Tremain et al.: Sportfish species movements in relation to an estuarine no-take zone 



541 



RI sampling activities outside the NTZ, leading to lower 

 tag recovery rates from this area. However, several fish 

 from the Banana River study area were recaptured on 

 multiple occasions — a common occurrence in this region 

 where fish are caught and released in fishing practices. 

 Although there is some postrelease cryptic mortality 

 associated with catch-and-release practices, these re- 

 leases likely limited the effects of local fishing on our 

 analyses. Second, our assumption that the migration 

 patterns of recaptured fish represented the migration 

 patterns of the overall population may not be valid if 

 the respective length frequencies were not also equally 

 represented. The use of multiple gear types and sam- 

 pling strategies to collect fish for tagging increased the 

 likelihood that the length frequencies of species in our 

 collections represented the available population. Report- 

 ed recapture length frequencies closely approximated 

 the population length frequencies in our collections for 

 red drum, black drum, and sheepshead but over-repre- 

 sented the frequency of larger individuals for common 

 snook and spotted seatrout. Because red drum and 

 black drum were the principal species that displayed 

 multidirectional migration patterns, we considered the 

 potential for size bias to be minimal in our comparisons 

 of estimated ingress and egress rates. 



Ultimately, a determination of the net result of these 

 migration patterns, in terms of replenishment to or 

 withdrawal from adjacent fisheries, would require ac- 

 curate assessments of species population abundances 

 that were beyond the scope of this study. If there are 

 large enough differences in population densities across 

 the NTZ boundary, either as a result of increased pro- 

 duction inside the reserve or high fishing mortality 

 outside, then the relatively low emigration rates that we 

 observed could still result in a net export of exploitable 

 individuals to fished populations in surrounding waters. 

 In trammel-net collections from this same reserve dur- 

 ing the late 1980's, Johnson et al. (1999) estimated 

 that in the protected habitats, relative abundances of 

 red drum populations were 6.3 times greater and of 

 black drum were 12.8 times greater than the relative 

 abundances of these populations in adjacent unpro- 

 tected areas. More recent shoreline haul-seine data 

 from 1997-2000 show that these abundances were only 

 1.8 times greater for red drum and 1.5 times greater 

 for black drum (FMRI, unpubl. data). To what extent 

 the difference in abundance estimates between these 

 two temporally separate studies is related to fish move- 

 ments, to stringent changes in management regulations 

 that have occurred, or to the difference in sampling 

 methods used is undetermined. However, if we consider 

 the more recent population level differences between the 

 NTZ and adjacent waters, then the emigration and im- 

 migration rates observed in the present study indicate 

 that there is a potential for more substantial move- 

 ments by these species towards protected habitats than 

 away from them. 



One limitation of tag-recapture data is that such data 

 provide only a snapshot view of overall fish movements, 

 and the whereabouts of tagged individuals between 



the time of tagging and recapture are unknown. It 

 is possible that the movements we observed for red 

 drum and black drum in the vicinity of the NTZ were 

 simply instantaneous views of a more complex series of 

 movements between the NTZ and adjacent waters. One 

 possibility is that these movements could be related 

 to daily or seasonal home ranges that extend across 

 reserve boundaries. Studies that attempt to quantify 

 home ranges for these species at any temporal scale 

 are limited. Carr and Chaney 1 1976 1 followed a single 

 red drum, which was fitted with an ultrasonic trans- 

 mitter, for up to two days after releasing it into the 

 Intracoastal Waterway near St. Augustine, Florida. 

 During that time, fish movements were oriented against 

 the direction of tidal flow but remained within 2 km 

 of the release point. Adams and Tremain (2000) found 

 that large juvenile red drum repeatedly used or were 

 continually associated with a 2-km section of a northern 

 IRL tidal creek for periods of up to 18 months. Tag- 

 ging studies from estuarine waters generally indicate 

 that the majority of red drum and black drum do not 

 make substantial movements from their release sites, 

 although some individuals are capable of migrating up 

 to several hundred kilometers (Beaumariage, 1969: 

 Osburn et al. 1982; Music and Pafford, 1984; Murphy et 

 al., 1998i. During the present study, 20 red drum were 

 recaptured on multiple occasions; however, none of these 

 fish exhibited movements that could provide evidence 

 for home ranges that overlapped the NTZ boundar- 

 ies. Another possibility for the movement patterns we 

 observed is that they are related to population equilib- 

 rium adjustments that occur when the relative attri- 

 butes of the NTZ and surrounding areas change with 

 respect to each other. For example, beginning in 1990 

 and coinciding with the onset of the present study, the 

 Banana River adjacent to the NTZ (including much of 

 our BR study area) was closed to motorized boat traffic. 

 Although the area remained open to fishing, it became 

 considerably more difficult to access by fishermen. If 

 this limitation resulted in lower fishing pressure (i.e., 

 predation) and fewer habitat disturbances, then the 

 relative habitat value and rates of migration into this 

 area may have increased during that time. There are 

 no quantifiable estimates of migration rates prior to 

 this study for comparison, but our results do not dem- 

 onstrate an equilibrium adjustment toward potentially 

 higher quality BR habitats during our study period. If 

 species movements are not equilibrium adjustments, 

 but rather are driven by an attraction to or retention 

 within habitats that offer protective benefits, then ul- 

 timately reserve habitats should become saturated. 

 Predicted equilibrium population sizes for queen conch 

 iStrombus gigas) and spiny lobster (Panulirus argus) 

 were achieved in just three years after the effective 

 creation of a Caribbean reef harvest refuge, but models 

 suggested that relatively minor changes in refuge area 

 and boundary condition (i.e., permeability) could result 

 in major population-level responses by exploited species, 

 depending upon dispersal dynamics and habitat avail- 

 ability (Acosta, 2002). The estuarine no-take zone at 



