167 
National Marine 
Fisheries Service 
NOAA 
Fishery Bulletin 
established in 1881 
Spencer F. Baird 
First U.S. Commissioner 
of Fisheries and founder 
of Fishery Bulletin 
Feeding habits and dietary owerlap of age-O 
winter flounder IPseud&pieuronectes 
americanm} and summer flounder iParalichthys 
dentatm} in southern New England tidal riwers 
David L. Taylor (contact author) 
Carissa L. Gervasi 
Email address for contact author: dtaylor@rwu.edu 
Department of Marine Biology 
Roger Williams University 
One Old Ferry Road 
Bristol, Rhode Island 02809 
Abstract— Age-0 winter flounder 
(Pseudopleuronectes americanus; 20- 
90 mm in total length [TL]) and sum¬ 
mer flounder (Paralichthys dentatus; 
19-172 mm TL) were collected from 
the Seekonk and Taunton Rivers (in 
Rhode Island and Massachusetts, 
respectively) from May through Sep¬ 
tember during 2009-2015, and stom¬ 
ach content analysis was used to as¬ 
sess diet composition and resource 
overlap for these species. Winter and 
summer flounder underwent ontoge¬ 
netic dietary shifts. Winter flounder 
<40 mm TL predominantly fed on co- 
pepods, transitioning to amphipods, 
isopods, and bivalves with increas¬ 
ing size. Polychaetes also were con¬ 
sumed frequently by winter flounder, 
irrespective of size. The principal 
prey of summer flounder <60 mm 
TL were mysid shrimp and cope- 
pods, whereas sand shrimp (Crangon 
septemspinosa), amphipods, and fish 
were the dominant prey of larger 
conspecifics. There was minimal di¬ 
etary overlap for the flounder spe¬ 
cies when comparisons were made 
independent of body size, indicating 
food niche segregation. For winter 
and summer flounder of equivalent 
sizes, however, dietary overlap was 
inversely related to TL. Moderate to 
high resource overlap occurred for 
small winter and summer flounder 
(<40 mm TL) and was attributed to 
their mutual reliance on copepods 
and amphipods. Despite evidence of 
dietary overlap, it is unlikely that 
shared prey resources were dimin¬ 
ished enough to negatively affect ei¬ 
ther flounder species. 
Manuscript submitted 7 June 2016. 
Manuscript accepted 20 December 2016. 
Fish. Bull. 115: 167-185 (2017). 
Online publication date: 2 February 2017. 
doi: 10.7755/FB.115.2.4 
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. 
The winter flounder {Pseudopleuro¬ 
nectes americanus) is a pleuronectid 
flatfish that inhabits northwest and 
mid-Atlantic waters from Nova Sco¬ 
tia southward to Maryland (Pereira 
et al., 1999). Winter flounder have 
traditionally supported valuable 
commercial and recreational fisheries 
within this geographic range, and, 
in the United States, this species is 
managed as 3 discrete stocks in the 
following areas: southern New Eng¬ 
land and Middle-Atlantic (SNE-MA), 
Gulf of Maine, and Georges Bank. 
There are ongoing concerns with re¬ 
spect to the SNE-MA stock complex 
because populations of winter floun¬ 
der have decreased precipitously 
since the early 1980s and have not 
rebounded over the last 3 decades 
(NEFSC^'2). Although overexploita¬ 
tion was paramount in their initial 
population decline (NEFSC^), other 
hypotheses have been purported to 
explain the failed recovery of winter 
1 NEFSC (Northeast Fisheries Science 
Center).2011. 52“'* Northeast regional 
stock assessment workshop (52"** SAW) 
assessment report. U.S. Dep. Commer., 
Northeast Fish. Sci. Cent. Ref. Doc. 11- 
17, 962 p. [Available from website.] 
2 NEFSC (Northeast Fisheries Science 
Center). 2015. Operational assess¬ 
ment of 20 Northeast groundfish stocks, 
updated through 2014. U.S. Dep. Com¬ 
mer., Northeast Fish. Sci. Cent. Ref. Doc. 
15-24, 251 p. [Available from website.] 
flounder in southern New England 
(e.g., the Narragansett Bay Estuary 
in Rhode Island and Massachusetts) 
(Collie et al., 2008). These hypothe¬ 
ses include a complex suite of abiotic 
(temperature) and biotic (predation 
and resource competition) factors 
that affect the survival of winter 
flounder during early development 
(Keller and Klein-MacPhee, 2000; 
DeLong et al., 2001; Taylor and Col¬ 
lie, 2003a, 2003b). 
Coastal populations of winter 
flounder spawn demersal eggs in¬ 
side estuaries during the winter and 
early spring (Pearcy, 1962). Larval 
winter flounder hatch 14-21 days af¬ 
ter spawning and are pelagic for -60 
days (Chambers and Leggett, 1987), 
after which they metamorphose into 
benthic juveniles during the late 
spring and early summer (Pearcy, 
1962). By virtue of adults spawning 
at cold temperatures (2-5°C), pelagic 
larvae benefit from reduced competi¬ 
tion with other species (Jeffries and 
Terceiro, 1985). After metamorpho¬ 
sis, however, inter- and intraspecific 
competition among juvenile winter 
flounder may be greatly enhanced 
(Karlson et al., 2007; Nissling et al., 
2007; Zloch and Sapota, 2010; Ustups 
et al., 2016). For example, juvenile 
winter flounder are often confined to 
specific depth ranges, have relatively 
low mobility, and possess more ob- 
