Direct evidence of limited dispersal of the reef fish Parapercis colias (Pinguipedidae) within a marine reserve and adjacent fished areas

1. Spillover of organisms from marine reserves may augment adjacent areas, and is often cited as an important reason for the establishment of marine p rotected areas. Spillover is dependent on residence or limited dispersal of organisms resulting in an increase in their abundance and size within a ma rine reserve. 2. To investigate movement (i.e. spillover versus residence) we tagged and released 90 blue cod Parapercis colias (Pinguipedidae) at each of four site s, two in and two adjacent to Long Island-Kokomohua Marine Reserve, Marlbor ough Sounds, New Zealand. The study was done 4-5 years after establishment of the no-rake reserve. 3. Abundances of blue cod were similar in and out of the marine reserve, bu t mean estimated size was 4 cm larger in the reserve than at fished sites. 4. Fewer tag resights were made in the reserve than at fished sites, and la gged blue cod were resighted at greater depths in the reserve than at fishe d sites. 5. Most resights (75% for fished sites, 73% for reserve sites) were made wi thin 100 m of the tagging sites, and the number of resights declined throug h time, though tagged individuals were resighted up to 31 months after tagg ing. 6. The lower number of tag resights at reserve sites, despite the lack of e xtraction, is consistent with some blue cod at reserve sites moving longer distances than those at fished sites. 7. The greater size of individuals in the reserve and limited dispersal of a proportion of the population show that survivorship of blue cod is increa sed within marine reserves. 8. Computer simulations based on measured dispersals indicate that even mar ine reserves of a few hundred metres long-shore extent have the potential t o supplement fished populations nearby. 9. These data provide direct evidence of limited dispersal of the most comm on edible reef fish in the Marlborough Sounds. Blue cod will grow to larger sizes in marine reserves and via spillover will become available to fisher s in adjacent areas of contiguous coast. Copyright (C) 2000 John Wiley & So ns, Ltd.