Effects of fishing pilot study: visual surveys on Cairns section closed reefs that will be opened under the new zoning plan

Abstract

In January 1992 we made baseline surveys of large fishes and other organisms on the five protected MNP B reefs in the Cairns Section that are to be opened to fishing under the new zoning plan and on five open 'control' reefs. The opening reefs were Ribbon #4, Escape, Channel, Wardle and Northeaster, while the appropriate 'controls' were St. Crispins, Ruby, Pellowe, Nathan and Potter. Surveys were aimed primarily at the large fishes targeted by fishermen, including coral trout, all species of Iethrinid and all species of lutjanid. In addition we made surveys of potential prey species (pomacentrids), other important reef organisms (chaetodontids, crown-of-thorns, giant clams) and encrusting communities (hard coral, soft coral). Underwater visual census techniques were used for the surveys, with 50 x 10 m transects for the large fishes, chaetodontids, crown-of-thorns and giant clams, and 20 x 2.5 m transects for the small prey fishes. The survey design incorporated three sites on the front of each reef and three on the back, with five replicate transects of each size counted in each site. The surveys on each reef took a day in the field using two observers.