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ENDANGERED SPECIES RESEARCH
Endang Species Res
Vol. 41: 289– 302, 2020
https://doi.org/10.3354/esr01015 Published March 12
1. INTRODUCTION
Fish aggregating devices (FADs) have traditionally
been defined as structures floating at the surface of
the ocean placed by fishers to increase fishing oppor-
tunities and specifically attract and capture both
pelagic juvenile and adult fishes, such as tropical
tuna including skipjack Katsuwonus pelamis, yel-
lowfin Thunnus albacares and bigeye Thunnus obe-
sus (Castro et al. 2002, Dempster & Taquet 2004,
Fonteneau et al. 2013, Hall & Roman 2013, Moreno et
al. 2016a). These devices are used widely in tropical
and subtropical waters, mainly in countries from the
Pacific, Atlantic and Indian Oceans which are part of
the tuna Regional Fisheries Management Organiza-
tions (RFMOs), for recreational, artisanal, industrial
and commercial fisheries with the aim to concentrate
and capture pelagic fish (Dempster & Taquet 2004,
© The authors 2020. Open Access under Creative Commons by
Attribution Licence. Use, distribution and reproduction are un -
restricted. Authors and original publication must be credited.
Publisher: Inter-Research · www.int-res.com
*Corresponding author: j.alava@oceans.ubc.ca
Marine mammals used as bait for improvised fish
aggregating devices in marine waters of Ecuador,
eastern tropical Pacific
Cristina Castro1, Koen Van Waerebeek2, Diana Cárdenas1,3, Juan José Alava4,5,*
1Pacific Whale Foundation-Ecuador, Malecón Julio Izurieta, Puerto López, Manabí, Ecuador
2Peruvian Centre for Cetacean Research - Centro Peruano de Estudios Cetológicos (CEPEC), Pucusana, Lima 20, Perú
3Escuela Superior Politécnica del Litoral, ESPOL, Facultad de Ciencias de la Vida, Laboratorio para Investigaciones
Biomédicas, Campus Gustavo Galindo Km 30.5 Vía Perimetral, P.O. Box 09-01-5863, Guayaquil, Ecuador
4Fundación Ecuatoriana para el Estudio de Mamíferos Marinos (FEMM), Guayaquil, Ecuador
5Institute for the Oceans and Fisheries, University of British Columbia, 2202 Main Mall, Vancouver, BC V6T 1Z4, Canada
ABSTRACT: Fish aggregating devices (FADs) are floating objects typically used to attract and
capture pelagic fish in industrial tuna fisheries. This study documents 9 cases, involving 31 marine
mammals, of incidentally captured, killed or otherwise retrieved cetaceans and pinnipeds which
were used, or presumably used, as bait for improvised fish aggregation devices (IFAD) by arti-
sanal fishers in coastal Ecuador. At least 3 species of small cetaceans were affected, including
pantropical spotted dolphin Stenella attenuata, short-finned pilot whale Globicephala macro -
rhynchus, pygmy killer whale Feresa attenuata and an unidentified small delphinid, as well as
South American sea lions Otaria byronia which were reportedly killed on purpose for this fishing
practice. A sperm whale Physeter macrocephalus and a humpback whale Megaptera novaean-
gliae were presumably found floating at sea and opportunistically exploited as FADs. The South
American sea lion represented 80.6% of marine mammals used as bait associated with FADs (25
sea lions out of 31 marine mammals), while the remaining 5 (possibly 6) cetacean species repre-
sented 19.4%. This is the first report of baited FADs in Ecuador, the extent of which is still
unknown. This fishing technique has not been documented in other nations along the west coast
of South America, although baiting of gillnets with marine mammal parts is common in Peru.
Without fisheries management and regulation, this illegal fishing practice could rapidly expand
and lead to further direct kills and conservation problems for targeted marine mammal popula-
tions in the eastern tropical Pacific. A bottom-up fisheries policy in concert with community-based
conservation to ban the use of marine mammals as FAD bait is recommended.
KEY WORDS: Cetacean · Pinniped · Sea turtles · Bycatch · Bait · Conservation · Fisheries
management · South America · Pacific Ocean
O
PEN
PEN
A
CCESS
CCESS
Contribution to the Special ‘Marine vertebrate bycatch: problems and solutions’
Endang Species Res 41: 289– 302, 2020
Fonteneau et. al. 2013, Gershman et al. 2015, Murua
et al. 2016). FADs can be constructed from artificial
or natural materials by the fishers, or they simply
consist of a floating object (Castro et al. 2002, Demp-
ster & Taquet 2004, Moreno et al. 2016a,b). The inter-
national tropical tuna purse-seine fisheries fleet
maintains as many as 121000 drifting fish aggregat-
ing devices (dFADs) deployed by fishers in tropical
oceans worldwide (Gershman et al. 2015, Moreno et
al. 2016a). Other oceanic megafauna and epipelagic
marine species such as sharks, sea turtles, and mar-
ine mammals also aggregate around FADs (Brehmer
et al. 2012, Dagorn et al. 2013). The potential delete-
rious impacts of FADs due to high levels of bycatch
and threats to the marine biodiversity of tropical
pelagic ecosystems have been reviewed, highlight-
ing the need for additional fisheries management
actions and an improved management plan (Dagorn
et al. 2013, Gershman et al. 2015). In particular,
pelagic sharks, sea turtles, and other vulnerable mar-
ine species are entangled and killed in these FADs
(Filmalter et al. 2013, Hall & Roman 2013, Murua et
al. 2016). Massive mortality of silky sharks Carcha-
rhinus falciformis was reported on an annual basis in
the Indian Ocean, where approximately 480000
to 960000 silky sharks are killed each year when
caught in FADs (Filmalter et al. 2013).
Ecuador has the largest small-scale (artisanal) fleet
in the southeastern Pacific (Alava et al. 2015,
Martínez-Ortiz et al. 2015). According to the Secre-
tariat of Fisheries Resources (Subsecretaría de Recur-
sos Pesqueros [SRP]), there are 234 fishing communi-
ties, with a total of 19770 to 45000 artisanal boats and
between 63970 and 87280 small-scale fishers regis-
tered as members of the current fishing population in
Ecuador (Alava et al. 2015, 2019, Martínez-Ortiz et
al. 2015). The small-scale fisheries on the Ecuadorian
continental coast are represented by the artisanal
coastal fishery, which uses small boats to fish in
coastal areas, and the artisanal oceanic long-line
fishery, which operates in the open sea with the sup-
port of a larger ship (Martínez-Ortiz et al. 2015). Both
of them capture demersal and pelagic fish. The main
fishing gear presently used include trammel or sur-
face gillnets (‘trasmallo’) of 800 m long by 3 m high,
the 3200 m long cachema longline (‘espinel corvi -
nero’) with 800 hooks, the longline (‘palangre’) of 36
to 72 m, and the purse-seine net (‘red de cerco’) up to
1300 m long and 30 m deep. In Ecuador, the small-
scale fishing fleet uses mainly longlines and surface
gillnets (mesh sizes: 7.5 to 13 cm) to catch large
pelagic fish species, including dorado or dolphin-fish
Coryphaena hippurus, several tuna, billfish species
and sharks (Alava et al. 2015, 2019, Martínez-Ortiz et
al. 2015). However, while Ecuador is one of the top
countries using drifting FADs in the tropical tuna
purse seine industrial fleet (Gershman et al. 2015),
the use of FADs has not been officially reported or
implemented in small-scale or artisanal fisheries of
Ecuador.
The lethal interaction of small cetaceans with fish-
eries is widely recognized as one of the biggest global
conservation problems in recent decades (North-
ridge 1985, Reeves et al. 2003, Hucke-Gaete et al.
2004, Avila et al. 2018). In Ecuador, human activities
have severe direct and indirect im pacts on marine
mam mals, including deleterious fisheries interac-
tions (Félix & Samaniego 1994, Van Waerebeek et al.
1997, Alava et al. 2005a, 2012, 2019, Félix et al. 1997,
Castro & Rosero 2010, Jiménez et al. 2018), vessel
collisions with cetaceans (Van Waerebeek et al. 2007,
Félix & Van Waerebeek 2005, Félix et al. 1997), and
short-term impacts generated by whale-watching
tourism (Scheidat et al. 2004). Additionally, skin dis-
eases in marine mammals have been indirectly
linked to contaminants (Castro et al. 2008, Jiménez &
Alava 2014, Van Bressem et al. 2015).
In Ecuador, 3 types of fishing gear have been asso-
ciated with incidental captures of marine mammals:
(1) surface gillnets set mainly for pelagic fishes,
such as swordfish Xiphias gladius and billfishes
(Istio phor idae); (2) longlines of different lengths
also targeting pelagic fish; and (3) purse-seines tar -
get ing different tuna species such as yellowfin Thun -
nus albacares, bigeye, skipjack or barrilete but also
dorado, croakers (Sciaenidae, Cy nos cion spp.) (Alava
et al. 2012, 2019, Castro & Rosero 2010, Castro et al.
2018).
Prior studies have reported incidental capture rates
of dolphins by Ecuadorian fishermen in coastal
waters. Two catch rates with drift gillnets were esti-
mated in the early 1990s, ranging from 0.04 dolphins
per boat in Puerto Lopéz to 0.10 dolphins per boat for
Santa Rosa (Félix & Samaniego 1994). In the Gulf of
Guayaquil, a daily catch rate for bottlenose dolphins
Tursiops truncatus was estimated at 0.0064 dolphins
d−1, or 0.019 bottlenose dolphins per trip, but the con-
fidence intervals were very wide (Van Waerebeek et
al. 1997). The highest incidental catch rate was ob -
tained in August 2009 when 0.18 dolphins d−1 per
equivalent trip was estimated (Castro & Rosero
2010). However, there is no information about the
use of marine mammals for fishing purposes in
coastal Ecuador. At Puerto Bolívar (southern Ecua -
dor), one fisherman admitted harpooning a bottle-
nose dolphin near Puná Island, for bait in the longline
290
Castro et al.: Marine mammals as bait in FADs 291
fishery, while fishers operating in the Gulf of Guaya -
quil indicated they either discarded bycaught dead
dolphins at sea or, when possible, sold them for bait
to Peruvian fishermen (Van Waerebeek et al. 1997).
While industrial tuna fishing operation deploying
FADs at sea is known and managed by the Inter-
American Tropical Tuna Commission (IATTC) in the
eastern tropical Pacific (Murua et al. 2016, Gershman
et al. 2015), the emerging use of FADs with bycaught
or otherwise dead marine mammals as bait has only
recently been identified in small-scale fisheries of
Ecuador and previously reported in a working do -
cument to the International Whaling Commission
(Castro et al. 2018).
This study presents the first well-documented
records on the take and use of cetaceans and pin-
nipeds as fishing bait in continental Ecuador. The
purpose is to document and raise awareness about
the occurrence of these illicit, unregulated and un -
reported practices, suggest regulations, and pro-
mote the adoption of management efforts to im -
prove the protection of marine mammal populations
in Ecuador.
2. MATERIALS AND METHODS
The information presented here was obtained by
the Pacific Whale Foundation (PWF) with information
from tourists, park rangers, and fishers and compiled
as a database of stranding and bycatch records, ob -
servations through fish market monitoring as well as
interviews with crew members of commercial fishing
vessels and local fishermen. Strandings information,
both from own observations and interviews with
locals, was collected opportunistically in the course
of multiple unscheduled visits to fishing ports, sur-
rounding beaches and other coastal locations of con-
tinental Ecuador in the period 2009 to 2019 (Fig. 1,
Table 1). Although daily search effort data were not
logged, between June 2001 and March 2017 the car-
casses of 130 cetaceans belonging to 18 species were
documented in the PWF database as stranded on the
coasts of continental Ecuador (Castro & Van Waere-
beek 2019). Only stranding records where we
observed fishing gear, indications of baiting, cutting,
tethering or other evidence of human manipulation,
were taken into account in the present study. Cases 1
Fig. 1. Ecuador’s continental coast showing the fishing villages and ports (Cojimíes, Pedernales, Puerto Lopez, Salango and
Las Tunas) in Manabí Province, where cases of marine mammals used as bait and/or associated with improvised fish aggregating
devices (IFADs) were found from 2009 to 2019
Endang Species Res 41: 289– 302, 2020
292
Case Date Location No. of Species CC IUCN category Observations
(d.mo.yr) ind. (international/national)
CITES status
1 10.11.09 Between Cojimíes 17 South American 3−4 International: Carcasses associated with
and Pedernales sea lion (Otaria byronia) Least Concern ropes and buoys
(0° 22’ 4” N, 80° 2’ 7” W) National: N/A
2 10.11.09 Between Cojimíes 1 Sperm whale 3−4 International: Stranded carcass associated
and Pedernales (Physeter macro- Vulnerable with ropes and buoys;
(0° 22’ 4” N, 80° 2’ 7” W) cephalus) National: Vulnerable: 1 marine turtle found nearby
(Alava et al. 2011a)
CITES Appendix I
3 23.11.12 Puerto López 1 Spotted dolphin 4 International: Carcass and rope tied
(1° 33’ 60” S, (Stenella attenuata) Least Concern tailstock
80° 48’ 60” W) National: Vulnerable
(Alava et al. 2011b)
CITES Appendix II
4 11.08.14 Salango 1 Sea lion 3−4 International: Bloated animal floating with
(1° 35’ 0” S, 80° 51’ 0” W) (likely O. byronia) Least Concern holes and thin black rope
National: N/A tied to the body
5 15.06.16 Puerto López 1 Unidentified small 4 Carcass exhibiting skin with
(1° 33’ 60”S, 80° 48’ 60”W) delphinid cut marks
6 17.09.16 Puerto López 1 Pygmy killer whale 4 International: The animal had its head
(1° 33’ 60” S, 80° 48’ 60”W) (Feresa attenuata) Least Concern severed and missing tail
National:
Near Threatened
(Alava et al. 2011c)
CITES Appendix II
7 30.09.16 Cojimies 7 Sea lion 3−4 International: Skeletal remains and car-
(2° 20’ 0’’N, 80° 02’ 00’’W) (likely to be O. byronia) Least Concern casses entangled with nylon
National: N/A rope connected with weights
and buoys. Presence of float
tanks, purse seine or gillnet,
and wooden structure with
floats. Four more sea lions
were found nearby
8 30.09.16 Cojimies 1 Short-finned pilot whale 3−4 International: Carcass with both dorsal fin
(2° 20’ 0’’N, 80° 02’ 00’’W) (Globicephala macro- Least Concern and flukes missing;
rhynchus) National: presumably a shark bite and
Near Threatened other damage. Rope,
(Castro et al. 2011a) weights, and buoys, as part
CITES Appendix II of a FAD, were attached.
3 dead sea turtles were
found at the same location
9 28.07.19 Las Tunas 1 Immature humpback 4 International: Carcass washed ashore with
(1° 39’ 0” S, 80° 49’ 15” W) whale (Megaptera Least Concern shark bites but no other
novaeangliae) National: Vulnerable visible traumata; light nylon
(Castro et al. 2011b) line attached to the tailstock.
CITES Appendix I Presumably collected and
used by fishermen
Table 1. Documented cases of marine mammals utilized as bait with improvised Fish Aggregating Devices (IFADs) on the
Ecuadorian coast from 2009 to 2019. Carcass condition codes (CC) follow Geraci & Lounsbury (2005) —1: alive, 2: freshly dead, 3:
early decomposition, 4: advanced decomposition, 5: bare bones or mummified. Cases 2 and 9 are unconfirmed but highly probable
cases. Conservation categories of the IUCN were based on IUCN (2019) at the international level and on various contributions to the
Red Book of Ecuador’s mammals (Tirira 2011) for the IUCN national categories in Ecuador. The CITES status was retrieved from the
checklist of CITES Species (http://checklist.cites.org). N/A: not available
Castro et al.: Marine mammals as bait in FADs
and 2 are based on information received from the
Municipality of Pedernales, Manabí province (Fig. 1)
and examination of photos for these specific cases
(Table 1) available online (information published by
the newspaper El Diario 2009). Condition codes of
carcasses (CC) were determined according to Geraci
& Lounsbury (2005), briefly, as follows: 1: alive;
2: reshly dead; 3: early decomposition; 4: advanced
de composition; 5: bare bones or mummified.
A FAD is defined as a floating man-made object or
structure used to attract ocean going pelagic fish,
such as tuna, billfish, and dorado. They usually con-
sist of buoys or floats tethered to the ocean floor with
concrete blocks. Industrial fisheries utilize large, com-
mercially produced FADs made of metal and plastic
floats, so they can be used for long periods (Morgan
2011a, Moreno et al. 2016a); however, there is a
recent tendency to replace these fishing devices with
biodegradable materials such as bamboo, palm
leaves, coconut fiber, and cotton (Moreno et al. 2016b,
Murua et al. 2016). For instance, efforts to test and
implement biodegradable FADs are underway in
Ecuador (Tunacons 2019). Once deployed at sea,
they are rarely lifted out of the water.
3. RESULTS
3.1. Marine mammals as bait
We found that smaller, improvised FADs (IFADs) fab-
ricated and used by artisanal fishers (Fig. 2) were often
baited with marine mammal remains. Nine cases of
marine mammal strandings that had been used as bait
(2 suspected) were registered at 4 different locations
along the coast of Manabí Province, i.e. Cojimíes-Ped-
ernales, Puerto López, Salango and Las Tunas (i.e. from
1° 39’ 0’’S, 80° 49’ 15’’ W at Las Tunas to 0° 22’ 4’’N,
80° 2’ 7’’W at Cojimíes-Pedernales) from 2009 to 2019
(Table 1, Fig. 1), but with strandings survey effort since
2001. When found washed ashore or floating nearshore,
carcasses were either directly attached to a FAD or
wrapped in some assemblage of fish netting, lines,
and buoys, with clear indications that they had been
handled by people and were not simply the result of
accidental entanglement in fishing gear (Figs. 3−6).
In total, 31 individuals of 6 (potentially 7) different
marine mammal species were determined as used for
bait associated with a FAD. The species most fre-
quently encountered was South American sea lion
Otaria byronia, with a prevalence rate of 80.6% (i.e.
25 out of 31 individuals) relative to the total number
of carcasses observed (Figs. 3 & 5), but 3, potentially
4, species of Delphinidae were also found: 1 pan -
tropical spotted dolphin Stenella attenuata (Fig.
4A), 1 unidentified small delphinid (Fig. 4C,D), a
short-finned pilot whale Globicephala macro rhyn -
chus (Fig. 4E,F), and a pygmy killer whale Feresa
attenuata, accounting for 19.4% of the reported car-
casses identified as FAD bait (Table 1). Two large
ceta ceans, including an odontocete (sperm whale
Physeter macrocephalus) and mysticete (humpback
whale Megaptera novaeangliae), were probably
found floating at sea and may have been opportunis-
293
Fig. 2. Conceptual illustration of the improvised fish aggregating device (IFAD) found on Cojimíes Beach, Ecuador, on 9 No-
vember 2009. The IFAD is assembled as a rectangular or square wooden raft or platform made of bamboo or wood fully or par-
tially covered and wrapped with mesh netting and tied up with ropes along the perimeter of the raft; gillnets or other fishing
nets with floats (plastic containers or bins), containing dead bodies or remains of marine mammals as bait, are connected
through ropes to the 4 corners of the raft. Illustrator: Alejandra Loaiza
Endang Species Res 41: 289– 302, 2020
294
tically exploited as IFADs by artisanal fishers. This
may be a common practice considering that acciden-
tal entanglements and ship strikes of sperm and
humpback whales have been occurring frequently in
Ecuador for decades (e.g. Haase & Félix 1994, Alava
et al. 2005a, 2012, Félix et al. 1997, Castro & Van
Waerebeek 2019). On 2 occasions, more than 1 large
marine ver tebrate was found associated with IFAD
parts and gear on the same beach in Cojimíes, Man-
abi Prov ince (Table 1). The animals associated with
IFADs had washed ashore, or were found floating
nearshore, as shown in Figs. 3−5, with remains of
ropes, floats, and weights, which in some cases were
attached to a still intact IFAD (Figs. 4 & 5). Compar-
ing the total number of stranded, dead marine mam-
mals (i.e. 5 cetaceans and 25 sea lions) associated
with IFADs as bait (n = 30 individuals, excluding the
humpback whale reported in 2019; Table 1) to the
total number of marine mammal strandings (n = 168
individuals, including cetaceans and pinnipeds such
as O. byronia and Arctocephalus sp.) from 2001 to
2017 (Castro & Van Waerebeek 2019, PWF database
unpubl. data), it is roughly estimated that approxi-
mately 18% of stranded marine mammals were asso-
ciated with IFADs.
The carcasses were mainly in an advanced state
of decomposition (condition code, C.C. = 4), as most
had apparently been found some time after the
stranding occurred, their skin was sunburnt, and
many showed holes typically made by scavenging
ghost crabs (Ocypodidae) and black turkey vultures
Coragyps atratus, which are common on Ecuador’s
beaches. Also, some bare bones were found
wrapped in small-mesh netting tied to large floats
(Case 7; Fig. 5) where all soft tissues had already
been scavenged by fishes or other marine organ-
isms. Certain cases deserve further comments, as
follows.
Case 1. On 9 November 2009, the regional news -
paper 'El Diario' published an article on the strand-
ing of 17 sea lions, 1 sperm whale and 1 sea turtle
(unidentified species) on the beach between Coji -
míes and Pedernales, Manabí Province. Unfortu-
nately, the dead animals were in an advanced state of
decomposition and quickly buried without ne cropsy
or scientific analysis. This seems to be the earliest
reported stranding event related to the use of marine
mammals as FAD bait in Ecuador. The Municipality
of Pedernales first raised the notion that the cause of
those strandings was associated with the use of FADs
by fishers (El Diario 2009). Although >1 IFAD was
likely in volved, we continued treating this as a single
case.
Cases 7 & 8. Another multiple-species FAD stranding
consisting of 7 sea lions (probably South American sea
lions O. byronia) and a short-finned pilot whale, along-
side 3 unidentified sea turtles was registered in Co-
jimíes in September 2016 (Table 1). Five sea lions were
tied with thin ropes to the same structure, with weights
and floats; the 2 others were found detached along
the same beach (Fig. 5A− D). The ske -
letal remains of some sea lions were
wrapped in netting tied to a wooden
structure with floats and a tank
(Figs. 5E−G). The pilot whale had cuts
in the dorsal fin and tail, possibly where
it was tied to the structure or some
floating tank (Fig. 4E,F). Several com-
ponents used in IFADs were observed
as shown in Fig. 5C− G. The IFAD was
found on the beach attached to green
plastic flotation tanks (Fig. 5G). Black
gillnet-like netting holding the com-
plete carcasses of sea lions was found
attached at both sides (Fig. 5E). In one
net, only bare bones were found, sug-
gesting that perhaps this bait was in
place for an ex tended time (Fig. 5G).
The origin of the FAD is unknown, but
due to its size, it is likely that it was be-
ing used by a larger fishing boat before
it was lost or broke loose from its moor-
ings and then washed ashore.
Fig. 3. The decomposing body of a South American sea lion (Case 4) found
floating near Isla Salango on 11 August 2014. A nylon rope was tied (not en-
tangled) around the forebody and around the base of the pectoral fins. Photo:
Pacific Whale Foundation
Castro et al.: Marine mammals as bait in FADs
Case 9. The single wrap of a 7−8 mm nylon cord
around the tailstock of the subadult humpback
whale appeared to be a human intervention on a
carcass (Fig. 6A). A live whale of this size would have
readily snapped such a light line had it been an acci-
dental entanglement with fishing gear. However, this
cord is thought to have held a dead floating whale
tethered as a Type 1 FAD (see Section 3.2) to some
fishing gear. Local rangers (Machalilla National Park)
blamed the industrial fishery (pers. comm. to KVW);
however, no evidence puts the artisanal fishery be -
yond suspicion. The cause of death of the whale re -
mained unknown, but ventrally no signs of traumata
were visible except (most likely postmortem) shark
bites (Fig. 6B). Unfortunately, no necropsy could be
performed as the carcass was quickly buried on the
beach by a Municipality backhoe loader.
3.2. Improvised fish aggregating devices
Artisanal fishermen do not seem to invest in the
large commercially available FADs. Instead, they
make their own: far simpler and smaller versions
(Figs. 2 & 4E,F), which we refer to as improvised
fish aggregating devices (IFADs). We suggest that
most of the latter are baited with the remains of mar-
ine mammals or sea turtles, often involving several
295
Fig. 4. Carcasses and remains of cetacean species associated with and used as bait in improvised fish aggregating devices
(IFADs). (A) Pantropical spotted dolphin (Case 3) as found on a Puerto López beach, on 23 November 2012; (B) the dolphin had
green nylon rope firmly tied to its tailstock, and floats attached (not shown here). (C, D) Body and head of unidentified del-
phinid (Case 5) found stranded at Puerto López on 15 June 2016; the body showed cut marks and sunburn. (E) Anterior upper
jaw of juvenile short-finned pilot whale (Case 8) found at fishing port of Puerto López; (F) evident cut-marks on the short-
finned pilot whale indicated utilization, almost certainly for baiting FADs. Note bulbous head in dorsal view consistent
with G. macrorhynchus, which is also thought to be a bycatch victim. Photos: Pacific Whale Foundation
Endang Species Res 41: 289– 302, 2020
specimens simultaneously (see illustration in Fig.
2). Based on field observations and comments pro-
vided by fishers, we provisionally distinguish 3
types of IFADs found washed ashore, the difference
being the presence or absence of floats and the type
of construction and materials used.
Type 1. Marine mammal carcasses moored with
thin ropes by their pectoral fins, body or tailstock.
They are possibly moored to certain fishing gear, and
they remain floating by their own decomposition-
enhanced buoyancy, attracting fish. No floats are
present. This type of IFAD is used by artisanal fishers
296
Fig. 5. Carcasses and skeletal remains of sea lions (probably South American sea lions, Otaria byronia) used as bait in impro-
vised fish aggregating devices (IFADs) (Case 7). (A,B,C) Two of 7 sea lions (Case 7) found in association with IFADs on
Cojimíes beach on 30 September 2016. Note (A) a black rope wrapped around the body and (B) the presence of white nylon
rope doubly wrapped and knotted around the flippers (not accidentally entangled). (C) Floats were attached to the lines (white
arrow), and (D) lead weights were also present. At least 4 different colored lines were used. (E,F,G) The skeletal remains of 2
sea lions (E,G) were also attached to the IFADs with recognizable pinniped scapula, humerus, and ribs, wrapped in small-
mesh netting. (F,G) Note the assembled raft covered with black mesh tied up with blue and green ropes and a yellow float on
it. (G) A green plastic bin used as a float, tied to mesh netting with green ropes and attached to the raft was also found. Photos
A−D by Pacific Whale Foundation. Photos E, F, and G courtesy of Johana Moreira, Ministry of Environment of Ecuador
Castro et al.: Marine mammals as bait in FADs
(Figs. 3 & 4B). We suspect that floating dead whales
may be used in this way, such as the sperm and
humpback whales found stranded in Pedernales
and Las Tunas, respectively.
Type 2. Marine mammals wrapped in netting and
tied to plastic floats to increase and prolong buoy-
ancy. The nets are heavier and have weights and
floats with mooring lines. Possibly used by artisanal
fishermen, chinchorreros and others (Fig. 5A−C).
Type 3. Marine mammals wrapped in fishing nets
but at the same time tied to floats supporting larger,
mostly rectangular wooden and bamboo structures,
which can hold several bait-carcasses simultaneously
(Fig. 5E−G); possibly used also by larger, semi-indus-
trial fishing boats.
Although no observations have been made of
operating baited FADs at sea, they are thought to
function by attracting smaller marine organisms
including small fish to feed on the bait, which
then, in turn, may attract and concentrate larger
fish species (tuna, billfishes, and sharks). The latter
are easily encircled by purse-seines or taken by
other means (e.g. long-lines), as is done with com-
mercial FADs.
Interviews with artisanal fishers revealed that small
cetaceans are obtained from incidental captures in
fishing nets, while sea lions if still alive following net
entanglement were beaten to death. According to
some artisanal fishers, the use of marine mammals as
bait is carried out only by industrial tuna fisheries
and ‘chinchorreros’ (purse-seine) who take advan-
tage of the night to opportunistically fish for other
species such as dorado using FADs. The name in
Spanish for this kind of FAD is ‘plantado’ (Morgan
2011b). However, some interviews revealed that arti-
sanal fishermen were also using small cetaceans and
sea lions obtained opportunistically, referred to as
‘siembra’. Thus, the words ‘plantado’ and ‘siembra’
are synonyms, applied to industrial or artisanal fish-
ing, respectively.
Based on anecdotal information from fishers, the
use of dead marine mammals as bait in FADs is very
effective, due to their strong smell, high amount of fat
and long permanence in the water. An interviewed
fisher from Puerto López stated: ‘The best thing to
catch dorado fish is the fat of sea lions and dolphins,
with which [the FAD] is baited as these remains stay
intact for several days’.
4. DISCUSSION
Here we reported the first cases of cetaceans and
sea lions used as bait in IFADs in artisanal fisheries
in Ecuador. Several questions were raised by our
findings. The main concern is to what ex tent impro-
vised FADs are used by Ecuadorean artisanal fish-
eries and since when. Also, the incidence of baiting
IFADs, whether it is standard practice or only an
occasional one, remains unclear. As it stands, the
available evidence is insufficient to clarify if the
observed mixed-species arrangements were a coinci-
dence or were arranged by design. Conceivably, each
bait species may have different characteristics, e.g.
decompose at a different pace, preferentially attract
different marine organisms, or other.
In 2 cases (Cases 2 and 8), dead sea turtles were
also observed washed ashore in close association
with IFADs (Table 1), raising the question whether
they were also applied as bait. If so, these would be
the first reports that we know of. However, since
these marine reptiles are confirmed entanglement
victims of commercial FADs drifting in open waters
(Fonteneau et al. 2013), it is challenging to uncover
the causality of their presence in and around the
stranded IFADs described here. As accidental entan-
297
Fig. 6. (A) Carcass of a subadult humpback whale with a nylon cord around the tailstock found in Las Tunas beach on 28 July
2019. (B) Note the ventral view of the whale with tailstock showing evidence of shark scavenging. Photos: Pacific Whale Foun-
dation (A) & K. Van Waerebeek (B)
Endang Species Res 41: 289– 302, 2020
glements cannot be excluded, more field research
will be needed to provide the necessary answers.
Indeed, the issue is further confounded by insights
from other sea turtle stranding events along Ecuador’s
coast. Strandings of olive ridley Lepidochelys oli-
vacea and green sea turtles Chelonia mydas are
common on Ecuador’s beaches (see Alava et al.
2005b). Massive die-offs have also been documented
(Alava et al. 2005b, Herrera et al. 1999). These
stranding episodes were associated with environ-
mental/ natural factors (e.g. changes in sea surface
temperature, food availability, parasitic and other
diseases) and anthropogenic impacts, including fish-
eries interactions, mainly bycatch in gillnets and
longlines, and boat collisions (Herrera et al. 1999,
Alava 2000, Alava et al. 2005b). While the FADs used
by industrial fisheries in Ecuador have begun to be
managed and regulated by the IATTC (Gershman et
al. 2015, 2016, 2018, Murua et al. 2016), artisanal
fishers have re quested regulation from the Ecuado-
rian Government (Castro et al. 2018). There are indi-
cations that industrial fishers may also have started to
bait FADs to increase effectiveness, but this has not
been substantiated. It is reasonable to believe that
the lack of enforcement of relevant legislation, regu-
lation, and control regarding the use of FADs may
have allowed artisanal fishermen in Ecuador to start
using baited IFADs so as to improve their fishing
operations. It will be difficult to study the extent of
use and evaluate the impact of this activity consider-
ing that the IFADs are hard to visibly trace when
deployed at sea. Indeed, the few IFADs that were
documented had reached the shore and were
encountered by chance. A well-designed interview
study might shed some light on these aspects, but a
considerable degree of re sistance and some false
declarations should be expected.
Little is known of the potential use of baited FADs
in waters of neighboring countries and where this
practice first arose. There is no evidence, for in -
stance, that baited FADs are or have been deployed
off Peru, Chile, or Colombia. However, the use of
small cetaceans as bait in longline fisheries, espe-
cially for sharks, has long been widespread in Peru
(e.g. Van Waerebeek & Reyes 1994, Van Waerebeek
et al. 2002, Mangel et al. 2010) and was also docu-
mented in Pacific Colombia (Avila et al. 2008). More
recently, Peruvian gillnet fishermen have re sorted to
attaching butchered parts of small cetaceans directly
to wide-mesh multifilament gillnets to attract sharks,
rays, and other large fishes; in some ways these are
similar to a Type 1 improvised FAD, but structured
FAD devices with floats (Type 2 and 3) have so far not
been documented. In a survey of fishing operations
of some artisanal fishing boats in Salaverry in 2005 to
2007, Mangel et al. (2010) found that 29% of small
cetaceans by-caught in gillnets were used as bait.
Also, all harpooned dolphins, both by gillnet and
longline vessels, were used as bait (Mangel et al.
2010).
The direct hunting (harpooning) of bottlenose dol-
phins for trading of meat as bait in the Gulf of
Guayaquil has also been documented and anecdo-
tally reported by artisanal fishers and rangers, but
the current status of this practice has yet to be con-
certedly assessed in coastal Ecuador (Van Waere-
beek et al. 1997, Jiménez et al. 2018). Previous evi-
dence indicated that some fishers were eager to
pay up to USD $75 for a dolphin carcass to obtain
bait in a fishing community (i.e. Puerto López) on the
central coast of Ecuador during the 1990s (Félix &
Samaniego 1994). However, questions remain con-
cerning the presence of a systematic market to trade
bait collected from bycaught small cetaceans, and it
is likely that a small-scale black market took place on
the southern coast of Ecuador, i.e. Puerto Bolívar
(Félix & Samaniego 1994, Van Waerebeek et al.
1997), where at least one boat harpooned dolphins in
the past (Van Waerebeek et al. 1997); similarly, at
least one bottlenose dolphin was harpooned by fish-
ers close to Puna Island, Gulf of Guayaquil (Van
Waerebeek et al. 1997). As it stands, the use of a cast
net (a fishing gear locally known as ‘voladora’) by a
fisher from Posorja Harbor (Guayaquil Gulf) to
directly take bottlenose dolphins to trade their meat
in local markets was reported by rangers from the
Reserva Ecológica de Vida Silvestre Manglares El
Morro (El Morro Mangrove Wildlife Ecological
Reserve) in 2017 (Jiménez et al. 2018). The exact
purpose remains unclear, i.e. whether bycaught or
hunted marine mammals are being traded for their
use in FADs in Ecuador. Recent anecdotal informa-
tion, archived in a recorded interview of an artisanal
fisher working on a tuna fishing boat, corroborates
that this seems to be the case for South American sea
lions taken in Peruvian waters. Excerpts from the
interview are provided as follows:
‘Here, the ‘lobos marinos’ [sea lions] for ‘plantados’
[the FADs] are brought from Piura, or Pisco (Peru);
the sea lions are bought from small boats in Peru that
are dedicated to the dorado fisheries. There, they call
the dorado ‘perico’. Nowadays they buy the sea lions
during the ‘brisa’ fishing period; they purchase them
from the small vessels, then the sea lions are frozen
and stored to be used for the ‘plantados’. The ‘brisa’ is
a ‘cardumen’, a specific school of tuna fish that occur
298
Castro et al.: Marine mammals as bait in FADs
on these dates, from December to January… A sea
lion is cheap and costs between USD $ 70 to 100 each
one, which is a lot of money for the Peruvian fishers;
they buy between 40 to 50 sea lions, depending on
the amount of sea lions available for sale by the fish-
ers in the boats. The sea lions are not taken in
Ecuador as there are very few here and the species is
more regulated by the authorities; the sea lions are
from Peru where they are very abundant and not
regulated, except for the surveillance of the Peruvian
Navy… Between December and January until mid-
February, during the brisa period, the sea lions are
bought’ (J. M. confidential pers. comm. to C. Castro).
Although no evidence or assessment is presently
available regarding the use of FADs in artisanal fish-
ing operations in Ecuador, we suspect that both the
coastal gillnet fisheries and the large oceanic long-
line fisheries, targeting large pelagic fish such as
tuna, billfishes, and various shark species, may be
the main users of IFADs. This rationale is based on
the fact that the artisanal fisheries fleet usually oper-
ates within the 200 nautical miles (nm) of Ecuador’s
Economic Exclusive Zone (EEZ), including the coastal
multifilament gillnet fisheries and the oceanic arti-
sanal longline fisheries fleet (Alava et al. 2015,
Martínez-Ortiz et al. 2015). However, it is likely that
the artisanal fisheries fleet is currently expanding its
fishing operations beyond the 200 nm, specifically
the large oceanic artisanal longline fishery which is
unique to Ecuador and operates far offshore deploy-
ing a mothership with a fleet of small vessels (Alava
et al. 2015, Martínez-Ortiz et al. 2015). Assuming the
wide distribution of fishing zones and extension of
artisanal fishing fleet off Ecuador’s continental coast
as a proxy, we project that IFADs may also be used in
these fishing areas.
The overall scarcity of information begs for more
thorough fact-finding investigations that could then
serve as guidance to propose legislation that would
control or prohibit the use of marine mammals as
bait, search for alternatives and recommendations,
and establish exemplary sanctions. As it stands, the
deployment of FADs using marine mammals as bait
in Ecuador can have negative repercussions in the
face of new regulations established in 2017 under the
US Marine Mammal Protection Act (NMFS 2016),
commanding the implementation of a regulatory pro-
gram to monitor and mitigate marine mammals
bycatch in countries exporting seafood/fish to the
USA by 2022. Ecuador falls in this categoy as this
nation exports seafood to the USA but has not yet
implemented such a regulatory program (Jiménez et
al. 2018).
Since 2013, the IATTC, as the regional fisheries
management organization (RFMO) in the Eastern
Tropical Pacific, recommended the use of non-en -
tangling drifting FADs as a measure to mitigate the
entanglement and minimize deleterious damage to
susceptible marine fauna (Gershman et al. 2015,
Murua et al. 2016). Along with this measure, incen-
tives for marine observers and fishers should be
developed and fostered by local fisheries manage-
ment authorities, so as to record and retrieve aban-
doned, lost or discarded fishing gear, including de -
relict drifting FADs encountered at sea, and to
deliver the derelict fishing gear to port reception
facilities for recycling and disposal (Gilman 2015,
Gilman et al. 2016). The precautionary principle has
been emphasized as an approach to reduce, or at
least monitor and control, the use of dFADs to miti-
gate their adverse effects not only on yellowfin and
bigeye tuna stocks, sharks and sea turtles but also on
open-ocean ecosystems (Fonteneau et al. 2013). As
an option, the International Seafood Sustainability
Foundation has also recommended the use of non-
entangling biodegradable FADS, with minimal risk
of entanglement, constructed using only natural
and/or biodegradable materials (e.g. bamboo, sisal,
yute, palm leaves, coconut fiber, cotton) instead of
plastics and/or metals to further reduce and avoid the
environmental impact of marine pollution by drifting
FADs on the oceans (Murua et al. 2016, Moreno et al.
2016b). In October 2018, Ecuador’s Tuna Conserva-
tion Group launched a contest aimed at developing
bio degradable FADs (Eco-FADs) for industrial fish-
eries, especially tuna fishing in Ecuador to reduce
pollution (Tunacons 2019). Experiments by tuna pro-
cessing companies with certain bio degradable and
plant materials to test the designs are underway in
the country. Similar mitigation actions and incentives
should be promoted among small-scale (artisanal)
fishers by fisheries management authorities.
The issue of marine mammal-baited IFADs has
recently emerged as a threat to the conservation of
marine mammals in Ecuador and should be ad -
dressed. As estimated in this study, approximately a
fifth of dead marine mammals found stranded along
Ecuador’s beaches were associated with IFADs over
the period 2001 to 2017. If not addressed, within a
short period of time, illicit directed takes of both
cetaceans and pinnipeds could increase dramatically
and lead to severe conservation problems for
Ecuador’s marine mammal populations. Commu-
nity-based conservation including an open, bottom-
up dialogue is required urgently between Ecuador’s
artisanal fishing communities and fisheries manage-
299
Endang Species Res 41: 289– 302, 2020
ment actors assisted by experts. These should pro-
vide insights into the pervasiveness of IFAD use and
the origin of marine mammal-sourced bait, as well as
test and evaluate alternative bait (e.g. low-cost
frozen abattoir remains considered unfit for con-
sumption) and fully biodegradable IFAD materials.
Finally, these approaches can serve as potential
recommendations to deter and help pre vent the use
of marine mammals as bait.
Acknowledgements. This work is dedicated to the
memory of the late Gregory Kaufman, who was a great
colleague and devoted researcher from the Pacific Whale
Foundation. We thank the volunteers of the Pacific Whale
Foundation and park rangers, especially Johana Moreira
and Ruben Aleman, for their tenacity and dedication in
obtaining data. Ben Haase is acknowledged for confirming
Otaria byronia as the most frequent pinniped in Ecuador’s
continental waters, and Julio C. Reyes for providing a
helpful taxonomic opinion about some problematic photo-
graphs. Special thanks to Gregory Kaufman for providing
valuable insights and edits to an earlier version of this
manuscript. Alejandra Loaiza C. is thanked for preparing
the FAD illustration.
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Editorial responsibility: Bryan P. Wallace,
Fort Collins, CO, USA
Submitted: September 3, 2019; Accepted: November 25, 2019
Proofs received from author(s): March 3, 2020
