Table 1. — Monthly occurrence of young Gulf menhaden in collections by channel net from 

 Pensacola Bay and from East Bay and East Bay River, 1969-70 and 1970-71. 



1969-70 



1970-71 



(4.8 km) upstream ranged from to 2.3 °/oo 

 surface and from to 19.2 bottom. Water temper- 

 atures of the Bay ranged from a January low of 

 6.7°C to an August high of 31.7°C. 



In summer and early fall, surface and bottom 

 waters of the River were cooler (1° to 5°C) than 

 those of the Bay, but in winter, the River usually 

 was warmer (1° to 2°C) than the Bay. Dissolved 

 oxygen readings were from 7 to 12 ppm. Water 

 transparency of the River ranged from 80 to 300 

 cm (highest in September and October); of the 

 Bay, 90 to 140 cm. The River was acidic (pH, 

 5.0-6.0) and the Bay was neutral or slightly alka- 

 line (pH, 7.0-8.0). 



The channel net was suspended from the Pen- 

 sacola Bay bridge on 2 to 4 days each month for 

 2 or 3 consecutive J^-hr intervals per day. It was 

 used primarily to capture larval fishes. The 

 bridge site was chosen because surface-water 

 currents were present to spread the net, and it 

 allowed early collecting of those larvae entering 

 the estuary through the inlet. 



Each end of East Bay and the interface area of 

 the River (between fresh water and a surface 

 salinity of 0.5 o/oo) were sampled once or twice 



a month with channel net and surface trawl. Each 

 net was towed for 10-min. periods between two 

 16-ft boats (4.9 m). The surface trawl was used 

 primarily to capture postlarval fishes and was 

 used at night because large juvenile menhaden 

 could escape the net during the day. The thin 

 elongated body of the menhaden larva begins to 

 deepen at 30 mm, and by 33 mm the body has 

 markedly deepened to the juvenile form. Our 

 references to young include larvae and juveniles. 



Samplin.g in East Bay and Ea.st Bay River also 

 included monthly seining of two adjacent coves 

 near the mid-southern-shore of the bay and 

 monthly collecting with channel net, surface 

 trawl, or seine at nonscheduled sites throughout 

 the 9-mile study area (14.5 km). Collections were 

 obtained at nonscheduled sites after regular 

 sampling to better determine the distribution of 

 menhaden in the bay and above and below the 

 interface area. 



The smallest and largest fish of each species 

 in a sample were measured to the nearest mm TL 

 (total length). All menhaden in catches of less 

 than 100 and a subsample of 100 in larger catches 

 were measured. Size distribution of juveniles for 



