74 
Fishery Bulletin 109(1) 
(2001). Further, the examination of larval ingress im- 
mediately north (Oregon Inlet) and south (Beaufort In- 
let) of Cape Hatteras indicates that this change occurs 
as a distinct step and not a smooth gradient (Burke et 
ah, 2000). 
To further resolve the identification of summer floun- 
der stocks, it is necessary to understand population 
connectivity (e.g., larval dispersal, juvenile and adult 
movements) and associated vital rates (e.g., growth, 
mortality, recruitment) throughout their distribution 
range (Begg and Waldman, 1999; Hare, 2005). To com- 
plicate matters, Nye et al. (2009) documented changes 
in the latitude and depth of adult summer flounder 
from the late-1960s to the present, and these changes 
raise the possibility that stock boundaries are shifting 
over time. Identifying stocks and understanding their 
dynamic distribution remains a major issue for the 
management of U.S. east coast fisheries. 
The ability to define the relationship between larval 
supply at ingress relative to spawning stock biomass 
and recruitment may be influenced by the scale of the 
different measures. Larval supply at ingress is mea- 
sured at local inlets and it is assumed that they are 
representative of the separate stocks north and south of 
Cape Hatteras. This interpretation is supported by the 
Jul 
Jun - 
May- 
Apr - 
Mar- 
Feb- 
Jan . 
Dec_ 
Nov_ 
Oct _ 
A 
Little Egg Inlet, NJ 
~i — i — i — i — r~ 
Jul ' 
Jun ■ 
May ■ 
Apr - 
Mar - 
Feb- 
Jan 
Dec 
Nov - 
Oct 
B 
Beaufort Inlet, NC 
• . A *• • • •• 
•V* # • * • 
1986 
1990 
1994 
1998 
2002 
2006 
Year 
Figure 5 
Approximate months when 50% of summer floun- 
der (Paralichthys dentatus) larvae had entered (A) 
Little Egg Inlet, New Jersey, and (B) Beaufort Inlet, 
North Carolina, for a given year. 
available literature. The measures of spawning stock 
biomass and recruitment used here were calculated for 
the portion of the population north of Cape Hatteras. 
Larval abundance at ingress and spawning stock biomass 
The long-term patterns of larval abundance at Little 
Egg Inlet and spawning stock biomass north of Cape 
Hatteras indicate that spawning and larval abundance 
at ingress are linked, presumably because increased 
spawning by larger, more abundant fish during the 
late 1990s and early 2000s resulted in increased larval 
abundance and survival and ultimately increased larval 
supply. Although the positive correlation may be biased 
by a few high values, we hypothesize that high spawn- 
ing stock biomass is responsible for this increase in 
larval abundance at ingress. If a mechanistic link 
exists between these two data sets, data at ingress from 
Little Egg Inlet can be used as a fishery-independent 
index of spawning stock biomass for the “northern 
stock” of summer flounder. The lack of a relationship 
between spawning stock biomass and Beaufort Inlet 
larval abundance at ingress is not surprising because 
larvae entering Beaufort Inlet may be the result of a 
spawning event from a separate stock (see previous 
discussion). In a recent multispecies analysis of the 
Beaufort Inlet ichthyoplankton community, Taylor et 
al. (2009) concluded that the larval ingress from spe- 
cies spawning predominantly north of Cape Hatteras, 
including summer flounder, was not related to juve- 
nile abundance in the Pamlico Sound system, but that 
ingress and juvenile abundance were related for spe- 
cies spawning predominantly south of Cape Hatteras. 
They proposed that larval supply to Pamlico Sound by 
northern spawning species is predominantly through 
inlets north of Cape Hatteras. The Beaufort Inlet site 
is south of Cape Hatteras. 
One alternative explanation for the relationship be- 
tween spawning stock biomass and larval ingress is 
that general warming trends in the Mid-Atlantic Bight 
region (Nye et al., 2009) may be contributing to an 
increased availability of summer flounder larvae to 
Little Egg Inlet. Hare and Able (2007) suggested for 
another common estuarine dependent species (Atlantic 
croaker [Micropogonias undulatus ]) that warmer water 
temperatures are allowing juveniles to survive critical 
developmental periods. Thus, there are multiple hypoth- 
eses to explain the concomitant increase in spawning 
stock biomass and abundance at ingress into Little Egg 
Inlet and these hypotheses should be explored. In the 
meantime, abundance at ingress into Little Egg Inlet 
can be used as a fishery-independent index of spawning 
stock biomass. 
Recruitment 
Many studies have shown that larval fish supply influ- 
ences subsequent recruitment to adult populations 
(Powell and Steele, 1995; Myers and Barrowman, 1996; 
Hamer and Jenkins, 1996; Leggett and Frank, 1997; 
