. CalCOFI 23: 246-251. • Landa, J.T. 1998. Bioeconomics of schooling fishes: selfish fish, quasi-free riders, and other fishy tales. Environmental Biology of Fishes. 53.4:353-364. •  Alexander, R.M. 2004. Hitching a lift hydrodynamically- in swimming, flying and cycling. Journal of Biology. 3.2:7. • Weiner, Jon. "Ideas for Wind Farming."California Institution of Technology News. CalTech University, 17 May 2012. Web. 25 Nov. 2012. <http://www.caltech.edu/content/schooling-fish-offer-new-ideas-wind-farming>. Images • http://www.sharkattackfile.net/species.htm#spinner • http://www.extremescience.com/sailfish.htm • http://dsc.discovery.com/sharks/shark-pictures/pelagic-thresher-shark.html • http://natural-wild-life.blogspot.com/2011/09/barracuda.html • http://digital-art-gallery.com/photo/gallery/birds • http://www.eaglewingtours.com/016_WhalesandWild/2719_EagleWingWhal.html • http://science.kqed.org/quest/2010/09/13/back-to-school-for-sardines/