Study Area and Methods 



The artificial reef, composed of three sunken 

 World War II liberty ships, is located approxi- 

 mately 29 km offshore (lat. 27°35'N, long. 

 96°54'W) from Port Aransas, Tex., in 33 m of 

 water. Red snapper were collected from the reef 

 with fish traps in March, May, July, September, 

 November, and December 1979. The rectangu- 

 lar traps (1.8m X 1.2m X 0.6m) were made of 

 1.25 cm reinforcing bar covered with 3.4 cm 

 mesh plastic coated wire. The entrance cone had 

 an initial opening of 60.9 X 45.7 cm terminating 

 in a 90° downturn with a 25.4 cm diameter 

 entrance port. During each sampling period, five 

 traps were baited with fish scraps and set on the 

 bottom around the reef for 24 h. All red snapper 

 captured in traps were measured in standard 

 and total lengths and placed in a flowing sea- 

 water live box onboard ship. Snapper which 

 were in good condition after 1 h on board ship 

 were tagged with numbered internal-anchor 

 tags and released over the artificial reef. 



Small red snappers (<160 mm) were collected 

 from the south Texas outer continental shelf 

 during 1975 through 1977 with a 10.7 m "flat 

 trawl" with 4.45 cm stretch mesh in the body and 

 2.5 cm stretch mesh in the bag. From 1975 to 

 June 1976 a 9.5 mm stretch mesh liner was 

 used inside the bag. Trawl sampling depths 

 ranged from 10 m to 132 m. Seventy-two trawl 

 samples were taken in 1975, 222 in 1976, and 294 

 in 1977. All trawls were made at a speed of about 



2 kn for 15min,(Fordetailsof sampling sites and 

 procedures see Flint 1981.) 



Results 



Growth 



The smallest fish taken in the trawl samples 

 were generally 20-29 mm (Table 1). Juveniles 

 <40 mm were caught in August, September, and 

 October, and eight individuals of this size were 

 taken in June 1976. Two year classes can be 

 identified in the length-frequency table (Table 1) 

 and followed for 12-18 mo. The smallest fish 

 taken in traps at the ship reef were 100-110 mm. 

 Snapper <100 mm could escape through the 

 mesh. 



Length-frequency histograms for combined 

 trawl and trap data are shown for each month 

 (Fig. 1). Two cohorts, age group and age group 

 I, are apparent in the data and a third cohort, age 

 group II, may be present in the March and July 

 data. 



Recruitment of small snapper (<40 mm) into 

 the population occurred primarily in June and 

 July as evidenced by the modal size of the age 

 year class in August, September, and October. 

 Limited recruitment of small fish continued into 

 October. Length-frequencies of snappers cap- 

 tured in June through December were distinctly 

 bimodal. Modal size classes for age I fish were 

 110 mm in June and 130 mm in July. Modal size 

 classes for age 1+ fish were 150 mm in December 



Table 1.— Length-frequency distribution of red snapper caught in trawl samples. The number of individuals of each size class in 

 each month is shown. No samples were taken in months with an asterisk (*). 



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