FISHERY BULLETIN: VOL. 74, NO. 2 



Figure 2. — Sardinellaanchovia,Decapteruspunctatus, and Scomber japonicus, in a mixed school, under Stage II ofTPanama City, Fla. 



or spring. Estimates of abundance during the 

 spring, summer-fall, and winter observations 

 (Tables 1,2) indicate that most species disappear 

 from the area of the stages during the winter 

 months, then gradually reappear during the 

 spring and summer. They apparently either move 

 offshore to deeper water, or else they migrate 

 southward along the Florida coast (see Hastings 

 1972). This decrease in number of species (as well 

 as number of individuals) occurred at both stages, 

 but was most profound at Stage II, where temper- 

 ature extremes were greater. About 509^ of the 

 number of species recorded at Stage I were pres- 

 ent in December and January, but at Stage II, 

 67% were present in December and only 15% in 

 February. These seasonal changes were most 

 striking in the schooling clupeids and carangids 

 (such as H. pensacolae, Sardinella anchovia, and 

 D. punctatus) which were extremely numerous 

 during the summer and fall, but usually rare or 

 absent in January or February (although Decap- 

 terus was common at Stage II during February). 



Habitat Occupation and 

 Activity Patterns 



The usual habitat occupied by each species in 

 the vicinity of the platforms is indicated in Tables 

 1 and 2. Station counts for some species at Stage 

 II, indicating diel changes in activity and occur- 

 rence at the stage, are shown in Table 3. 



The pelagic species which congregate about the 

 stages normally occupied the upper water col- 

 umn, either surrounding or below the platform. 

 The clupeids, H. pensacolae and S. anchovia, 

 formed dense schools below the platform, usually 

 near the surface but with Sardinella usually 

 somewhat deeper. The carangids, D. punctatus 

 and Trachurus lathami, were also quite numer- 

 ous, Decapturus normally in mid-water or near 

 the surface and Trachurus very near the bottom. 

 At times, these and other schooling species of 

 comparable size, such as Opisthonema oglinum 

 and Scomber japonicus, formed mixed schools 

 under the platform (Figure 2). These species 



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