542 



Fishery Bulletin 102(3) 



MINWR has been in effect for approximately 40 years, 

 presumably long enough for fish populations to reach 

 equilibrium levels, yet we observed a net movement of 

 fish into protected habitats over the past decade. 



A wide range of factors interact to determine the 

 distributions of large mobile fish in the IRL, where 

 physical environmental conditions (salinity, inlet dis- 

 tance, temperature, etc.) have a primary influence on 

 the species' distributions over a lagoon-wide scale, and 

 where species responses to biological variables (sea- 

 grass cover, depth, seasonality, etc.) act secondarily to 

 influence distributions at smaller scales (Kupschus and 

 Tremain, 2001). The specific mechanisms that lead to 

 the greater ingress rates into the NTZ for red drum and 

 black drum in the present study cannot be determined 

 from our data. Possibilities include a behavioral attrac- 

 tion to the NTZ due to the interrelated influences of 

 habitat preference, spawning, and social structure, or 

 due to potentially higher retention rates after migra- 

 tion into the reserve. Red drum and black drum were 

 routinely observed foraging in large schools within both 

 the NTZ and surrounding waters, which suggested that 

 food resources were available in each of these habitats; 

 however, there are few studies that have attempted to 

 quantify differences in resource availability between 

 these areas. Johnson et al. (1999) described the habitat 

 characteristics of their study areas within the same re- 

 serve system but found that protection from fishing, and 

 not habitat difference, was the primary factor contribut- 

 ing to differences in the abundance of sportfish species 

 between fished and unfished areas. The availability of 

 suitable spawning habitats within the NTZ may also 

 attract red drum and black drum to the reserve habi- 

 tats. We observed indications of reproductive behavior 

 by both of these species inside the NTZ that is common 

 among members of the drum family, including concen- 

 trations of drumming fish (Mok and Gilmore, 1983) 

 and repeated side-to-side contact among individual fish 

 (Tabb, 1966) in the presence of ripe and running males. 

 Although we did not directly observe these behaviors 

 for either species outside of the NTZ, black drum and 

 red drum are documented to spawn elsewhere within 

 the IRL system (Mok and Gilmore, 1983; Johnson and 

 Funicelli. 1991) and we cannot automatically presume 

 that suitable spawning habitats do not also occur in the 

 surrounding waters. If there is a behavioral attraction 

 to protected habitats, then the subsequent retention of 

 individuals that have immigrated into these areas may 

 be prolonged by the limited boundary permeability of 

 this reserve, which contains only two potential egress 

 pathways back into the adjacent waters. In order to ful- 

 ly understand the protective functions of this estuarine 

 reserve and others, it will be important to identify the 

 biological, behavioral, and physical mechanisms that 

 influence species movements in relation to the reserve 

 boundaries. 



The opportunistic nature of our tagging efforts within 

 the design of a larger sampling program precluded sta- 

 tistically valid sample replication, and only one reserve 

 and adjacent fished area were examined; therefore, 



the results of this study should not be generalized to 

 other areas. Still, the IRL is typical of other bar-built 

 estuaries where access by estuarine fishes to coastal 

 waters through passes or inlets may be limited, and 

 it is reasonable to expect that the geographical, en- 

 vironmental, and biological processes that influence 

 species movements in the IRL would also be important 

 in other estuaries of similar structure. Studies show- 

 that no-take areas in estuarine systems can have an 

 effect on species' abundances and size distributions 

 within these protected areas and may indicate that 

 these areas protect species from the effects of fishing 

 pressure (Johnson et al., 1999; FMRI unpubl. datai. 

 Whether or not these areas will actually increase fish 

 abundance in adjacent waters or benefit surrounding 

 fisheries through direct supplemental replenishment of 

 exploitable species is less evident. Certainly, some indi- 

 viduals will migrate out of protected areas in response 

 to environmental, biological, or physiological stimuli, 

 and these individuals may contribute to trophy fisheries 

 in surrounding waters (Roberts et al.. 2001); however, 

 our data indicated that within estuaries, reciprocal 

 movements over relatively large distances into protected 

 areas also occur and have the potential to extract ex- 

 ploitable individuals from surrounding fisheries. The 

 overall impact of such withdrawals on these fisheries 

 will depend on the degree of retention following migra- 

 tions into protected areas. If retention rates are high, 

 then increased egg production, larval export, and juve- 

 nile recruitment may be more important mechanisms 

 for replenishment of nearby fisheries than spillover of 

 exploitable species, but production and export will be 

 limited unless reserves encompass spawning or nursery- 

 habitats (or both) that will support long-term protection 

 and population growth. For estuarine-dependent coastal 

 species that support estuarine fisheries, the benefits 

 obtained within protected areas will be determined, 

 in part, by their specific life-history characteristics, 

 movement patterns, and the reserve design. Although 

 the establishment and study of reserves in marine or 

 coastal systems has increased in recent years, research 

 on the effects of protected no-take reserves in estuarine 

 habitats is still in its infancy. Information on the daily, 

 seasonal, or annual movement patterns of estuarine- 

 resident or estuarine-dependent coastal species is neces- 

 sary for understanding and designing effective reserve 

 areas in these habitats. 



Acknowledgments 



We wish to thank the crewmembers and volunteers at 

 FMRI's Indian River Field Laboratory for collecting data 

 and assisting in this study and the many fishermen who 

 willingly provided us with recapture information. We 

 are grateful to U.S. Fish and Wildlife Service personnel 

 for providing access to sampling areas within restricted 

 areas of the Merritt Island National Wildlife Refuge. 

 This paper benefitted from reviews by R. Cody. J. Col- 

 vocoresses, L. French, J. Leiby, R. Paperno, J. Quinn, 



