376 
Physical environment and recruitment 
variability of Atlantic herring, 
Clupea harengus, in the Gulf of Maine 
Mark A. Lazzari 
David K. Stevenson 
Stephen M. Ezzy 
Marine Resources Laboratory, Maine Department of Marine Resources 
RO. Box 8, West Boothbay Harbor, Maine 04575 
E-mail address: mrmlazz@state.me.us 
Recruitment is generally recog- 
nized as a complex ecological pro- 
cess determined by the interrela- 
tion of many biological and environ- 
mental variables and has always 
been one of the most difficult terms 
to estimate in fisheries science 
(Russell, 1931). Methods for fore- 
casting fisheries yields with time- 
series analyses (Saila et al., 1980; 
Mendelssohn, 1980), surplus pro- 
duction models (Schaaf et al., 
1975), and models employed to re- 
late recruitment to egg production 
(Koslow et al., 1987), larval abun- 
dance (Lett and Kohler, 1976; 
Lough et al., 1981; Smith, 1981), or 
spawning stock size (Sissenwine, 
1984) have had limited success. 
Factors dominating recruitment 
appear to operate on local scales 
(Cohen et al., 1991); changes in 
physical factors operating through 
marine food webs are a major force 
affecting the abundance of fish 
stocks (Mann, 1993). 
Clupea harengus , are an impor- 
tant component of the fisheries of 
the Northwest Atlantic and show 
great variability in recruitment. 
Spawning usually begins in the 
eastern part of the Gulf of Maine 
(Fig. 1) during August (Graham, 
1982; Stevenson et al., 1989) and 
over the Nova Scotian shelf (Mc- 
Kenzie, 1964), and occurs as late as 
November or December (Graham, 
1982; Lazzari and Stevenson, 1992). 
Eggs are deposited on the bottom 
(Boyar et al., 1973; Caddy and lies, 
1973; Stevenson and Knowles, 
1988) and hatch in one to two weeks 
depending on temperature. Larvae 
are transported to estuaries and 
embayments along the central and 
western Maine coast (Graham, 
1982; Graham and Townsend, 
1985) or remain offshore for the 
winter (Townsend, 1992). The 
planktonic larval stage lasts until 
spring when larvae undergo meta- 
morphosis into the juvenile form. 
Recruitment to the fishery occurs 
primarily in the following spring 
(at age 2) when juveniles reach a 
size appropriate for canning (150- 
200 mm). 
The recruitment success of her- 
ring may be associated with vari- 
ous physical environmental factors, 
including sea surface temperature 
(SST) (Sutcliffe et al., 1977; Cush- 
ing, 1982; Anthony and Fogarty, 
1985; Murawski, 1993), residual 
surface currents (Norcross and 
Shaw, 1984), winds (Corten 1 ; Chris- 
tensen et al. 2 ), or atmospheric-pres- 
sure gradients (Carruthers, 1938), 
or a combination of the last two. 
Theoretical models for predicting 
variations in juvenile herring pro- 
duction in the Gulf of Maine were 
developed by using sea surface tem- 
perature from the late-larval to 
early-juvenile period (Anthony and 
Fogarty, 1985), first quarter ( Janu- 
ary-March) sunshine (Ezzy, 1988), 
and by using either food supply and 
spawning distribution when year- 
class strength was established dur- 
ing the larval stage or predation for 
those years when year-class strength 
was established in the brit stage 
(Campbell and Graham, 1991). 
In addition, several hypotheses 
concerning wind events or larval 
dispersal may help us to under- 
stand herring recruitment in the 
Gulf of Maine. Ridgway (1975) pro- 
posed a conceptual model of recruit- 
ment variability based on changes 
in the dispersal of herring larvae 
by ocean currents from spawning 
areas to nursery areas. Water col- 
umn stability and its impact on the 
availability of food resources for 
larval fish at some critical life stage 
also has been proposed to affect re- 
cruitment (Lasker, 1975). Periodic 
winds that produce moderate tur- 
bulence may enhance larval sur- 
vival by increasing the probability 
of encounter between larvae and 
their prey (Sundby et al., 1989; 
MacKenzie et al., 1994). 
The purpose of this study was to 
associate physical environmental 
factors with size estimates of age-2 
herring of the coastal Atlantic her- 
ring stock in order to identify the 
important environmental factors 
underlying recruitment variablity 
and to examine the importance of 
the wind and dispersal hypotheses 
1 Corten, A. 1984. The recruitment fail- 
ure of herring in the central and northern 
North Sea in the years 1974-78 and the 
mid-1970s hydrographic anomaly. ICES 
Mini-Symposium. Council Meeting 1984/ 
Gen., 12 p. 
2 Christensen, V., M. Heath, T. Kiorboe, P. 
Munk, H. Paulsen, and K. Richard- 
son. 1985. Investigations on the rela- 
tionship of herring larvae, plankton pro- 
duction and hydrography at Aberdeen 
Bank, Buchan Area, September 1984. 
ICES Council Meeting 985/L, 23 p. 
Manuscript accepted 7 November 1996. 
Fishery Bulletin 95:376-385 (1997). 
