FISHERY BULLETIN: VOL. 85, NO. 4 



Figure 1. — Location of the queen conch study area (stippled) off La Parguera, Puerto Rico. Dashed line is the edge of the insular shelf 



Shaded areas are emergent coral reefs. 



casional patch reefs. The total study area is esti- 

 mated to be 0.4 km^, although for the first two 

 periods sampling was limited to approximately 

 the eastern 50% of the area. 



Sampling occurred quarterly, generally in the 

 latter half of August, November, February, and 

 May, resulting in 9 sampling periods spanning 2 

 years from August 1983 to August 1985. Sam- 

 pling during each period was conducted in the 

 following manner. The area was surveyed by 

 scuba divers and all data were collected in situ. 

 Attempts were made to locate a minimum of 200 

 individuals. The maximum number was variable 

 and subject to limits on queen conch density, the 

 time dedicated to sampling (generally 3 weeks), 

 and the weather during that time. During each 

 period a two-stage haphazard sampling plan was 

 used. Dive sites were located haphazardly 

 throughout the full range of the study area, and 

 the bottom covered during each dive was a func- 

 tion of direction and distance travelled, which 

 also were determined haphazardly. 



All queen conchs were tagged, when initially 

 encountered, and measured for siphonal length to 

 the nearest 1 mm using calipers. In addition, 



adults, defined by the presence of a flared shell- 

 lip, were measured for lip-thickness in a similar 

 manner. Tags consisted of 4.5 cm strips of Dymo^ 

 label tape, upon which a unique identification 

 number was embossed. They were tied around the 

 shell spire with nylon line (Fig. 2). The spines 

 characteristic of queen conch shells held the tag 

 firmly in place. Upon subsequent sightings tag 

 number was recorded and shell dimensions re- 

 measured. 



During the 2-yr study period, casual assess- 

 ments were made of fishing activity in the area. 

 This was easy to do routinely as fishermen were 

 willing to return tags from fished shells, and the 

 presence of newly fished, empty shells on the bot- 

 tom (left behind after meat extraction) was obvi- 

 ous after fishing had occurred. When encoun- 

 tered, tag numbers of these shells were recorded. 



Data analysis used the Jolly-Seber method. The 

 theory and practical mechanics of the method are 

 presented in detail by Seber (1982: Section 5.1). It 

 is valid for open populations where the effects of 



^Reference to trade names does not imply endorsement by the 

 National Marine Fisheries Service, NOAA. 



798 



