NYMAN and CONOVER: YOUNG-OF-THE-YEAR BLUEFISH 



b. '°'- 



^ 26 

 o 



o 



a. 22 



liJ 



18 



< 14 

 10, 



J- 



^ 20|- 



UJ 



UJ 



en 16 



iZ 12 



3 



a 



(3) 

 45.3 



J 



(9) 



"(12) (8) (10(3) 

 OOP 



— I r 



(3) 



(10) 



(10) 



(10) 



(10) 



(13) 



(7) 



(e)(4) 



MAY 



JUNE 



1 r 



JULY AUG SEPT OCT 



Figure 2. — Continued — on each sampling date, (a) 1985; 

 (b) 1986. Number of seine hauls is in (). 



Back-Calculated Date of 

 First Ring Deposition 



A representative sample of 169 YOY bluefish 

 (n - 88 from 1985, n = 81 from 1986) captured in 

 Great South Bay were aged by counting the total 

 number of otolith rings. The date of first ring 

 deposition for each aged fish was then calculated 

 based on the date of capture. In both 1985 and 

 1986, the dates of first ring deposition for YOY 

 bluefish were predominantly in March and April 

 (Fig. 8a, b). 



Four fish from each of the two apparent length 

 modes in the 30 July collection from the Hudson 

 River (Fig. 6) were aged to determine if these 

 represented a difference in spawning season. The 

 fish examined were 7.8—13.8 cm in size, and back- 

 calculated dates of first ring deposition extended 

 from 7 to 30 April. Hence, these fish could all be 



attributed to the same spring spawning period as 

 those from the south shore of Long Island. 



However, YOY bluefish from the smaller (10- 

 14 cm) size class caught on 23 September in the 

 Hudson River (Fig. 6) were also aged and their 

 back-calculated dates of first ring deposition were 

 found to be predominantly in June and July, and 

 to a lesser extent in May (Fig. 8c). These dates 

 differed greatly from those offish captured earlier 

 in the year in the Hudson River, and along the 

 south shore of Long Island. 



The relationship of ring number and fork 

 length for each year was best described by the 

 following equations: Y = 132.308X - 29.890 in 

 1985 and Y = 95.532X + 1.186 in 1986, where X 

 is log fork length and Y is the number of rings 

 (Fig. 9). The slopes of these regressions differed 

 significantly (ANCOVA, P < 0.001). Total otolith 

 length and fork length were highly correlated 

 (r > 0.99) and increased isometrically. Total 

 otolith length and ring number also had a high 

 correlation (r = 0.91). 



241 



