408 
Abstract — Despite its recreational 
and commercial importance, the move- 
ment patterns and spawning habitats 
of winter flounder (Pseudopleuronectes 
americanus) in the Gulf of Maine 
are poorly understood. To address 
these uncertainties, 72 adult winter 
flounder (27-48 cm) were fitted with 
acoustic transmitters and tracked by 
passive telemetry in the southern Gulf 
of Maine between 2007 and 2009. Two 
sympatric contingents of adult winter 
flounder were observed, which exhib- 
ited divergent spawning migrations. 
One contingent remained in coastal 
waters during the spawning season, 
while a smaller contingent of winter 
flounder was observed migrating to 
estuarine habitats. Estuarine resi- 
dence times were highly variable, and 
ranged from 2 to 91 days (mean = 28 
days). Flounder were nearly absent 
from the estuary during the fall 
and winter months and were most 
abundant in the estuary from late 
spring to early summer. The observed 
seasonal movements appeared to be 
strongly related to water temperature. 
This is the first study to investigate 
the seasonal distribution, migra- 
tion, and spawning behavior of adult 
winter flounder in the Gulf of Maine 
by using passive acoustic telemetry. 
This approach offered valuable insight 
into the life history of this species in 
nearshore and estuarine habitats and 
improved the information available for 
the conservation and management of 
this species. 
Manuscript submitted 4 February 2010. 
Manuscript accepted 30 June 2010. 
Fish. Bull. 108:408-419 (2010). 
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. 
Movement patterns of winter flounder 
(Pseudopleuronectes americanus ) 
in the southern Gulf of Maine: observations 
with the use of passive acoustic telemetry 
Gregory R. DeCelles (contact author) 
Steven X. Cadrin 
Email address for contact author: gdecelles@umassd.edu 
National Oceanic and Atmospheric Administration 
and University of Massachusetts Cooperative Marine Education and Research Program 
School for Marine Science and Technology 
200 Mill Rd„ Suite 325 
Fairhaven, Massachusetts 02719 
Winter flounder ( Pseudopleuronectes 
americanus) is a commercially and 
recreationally important flatfish spe- 
cies that is distributed along the east 
coast of North America from North 
Carolina northward to Newfoundland 
(Bigelow and Schroeder, 1953). Within 
U.S. waters, this species is managed 
as three stock units: the southern New 
England and Mid-Atlantic (SNE-MA); 
Gulf of Maine; and Georges Bank. To 
date, there has been less research on 
the Gulf of Maine stock than on the 
SNE-MA stock. Seasonal distribution 
patterns of winter flounder in the Gulf 
of Maine have emerged from fisheries 
catch data (McCracken, 1963), mark 
recapture experiments (Perlmutter, 
1947; Howe and Coates, 1975) and 
annual trawl surveys. However, these 
sources of data offer limited insight 
into patterns of estuarine residence 
and nearshore habitat use for winter 
flounder because trawl fisheries and 
research surveys in the Gulf of Maine 
are typically limited to coastal and 
offshore waters. In addition, these tra- 
ditional sampling sources for obtain- 
ing distribution data cannot identify 
individual variability in movement 
or spawning behavior. In the present 
study, we sought to investigate spawn- 
ing patterns and seasonal distribu- 
tion of winter flounder in nearshore 
and estuarine waters in the southern 
Gulf of Maine using passive acoustic 
telemetry. 
The magnitude of variability in in- 
dividual migration patterns remains 
poorly understood for even the most 
economically valuable fish species 
(Able and Grothues, 2007), in part 
because we have yet to recognize the 
importance of contingent behavior. 
Contingents are cohesive groups of 
fish within a population that ex- 
hibit a common migration pattern 
(Cadrin and Secor, 2009). Acoustic 
telemetry offers new opportunities to 
investigate the fine-scale movements 
and behavior of individual fish. This 
technology allows for the recognition 
of contingent groups within popula- 
tions (Secor, 1999) and offers insight 
into the amount of connectivity be- 
tween estuarine and coastal popula- 
tions (Able, 2005). Acoustic telem- 
etry has been used to gather high 
resolution data on the behavior of 
juvenile winter flounder in the Gulf 
of Maine (Fairchild et al., 2009). 
However, before the present study, 
this technology had not been used 
to study adult winter flounder in the 
Gulf of Maine. 
Traditionally, winter flounder 
spawning in the Gulf of Maine was 
thought to be restricted to estuarine 
habitats (Bigelow and Schroeder, 
1953). This assumption was subse- 
quently reflected in designations of 
Essential Fish Habitat (EFH) for 
this species (NMFS, 1999). How- 
ever, other observations indicate 
that winter flounder in the Gulf of 
Maine also use coastal waters as 
spawning grounds (i.e., Howe and 
Coates, 1975). If a proportion of in- 
