Using a Partial Sum Method and GPS Tracking Data to Identify Area Restricted Search by Artisanal Fishers at Moored Fish Aggregating Devices in the Commonwealth of Dominica Page: 3
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.1PLO S ONE Identifying ARS at FADs Using GPS Tracking Data
who fished. Fishing at Desa Ikan is classically artisanal and small-scale [31]. Boats are small
(4m-8m in length), constructed with wood or wood reinforced with fiberglass, and powered
with two-stroke outboard motors that range from 15hp to 85hp motors (mode = 48hp). Modal
crew size is two, and ranges from one to three persons. Trips are diurnal, rarely last more than
12 hours or travel more than 50km from shore. There is no export market in Dominica. Fish
are sold locally, in nearby communities, or occasionally transported 45km by road to Roseau,
the capital.
As a group, the fishers target a variety of both demersal and pelagic fish. Strategies at Desa
Ikan vary with season across three general strategies. Near-shore, shallow-water, bank fishing
with hook and line and traps for demersals such as snapper (Lutjanus spp.) is practiced year-
around. Most fishers take part in the late winter-spring 'channel' fishing season which involves
hunting for schools of dolphinfish (Coryphaena hippurus) and other pelagics and capturing
them with hook and line in the deep water off the banks. Finally, with the introduction of
FADs around 1999, a number of the fishermen have been able to target large coastal and migra-
tory pelagic fish, particularly tuna (Thunnus spp.), marlin (Makaira spp.) and dolphinfish [32].
The deep water FADs deployed from Desa Ikan are anchored to the ocean floor with halved
55 gallon drums filled with concrete (Fig. 1; see also [33]). A length of polypropylene rope joins
the anchor to the FAD's head at the surface which usually consists of a number of round floats
in addition to the FAD's attraction. To prevent twisting, metal swivels are placed at key connec-
tion points. Attraction usually consists of tarps and nets attached to both the mainline near the
surface and the head of the FAD. The FADs that are the focus of this research are placed in
water between 1000m-2500m deep at distances of 15-50km from shore and are referred here
to as deep water FADs to contrast them with the shallow water FADs that are placed close to
shore and primarily target barracudas (Sphyraena spp).
Materials and Methods
Ethics Statement
This study was approved by Texas A&M University's Office of Research Compliance Internal
Review Board (Study Number: IRB2009-0209) and the Commonwealth of Dominica Fisheries
Division (Research License RP-05/129 FIS-3). Texas A&M Institutional Review Board ap-
proved the use of oral consent obtained from fishers and boat owner under the criteria listed
by the U. S. Code of Federal Regulations section 45 CFR 46.117. Our experience suggested that
asking for signed consent in the context of ethnographic research, like that done in Dominica,
puts significant strain on the research-subject relationship. It is likely that the research could
not have been carried out without the waiver, as suspicion of our motives would have increased
significantly. Subjects were completely informed concerning the nature of the research with the
clear option of declining.
Sample
During the data collection period, 505 fishing trips were observed leaving and returning to the
landing site at Desa Ikan. We placed GPS devices aboard the boats and collected movement
data from a sample of 351 of these trips [33]. For 25 of these trips, along with the GPS data,
ground truth data were simultaneously collected during time-synchronized focal follows where
one of us joined the crew and recorded behavioral data during the course of the trip. Twenty-
three trips involved trips to FADs. One set of notes was lost overboard leaving a sample of
N = 22 FAD focal follows. A variety of data were collected during these focal follows, but ger-
mane to this analysis, the observer noted when the boat was at a FAD. The analysis here is lim-ited primarily to the 22 focal follows trips that included trips to FADs.
PLOS ONE I DOI:10.1371/journal.pone.0115552 February 3, 2015
3 /23
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Alvard, Michael; Carlson, David & McGaffey, Ethan. Using a Partial Sum Method and GPS Tracking Data to Identify Area Restricted Search by Artisanal Fishers at Moored Fish Aggregating Devices in the Commonwealth of Dominica, article, February 3, 2015; San Francisco, California. (https://digital.library.unt.edu/ark:/67531/metadc980839/m1/3/: accessed April 25, 2024), University of North Texas Libraries, UNT Digital Library, https://digital.library.unt.edu; crediting UNT College of Arts and Sciences.