FISHERY BULLETIN: VOL. 86, NO. 2 



0.4 0.6 0.8 10 12 



LOG^O FORK LENGTH (cm) 



Figure 9. — Relation between log fork length (X) and number of otolith rings (7) for YOY 

 bluefish from Great South Bay, NY. The regression equations are 7 = 132.308X - 29.890 

 (n = 88) for 1985 and y = 95.532A: + 1.186 (n = 81) in 1986. 



teens, we no longer captured YOY bluefish. Oben 

 (1957) noted that in the Black Sea, YOY bluefish 

 appeared in the shore zone at temperatures of 

 18°-24.5°C, and left the shore zone in October and 

 November when temperatures dropped to 13°- 

 15°C. 



Length-frequency distributions of YOY blue- 

 fish from the south shore samples showed only a 

 single mode that attained progressively larger 

 size through the summer and fall, and corre- 

 sponded to the initial recruitment offish. If multi- 

 ple spawning and recruitment events contributed 

 YOY bluefish to Long Island, multimodal length- 

 frequency distributions should have been ob- 

 served. The unimodal distributions suggested 

 that only one spawning period contributed the 

 majority of YOY bluefish to Long Island. 



Interannual variation in the length-age rela- 

 tionship of YOY bluefish was observed. Although 

 recruitment occurred two weeks earlier in 1985 

 than in 1986, the empirical mean lengths at re- 

 cruitment were similar (Fig. 4). Postrecruitment 

 growth, however, was slower in 1985 than 1986 so 

 that empirical mean lengths became similar by 

 mid-July. Correspondingly, the slope of the 

 length-age regressions differed significantly 

 among years: YOY bluefish at an age of about 

 50-70 days had greater fork lengths in 1985 than 



in 1986 (Fig. 9), but the reverse was true among 

 older, larger fish. Apparently, the growth rate of 

 YOY bluefish prior to recruitment was higher in 

 1985 than 1986, but this pattern among the two 

 years was reversed during the period of postre- 

 cruitment growth. 



Validation of Daily Otolith Rings 



Our experimental results demonstrate that 

 otolith ring deposition is daily in YOY bluefish. A 

 regression slope of 0.971 indicates a one-to-one 

 correspondence between number of days after in- 

 jection and the number of rings beyond the tetra- 

 cycline mark. This outcome is not particularly 

 surprising because numerous studies have shown 

 that increment production is daily, particularly 

 in the early life history when somatic growth is 

 rapid (Brothers et al. 1976; Campana and Neilson 

 1985; Jones 1985). Cases where ring periodicity is 

 reportedly less-than-daily have involved subopti- 

 mal growing conditions (Geffen 1982, 1987; Rice 

 et al. 1985). In our study, the confinement of YOY 

 bluefish in a field cage apparently had little effect 

 on growth rate, or the production of daily growth 

 increments. The field cage allowed for natural 

 light, temperature, and salinity variations that 

 the fish would normally have experienced in na- 



246 



