DeCelles and Cadrin: Movement patterns of Pseudopleuronectes americanus in the southern Gulf of Maine 
415 
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Figure 5 
Weekly averaged bottom water temperatures observed between November 
2007 and July 2009. Water temperature was recorded every 30 minutes at 
four locations during the study: Plymouth Bay; the mouth of the Plymouth 
Estuary; Kingston Bay (western portion of Plymouth Estuary); and Duxbury 
Bay (northern portion of Plymouth Estuary). 
O 
2008 
Figure 6 
The relationship between water temperature and the emigration of tagged 
winter flounder (Pseudopleuronectes americanus ) from the Plymouth Estu- 
ary in 2008. Winter flounder emigrated rapidly from the Plymouth Estuary 
as water temperatures increased from 10° to 15°C at the beginning of the 
summer. 
researchers (W. Hoffman, personal 
commun. 4 ), documenting more sub- 
stantial movements beyond the 
study area. One tagged winter floun- 
der (tag 5837) moved from the Gulf 
of Maine stock area to the SNE-MA 
stock area and was detected east of 
Cape Cod on 26 August 2008 (Table 
1). This individual was tagged in 
Plymouth Bay on 30 November 2007 
and was never detected in our re- 
ceiver array. Tag 53877 was detected 
throughout our array in 2009 and 
was later detected in Massachusetts 
Bay on 26 August 2009 (Table 1). 
Receiver efficiency 
Despite the loss of some receivers, it 
appears that the array was efficient 
for the detection of the migrations 
of winter flounder. Twenty eight 
winter flounder released during the 
first year of the study were later 
detected in the estuary. Each fish 
was detected in the estuary an aver- 
age of 416 times (range = l-3227 
detections) at an average rate of 1.9 
detections/day at liberty. Seventeen 
of the 24 winter flounder released in 
Plymouth Bay were never detected 
inside the estuary. These 24 winter 
flounder were released outside the 
receiver array that was used in the 
first year (Fig. 1); therefore, if these 
fish remained in coastal waters they 
would not have been detected by our 
array. Twenty two of the 25 winter 
flounder released in the second year 
of the study were later detected in 
our array. On average, each tagged 
winter flounder was detected 2861 
times (range 57-23,842 detections) 
at an average rate of 14.1 detec- 
tions/day at liberty. Winter flounder 
tagged on 8 May 2009, were released 
slightly eastward of the receiver 
array (Fig. 1), and this location may 
explain why two of these tagged fish 
were never detected again. 
In the fall of 2008, receivers I and M were lost from 
the inner gate of receivers that spanned the mouth of 
the estuary. After these receivers were lost, two tagged 
winter flounder (tags 5833 and 5873) were detected in- 
side the estuary at the end of September and October, 
respectively, without being detected at the inner gate of 
receivers. One flounder (tag 5855) was released inside 
4 Hoffman, William. 2009. Massachusetts Division of Marine 
Fisheries, Gloucester, MA 01930. 
the estuary on 24 May 2008, and was detected two days 
later at receiver D. However, this individual was never 
detected at another receiver during the study. The fate 
of this fish is unknown. It may have been captured in 
the recreational fishery, eaten by another animal, or 
died after having been tagged. This was the only win- 
ter flounder that was released and detected inside the 
estuary (tag 5855) that was never detected at the inner 
gate. In the second year of the study, only one tagged 
winter flounder (tag 53894) that was detected inside 
