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Fishery Bulletin 117(4) 
Figure 1 
Map showing the locations of acoustic receivers in the Peace River, Florida, used to monitor move¬ 
ments of smalltooth sawfish (Pristis pectinata) from May through October 2016. Additional receiv¬ 
ers were maintained outside the map area. The rectangle along the southern shoreline identifies 
receivers that composed the Vemco Positioning System (VPS) near the constructed oyster reefs 
where sawfish resided at night (for the location of oyster reefs, see Figure 3). The rectangle along 
the northern shoreline encompasses the protected cove where sawfish resided during the day. The 
dashed box outline is the approximate boundary of the nursery hotspot. The inset shows the position 
of the (1) nursery hotspot (same area indicated by the dashed box outline in main map) within the 
(2) overall nursery in upper Charlotte Harbor (Norton et al., 2012) and the (3) Charlotte Harbor 
Estuary Unit of the critical habitat for juvenile smalltooth sawfish (Norton et al., 2012). Note that 
only estuarine waters are included in juvenile critical habitat and that the sawfish nursery in the 
Caloosahatchee River is not identified. 
Acoustic tags were prepared in the laboratory for exter¬ 
nal attachment prior to field sampling by using a cable tie 
covered with an epoxy gel to attach the acoustic tag to the 
flat half of a plastic dorsal fin tag (Rototag Identification 
Tag, 35 mm long by 9 mm wide, Dalton ID Systems Ltd., 
Henley-on-Thames, UK). Tags were applied to the thicker 
anterior margin of the second dorsal fin: a leather punch 
was used to make a hole for the projecting half of the Roto¬ 
tag, and then the 2 halves were attached (e.g., Whitty 
et al., 2009; Poulakis et al., 2013). 
Acoustic monitoring 
A total of 37 moored, single-frequency, omnidirectional 
VR2W or VR2Tx acoustic receivers (Vemco) were main¬ 
tained in northern Charlotte Harbor, including in the 
Peace River, to monitor tagged smalltooth sawfish (Fig. 1; 
Huston et al., 2017; Scharer et al., 2017). When the signal 
of a tagged sawfish was detected by a receiver (maximum 
and mean detection ranges: 800 m and 450 m, respec¬ 
tively; Collins et al., 2008), date, time, and tag number 
were recorded. Data were downloaded from all receivers, 
and accumulated biofouling was removed every other 
month. 
Positioning system 
To accurately estimate positions of tagged smalltooth 
sawfish (hereafter referred to as position estimates ) along 
the southern shoreline of the Peace River, with respect to 
the constructed oyster reefs, 3 VR2Tx acoustic receivers, 
6 VR2W receivers, and 2 spatial reference tags were used 
to form a Vemco Positioning System (VPS; Fig. 1). These 
receivers were time synchronized to estimate positions 
of tagged sawfish on the basis of the times signals were 
received at each receiver (Ozgiil et al., 2015). The 6 VR2W 
