644 



Fishery Bulletin 98(3) 



The south point aggregation site (where the tagged 

 E. striatus was recaptured) has supported a seasonal 

 fishery (fish trap, and hook and hne) since before 1900 

 (Cohn, 1992). During spawning aggregation periods, the 

 site draws 2000-3000 E. striatus; density decreases during 

 nonspawning periods (Cohn, 1992). Notably, an E. stria- 

 tus spawning aggregation site is known to have previously 

 existed within the ECLSP boundaries at the "Wide Open- 

 ing," approximately 20 km to the NNW of the tagging site.- 

 However, it is not known if the site currently sustains 

 spawning Nassau grouper. If this and other nearby spawn- 

 ing sites do exist (denoted by a cross ( + ) in Fig. 1), one can 

 only speculate as to why a fish would migrate a consider- 

 ably greater distance to spawn. 



I suggest that E. striatus learn the routes to historic 

 spawning sites by local enhancement from older individu- 

 als (i.e. older animal directs attention of younger animal 

 to a particular part or object in the environment), per- 

 haps by socially transmitted traditions (see Helfman and 

 Schultz, 1984, for definitions). The fact that traditions 

 differ among subpopulations would account for both the 

 number of spawning sites in an area and their historical 

 nature. If spawning sites are learned from older individu- 

 als, then one could conjecture how this learning behavior 

 affects recovering E. striatus populations; older individu- 

 als are required to socially transmit the location of spawn- 

 ing sites, and young adults need to be present to learn. 

 Current and future studies of sensory systems and migra- 

 tion should provide insight into these h}rpotheses. 



Because actual spawning was not observed and gonads 

 were not available, the reproductive status of the recap- 

 tured E. striatus is unknown. Hence, fishermen reports 

 and water temperature data were used to investigate the 

 likelihood of E. striatus spawning at time of recapture. 

 The recaptured fish was captured on 16 February from 

 a spawning "school" five days after the full moon.'^ Local 

 fishermen believe that spawning was occurring at this 

 time because catches of E. striatus were abundant, the 

 fishermen were targeting a known spawning site, and the 

 fish were "full |of eggs]".- Spawning is usually synchro- 

 nous with the full moon; thus it is speculated that the 

 Nassau grouper use the moon as a visual cue in migrating 

 to common spawning areas. 



The geographic differences in spawning season of £. stri- 

 atus are thought to correlate with water temperatures, of 

 which optimal spawning temperature is most likely in the 

 range of 25-26°C (Colin, 1992; Tucker et al., 1993). Mean 

 monthly water temperature at the Long Island south point 

 aggregation site was 24.68°C in February 1988 (no spawn- 

 ing; Colin, 1992) and 23.94°C in February 1998 (presumed 

 spawnmg; present study). If spawning is correlated only 

 with water temperature, then it is unlikely that the recap- 

 tured E. striatus grouper was actively spawning. However 

 it is more likely that temperature is only one of many 



2 Darville R. 1998. Personal commun. ECLSP Park Warden, 



P.O. Box N-410.'5 Nassau, Bahamas. 

 ^ Fishermen refer to the aggregations as "schools" because a large 



number of fishes are present in reproductive condition. 



physical attributes influencing the spawning of £. striatus 

 and if the fishermen reports are correct, it is entirely pos- 

 sible that the recaptured E. striatus was removed from a 

 spawning aggregation. 



ECLSP is a marine reserve for the preservation of 

 animals, plant, and other marine life. For management 

 purposes, the intent of a marine reserve is to provide 

 spatial refuge from fishing, whereas the intent of tradi- 

 tional fishery restrictions on the resource is to allow a suf- 

 ficient number of animals to reproduce. (Bohnsack, 1998). 

 Evidence provided in the present study indicates that spa- 

 tial refuge alone may be insufficient because the ECLSP 

 reserve provided protection only until the animal migrated 

 to spawn and thus was captured. If the Nassau grouper 

 stock are to be preserved, protection throughout the ani- 

 mal's life history including spawning needs to be con- 

 sidered. Possible ways to provide this protection include 

 closing documented spawning aggregation sites to fish- 

 ing, enforcing seasonal closures, or providing protection 

 for migrating and spawning individuals. 



Acknowledgments 



This research was conducted under a grant from NOAA 

 Office of Protected Species, and a Research Permit from 

 the Govt, of the Bahamas. I thank the National Marine 

 Fisheries Service for financial support and the Nature 

 Conservancy for field assistance. Special appreciation to 

 Bell Island Ltd. and K. James for logistical support. Com- 

 ments by W.J. Richards, J. Bohnsack, and three anonymous 

 reviewers greatly improved the content. I would like to also 

 thank Captain A. Cartwright and the Long Island fisher- 

 man who provided local fishing knowledge, L. Massey for 

 creating the map, and N. Mehta of CMRC for temperature 

 data. Field assistance by J. Kelly, H. Luciano IV, and K. 

 Sullivan is appreciated. 



Literature cited 



Aguilar-Perera, A., and W. Aguilar-Davila. 



1996. A spawning aggregation of Nassau grouper Epinephe- 

 lus striatus (Pisces: Serranidae) in the Mexican Caribbean. 

 Env. Biol. Fish. 45:351-361. 

 Bardach, J. E., C. L. Smith, and D. W. Menzel. 



1958. Bermuda fisheries research program final report. 

 Bermuda Trade Development Board, Hamilton, Bermuda, 

 59 p. 

 Bohnsack, J. A. 



1998. Application of marine reserves to reef fisheries man- 

 agement. Aust. J. Ecol. 23:298-304. 

 Carter, J. 



1988. Grouper mating ritual on a Caribbean reef Under- 

 water Natur 17:8-11. 

 Colin, P L. 



1992. Reproduction of the Nassau grouper, Epinephelus stri- 

 atus (Pisces: Serranidae) and its relationship to environ- 

 mental conditions. Env. Biol. Fish. 34:357-377. 

 1996. Longevity of some cora! reef fish spawning aggrega- 

 tions. Copeia 1996:189-191. 



