68 
Larval abundance of summer flounder 
( Paralichthys dentatus ) as a measure 
of recruitment and stock status 
Mark C. Sullivan 2 
Jonathan A. Hare 3 
Gretchen Bath-Martin 4 
J. Christopher Taylor 5 
Roland Hagan 1 
Email address for contact author: able@marine.rutgers.edu 
1 Marine Field Station 
Institute of Marine and Coastal Sciences 
Rutgers University 
800 c/o 132 Great Bay Boulevard 
Tuckerton, New Jersey 08087 
2 School of Natural Sciences and Mathematics 
The Richard Stockton College of New Jersey 
PO Box 195, Jimmie Leeds Road 
Pomona, New Jersey 08240 
3 Narragansett Laboratory 
Northeast Fisheries Science Center 
National Marine Fisheries Service, NOAA 
28 Tarzwell Drive 
Narragansett, Rhode Island 02882 
4 Beaufort Laboratory 
Southeast Fisheries Science Center 
National Marine Fisheries Service, NOAA 
101 Pivers Island Rd 
Beaufort, North Carolina 28516 
5 Center for Coastal Fisheries and Habitat 
Research 
National Centers for Coastal Ocean Science 
National Ocean Service, NOAA 
101 Pivers Island Rd 
Beaufort, North Carolina 28516 
Abstract — Summer flounder (Para- 
lichthys dentatus) is one of the most 
economically and ecologically impor- 
tant estuarine-dependent species in 
the northeastern United States. The 
status of the population is currently 
a topic of controversy. Our goal was 
to assess the potential of using larval 
abundance at ingress as another fish- 
ery independent measure of spawn- 
ing stock biomass or recruitment. 
Weekly long-term ichthyoplankton 
time series were analyzed from Little 
Egg Inlet, New Jersey (1989-2006) 
and Beaufort Inlet, North Carolina 
(1986-2004). Mean size-at-ingress 
and stage were similar between sites, 
whereas timing of ingress and abun- 
dance at ingress were not similar. 
Ingress primarily occurred during 
the fall at Little Egg Inlet and the 
winter at Beaufort Inlet. These find- 
ings agree with those from earlier 
studies in which at least two stocks 
(one north and one south of Cape Hat- 
teras) were identified with different 
spawning periods. Larval abundance 
at Little Egg Inlet has increased since 
the late 1990s and most individuals 
now enter the estuary earlier during 
the season of ingress. Abundance at 
Little Egg Inlet was correlated with 
an increase in spawning stock bio- 
mass, presumably because spawning 
by larger, more abundant fish during 
the late 1990s and early 2000s pro- 
vided increased larval supply, at least 
in some years. Larval abundance at 
ingress at Beaufort Inlet was not cor- 
related with spawning stock biomass 
or with larval abundance at ingress 
at Little Egg Inlet, further support- 
ing the hypothesis of at least two 
stocks. Larval abundance at Little 
Egg Inlet could be used as a fishery- 
independent index of spawning stock 
size north of Cape Hatteras in future 
stock assessments. Larval occurrence 
at Beaufort Inlet may provide infor- 
mation on the abundance of the stock 
south of Cape Hatteras, but additional 
stock assessment work is required. 
Manuscript submitted 1 October 2009. 
Manuscript accepted 5 October 2010. 
Fish. Bull. 109:68-78 (2011). 
The views and opinions expressed 
or implied in this article are those of the 
author (or authors) and do not necessarily 
reflect the position of the National Marine 
Fisheries Service, NOAA. 
Kenneth W. Able (contact author ) 1 
Summer flounder ( Paralichthys den- 
tatus) is one of the most economically 
important species in the northeast- 
ern United States because of the cen- 
tral role it plays in both commercial 
and recreational fisheries (Collette 
and Klein-McPhee, 2002). There was 
considerable concern over this spe- 
cies in the late 1980s when land- 
ings and spawning stock biomass 
declined precipitously (Kraus and 
Musick, 2001; Terceiro, 2002). In 
recent years, summer flounder has 
started to recover, but there is con- 
tinued controversy over the rate of 
recovery relative to established bench- 
marks and recruitment success based 
on recent stock assessments (NRC, 
2000; NEFSC 1 ). 
1 NEFSC(Northeast Fisheries Science 
Center). 2008. 47th northeast regional 
stock assessment workshop (47th SAW) 
assessment report. NMFS NEFSC Ref. 
Doc. 08— 12a, 335 p. NEFSC, Woods Hole, 
MA 
Two major issues contribute to 
this controversy. First, there are dif- 
fering opinions as to the number of 
stocks present off of the U.S. east 
coast. Summer flounder is managed 
as a unit from the southern border 
of North Carolina to the U.S. -Cana- 
da border (Terceiro, 2002) based on 
stock-definition research (Wilk et al., 
1980) and a population genetics study 
(Jones and Quattro, 1999). The as- 
sessment unit, from which catch and 
survey data are obtained, however, is 
an area from Cape Hatteras, North 
Carolina, to the U.S. -Canada border, 
consistent with a recent review of 
stock definition (Kraus and Musick, 
2001). A coastal North Carolina stock 
(extending from Cape Hatteras south- 
ward) has been hypothesized (Burke 
et al., 2000; Kraus and Musick, 2001), 
but this unit is not subject to a sepa- 
rate assessment (Terceiro, 2002). Sec- 
ond, recruitment processes in summer 
flounder are unclear, particularly the 
relationship between spawning stock 
