551 



AbStfclCt.— Marine fishery reserves 

 (MFR'sl have been set aside in coastal 

 areas throughout the world with the 

 hope of reversing population decreases 

 commonly observed in many marine 

 resources. In this study, a comparison 

 of population structure of the commer- 

 cially important gastropod Strombus 

 gigas, queen conch, was made between 

 a fished area and an MFR in the Exuma 

 Cays, central Bahamas. There were 31 

 times more adult conch on the shallow 

 (<5 m) Great Bahama Bank in the 

 MFR, and in a survey at 7 depth inter- 

 vals (to 30 m) on the island shelf in the 

 Exuma Sound, mean adult density was 

 always higher in the MFR, by as much 

 as 15 times. Shell length and lip-thick- 

 ness measurements indicated that 

 adults in the MFR migrate with age 

 from bank nursery sites into deeper 

 sound water, whereas those on the bank 

 in the fished area were harvested be- 

 fore reaching water sufficiently deep to 

 protect them from free-diving fisher- 

 men. Although sparsely distributed ju- 

 veniles in shallow-water (<15 m) habi- 

 tats of the sound were the primary 

 source of adults in the fished area, large 

 juvenile aggregations on the bank also 

 contributed to the deep-water adult 

 stock in the MFR. 



Total larval densities in the MFR 

 were frequently an order of magnitude 

 higher than those found in the fished 

 area, and densities of late-stage larvae 

 were 4 to 17 times higher. Because the 

 surface current along the Exuma Cays 

 shelf flows to the northwest, late-stage 

 larvae found inside the reserve must 

 have been spawned outside the reserve; 

 thus the high densities of juvenile and 

 adult conch are the result of natural 

 accumulation of larvae in the area, as 

 well as the result of protection from 

 fishing. Although the fate of larvae dis- 

 persed from the reserve is uncertain, it 

 is likely that high numbers of reproduc- 

 tive stock and larvae in the reserve 

 have a significant positive effect on 

 populations in the northern Exuma 

 Sound. Designs of reserves that con- 

 sider ontogenetic requirements of the 

 target species and strategic locations 

 for larval production, import, export, 

 and metapopulation dynamics will op- 

 timize fishery benefits for the many 

 marine vertebrate and invertebrate 

 species that possess pelagic larvae. 



Queen conch, Strombus gigas, 

 in fished and unfished locations of 

 the Bahamas: effects of a marine 

 fishery reserve on adults, juveniles, 

 and larval production 



Allan W. Stoner 



Caribbean Marine Research Center 



805 East 46th Place 



Vera Beach. Florida 32963 



Present address James J Howard Marine Science Laboratory, 



Northeast Fisheries Science Center 



National Marine Fisheries Service, NOAA 



74 Magruder Road 



Highlands, New Jersey 07732 



Melody Ray 



Caribbean Marine Research Center 



805 East 46th Place 



Vera Beach, Florida 32963 



Manuscript accepted 25 April 1996. 

 Fishery Bulletin 94:551-565 ( 1996). 



In coastal areas throughout the 

 world, tracts of coastline, reef, and 

 banks known to be important spawn- 

 ing or nursery grounds for economi- 

 cally significant species are being 

 set aside as marine fishery reserves 

 (MFR's). Fishing in such areas is 

 either controlled or prohibited to 

 conserve or enhance production of 

 selected species. Bohnsack (1990) 

 listed 21 potential advantages of 

 fishery reserves including impor- 

 tant ecological benefits such as 1) 

 protection of reproductive stocks 

 and genetic diversity, 2) mainte- 

 nance of the age and social struc- 

 ture of populations, 3) maintenance 

 of areas of undisturbed critical habi- 

 tat, 4) supplemental restocking of 

 fished areas through emigration, 

 and 5) provision for a larval source 

 for recruitment to surrounding ar- 

 eas. Numerous other advantages of 

 reserves relate to data collection 

 and enforcement of regulations. 

 Surveys of the literature (Roberts 

 and Polunin, 1991; Dugan and 

 Davis, 1993; Rowley, 1992) have 



yielded evidence that, in most cases, 

 abundance and size of protected 

 species increase within reserves, 

 but there are few data to support 

 the other predicted advantages (see 

 also Roberts and Polunin, 1991; 

 Polunin and Roberts, 1993). 



Many fish and invertebrates pro- 

 duce planktonic larvae; therefore, in 

 order to enhance fishery yields in 

 the surrounding waters, an MFR 

 must be located such that its larval 

 production is exported to suitable 

 habitats and to fished areas. Whether 

 or not reserves are sources of recruit- 

 ment for areas outside the protected 

 waters is debated by environmen- 

 tal scientists, managers, and user 

 groups. There are virtually no data 

 to speak for or against the larval 

 export benefit (Carr and Reed, 

 1993), although theoretical models 

 incorporating the concepts of meta- 

 population dynamics indicate that 

 MFR's should provide for larval re- 

 cruitment to fished areas (Man et 

 al., 1995). Similarly, there is little 

 information on the emigration of 



