344 



Fishery Bulletin 91(2). 1993 



<2 weeks 



5 to B weeks 



■€■ 



Figure 6 



Composite representation of the distribution of Atlantic herring Clupea harengus larvae by age in the Georges Bank area, 1988-90. 



status. Cushing (1986) also took exception to the re- 

 tention hypothesis as applied by lies & Sinclair (1982) 

 to the North Sea area. Cushing ( 1986) noted that her- 

 ring do not always spawn in transition zones around 

 the British Isles and, where they do, the fronts brake 

 down within a month after hatching. He further dis- 

 missed the retention concept by demonstrating that 

 postlarval metamorphosis takes place near the nurs- 

 ery grounds after prolonged larval drift. 



Our analysis of the 20 yr larval time-series supports 

 that segment of the literature showing herring larvae 

 vulnerable to advection after hatching (e.g., Cushing 

 1986, Bartsch et al. 1989, Heath & Walker 1987). Al- 

 though transport in our dataset is not extensive, it is 

 not restricted to the retention areas described by 

 Sinclair & lies (1985). Larvae drift from Massachu- 

 setts Bay southward to Nantucket Shoals, and the an- 

 ticyclonic gyre on Georges Bank mixes larvae originat- 

 ing there with those spawned on the shoals. The 

 direction of transport generally corresponds with re- 

 ported circulation, a pattern consistent with that of 

 Parrish et al. (1981). Mixing of larvae from the three 

 subareas occurs within weeks after hatching, or ear- 



lier in the life cycle than proposed by Sinclair & 

 Tremblay ( 1984) and Sinclair & lies (1985). 



Drift trajectories of herring larvae from other stud- 

 ies in the Gulf of Maine region agree with our findings 

 in that they correspond to dominant circulation pat- 

 terns described by Ingham (1982) and Butman & 

 Beardsley (1987). Graham et al. (1972) and Graham 

 (1982) recognized that some herring larvae spawned 

 off eastern Maine drifted westward to mix with larvae 

 originating in central and western Maine waters. 

 Townsend et al. (1986) provided further evidence that 

 herring larvae off Maine are advected from east to 

 west. Although Chenoweth et al. (1989) noted that re- 

 sidual currents do not demonstrate a persistent flow 

 in any direction off eastern Maine, they too observed a 

 westward displacement of herring larvae. Finally, Boyar 

 et al. (1973a) showed herring larvae spawned on 

 Jeffreys Ledge, another of the retention areas of 

 Sinclair & lies (1985), drifting into Massachusetts Bay 

 where they could mix with larvae originating on and 

 around Stellwagen Bank. Given these reports of drift 

 and mixing in western Gulf of Maine waters near our 

 study area and the demonstrated dispersion and 



