Delgado et al.: Translocation of Strombus gigas as a strategy to rehabilitate the Florida Keys conch population 



279 



DK 



Key West 4jS t-^*' 



PS 



Atlantic Ocean 



I I Hawk Channel 

 Reef Tract 



25 00' N 



24 30' N 



8130'W 



81 00' W 



80 30' W 



Figure 1 



Queen conch lStroi7ibus gigas) translocation sites in the Florida Keys (adapted from 

 McCarthy et al. 2002). The nearshore region is the stretch of water on the landward 

 side of Hawk Channel; the offshore region is the stretch of water on the other side 

 of the channel, contiguous with the Atlantic Ocean. Nearshore conch were translo- 

 cated from Tinglers Island (TI) to Alligator Reef (AR) and from Duck Key (DK) to 

 Pelican Shoal (PS). 



1998; McCarthy et al., 2002). In a metapopulation context, 

 the nearshore region in the Florida Keys can be considered 

 a "blackhole sink" for larval recruitment because conch 

 that settle there do not spawn and thus do not contribute 

 to the reproductive output of the stock (se?isu Morgan and 

 Botsford, 2001). 



In 1990, the Florida Fish and Wildlife Conservation 

 Commission's (FWC) Florida Marine Research Institute 

 constructed an experimental hatchery to test the feasi- 

 bility of rehabilitating queen conch stocks in the Florida 

 Keys by releasing hatchery-reared juveniles. A series of 

 experiments to determine the best size of juveniles, time 

 of release, and area to release hatchery-reared juvenile 

 conch were conducted, and a cost-benefit analysis was 

 performed. Unfortunately, the high mortality of conch 

 after release, coupled with high production costs, caused 

 us to examine alternate strategies (Glazer and Delgado, 

 2003). 



Translocation is defined as the intentional introduction 

 or reintroduction of animals in an attempt to establish, 

 reestablish, or augment a population in order to aid in the 

 recovery of a native species whose numbers have been re- 

 duced by overharvesting or habitat loss (or both) (Griffith 

 et al., 1989). This method of population recovery has been 

 used to facilitate the recovery of numerous species of birds 

 and mammals (Griffith et al., 1989) and several aquatic 

 species, including cutthroat trout (Harig et al., 2000) and 

 corals (Edwards and Clark, 1999; Rinkevich, 1995; van 

 Treeck and Schuhmacher, 1997). Nest translocations 

 have also proven effective in efforts to recover sea turtles 

 (Garcia et al., 1996). 



The present study was initiated to determine the po- 

 tential of translocating nonspawning nearshore conch to 

 offshore sites as a method to augment spawning aggrega- 

 tions and as an aid in the recovery of the queen conch 

 population in the Florida Keys. However, this strategy will 

 be beneficial only if the translocated conch regain their 

 reproductive capacity. To test this approach, we translo- 

 cated adult conch from the nearshore region into existing 

 offshore breeding aggregations and examined changes 

 in reproductive behavior (i.e., mating and spawning) and 

 gonadal development. 



Materials and methods 



Translocations and reproductive behavior 



During March 1999, we translocated adult conch from 

 nearshore aggregations to aggregations offshore. Near- 

 shore aggregations were located at Tinglers Island 

 (24°41'N, 8r05'W; water depth <l-2 m) and Duck Key 

 (24°45'N, 80°55'W; water depth <l-2 m) (Fig. 1). The 

 habitat at the two nearshore sites was characterized as a 

 matrix of hard-bottom and Thalassia testudinum patches. 

 Offshore aggregations were located at Alligator Reef 

 (24°51'N, 80°37'W; water depth 9-11 m) and Pelican Shoal 

 (24°30'N, 81°37'W; water depth 5-7 m) (Fig. 1). The habitat 

 at the offshore sites consisted of back-reef rubble, sandy 

 plains, and patches of Thalassia testudinum. 



We tagged 44 adult conch at Tinglers Island; 23 were 

 translocated to Alligator Reef, and 21 were rereleased at 



