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Fish Behavior - Grouping

Fish Behavior - Grouping. Shoals and Other Aggregations • Forms of fish grouping – Solitary – Shoal – School – Pod . Let’s Regroup!. • Reasons for grouping – Traveling – Feeding – Dealing with predators – Reproduction. Definitions.

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Fish Behavior - Grouping

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  1. Fish Behavior - Grouping Shoals and Other Aggregations • Forms of fish grouping – Solitary – Shoal – School – Pod

  2. Let’s Regroup! • Reasons for grouping – Traveling – Feeding – Dealing with predators – Reproduction

  3. Definitions Shoal - any group of fishes that remains together for social reasons School - a polarized, synchronized shoal (has coordinated, directed movements)

  4. How do Schools Work? Requires great deal of coordination among individuals in the school Vision is primary sensory cue for coordinating movement Use of optomotor reaction - individual movement is coordinated with movement of some other visually distinctive object - e.g. a spot or a stripe

  5. Functions of Schooling Behavior Hydrodynamic (swimming) efficiency Reduced predation risk Feeding Reproduction

  6. Functions of Schooling Behavior • Hydrodynamic efficiency • individuals obtain reduction in drag by following in “slip-stream” of neighbors • limited evidence in support of this

  7. Functions of Schooling Behavior • Reduced predation risk • creates patchy distribution of prey - large areas with no prey • once school is found, individual risk of being captured is reduced by dilution • confusion of prey by protean displays, encirclement, other behaviors

  8. Functions of Schooling Behavior • Feeding • increases effective search space for the individual (more eyes, separated by greater distance) • coordinated movements to help break up schools of prey - analogous to pack behavior in wolves - by tunas, jacks

  9. Functions of Schooling Behavior • Reproduction • increases likelihood of finding a mate • facilitates coordination of preparedness (behavioral and pheromonal cues) • facilitates arriving at right spawning site at right time

  10. Fish Behavior & Communication Shoaling • A social grouping of fish • Occurs throughout life in about 25% of fish species • Half of all fish shoal at some time

  11. Benefits of Shoaling • Gives a predator many moving targets – Confuses predators – Increases chances at the individual level – Increases food finding ability • Keeps potential mates in close proximity

  12. Fish Behavior & Communication Pods • Tightly grouped school • Move as a single unit (including making quick turns) • Makes the school appear like one large organism – Protection from predators

  13. Liabilities of Grouping Behavior • Increased likelihood of disease & parasite transmission • Becoming more conspicuous to some predators – Harvested more easily by man

  14. Assignment- Draw fish schoolingDescribe why fish swim in groups on the bottom

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