342 



Fishery Bulletin 91(2), 1993 



£" 



<2 weeks 



fc. ---"I 



5 to 8 weeks 



2 to 5 weeks 



k^ 



&- 



>8 weeks 



Figure 4 



Composite representation of the distribution of Atlantic herring Clupea harengus larvae by age in the Georges Bank area, 1976-84. 



and Cape Cod bays. As during the 1971-75 interval, 

 larvae partitioned by age exhibited the influence of 

 transport, especially in 1981 and 1982 when distribu- 

 tion patterns expanded from Massachusetts Bay to 

 Nantucket Shoals. Averaging catches over a 9yr 

 period did not mask the effects of larval transport dur- 

 ing the 1981 and 1982 spawning seasons (Fig. 4). 



Further change marked the ensuing 3yr period 

 (1985-87), providing the first evidence that the her- 

 ring population in the study area was beginning to 

 recover. Spawning beds on Nantucket Shoals were re- 

 activated in 1985, and the center of larval abundance 

 shifted from Massachusetts Bay to Nantucket Shoals 

 (Fig. 5). The influences of advective processes on the 

 distribution of larvae were evident within a month 

 after hatching. Nantucket Shoals larvae 2-5 wk old 

 were transported by the Georges Bank gyre eastward 

 across the northern part of the bank as far as the 68° 

 meridian. The distribution pattern of 5-8 wk old lar- 

 vae resembled that of 2-5 wk old fish, but exhibited 

 the influence of further drift away from the Nantucket 

 Shoals spawning beds. Larvae >8 wk old were caught 

 in Massachusetts Bay and from Nantucket Shoals east- 



ward onto Georges Bank. As in the 1976-84 period, no 

 recently-hatched larvae occurred over the traditional 

 spawning beds on eastern Georges Bank through 1987 

 (Fig. 5). 



The reoccupation of spawning beds on the western 

 half of Georges Bank and the increasing abundance of 

 larvae on Nantucket Shoals during 1988-90 provided 

 further signals of the changing status of herring in the 

 study area (Fig. 6). Although the principal spawning 

 grounds remained on Nantucket Shoals, the appear- 

 ance of recently-hatched larvae on Georges and Culti- 

 vator shoals in all 3yr provided the first evidence in a 

 decade of spawning east of the 68° meridian on Georges 

 Bank. Within 5 wk of hatching, larvae were dispersed 

 over all but the eastern tip of the bank. By the time 

 larvae reached 8 wk of age, they occurred throughout 

 the study area (Fig. 6). As with the reactivation of 

 Nantucket Shoals spawning beds in 1985, 3yr lapsed 

 from the time we first observed larval transport onto 

 Georges Bank until we found evidence of spawning on 

 the bank. Although the recovery of herring in the 

 Georges Bank region was clearly underway during the 

 closing years of the 1980s, we found no evidence in 



