An empirical evaluation of the design and function of a small marine reserve (Waikīkī Marine Life Conservation District)

Abstract

The effectiveness of a small (0.34km2) "no fishing" marine reserve (Waikiki Marine Life Conservation District) was empirically evaluated by quantifying three components of reserve design and function: (1) spatial adequacy for containing daily movements of target species; (2) abundance and size of reef fishes in the reserve and adjacent fished areas; and (3) distribution and impact of fishing activities at the reserve site. Reef fish movements were quantified using a combination of sonic tracking and conventional identification tags. Tracked fishes were typically site-attached to well-defined home ranges and had predictable patterns of behavior including a crepuscular 'commute' between separate day and night habitats. Surgeonfishes (Naso unicornis) had relatively small home ranges that were strongly associated with high rugosity habitat contained within reserve boundaries. Goatfishes (Mulloidichthys jlavolineatus) and jacks (Caranx melampygus and C. sexfasciatus) had home ranges that were relatively large, and extended from the reserve into adjacent fished areas. Mobile species (goatfish and jacks) used a combined area of 1.013 km2, indicating that the existing reserve is too small to fully protect these species. Abundance & size of both target and non-target species was greater in reserve than in adjacent fished areas, suggesting that fishing is not the only factor determining patterns of fish abundance and size at Waikiki. Habitat complexity is generally greater in the reserve than in adjacent fished areas and appears to be an important factor determining patterns of fish abundance and size at Waikiki. Spear and shoreline pole & line fishing were the dominant fishing activities at Waikiki. Spear fishing had a higher catch per unit effort (kg/man h) and caught larger fish than pole & line fishing. Fishing activities were patchily distributed and clustered around public shoreline access points close to free parking. Some fishing did occur inside the reserve but at significantly lower levels than in adjacent fished areas. Little fishing occurred in the areas immediately adjacent to the northern and seaward reserve boundaries, suggesting that a fishing impact buffer zone exists around the reserve. This phenomenon may partly explain why mobile target species remain abundant inside the reserve despite daily excursions into adjacent, unprotected areas.