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Fishery Bulletin 108(4) 
Figure 2 
An example of the external attachment method that was used to secure the acoustic transmitters to winter 
flounder (Pseudopleuronectes americanus) to monitor their movements in the southern Gulf of Maine. The Vemco 
V92L transmitters were fitted into a harness of 9/16” soft latex tubing and secured in the harness with two-part 
epoxy (A). Two nickel tagging pins were passed upwards through the blind side of the fish, through the dorsal 
musculature (B). 
salinity in the estuary ranges from 0.0 to 33.0 (Iwano- 
wicz et al. 2 ). The bathymetry of the estuary is complex, 
and extensive sand and mud flats are exposed at low 
tide when the surface area of the estuary is reduced 
front 10,057 acres to 5465 acres (Iwanowicz et al. 2 ). 
A deeper channel is present between Saquish Head 
and Plymouth Beach, where depths reach nearly 26 m. 
There are four main sources of freshwater input to the 
Plymouth Estuary: the Back River, Bluefish River, Jones 
River, and Eel River. 
Acoustic telemetry 
Adult flounder were captured by using either a small 
otter trawl, a commercial trawl vessel, or by hook and 
line. Sampling was nonrandom, and sampling locations 
were chosen from areas where adult winter flounder 
have historically been abundant. Tow times with the 
small otter trawl varied from 10 to 30 minutes, and tows 
with the commercial vessel were 30 minutes in duration. 
The total length of each fish was measured to the near- 
est centimeter, and only adult fish (>27 cm) in good or 
excellent condition were fitted with acoustic tags. After 
tagging, fish were held onboard for observation until 
they were deemed healthy enough for release. All fish 
were released in close proximity to the capture site in 
order to minimize tagging-induced stress. 
In total, 72 adult winter flounder (27-48 cm) were 
fitted externally with acoustic transmitters (model 
V92L, 69 kHz, 9 mmx21 mm, Vemco Ltd., Halifax, 
NS, Canada) between November 2007 and May 2009. 
2 Iwanowicz, H. R., R. D. Anderson, and B. A. Ketschke. 1974. A 
study of the marine resources of Plymouth, Kingston and 
Duxbury Bay. Monograph Series Number 17, 37 p. Divi- 
sion of Marine Fisheries, Boston, MA. 
Each transmitter had an average pulse rate of 80 sec- 
onds (range = 40-120 seconds) and an expected battery 
life of 384 days. A novel external attachment method 
was developed for this study. Acoustic transmitters 
were secured into a harness of 9/16 inch (14.3 mm) 
soft latex tubing by using two-part epoxy (Fig. 2). Two 
nickel tagging pins were passed upwards from the blind 
side of the flounder through the dorsal musculature. 
The harness was then secured to the nickel pins on 
the eyed-side of the fish with plastic earring backings. 
The tagging procedure took an average of two to three 
minutes per fish. A laboratory holding study indicated 
100% transmitter retention and 100% survival over a 
seven-month period. A separate holding study conducted 
at the University of New Hampshire in 2009 indicated 
that the tag attachment method did not interfere with 
the swimming or spawning behavior of tagged fish (E. 
Fairchild, personal commun. 3 ). 
In November 2007, 24 prespawning winter flounder 
were tagged in Plymouth Bay, approximately 5 km from 
the mouth of the Plymouth Estuary (Fig. 1). Three 
of these winter flounder were observed to be gravid 
females at the time of release. Repeated efforts were 
made to capture spawning flounder within the estuary 
during March, April, and early May of 2008, but we 
were not able to capture adult fish until late May 2008. 
Twenty three adult winter flounder were tagged within 
the Plymouth Estuary between 24 May and 16 June 
2008 (Fig. 1). In the second year of the study, an addi- 
tional 25 winter flounder were tagged in Plymouth Bay 
between December 2008 and May 2009 (Fig. 1). Eight 
winter flounder tagged on 8 May 2009 were observed to 
be gravid females that were in spawning condition. 
3 Fairchild, Elizabeth. 2009. Department of Biological Sci- 
ences, Univ. New Hampshire, Durham, NH 03824. 
