Mechanics of Fish Interactions with Planar Rigid Boundaries

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Terrestrial animals must continually support their bodies against the force of gravity which restricts the range of locomotion methods used by these animals. In contrast, fish live in an environment which buoys up the body, so that locomotor effort can be focussed on moving through the environment. As a result aquatic animals, and especially fish, move using a wider diversity of methods than their terrestrial relatives. Nevertheless, certain body and fin forms allow for more effective use of some locomotor methods compared to others, and, as a corollary, affects the habitat in which fishes live and their behavior. Most work to date has examined how fish form, function and habitat interrelate for fish living in open water environments. In practice, fish usually occupy, and indeed prefer, habitats including structures, especially surfaces such as the water bed, sides and weeds. This area of fish biology has been neglected, a situation that the proposed research seeks to rectify. Theoretical models show that the distance separating an animal or its propulsor from the ground is most important in determining the effect of a surface on the system. The research will systematically determine how different shapes of the body and of propulsors of fish affect the performance of typical species near and distant from horizontal surfaces (representing the bottom) and vertical surfaces (representing sides, weeds beds, and branching corals). The result will provide a comprehensive descriptive mechanical model for fish interactions with rigid surfaces which will be used to understand and interpret distributions of fish in different habitats and microhabitats. In addition to obtaining fundamental new knowledge on fish biology, it is essential to recognize that modern animal management, including fish and aquatic habitats, seeks to base its practices on first principles population and community structure models. The proposed research addresses the latter. Therefore, the research is expected to contribute to a variety of applications. For example, the research is expected to provide design principles for physical structures that would attract different types of fish, refining the design of artificial reefs, rehabilitation or protection of shoreline development, and selection of sites for underwater parks. In addition, the research will show how surfaces affect performance of bethic fish. Studies such as these have contributed to the design of fishing gear, and the research is anticipated to suggest novel designs for gear selective for fish species based on form.