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Fishery Bulletin 117(4) 
Figure 3 
Maps showing the receiver locations and position estimates for 3 
tagged young-of-the-year smalltooth sawfish (Pristis pectinata ) 
when they interacted with the constructed oyster reefs in 2016 in 
the Peace River, Florida. Receivers shown were time synchronized to 
estimate positions of tagged sawfish based on the time that signals 
were received at each receiver. Each map presents position estimates 
during a short time segment for each sawfish: (A) sawfish 18, detected 
on 7 June from 0423 to 1359; (B) sawfish 16, detected on 5 July from 
0100 to 0803; and (C) sawfish 19, detected on 9 October from 0043 to 
0622 (sawfish ID numbers correspond to those in Table 1). The inset 
in the lower left corner shows the entire study area. 
conservation priorities when preserving the entire nurs¬ 
ery is not possible. Second, the nursery itself encompasses 
any hotspots, and the corridors between them, where 
young may remain for their first 2-3 years (Norton et al., 
2012). Third, for this species, juvenile critical habitat is 
purely a management designation required in the United 
States as part of the Endangered Species Act and encom¬ 
passes all nurseries and the non-nursery habitats that 
connect them. There are 2 large units of juvenile critical 
habitat for this species, 1 unit encompasses the Charlotte 
Harbor estuarine system, where this study was con¬ 
ducted, and the other includes the entire Ten Thousand 
Islands region and Everglades National Park (Norton 
et al., 2012). Other elasmobranchs are likely to have 
variations of these spatial scales and the life his¬ 
tory stages within them; therefore, adapting 
these ideas as results from future studies emerge 
would be expected. 
Within the Charlotte Harbor Estuary Unit of 
critical habitat for smalltooth sawfish, there are 2 
distinct nurseries in the Peace and Caloosahatchee 
Rivers (Norton et al., 2012; Feldheim et al., 2017). 
Within those sawfish nurseries, 5 hotspots have 
been identified (Poulakis et al., 2011, 2016). The 
Peace River has only one known hotspot, and its 
approximate boundaries, within the broader nurs¬ 
ery, have been refined through recent research 
(Huston et al., 2017). In our study, using rela¬ 
tively new technology, we further refined habi¬ 
tat use within the hotspot and identified sawfish 
behavior associated with the southern shoreline of 
the Peace River. Collectively, the results of these 
studies have already resulted in management 
decisions (NMFS 1 ) and have served to enhance 
our understanding of the early life history of this 
endangered species. This research has never been 
used to restrict previous nursery designations, as 
was recently suggested by Heupel et al. (2018). In 
fact, the concepts of nursery and nursery hotspot 
are complementary and help prioritize areas for 
management and conservation actions (Poulakis 
and Grubbs, 2019). Both of these concepts should 
be considered as more research is conducted on 
this and other elasmobranch species, especially 
if they occur in regions where substantial habitat 
loss could occur and data to support management 
and conservation actions may be required to sus¬ 
tain or recover populations. 
As in previous studies (Poulakis et al., 2016; 
Huston et al., 2017; Lear et al., 2019), diel behav¬ 
iors were observed in this study. In general, 
smalltooth sawfish resided along the northern 
shoreline of the Peace River in a protected cove 
during the day and ventured away from the cove 
and toward the southern shoreline at night. 
However, because of the increased accuracy of 
the time-synchronized array of acoustic receiv¬ 
ers, which provided continuous tracking data 
for this study, complete crossing of the river was 
documented for the first time with near-exact, autono¬ 
mously recorded GPS locations of the sawfish. Both size 
classes remained along the northern shoreline during 
the day, but individuals age 1 or older began to use the 
entire hotspot, including the southern shoreline, well 
before YOY, a difference that may relate to known onto¬ 
genetic changes in the areas where individuals are active 
and in the depths where they occur throughout the range 
of this species (Simpfendorfer et al., 2010; Poulakis et al., 
2011, 2013; Brame et al., 2019). 
Restoration projects have become necessary to promote 
recovery of oyster populations and to enhance accretion 
rates (Coen et al., 2007; Rodriguez et al., 2014). Juvenile 
smalltooth sawfish are known to frequent shallow 
