Study Area and Methods 



The study area was located about 300-800 m 

 northwest of Courtney Point in St. Andrew Bay 

 (Figure 1). Hydrological, physical, and sedimen- 

 tological characteristics of the bay system were 

 described by Ichiye and Jones (1961), Waller 

 (1961), and Hopkins (1966). The bay system ex- 

 changes water with the Gulf of Mexico through 

 East and West passes (Figure 1). Prevailing 

 winds are from the southwest in the summer, 

 north and northeast in the autumn, and north 

 and southeast in the winter and spring. Tides are 

 usually diurnal with a mean range of about 0.4 m 

 in St. Andrew Bay (U.S. Department of Com- 

 merce 1967). 



Eleven gill nets of different mesh sizes were 

 fished for 87 consecutive days from 17 September 

 to 13 December 1973. Each net was 33.3 m long 

 and 3.3 m deep. Stretched mesh sizes ranged from 

 6.4 to 12.7 cm, the mesh sizes increasing by 

 0.6-cm increments. The nets were made of #208 

 monofilament nylon webbing hung to the float 

 and lead lines on the half basis (two lengths of 

 stretched mesh to one length of float line). 



Nets were set parallel to each other about 50 m 

 apart, perpendicular to shore, and in water 

 depths (mean low tide) of 2.2 to 2.6 m (Figure 1). 

 Nets remained in the water continuously except 

 for 12 brief periods when they were randomly 

 reset among net locations during the 87-day 

 period. Damaged webbing never exceeded 5% of 

 the total surface area of each net. 



Fishes were removed from the nets at sunrise 

 ±2 h and occasionally at sunset ±1 h. The total 

 number of each species caught, including the 



ST. ANDREW BAY 



\ 11 



9 ^f. 



\ 



'■■■i- i ' . 



^ GUIF OF MEXICO 



** 8S*'40W 



DEPTH CONTOUR 



MAGNOLIA BEACH 



damaged specimens, was counted. Lengths of the 

 undamaged specimens were determined on a 

 measuring board to the nearest 0.5 cm in fork 

 length (tip of snout to fork of tail) for those fishes 

 having forked tails and in total length (tip of 

 snout to extremity of caudal fin) for Atlantic 

 croaker and sharks. 



Total catch and catches of each of the 10 most 

 abundant species per 24-h period (catches per 

 day) during and between frontal periods were 

 compared using a t-test for unpaired observations 

 (Steel and Torrie 1960). We tested the hypothesis 

 that the mean catch during frontal periods (n = 

 23) equaled the mean catch between frontal 

 periods in = 64). We also used the t-test to test the 

 hypothesis that the mean lengths of each of the 

 10 most abundant species caught during and be- 

 tween frontal periods were equal. 



Water temperature was recorded continuously 

 by a Peabody-Ryan^ thermograph (Model F; accu- 

 rate within 2% on time and temperature) about 1 

 m below the water surface at a dockside location 

 about 100 m from the south end of the study area. 

 Mean water temperatures per 24-h period were 

 computed from readings taken every 6 h from the 

 continuous data. Air temperatures, measured 

 hourly, were obtained from the weather station at 

 Tyndall Air Force Base located about 13 km east 

 of the study area. Air and water temperatures 

 were averaged over a 24-h period ending at 0600 

 h. Changes in water temperature per 24-h period 

 were determined from these means. 



Species and Numbers of Fish Caught 



A total of 15,398 individuals representing at 

 least 65 species (not all species o{ Sphyrna and 

 none o^ Scorpaena were specifically identified) of 

 marine fishes was caught during the study (Table 

 1). Catch per day ranged from 10 to 967 individu- 

 als and from 6 to 25 species; increases and de- 

 creases in the total number of fish caught per day 

 were generally accompanied by similar changes 

 in the number of species of fish caught per day 

 (Figure 2). 



The 10 most abundant species comprised 88% 

 of the total catch. The 10 were: Gulf menhaden, 

 Brevoortia patronus; spot, Leiostomus xanthurus; 

 Atlantic croaker, Micropogon undulatus; pinfish, 

 Lagodon rhomboides; pigfish, Orthopristis 



Figure l . — Study area and net locations in St. Andrew Bay, Fla . 



450 



^Reference to trade names does not imply endorsement by the 

 National Marine Fisheries Service, NOAA. 



