FISHERY BULLETIN: VOL. 75, NO. 4 



39°20' 



DELAWARE BAY 

 0_l_2_3 



NAUTICAL MILES 



7 5° 30' 7 6°20 



3 8°50' 



FIGURE 1. — Delaware Bay with sampling sectors shaded. 



Delaware Bay was sampled on four occasions in 

 1966 by measuring all (1,060) fish caught by a 

 14-m trawler using both a 15-m (50- ft) otter trawl, 

 body — 7.6-cm (3-in) stretch mesh, cod end — 5.1 cm 

 (2 in), and a 16-m (52-ft) otter trawl, body— 10.2 

 cm (4 in), cod end — 7.6 cm (3 in). This vessel was 

 typical of the few commercial boats operating in 

 the bay then, and 1966 was the last year trawling 

 was permitted. 



GENERAL OBSERVATIONS 



Summer flounder seem to have a ubiquitous 

 range in Delaware Bay. They were caught in all 

 sectors sampled; and in water with temperatures 

 from 1.6° to 26.8°C, salinities from 10.6 to 31.8%o, 

 and depths from the shore to 25 m. Most (95% ) fish 

 were caught from May through September. A few 

 juvenile fish were taken in every winter month, 

 indicating that some juveniles move to deeper 

 parts of the estuary during the winter rather than 

 offshore. Poole (1966) suggested a similar 

 phenomenon for estuaries in North Carolina. 



During the 5-yr survey, the yearly mean 

 number of summer flounder caught per nautical 

 mile of trawling (number offish caught per year 

 divided by the total length of tows containing 



summer flounder) varied from 1.5 to 4.7, with no 

 significant trend. No real difference was apparent 

 in the number (34 day versus 29 night) of flounder 

 caught between day and night tows. 



AGE AND GROWTH ANALYSIS 



Otoliths were used for aging fish because they 

 were much easier to read than scales, and both 

 Poole (1961) and Eldridge (1962) found them suit- 

 able for aging. Left and right otoliths were 

 examined, and we found the radial length (dis- 

 tance from the center of the core to the anterior tip) 

 was different between left and right ones from the 

 same fish. This occurred because the center area or 

 core (Figure 2) was located more posteriorly in the 

 right otolith. We did not compare left and right 

 otoliths to see if the relationship between radial 

 length and the various annuli lengths were the 

 same for both. 



Left otoliths were removed from all flounder 

 (either fresh or previously frozen) caught in 



8 

 6 



CORE 



FIGURE 2. — Left otolith from an age-group 8 summer flounder, 

 total length 69 cm, with estimated age indicated against respec- 

 tive annuli (rule marking in millimeters). 



824 



