Using behavior and ecology to exploit schooling fishes

By the late 1980's, humans were removing 76 million metric tons (MMT) of ma rine fishes annually. The potential sustainable catch is somewhere between 69 and 96 MMT. As a result, major fisheries have collapsed or are in danger of collapsing. Many of these species school. Schooling is effective agains t gape-limited predators because of dilution and confusion. However, larger predators may exploit schooling behavior to sequester and consume a non-tr ivial fraction of the group. This is the strategy of fishers. Both gear and fisher behavior have 'evolved' to take advantage of the seemingly canalize d response of schooling species. This paper examines the ways artisanal and western fishers have exploited knowledge of the behavior and ecology of sc hooling species to aid in fish capture. Topics include object association; use of light, sound, and chemicals; perceived barriers; predator-prey and o ther trophic interactions; inherent cyclical rhythms such as diel migration , lunar spawning, and seasonality; and correlations with the physical envir onment. Exploiting schooling allows fishers to increase efficiency through knowledge of when and where fish aggregate, or by extending the conditions under which aggregation occurs. However, knowledge of behavioral ecology ca n also be used to conserve schooling stocks. Gear selectivity, group size a nd population dynamics, and fisher efficiency are all potential areas of in tegration between behavioral ecology and fishery management. However, no am ount of integration of behavioral ecology into fishery management will have the intended conservation effects if fishing effort is not limited to at l east numerical if not behaviorally-sustainable levels.