FISHERY BULLETIN: VOL. 74, NO. 1 



Figure l. — Study area and sampling locations in the Jamaica 

 Beach area of West Bay, Tex. 



Winkler method (Carritt and Carpenter 1966). 

 Crustaceans were collected in a trawl that had a 

 mouth opening of 0.6 m by 3.0 m and a stretched 

 mesh of 28.0 mm in the body and 2.5 mm in the 

 cod end. At each station the trawl was towed 200 

 m at about 2 knots. "Abundance" and "catch" are 

 used synonymously in this report as our index of 

 relative abundance. These terms refer to either 

 the number or average number of animals caught 

 per 200-m tow with the trawl. 



Data were treated differently than those re- 

 ported by Trent et al. (1972) in that stations 1-5 

 in the altered area were subclassified into upland 

 canal area (stations 1-3) and bay ward canal area 

 (stations 4, 5); classification of stations 6-9 in the 

 marsh and station 10 in the bay remained the 

 same. 



The data were treated statistically as follows 

 for the five species caught in greatest abundance 

 (Table 1): differences in catches between day and 

 night were tested with a paired-comparison ^test 

 using individual catches at a station as observa- 

 tions; differences between areas were tested with 

 Tukey's a;-procedure (Steel and Torrie 1960) 

 using the average catch by area, date, and time of 

 day as observations. 



COMPARISONS OF CATCH 

 BETWEEN DAY AND NIGHT 



Eight genera and at least 11 species were rep- 

 resented in the catches (Table 1). Four species 

 and members of the genus Palaemonetes were 



about 45 hectares of emergent marsh vegetation 

 (predominantly Spartina alterniftora) , intertidal 

 mud flats, and subtidal water area was reduced to 

 about 32 hectares of subtidal water area by 

 dredging and filling; water volume (mean low 

 tide level) was increased from about 184,000 m^ 

 to about 394,000 m^. Ten sampling stations were 

 established in the study area. Average water 

 depths (mean low tide level) at stations 1 through 

 10 were 1.6, 2.6, 2.2, 1.4, 1.3, 0.5, 0.2, 0.4, 0.5, and 

 1.0 m, respectively. 



Samples of water and crustaceans were col- 

 lected during the day between 1000 and 1400 h 

 and at night between 2200 and 0200 h at 2-wk 

 intervals from 25 March to 21 October 1969 at 

 each station. Water samples for determining dis- 

 solved oxygen were taken 30 cm above the bot- 

 tom. Oxygen was measured using a modified 



Table l. — Species or genera and total numbers of crustaceans 

 caught by area during the study. 



Species 



Brown shrimp, 



Penaeus aztecus 

 White shrimp, 



P. setiferus 

 Grass shnmp, 



Palaemonetes sp. 

 Blue crab. 



Callinectes sapidus 

 Pinl< shrimp. 



Penaeus duorarum 

 Mantis shrimp, 



Squilla sp. 

 Brokenback shrimp, 



Trachypenaeus sp. 

 Stone crab, 



Menippe mercenaha 

 Mud crab, 



Eurypanopeus sp. 

 Swimming crab, 



Callinectes similis 

 Pistol shrimp, 



Alpheus sp. 



Upland Bayward 

 canal canal Marsh 



Bay 



196 



