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A field effort to capture critically endangered vaquitas Phocoena sinus for protection from entanglement in illegal gillnets


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In 2017 an emergency field effort was undertaken in an attempt to prevent the extinction of the world's most endangered marine mammal, the vaquita Phocoena sinus. The rescue effort involved 90 experts from 9 countries and cost US$ 5 million. Following a long decline due to entanglement in legal gillnet fisheries, the vaquita population had fallen from more than 200 to fewer than 30 individuals from 2008 to 2016, due to entanglement in an illegal gillnet fishery that supplies swim bladders of the endangered totoaba Totoaba macdonaldi to Chinese black markets. An emergency ban of gillnets and increased enforcement failed to slow the decline, triggering an emergency effort to catch vaquitas and place them under protection in captivity. Two animals were targeted and captured using light gill nets; a juvenile was released 4 h later because it appeared stressed, and an adult female died of capture myopathy. The program was suspended because of the risk of additional mortalities to the population. The lack of success in capturing vaquitas for temporary protection emphasizes the need to improve our understanding of the effects of chase, capture, handling and enclosure on cetaceans, and to consider intervention before populations reach critically low levels, when there is sufficient time to use phased, precautionary approaches. Furthermore, conservation approaches focused on single species must be integrated into broader efforts to conserve ecosystems and involve the human communities that depend on them.
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Endang Species Res
Vol. 38: 11–27, 2019 Published January 11
Here we describe ‘VaquitaCPR’ (CPR: conservation,
protection, recovery), a project intended to save the
vaquita Phocoena sinus from extinction by temporarily
removing individuals from adverse in situ conditions
and placing them into emergency care. The vaquita,
first described in 1958 (Norris & McFarland 1958), is a
species of porpoise endemic to the Upper Gulf of Cali-
fornia, México. Since its discovery, the population has
declined at an increasing rate: estimated population
size was 567 in 1997, 245 in 2008, 60 in 2015, and 30 in
2016 (Thomas et al. 2017). Between 1997 and 2008 the
population decline of 7−8% yr−1 was primarily due to
© The authors, and outside the USA, the US Government 2019.
Open Access under Creative Commons by Attribution Licence.
Use, distribution and reproduction are un restricted. Authors and
original publication must be credited.
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A field effort to capture critically endangered
vaquitas Phocoena sinus for protection from
entanglement in illegal gillnets
L. Rojas-Bracho1, F. M. D. Gulland2,*, C. R. Smith3, B. Taylor4, R. S. Wells5,
P. O. Thomas6, B. Bauer3, M. P. Heide-Jørgensen7, J. Teilmann8, R. Dietz8,
J. D. Balle8, M. V. Jensen8, M. H. S. Sinding7, A. Jaramillo-Legorreta9, G. Abel3,
A. J. Read10, A. J. Westgate11, K. Colegrove12, F. Gomez3, K. Martz3, R. Rebolledo3,
S. Ridgway3,13, T. Rowles14, C. E. van Elk15, J. Boehm2, G. Cardenas-Hinojosa9,21,
R. Constandse16, E. Nieto-Garcia9, W. Phillips16, D. Sabio17, R. Sanchez16,
J. Sweeney18, F. Townsend19, J. Vivanco20, J. C. Vivanco20, S. Walker3
1Comisión Nacional de Áreas Naturales Protegidas/SEMARNAT, Ensenada, BC 22860, Mexico
2The Marine Mammal Center, Sausalito, CA 94965, USA
Addresses for other authors are given in the Supplement at www. int-res. com/ articles/ suppl/ n038p011 _ supp. pdf
ABSTRACT: In 2017 an emergency field effort was undertaken in an attempt to prevent the extinc-
tion of the world’s most endangered marine mammal, the vaquita Phocoena sinus. The rescue
effort involved 90 experts from 9 countries and cost US$ 5 million. Following a long decline due to
entanglement in legal gillnet fisheries, the vaquita population had fallen from more than 200 to
fewer than 30 individuals from 2008 to 2016, due to entanglement in an illegal gillnet fishery that
supplies swim bladders of the endangered totoaba Totoaba macdonaldi to Chinese black markets.
An emergency ban of gillnets and increased enforcement failed to slow the decline, triggering an
emergency effort to catch vaquitas and place them under protection in captivity. Two animals were
targeted and captured using light gill nets; a juvenile was released 4 h later because it appeared
stressed, and an adult female died of capture myopathy. The program was suspended because of
the risk of additional mortalities to the population. The lack of success in capturing vaquitas for
temporary protection emphasizes the need to improve our understanding of the effects of chase,
capture, handling and enclosure on cetaceans, and to consider intervention before populations
reach critically low levels, when there is sufficient time to use phased, precautionary approaches.
Furthermore, conservation approaches focused on single species must be integrated into broader
efforts to conserve ecosystems and involve the human communities that depend on them.
KEY WORDS: Vaquita · Cetacean conservation · Porpoise · Capture myopathy · Ex situ
Endang Species Res 38: 11–27, 2019
mortality in gillnets set for shrimp and finfish (Rojas-
Bracho & Reeves 2013). From 2011 to 2016, the rate of
decline increased to 39% yr−1 due to entanglement in
illegal gillnets set for totoaba Totoaba macdonaldi.
This illegal fishery was driven by the lucrative black
market for swim bladders of the endangered totoaba
in Hong Kong and China, which enabled fishers to re-
ceive up to US$ 20 000 kg−1 of swim bladder, and as
much as US$ 116 000 in 1 day (Crosta & Sutherland
2017). The increase in the black market for totoaba
swim bladders is relatively recent and has had dra-
matic effects on vaquitas, although mortality of
vaquitas in gillnets set for totoaba is not a new phe-
nomenon. In the 1960s, vaquitas were described as
difficult to find and the population was believed to be
in decline, due to entanglement in the totoaba gillnet
fishery, with mortalities on the order of 10−100
vaquitas yr−1 (Norris & Prescott 1961, Brownell 1976).
Despite closure of the fishery in 1975, Vidal (1995) re-
ported that at least 65% of 128 dead
vaquitas found between 1985 and
1992 had died in totoaba gillnets.
The International Committee for
the Recovery of Vaquita (CIRVA)
was established in 1997 to advise the
Government of México (GoM) on
conservation actions for vaquitas.
For 20 yr CIRVA has recommended
reducing vaquita bycatch to zero by
eliminating gillnets and developing
alternative fisheries and socio-eco-
nomic alternatives for affected fish-
ers. In addition, CIRVA recom-
mended increased enforcement and
population monitoring using passive
acoustics (CIRVA Reports 2−10,
IUCN Cetacean Specialist Group
webpage at To
reduce vaquita entanglement in
legal fisheries for shrimp and fin-
fish, a vaquita refuge was estab-
lished in 2005 in which gillnets
were prohibited. Approximately half
of the vaquitas detected in 2008
visual and acoustic surveys were
found in the refuge area, which was
partially enforced from 2008 on -
wards (Fig. 1). A variety of other con-
servation measures were imple-
mented by the GoM (CIRVA-9 2017).
An improved passive acoustic
monitoring program was established
in 2011 to quantify anticipated posi-
tive results of these conservation measures. Instead,
in 2014 the acoustic program revealed a catastrophic
vaquita population decline. This prompted a tempo-
rary 2-yr ban of most gillnet fisheries in 2015, which
was made permanent in 2017 (Rojas-Bracho &
Reeves 2013, International Whaling Commission
2018). During this period, affected fishers were com-
pensated, the Mexican Navy assumed the responsi-
bility of enforcing the measures, and work on the
development of alternative fishing methods was
accelerated. Despite these actions, the exorbitant
revenues derived from totoaba swim bladders incen-
tivized continued illegal gillnet fishing, and the pop-
ulation decline continued unabated (Jaramillo-
Legorreta et al. 2017, Thomas et al. 2017). In a single
totoaba fishing season, between December 2016 and
May 2017, 150 illegal totoaba nets (large mesh gill-
nets designed to catch totoaba) were retrieved from
the vaquitas’ range (CIRVA-9 2017). After consider-
Fig. 1. Upper Gulf of California including the vaquita refuge partially enforced
from 2008 and onwards with signatures on the passive acoustic monitoring sta-
tions (C-PODs) and observations and capture sites from the operation from 13
October to 4 November 2017. Ex situ facilities were situated at Machorro Cove
and El Nido. Days: number of whole days (24 h) sampled. Enc.: acoustic
encounter rate. The dashed line indicates the vaquita refuge area
Rojas-Bracho et al.: Vaquita porpoise capture effort
ing these developments, in 2017 CIRVA concluded
that ‘the only hope for the survival of the species in
the short term is to capture vaquitas and bring them
into human care’ (CIRVA-9 2017, p. 4). This report
recognized that ‘the risks of capture and captive
management are high, but these are greatly out-
weighed by the risk of entanglement in illegal gill-
nets in the wild.’
Ex situ conservation strategies, such as temporary
housing for protection and captive breeding for rein-
troduction, can be useful tools to prevent extinction,
although there are concerns over the value of such
efforts (Price 1986, Martin et al. 2012, Ralls & Ballou
2013). Captive breeding with subsequent release
into the wild has not been used in prior conservation
efforts with small cetaceans, despite captive breed-
ing success with some related species (e.g. harbor
porpoise Phocoena phocoena, Yangtze finless por-
poise Neophocaena asiaeorientalis asiaeorientalis,
bottlenose dolphins Tursiops truncatus and T. adun-
cus; Wang et al. 2009, 2015, Curry et al. 2013). This is
due in part to the difficulty with initial acclimation of
some cetacean species to human care (e.g. Dall’s por-
poises Phocoenoides dalli, Irrawaddy dolphins
Orcaella brevirostris; Reeves & Mead 1999, Curry et
al. 2013); the limited success of breeding some spe-
cies of cetaceans in captivity; controversy over the
utility of the action, and philosophical opposition to
keeping cetaceans in captivity (Curry et al. 2013,
Butterworth 2017). A major concern in proposing to
establish ex situ populations is that these efforts may
detract from vital in situ efforts by seeming to provide
alternative options for management authorities, or
using funds that could be better directed to enhanc-
ing in situ actions (Bowkett 2009). Short-term ex situ
methods, without captive propagation, have been
applied to other marine mammals, with the translo-
cation and/or release of individuals temporarily
removed from the wild. For example, human inter-
vention has led to increased survival of endangered
Hawaiian monk seals Neomonachus schauinslandi,
with as much as a third of the population benefitting
from such efforts (Harting et al. 2014, Norris et al.
2017). One major challenge with implementing an ex
situ approach with the vaquita is that experience
with releasing cetaceans from human care is mini-
mal. A recent review emphasized the challenges of
capture, maintenance, and captive reproduction of
poorly known small cetaceans: there is a significant
body of knowledge with more commonly housed
cetaceans such as bottlenose dolphins, but there is
much less experience with other species (Curry et al.
2013). Bottlenose dolphins have been released after
years, or even birth, in captivity, with mixed success
(Gales & Waples 1993, Wells et al. 1998, 2013). In
2004, international experts recommended transloca-
tion of the few remaining baiji Lipotes vexillifer to an
established semi-natural reserve, but by the time the
effort was initiated, the species had been lost
(Braulik et al. 2005).
Over the past decade, techniques for the capture,
transport, rehabilitation and release of harbor and
finless porpoises have improved considerably. The
success rate of rehabilitating stranded or bycaught
harbor porpoises has increased markedly (Kastelein
et al. 1990, Neimanis et al. 2004, Zagzebski et al.
2006). In the Netherlands, a harbor porpoise rehabil-
itation program ran from 1967 to 2016, during which
179 porpoises were admitted; 64 of these individuals
were released after treatment and 21 were adopted
into the permanent collection as they were deemed
unfit for release (C. E. van Elk unpubl. data). Despite
limited breeding effort with the collection animals, 4
calves were born and successfully reared. Several
aquaria in Japan currently house finless porpoises
that were caught intentionally, or captured acciden-
tally in fishing nets and subsequently taken into cap-
tivity, and in China, a stranded finless porpoise was
rehabilitated and released from Beijing Aquarium
(Yu et al. 2009). However, the most dramatic and suc-
cessful use of a protected reserve can be found in the
translocation of the Yangtze River finless porpoises
into a protected oxbow lake (Wang 2009, Interna-
tional Whaling Commission 2018). The initial net
transfer of 19 animals from 1990 to 2004 has now
resulted in a breeding population of over 60 animals
which represent 6% of the known population (Mei et
al. 2014, Wang 2015). Almost 200 harbor porpoises
were handled, tagged and released between 1997
and 2018 in European waters, and only 3 died (J.
Teilmann pers. obs.), and 37 harbor porpoises were
caught actively in drifting gillnets in Greenlandic
and Danish waters with no casualties (van Beest et al.
2018, Nielsen et al. 2018). In the North Sea, harbor
porpoises that were accidentally entrapped alive in
pound nets have been sampled, tagged, released and
tracked. These animals showed indicators of stress
(increased respiratory and heart rates, high blood
cortisol levels) that varied markedly among the 42
individuals, but no deaths were reported (Eskesen et
al. 2009).
Other than 1 live-stranded neonate which died
shortly after collection 2 decades ago (see Curry et al.
2013), there were no records of capture, handling or
housing vaquitas prior to the initiation of the Vaquita
CPR project. Thus, development of an ex situ pro-
Endang Species Res 38: 11–27, 2019
gram faced numerous serious challenges from the
start. For example, it was not known whether: (1) it
would be possible to find vaquitas, given the severity
of population decline, their small size and elusive
nature, and the size of the refuge; (2) vaquitas could
be captured safely; (3) vaquitas could be transported
from a capture site to holding facilities; (4) vaquitas
could adapt to holding facilities; (5) vaquitas could be
maintained for the time period (likely years) required
to clear their habitat from gillnets; (6) vaquitas would
breed under human care; or (7) vaquitas could be
released successfully after captivity.
Despite these challenges, the proximity of consid-
erable cetacean capture and care resources within
5 h drive of vaquita habitat made consideration of an
ex situ approach feasible, and in 2017 the imminent
risk of extinction due to entanglement in totoaba nets
was considered higher than the risks to individual
vaquitas from capture and placement in protected
enclosures. Therefore, under the direction of the
Mexican government, a program was initiated to
capture vaquitas and place them in a facility in the
Upper Gulf of California to protect them from gill-
nets, with the intent of releasing them once the gill-
net threat was eliminated. This paper gives an
overview of these efforts.
2.1. Planning
In proposing an ex situ approach as part of the con-
servation strategy, it was vital that other conservation
actions, particularly elimination of gillnets from the
vaquitas’ habitat, were not compromised. Plans for
VaquitaCPR were developed in parallel with efforts
to declare and enforce an expanded ban on the use of
gillnets, remove illegal, abandoned, lost and dis-
carded gillnets from the vaquitas’ range, develop
alternative fishing techniques, and increase aware-
ness of the vaquitas’ plight. Planning for the possibil-
ity of the use of an ex situ approach was initiated in
2015, 2 yr prior to the recommendation by CIRVA to
initiate such a program.
To minimize risks associated with catching, han-
dling and housing vaquitas, a step-wise, precaution-
ary approach was developed in September 2015,
with each step of the plan contingent upon the suc-
cess of previous steps (see Annex 3 of CIRVA-7
2016), and this was presented to CIRVA in May
2016. CIRVA then recommended a site visit to the
Upper Gulf of California to assess the feasibility of
ex situ conser vation actions, and refinement of the
objectives of an ex situ conservation strategy. In
November 2016, CIRVA recommended starting the
ex situ program using a precautionary approach
(CIRVA-8 2016), and the GoM requested that plan-
ning and fundraising efforts be accelerated and that
the multiple steps be compressed into a single field
effort. The field program was initiated in Octo-
ber 2017. The plan (www.
conservation-program-plan/) was reviewed by an
independent review panel (IRP), which also was
charged with review of circumstances around any
injury or mortality, and then making a recommen-
dation to the VaquitaCPR program lead, the GoM,
and CIRVA, as to whether the project should pro-
ceed with or without modification, or be terminated.
The goals of the VaquitaCPR program were to find,
catch, and house up to 10 vaquitas in net pens or soft-
sided pools adjacent to the vaquita refuge, and once
catch operations and acclimation of vaquitas to
human care were successful, build a large sanctuary
in the Upper Gulf of California for long-term housing
and captive breeding. The ultimate aim of the cap-
ture initiative was to preserve the species for future
release into a fully protected (i.e. gillnet-free) wild
habitat. The first step, requiring the greatest lead
time, was construction of appropriate housing facili-
ties. Field efforts to capture vaquitas were expected
to be feasible only during very calm seas (Beaufort
sea state 0−2), due to the small size and cryptic
nature of the animals. Once funding was secured and
facilities were available, the earliest period of poten-
tial good weather was October 2017. This coincided
with the season when vaquita calves would be wean-
ing, so capture of females with neonates would be
avoided, as peak birth season is March−May (Hohn
et al. 1996).
2.2. Communications and fundraising
A fundraising team was charged with raising
approximately US$ 5 million within 6 mo. The team
solicited individuals, foundations, associations, and
corporations, and resulting support was through 2
primary supporters, the GoM and the Association of
Zoos and Aquariums (AZA), through its members
(see for all supporters). The
challenge inherent for this campaign was raising
funds for an effort with no proof of concept, on an
extremely short timeline. A communications team
was also established, led by GoM and VaquitaCPR
communications officers. In preparation for field
Rojas-Bracho et al.: Vaquita porpoise capture effort
efforts, a VaquitaCPR communications plan and a
crisis communications plan, a VaquitaCPR website
(, social media and website con-
tent, a VaquitaCPR logo, press releases, talking
points, communications and outreach materials, and
media agreements were all generated.
2.3. Facilities
The land-based vaquita care center was con-
structed at Machorro Cove, San Felipe, México (Fig.
1). This location was selected because (1) it was one
of the few locations near the vaquita refuge that
offered protection from some of the strong winds that
frequently occur in the area; (2) water quality in the
cove was adequate for housing animals (e.g. low col-
iform counts, appropriate salinity and water temper-
ature); (3) it was near the largest town in the area,
San Felipe, facilitating construction, communica-
tions, security, and access to supplies and ground and
air transportation; and (4) San Felipe has the only
harbor near the vaquita refuge with shelter for large
and small vessels and a Mexican Navy base suitable
for housing US Navy dolphins (see Section 2.4.).
The vaquita care center included a 9.14 ×36.6 m
reinforced tent (Alaska Structures), equipped with
HEPA air filtration and climate control, and 3 pools
with water filtration, cooling, and heating systems
(Aqua Logic). Two oval (15 ×5 m) 22500 gallon
(~85 000 l) soft-sided pools (Sofpool) and a rectangu-
lar (9 ×5 m) 15 000 gallon (~57 000 l) pool (Splash
Pools) were staged on sound-proof flooring. Seawa-
ter was pumped in from Machorro Cove. An adjacent
building was renovated and outfitted for offices, a
laboratory, fish preparation, and cold storage. Addi-
tional soft-sided above-ground pools of varying sizes
were staged for potential use. A Mexican Navy secu-
rity outpost was constructed on site with project
funding. A private security firm was hired to ensure
the safety of animals, personnel, and facilities.
A 40 m diameter circular anchored sea-pen with 2
enclosed smaller pens (6 m and 9 m diameter) was
located just offshore of the vaquita care center. Orig-
inally built to house bluefin tuna Thunnus orientalis,
the pen was towed 2490 km from Ensenada, México,
and modified for vaquitas. The sea-pen walls were
constructed with small-mesh net (5.7 cm stretch
knotless nylon net dipped in Flexabar paint) and the
net was stretched between rigid, hollow pipes at the
top (surface) and bottom (sub-surface) of the pens to
minimize risk of entanglement by eliminating billow-
ing. The depth of the enclosure could be controlled
by raising and lowering the bottom perimeter ring,
with a minimum depth of 1.5 m in the 2 smaller sea-
pens and a minimum depth of 4 m in the 40 m sea-
pen. The 40 m diameter sea-pen was constructed to
be modular and the smaller internal sea-pens were
removable, so that animals could be moved between
pools as appropriate. Small fish and invertebrates
were able to swim in and out of the pens. Above
water, a soft net fence was secured to the perimeter
of the outer sea-pen to deter California sea lions
Zalophus californianus. Six 1-ton Danforth anchors
were used to secure the net against the extreme tidal
flux (up to 6.3 m) and strong currents (up to 5.2 knots;
~2.68 m s−1). A floating barge with solar-powered
facilities for live fish housing, food fish preparation
and cold storage, veterinary medical facilities, emer-
gency equipment, and personnel support was
anchored within the sea-pen.
2.4. Search effort
Search activities to locate vaquitas for capture
included 3 primary components: (1) acoustic search-
ing by means of a passive acoustic array established
in and near the vaquita refuge; (2) visual searching
by experienced observers; and (3) dolphin-assisted
Decades-long experience with passive acoustic
monitoring of vaquitas was critical to the success of
daily search efforts. An array of 87 underwater
autonomous passive acoustic odontocete detectors
(C-PODs, was deployed from
June to September 2017. This array expanded on
the area monitored annually since 2011 to provide
an acoustic assessment of trends in vaquita abun-
dance (Jaramillo-Legorreta et al. 2017). The larger
array was removed prior to the onset of October
field efforts and a subset of 36 C-PODs was placed
in the areas with the highest rates of vaquita
acoustic detection, primarily in the western and
southern portions of the vaquita refuge (see Fig. 1).
It was later expanded with 8 additional C-PODs.
Weather permitting, teams in small boats traveled
to each sampling site on a daily basis, interchanged
C-POD units, and brought them to shore for analy-
sis. Areas where vaquitas were detected by the C-
PODS were reported to field team leaders between
02:00−03:00 h each day. The catch team and visual
search team leaders considered these data, and sea
conditions, as they made their plan each morning
to guide the visual observers, who commenced
their work at dawn.
Endang Species Res 38: 11–27, 2019
The visual search operation consisted of a live-
aboard 39 m mother ship, the ‘Maria Cleofas’, and 2
smaller (13 m) search vessels. Three rigid-hulled
inflatable boats (RHIBs) served as catch boats. US
Navy dolphin tender boats assisted with localization
(see end of this section), and Mexican Navy vessels
assisted in aspects of sighting, catching, security, and
transport. All vessels were equipped with automatic
identification system (AIS) for real-time monitoring
of their position by the leader of the search team
aboard the ‘Maria Cleofas’. The visual search team
started each day’s efforts at a site determined
through passive acoustic detections from the previ-
ous day.
Vaquitas are small, and are typically found in small
groups that surface inconspicuously and avoid ves-
sels (Jaramillo-Legorreta et al. 1999). To maximize
chances of finding animals to capture, all members of
the visual search team had extensive prior survey
experience with this species. The sighting platform
on the ‘Maria Cleofas’ was 6.53 m above the water’s
surface and afforded a stable platform for 2 pairs of
‘Bigeye’ 25-power Fujinon binoculars. The 2 smaller
vessels had flying bridges 2.69 and 2.46 m, respec-
tively, above the water and observers on these boats
used handheld binoculars or binoculars on mono -
pods. During search mode, the 3 primary search ves-
sels moved in a shallow V-formation, separated by
about 600 m, with the ‘Maria Cleofas’ in the center
and slightly behind the other 2 boats. A custom pro-
gram was used to track each vessel using AIS data
and plot the position of sighted vaquitas using com-
pass angles and estimated distances. The search
team was supplemented by the 3 RHIBs, which were
deployed 300 m outside the primary search boats.
The fleet moved together at about 9 knots (4.63 m
s−1). Once vaquitas were sighted, efforts were made
to maneuver the 3 primary search boats into a trian-
gle with the vaquitas in the center, to maintain visual
contact, while directing the catch boats into position.
To supplement this visual search effort, US Navy
bottlenose dolphins experienced in underwater
swimmer detection (Renwick et al. 1997, Myers 2015)
were employed to locate and track vaquitas at short
ranges and to help guide the capture boats. In prepa-
ration for vaquita detection efforts, US Navy dolphins
were deployed to San Francisco Bay where they
searched for harbor porpoises utilizing their echolo-
cation and detected them at a range of a few 100 m.
The dolphins were trained to search from below the
bow of a small Navy vessel and provide a visual cue
(e.g. a leap) when a porpoise was detected, to inform
the capture team of the animal’s location. When
searching for vaquitas in the Gulf of California, the
dolphin-tending vessel remained at a distance
behind the visual search fleet, where it could bring
the search dolphin to the sighting area within min-
utes following a very-high-frequency (VHF) radio
message. Once the dolphin was called in to search,
the tender moved to a location within a few 100 m of
the most recent sighting and the dolphin was
2.5. Catch and initial assessment
The primary factors considered in selecting a safe
and effective capture technique included: (1) the
need for the animals to be able to surface to breathe
once captured; (2) depth of the habitat (typically
>10 m deep); (3) extreme turbidity of the Upper Gulf
of California, which precludes seeing animals more
than 1 m below the surface; (4) strong currents asso-
ciated with extreme tides; and (5) the elusive nature
of vaquitas. Several techniques were considered
based on experience with closely related species, but
ultimately gillnets used to capture harbor porpoises
in Denmark and Greenland waters for telemetry re -
search were adapted for vaquitas, although it was not
known whether vaquitas would respond to boat
chase techniques in the same manner as harbor por-
poises (Nielsen et al. 2018, van Beest et al. 2018).
Methods such as purse seines, weirs and herding into
shallow waters were rejected due to concern over
several factors, including the inability to observe
vaquitas in turbid water, the possibility of net col-
lapse, extreme tidal currents, and the elusive nature
of vaquitas.
Modified monofilament gillnets, 260 m long and
9 m deep, with an 18 cm stretch mesh size, 0.7 mm
twine diameter, no. 1.5 lead line and an iridescent
green Hau-Danline-Deep Sea no. 7 floating line,
were constructed in Denmark. The nets were de -
signed to be deployed at fast speed over the stern of
the RHIBs. The nets were marked by a flag at one
end and a buoy on the other. Two ~8 m fast RHIBs
were used for net deployment and porpoise retrieval.
Capture crews had expertise in porpoise catching,
handling, and veterinary medicine. Once vaquitas
were sighted from the RHIBs, one or more nets were
set ahead of, and if possible around, the anticipated
path of the animals. Each deployed net was moni-
tored by one or more catch boats, while the other
boat(s) attempted to herd vaquitas toward the nets.
Once a vaquita was observed caught in the net, the
closest boat moved in, disentangled the animal and
Rojas-Bracho et al.: Vaquita porpoise capture effort
lifted it onto a stretcher. The stretcher containing the
vaquita was either held beside the capture boat, or
placed inside a soft-sided transport container padded
with and placed on foam that contained enough
water to relieve pressure on the animal’s thorax.
Once it appeared stable, the vaquita was transported
to one of the housing facilities. If the animal ap -
peared agitated, the boat was slowed until the ani-
mal appeared calmer. Drugs and equipment for se -
dation, emergency resuscitation and supportive care
were available on each transport boat. Satellite-
linked SPOT fin-mount tags (Wildlife Computers),
attached by a single delrin pin to the dorsal fin, were
available so that a vaquita could be tagged within
minutes if emergency release for animal safety was
deemed necessary.
2.6. Veterinary assessment
The VaquitaCPR team included more than 15 vet-
erinarians and veterinary technicians with experi-
ence in all aspects of cetacean medicine. Detailed
protocols were developed prior to the field effort for
all aspects of handling and care. Once a vaquita was
captured, a clinical assessment was made, noting
respiratory rate (RR) and character (deep or shallow),
heart rate (HR) and rhythm (using stethoscope, hand
contact or portable ECG unit), and behavior. Sex,
length, and any external injuries were recorded, and
an assessment was made of age class (juvenile or
adult). A SonoSite Edge portable ultrasound system
(FujiFilm), with a C60x 5-2 MHz curvilinear trans-
ducer and outfitted with Zeiss Cinemizer heads-up
display goggles, was used for thoracic and abdomi-
nal examination, including pregnancy determina-
tion. During transport, RR was monitored continu-
ously, HR intermittently, and blood was collected
from the periarterial venous rete of the fluke using a
23G butterfly catheter into EDTA, serum separator,
and heparinized BD Vacutainer®tubes. Hematology
and serum chemistry parameters were analyzed at
the SeaWorld Clinical Pathology Laboratory in San
Diego, serum cortisol levels were measured at Cor-
nell University, plasma catecholamines at Mystic
Aquarium, and creatinine kinase isoenzymes at the
University of Miami Avian and Wildlife Laboratory.
Additionally, blood was collected into a PICO syringe
for rapid chemistry analysis using an iSTAT point-of-
care handheld blood analyzer with CHEM8+ car-
tridge. Once animals were transferred to either soft-
sided pools or sea-pens, respiration and behavior
were monitored continuously.
2.7. Age determination
Teeth collected post mortem were decalcified and
thin-sectioned following standard protocols (Perrin &
Myrick 1980). After staining with hematoxylin, age
was estimated by counting growth-layer groups
(GLGs), which are annual patterns of dark and light
lines in the dentine and cementum. Age was esti-
mated independently by 3 experts and a final age
was derived by consensus.
Search and capture efforts were conducted on 11
full or partial field days from 13 October to 4 Novem-
ber 2017. Vaquitas were sighted on 8 d, they were
kept in view consistently enough for the nets to be
deployed on 3 d at 3 different sites, and vaquitas
were caught on 2 d. The first vaquita, caught on
18 October, was a juvenile female (V01F) which was
released within hours of capture due to symptoms of
stress. The second, caught on 4 November, was an
adult female (V02F), which died on the day of
3.1. Search efforts
Acoustic data were available from 964 site-days.
Vaquita vocal activity was found at 21 of the 36 sites
in the original network and at 23 sites of the
expanded network (see Fig. 1). The acoustic activity
was intense at 2 of the sites, at which there was per-
sistent vocal activity. In total, 125 vaquita acoustic
encounters were detected. This near real-time
acoustic information was critical in guiding the
visual search team toward areas with recent vaquita
As in past studies (Silber 1988, Taylor et al. 2017),
the most common group size observed was 2, and
there was some difficulty in distinguishing mother/
calf pairs from pairs of older animals. Calves were
approximately 6 mo old during the field season, as
most births occur from February to April (Hohn et al.
1996). Many animals responded to the approach of
the catch vessels by forming tight pairs and porpois-
ing to avoid the pursuit boats. In such cases, size dif-
ferences between adults and juveniles were more
obvious, although still challenging to discern.
Navy dolphins were utilized for initial detection of
vaquitas only on the first day, as the use of multiple
vessels to locate and track vaquitas visually proved
Endang Species Res 38: 11–27, 2019
more successful than anticipated. However, in several
instances, vaquitas eluded visual contact after surfac-
ing in the middle of the vessel formation and in very
calm waters. Navy dolphins were deployed twice to
try and locate lost sightings but without success.
Once, Navy dolphins relocated the vaquitas at the
same time as vaquitas were visually relocated. Opera-
tional conditions complicated the dolphins’ ability to
perform this task, as the dolphins were trained to
search from below the bow of a small boat. This boat
may have deterred vaquitas, as they maintained a dis-
tance of several 100 m from any motorized vessels.
Furthermore, the dolphins were trained to use echolo-
cation to locate porpoises, which is likely effective
only at distances of a few 100 m. Despite these obsta-
cles, Navy dolphins did relocate a vaquita on 1 occa-
sion when observers had lost track of the animal.
It was possible to herd vaquitas for about 1 km to-
wards the nets by operating the catch RHIBs at high
speed near the animals. In the first event, a young fe-
male was captured (V01F, see Section 3.2.). Two
other individuals in the group were then pursued for
about 2 h, but it was difficult to determine if the same
individuals were pursued during the whole period.
During the pursuit the animals were observed to
swim around and under the net, confirming that
vaquitas can detect and avoid nets in some situations
(i.e. set on the surface during daylight). Following
capture of the second animal (VO2F), 1 or 2 other in-
dividuals in the vicinity (one of which may have been
entangled with VO2F but escaped) were successfully
herded back towards the nets, but ultimately eluded
capture. Pursuit of vaquitas in the vicinity of the
V02F capture lasted for 90 min until dusk.
3.2. Captures
3.2.1. V01F
The first vaquita (V01F), a juvenile female, 102 cm
long, weighing ~20 kg, was caught in a net set near a
group of 3 animals at 10:56 h on 18 October 2017 (see
Table S1 in the Supplement at www. int-res. com/
articles/ suppl/ n038 p011 _ supp. pdf for a timeline of
events). In spite of its small size, it was able to easily
lift the net to the surface and breathe until it was dis-
entangled and lifted out of the net (Fig. 2). The
vaquita was placed in the stretcher, suspended in a
seawater-filled transport container, and transported
to the shore-based pool. Initial HR was ~150 beats
min−1 (bpm) with no sinus arrhythmia (defined as
higher HR immediately after a respiration and lower
HR immediately prior to a respiration; characteristic
of cetacean breathing) and RR >10 min−1. Diazepam
was administered as deemed appropriate to mitigate
stress (Table S1). During transport, HR lowered
slightly to ~130 bpm and RR reduced to ~8 min−1.
Once released into the pool, the vaquita swam
erratically, mostly along the pool perimeter, and
repeatedly collided with the pool sides and personnel
deployed in the pool to deflect it from the sides. HR
averaged ~150 bpm with no detectable sinus ar -
rhythmia (intermittently measured when animal was
handled to divert from the pool sides) and RR
increased to ~10 min−1 (continuously monitored).
After approximately 1 h in the pool, white foam was
observed emanating from the blow-hole, suggesting
the development of pulmonary edema. Furosemide
at 4 mg kg−1 intramuscularly (IM) and methylpred-
nisolone sodium succinate 5 mg kg−1 IM were admin-
istered, and the foam disappeared within 5 min and
was not observed again. At this point, due to the con-
tinuation of agitated behavior, the decision was made
to move the vaquita to the sea-pen, because its slop-
ing sides would present less of a collision risk. In the
sea-pen, V01F continued to appear agitated, and its
behavior deteriorated slightly, with increased lifting
of the head out of the water, and erratic swimming
patterns. The decision was then made to release the
animal as close as possible to its capture site, where
other vaquitas had been observed. The animal was
transported back to the refuge in the same stretcher
and container as described above. During transport,
HR was 130−160 bpm and RR stabilized at ~8 min−1.
Fig. 2. Vaquita V01F (A) at capture and (B) at release
Rojas-Bracho et al.: Vaquita porpoise capture effort
Blood was collected during transport for serum
chemistry, hematology and serum cortisol assess-
ments (see Table S3). Blood results demonstrated a
typical cetacean stress response (Atkinson & Dierauf
2018), characterized by elevated cortisol (23.4 µg
dl−1) and a neutrophilia (92% of the total white blood
cell count) with lymphopenia (5% of the total white
blood cell count). Based on the blood cortisol level,
which was about 10-fold higher than values reported
in a variety of live-handled odontocetes (Atkinson &
Dierauf 2018), V01F developed a profound stress
response to handling, consistent with its outward
clinical signs. Blood results also showed elevated cre-
atine kinase (CK) (4244 U l−1), elevated lactate dehy-
drogenase (LDH) (1919 U l−1) and hypoglobulinemia
(1.3 g dl−1), compared to published values for harbor
porpoises released from herring Clupea harengus
weirs (Koopman et al. 1995, 1999), captive finless
porpoises (Kasamatsu et al. 2012), and Stenella
chased and encircled in the Eastern Tropical Pacific
(St. Aubin et al. 2013). Elevation of blood CK and
LDH levels indicate leakage of these enzymes from
damaged skeletal muscle cells, suggesting that some
myopathy occurred.
During transport to the release site, while respira-
tion rate had stabilized, morphometric measure-
ments were recorded, and an 8 mm diameter skin
and blubber punch biopsy to be used for cell culture
and cryopreservation was collected from the right
dorsum at the level of the caudal margin of the dorsal
fin, following an anesthetic ring block using lido-
caine with epinephrine. The biopsy was placed in
transport media with antibiotics and fungicide and
refrigerated overnight (see Houck et al. 2017). The
following day, the sample was shaken to dislodge
external debris, decanted into a second transport
vial, and transported to NOAA Southwest Fisheries
Science Center, La Jolla, USA, where blubber was
separated, dabbed on the culture plate to remove
transport media and frozen at −80°C. The remaining
skin was sectioned, one third was archived at −80°C,
the remaining 2-thirds were placed into fresh trans-
port media and transported on wet ice to San Diego
Zoo Global’s Frozen Zoo for cell culture and cryo -
preservation (see Houck et al. 2017). These live cells
from vaquitas can be used in eventual future de-
extinction programs.
Upon return to the sea, VO1F continued to swim at
the surface, lifting its head regularly out of the water,
and then began to make short dives over the next
20 min until visual contact was lost. The fate of V01 is
unknown; no carcass was discovered despite consid-
erable human presence in the area over the weeks
following capture, and the fin was not identified in
photographic identification records from efforts con-
tinued through 10 November 2017. The animal was
not tagged due to its small size and concern for
potential impacts of such tags on its health.
3.2.2. V02F
On 4 November 2017 at 16:18 h, 2 vaquitas were
caught in a net deployed approximately 15 min ear-
lier. Both were visible at the surface, and the catch
boats immediately approached the net. One vaquita
was loosely entangled and escaped; the other was
entangled with net around the head and flippers, but
was able to lift the net to the surface to breathe.
While attempts were made to recapture the second
animal, V02F was monitored while being held in a
stretcher in the water alongside the boat. This animal
was an adult female (40 kg and 136 cm standard
length), in good body condition, and was calm and
alert during initial handling (Table S2). The animal
appeared stable with a HR that consistently ranged
from 120−130 bpm, with no detectable sinus arrhyth-
mia, and RR of ~ 6 min−1. In an attempt to mitigate
stress and assist with acclimation, the animal re -
ceived diazepam at 0.175 mg kg−1 IM.
Diagnostic ultrasound of the animal’s thorax per-
formed over the side of the boat while the animal was
in the water was initially normal, but 50 min post-
capture showed evidence of alveolar interstitial syn-
drome developing in the ventral portion of both lungs
(see Fig. 3). This finding was considered consistent
with developing pulmonary edema based on ultra-
sound appearance, distribution of affected lungs, and
rapid onset (Smith et al. 2012). The animal received
furosemide (1 mg kg−1) and methylprednisolone
sodium succinate (5 mg kg−1) IM. A recheck ultra-
sound after drug therapy showed significant im -
provement on the left side but only partial improve-
ment on the right (Fig. 3). A second dose of
furosemide was administered which resulted in com-
plete resolution of the abnormal pulmonary finding
when rechecked 13 min later (see Table S2 for a
Once efforts to catch the other vaquita were discon-
tinued, V02F was suspended in a stretcher inside a
transport container and taken to the sea-pen. During
transport, the animal’s HR was stable at ~120 min−1
and RR rarely varied from ~6−8 min−1. Upon introduc-
tion to the sea-pen, the animal appeared agitated and
avoided the net pen walls, maneuvering to avoid colli-
sions. Despite behavioral indications that the animal
Endang Species Res 38: 11–27, 2019
was beginning to acclimatize, the animal abruptly de-
teriorated, characterized by decreased awareness of
surroundings and prolonged respiratory interval.
V02F was released approximately 4 h after capture,
but suffered a cardiac arrest upon release.
Emergency resuscitation efforts were initiated (see
Table S2), which included intubation (7.5 mm endotra-
cheal tube), ventilation, oxygen administration, chest
compressions as needed, emergency medications, in-
travenous and subcutaneous fluid administration, pre -
paration of the dorsal fin for potential tagging if
release became an option, and continuous monitoring.
The veterinary team was able to restart the vaquita’s
heart, but they were gravely concerned about inade-
quate peripheral vascular perfusion and inability to
transition from occasional spontaneous but ineffective
respirations to effective spontaneous ventilation. Fi-
nally, the team was unable to reverse a cardiac arrest
and V02F died 3 h after attempted release.
A post mortem examination was conducted within
1 h of death, and representative samples of all major
organs were fixed in 10% neutral buffered formalin
for histological examination. The reproductive tract
was examined, then placed in a plastic bag mois-
tened with sterile saline for further evaluation and
gamete archiving at SeaWorld laboratory. Samples
for cell culture were collected using sterile forceps
from kidney, trachea, liver and mesovarium, placed
into cell culture transport media, and transported to
San Diego Zoo within 48 h of collection for process-
ing for cell culture and cryopreservation as described
in Houck et al. 2017.
On gross examination, all internal organs ap -
peared within normal limits, and the teeth were
worn, suggesting old age. There was no evidence of
current pregnancy or lactation, although the ovaries
had corpora indicative of previous ovulations, with a
corpus luteum on the left ovary which was confirmed
Fig. 3. Ultrasound images of vaquita V02F lung fields. (A) Initial scan, lungs appear normal; (B) ultrasound scan after the first
dose of furosemide, with resolution of edema in the left lung but persistence of alveolar interstitial syndrome (AIS) in the
ventral right lung; (C) ultrasound scan after treatment showing resolution of AIS, no abnormalities in either lung
Rojas-Bracho et al.: Vaquita porpoise capture effort
to be functional by a concurrent serum progesterone
concentration that was above baseline (5 ng ml−1)
(see Table S3). Multiple linear scars and fluke/fin
notches typical of healed previous entanglement
injuries were present. The fore-stomach contained
semi-digested fish.
GLG patterns in the teeth were poorly defined and
there was considerable variation in the number of
accessory lines present within each annual GLG.
Despite these challenges, a final age estimate of 15 yr
was determined. This estimate was validated by
cementum layer counts by one of the people count-
ing GLGs. It is worth noting that because of the diffi-
culties in counting GLGs near the pulp cavity, V02F
could have been older than its estimated age.
Histological examination revealed myocardial and
skeletal muscle degeneration and necrosis with con-
current loss of myoglobin staining in necrotic
myocytes noted on immunohistochemical staining of
tissue with an anti-myoglobin antibody (MyoG,
AR012, BioGenex) (Fig. 4). Renal tubular degenera-
tion and necrosis were noted with accumulation of
myoglobin within tubule lumens consistent with
myoglobinuric nephrosis. These findings indicate
that the death of V02F was due to capture myopathy.
There was no evidence of any underlying chronic
disease that could have contributed to death. Addi-
tional histologic findings were subclinical and prima-
rily associated with older age and parasitic infection
(Table 1).
Blood collected at the end of transport and
during emergency response showed no significant
hematological changes, except hyperglycemia, with
elevated creatinine kinase and lactate dehydroge-
nase levels compared to other porpoises (as above
for V01F) (Table S3). Creatinine kinase ele va -
tions consisted predominantly of the mm (skeletal
muscle derived) and mb (cardiac muscle and dia -
phragm derived) isoenzymes, rather than the bb
(brain derived) isoenzyme. These data indicate
that most CK enzyme was from skeletal muscle
rather than brain, supporting a diagnosis of skeletal
myopathy. Hormonal analyses of blood collected at
20:00 h, which was 26 min after the first cardiac
arrest during emergency resuscitation, revealed
high cortisol, aldosterone, epinephrine and norepi-
nephrine levels, indicative of a severe acute stress
response (Table S3). Cortisol levels were 100-fold
higher than levels reported in a variety of handled
odontocetes, and epinephrine and norepinephrine
were at the highest levels reported to date for
cetaceans (Atkinson & Dierauf 2018). However, as
the sample was collected during emergency resus-
citation, caution must be taken when interpreting
these values.
Following the death of V02F, further capture
efforts were suspended immediately. The behavior of
the first animal, respiratory rates and blood cortisol
levels typical of acute stress, the development of pul-
monary edema in both animals, and the death of the
adult female suggested that both capture and con-
tainment posed excessive stress for vaquitas. It is
unknown whether or not the responses of these indi-
viduals should be expected for all vaquitas, and
whether the use of sedative or vasoactive drugs could
ameliorate the stress. But, with fewer than 30
vaquitas remaining, the field team decided, and the
IRP concurred, that captures be suspended because
the risk of mortality to the remaining individuals was
deemed high.
3.3. Photo-identification
Upon cessation of capture efforts, field assets were
redirected toward photographic identification for the
remainder of the field season. Acoustic searching
continued until 8 November at all 44 sites and until
9 November at the 3 sites with the highest acoustic
encounter rates. During capture efforts, photographs
indicated sufficient markings to identify some indi-
viduals, such that the potential to obtain an inde-
pendent estimate of abundance using photo-identifi-
cation warranted further exploration. Distinctive
dorsal fin notches and shapes have been used previ-
ously to identify individual vaquitas (Jefferson et al.
2009). In an attempt to refine abundance estimates
and learn about vaquita ranging patterns, dedicated
photographic identification efforts were made on all
workable field days after cessation of capture
attempts on 4 November. Experienced photogra-
phers with telephoto lenses of at least 300 mm were
distributed across 3 catch boats and the smaller
search vessels in an attempt to obtain high-quality,
high-resolution dorsal fin images. Upon initial sight-
ing by observers on the primary search vessel ‘Maria
Cleofas’, the closest smaller vessels attempted to
approach for photographs. Poor weather and elusive-
ness of the porpoises limited the number of photo-
graphs collected during these efforts, with dedicated
photo-identification operations possible on only 3 d.
Over the duration of the entire project, 192 images
from 7 photographers were examined. Seven indi-
vidual vaquitas were documented, including the 2
captured porpoises. Three fins were very similar to
those documented by Jefferson et al. (2009), but
Endang Species Res 38: 11–27, 2019
photo quality was insufficient to confirm matches.
The nature of some of the fin markings is suggestive
of previous interactions with fishing gear, indicating
that at least some individuals may have been able to
survive some entanglements and perhaps explaining
how some observed vaquitas appeared to be familiar
with nets and their avoidance.
4.1. Vaquitas
The protocols developed to detect vaquitas using
acoustic and visual methods resulted in finding
vaquitas on all 6 full good-weather days. The strat-
Fig. 4. Tissues from vaquita V02 stained with hematoxylin and eosin (A,C,E,F) and an anti-myoglobin antibody (B,D). (A,B)
Kidney with myoglobinuric nephrosis. Renal tubules contain myoglobin (arrows) and sloughed necrotic cells (ellipse). Scat-
tered tubular epithelial cells are necrotic (arrowhead). (C,D) Shrunken necrotic skeletal myocytes with loss of cross striations
and myoglobin staining (arrows). Accumulations of myoglobin adjacent to affected myocytes (ellipse). (E,F) Sections of heart
with myofiber degeneration and contraction band necrosis (arrows). Scale bars = 20 µm
Rojas-Bracho et al.: Vaquita porpoise capture effort
egy of using multiple observation vessels with a large
ship capable of tracking sightings from all vessels
facilitated the location and tracking of groups in real
time. Capture of the 2 vaquitas occurred rapidly after
net deployment (on 2 out of 3 net deployments),
although attempts to catch other vaquitas in the vi -
cinity were unsuccessful, as these vaquitas appeared
to detect and evade the nets. All remaining vaquitas
have survived intense gillnet fishing efforts and
some, including V02F, had scars consistent with hav-
ing been previously entangled. However, the death
of 4 individuals in spring 2017 and an adult female in
spring 2018 (after this ex situ effort) with clear entan-
glement lesions, indicate that despite their evasive
behaviors, death from entanglement continues. All of
the vaquitas observed during field operations, in -
cluding the 2 captured individuals, appeared in
excellent body condition.
4.2. Capture and holding
The light capture nets posed minimal physical
threat to the vaquitas during capture. However, both
captured vaquitas showed behavior, clinical signs
and blood parameter changes typical of a marked
stress response. The blood cortisol levels in V01F
during transport were 10-fold lower than those in
V02F during resuscitation, but 10-fold higher than
levels in bottlenose dolphins that have been caught
and released for health assessments (Hart et al.
2015). Thus, this animal was undergoing an adrenal
stress response, but apparently a less severe one
than V02F. To the best of our knowledge, there are
no published comparative data on catecholamine
(adrenal norepinephrine and epinephrine hormones)
levels in cetaceans that died of capture myopathy.
The very high cortisol and catecholamine levels, cou-
pled with the high muscle enzyme values indicative
of muscle breakdown, support a diagnosis of stress-
induced capture myopathy in V02F. The post mortem
lesions in this animal were highly consistent with
lesions previously reported in cetaceans and other
species, including humans, associated with stress
and catecholamine release or exposure (Jiang &
Downing 1990, Cowan & Curry 2008, Herráez et al.
2013). The respiratory acidosis that developed fol-
lowing initial cardiac arrest may have also con-
tributed to myocardial degeneration and necrosis.
What remains unclear is when the severe stress
Tissue Lesion Most likely cause
Brain Marked neuronal lipofuscin accumulation Age related
Heart Marked acute myocardial degeneration, Capture-related stress and catecholamine
contraction band necrosis, myocardial edema release; acidosis
Blood vessels Mild arteriosclerosis Age related
Lung Acute neutrophilic bronchitis and bronchiolitis Gastric material aspiration during capture or
with foreign material emergency medical procedures
Peribronchiolar concretions Previous lungworm infection
Mild focal histiocytic pneumonia Previous lungworm infection
Liver Focal biliary cyst Trematode infection
Hepatocyte hemosiderin accumulation Unknown
Marginal lymph node Moderate anthracosis Inhalation of dust particles
Spleen Mild lymphoid hyperplasia Antigenic stimulation
Mild hemosiderosis Unknown
Kidneys Moderate acute tubular degeneration and Release of myoglobin from damaged
necrosis with luminal myoglobin myocytes (myoglobinuric nephrosis)
Skeletal muscle Moderate acute degeneration and necrosis Capture-related stress and catecholamine
(neck and head) release
Skin Acute laceration Net entanglement prior to capture
Uterus Endometrial polyp Age related
Vascular hyalinization Previous pregnancy
Table 1. Histologic findings in V02F. No lesions were observed in the eyes or gastrointestinal tract
Endang Species Res 38: 11–27, 2019
response was initiated. V02F appeared calm follow-
ing capture, and the external signs of stress were
most apparent when swimming in the net pen, but
the early onset of pulmonary edema in both animals,
which is an uncommon finding in otherwise healthy
cetaceans, suggests chase and capture likely trig-
gered an initial stress response. Edema may be sec-
ondary to catecholamine surge and has been shown
to develop rapidly (several hours) in humans second-
ary to emotional stress cardiomyopathy (Pavin et al.
1997). Additionally, muscle, heart, and renal lesions
in V02F were well developed at the time of death,
further suggesting early onset of stress during chase,
capture and handling. Though mild acute aspiration
pneumonia was noted, this lesion was not deemed
severe enough to have contributed to respiratory or
cardiac arrest. V02F was an older animal with some
organ changes characteristic of aging in other
cetaceans (see Table 1). Whether old age enhanced
the effects of capture and handling on stress is
unknown. Furthermore, the small size of the vaquita
population could have resulted in few individual ani-
mals being chased repeatedly on subsequent days
before capture, thus potentially stressing animals
prior to the day of the actual capture and handling
To understand the stages of stress development in
these animals, a precautionary step-wise approach to
assess the responses to each stage (pursuit, capture,
handling, transport, enclosure) separately would
have been ideal. This was in the initial plan de -
veloped in 2015 (see Annex 3, CIRVA-7 2016), but
was not implemented due to the dire conservation
status of the species when field efforts were initiated.
Instead, in 2017 the aim was to catch as many
vaquitas as possible of any age and sex, and place all
animals caught into enclosures, with release as an
emergency option if animals did not adapt to the
enclosure. Research on the stages of this stress
response should be conducted on animals from
healthy populations of small cetaceans that are not
facing im minent extinction. Furthermore, as there
are no data on the response of vaquitas to medica-
tions, a precautionary approach using drugs that
have been widely used on a range of marine mammal
species with no side effects was adopted (Gulland et
al. 2018). Given the observations on these 2 vaquitas,
research on clinical treatment of stranded cetaceans
should include evaluation of the effects of stronger
sedatives and therapeutics effective in managing
cardiovascular effects of catecholamines, such as
To reduce risks of cardiomyopathy and capture
myopathy in any future operations, consideration
should be given to translocation rather than confine-
ment. If confinement is used in early stages, even
temporary pools should be designed to minimize
stress on individual animals. The holding pools used
in this field effort were intended for short-term use
until funds for construction of a sanctuary lagoon
were available. These funds were contingent upon
demonstration that capture of vaquitas was possible.
It is possible that immediate use of a larger enclosure
might have reduced stress.
4.3. Planning and logistics
The idea of an ex situ approach to vaquita conser-
vation, ‘which would involve removing individuals
from the wild population, either to develop a captive
breeding program or to safeguard the last few indi-
viduals of the species’ was considered and rejected
by CIRVA in 2014 (CIRVA-5 2014, p. 19). This deci-
sion was based on a number of reasons, including the
difficulty of finding and capturing live animals, the
risk to the survival of the animals during the capture
process, the low survival rate and breeding success
in captivity of small cetacean species not previously
held in captivity, the absence of suitable facilities in
Baja to house vaquitas, and the difficulties of permit-
ting and transport to US facilities (CIRVA-5 2014). In
addition, although not specified in the CIRVA-5
(2014) report, the recovery team was concerned that
efforts to eliminate gillnets from the vaquita habitat
would be hampered by such an ap proach. As the sit-
uation in the wild worsened, exploration of possible
ex situ conservation options was initiated in early
2015 through an independent process that explored
whether an ex situ option might be feasible, and
developed a staged, precautionary plan.
The initiation of ex situ efforts in 2017 resulted in
acceleration of the originally planned phased, pre-
cautionary approach, and did not allow for construc-
tion of a large sanctuary before animals were caught.
Had the program started earlier, when the vaquita
population was larger (several 100s of animals rather
than 10s), there would have been more time to exe-
cute a step-wise approach that could have evaluated
the vaquitas’ responses to capture, enclosure, diet
and social grouping, as well as to release after tem-
porary capture. If more animals had been available
in the wild, initial capture and handling procedures
could have been developed on juvenile male animals
rather than reproductive females, reducing popula-
tion level impacts from accidental loss of an individ-
ual. In the early stages of the California condor
Rojas-Bracho et al.: Vaquita porpoise capture effort
Gymnogyps californianus capture and reintroduction
project, a chick died after handling, but protocols
were adapted and the program ultimately saved the
species from extinction (Goodall et al. 2009). A larger
population from which to select target animals could
also reduce the number of times a specific individual
was pursued for capture, so reducing stress on the
individual. Thus, future efforts that propose use of ex
situ actions for other small cetaceans should be initi-
ated while populations are large enough to afford the
potential loss of individual animals, and to allow for
selection of juvenile male animals for technique de -
velopment. If time is available for a staged approach
to be taken, each step can be evaluated before pro-
gressing to the next one. This would allow use of an
adaptive management approach, with progression
based on evaluation of the results from each stage.
Specifically, responses to chase, capture, handling
and enclosure should be evaluated separately, and
methods to mitigate adverse responses, particularly
stress, evaluated. Sedatives and therapeutic drugs to
counteract effects of cortisol and catecholamines
could be evaluated (see Gulland et al. 2018). These
methods could be developed for taxonomically simi-
lar small cetaceans that are not facing imminent ex -
tinction. The results of such advanced studies could
have provided more explicit guidance on maximum
durations of chase and handling times, as well as an
evaluation of potential responses to captivity in en -
closures of varying sizes. Despite the rapid time line
from decision to capture vaquitas to field efforts, a
large, international, multidisciplinary team was as -
sembled, with shared leadership and expertise across
institutions and individuals that was essential to
keeping the project on track. Strong support from the
Mexican and US Governments was essential for all
aspects of the project, from fund-raising and donor
comfort, to security, facility construction and on-the-
water operations.
4.4. Political and public opinion
As predicted, the notion of an ex situ approach
when first presented at CIRVA-7 was embraced by
Mexican authorities as a promising avenue in an
extremely dire situation. CIRVA, which responded
cautiously to the initial presentation, emphasized
that priority must remain on protecting the wild
population even while exploring captive approaches.
The GoM followed the recommendations not only
to support VaquitaCPR, but also to increase net-
removal efforts and enhance enforcement. Initiating
VaquitaCPR planning did not detract from estab-
lishment of a gillnet ban, rather it emphasized the
need: gillnets (except those set for curvina and
sierra) were banned on 30 June 2017: www. dof.
gob. mx/ nota _ detalle. php ? codigo = 5488674 & fecha
=30/ 06/ 2017 (in Spanish). VaquitaCPR cost ap -
proximately US$ 5 million. In contrast, over US$ 64
million have been spent in the last 2.5 yr (2016−
2018) in efforts to develop non-gillnet gear and
financial compensation schemes for fishermen in
the Upper Gulf of California (www. gob. mx/ conanp/
acciones-y-programas/ programa-de-conservacion-
de-especies-en-riesgo-procer; in Spanish), indica-
ting that concurrent effort to find in situ remedies
was considerable.
Despite many past efforts to communicate the
plight of vaquitas to the world, the VaquitaCPR effort
received the most intense media coverage and public
attention to date. One strong thread of the story
involved the potential of one group of marine mam-
mals, the Navy dolphins, to save another, vaquitas.
The compressed timeline forced by the rapid slide
towards extinction and the focus on logistics to
assemble and deploy the large capture team limited
leverage of this international and national attention
in a positive way within the local communities of San
Felipe and El Golfo de Santa Clara. The VaquitaCPR
team did not include dedicated community outreach
because the funds available were barely enough to
meet basic project expenses and the assembled
experts lacked the skills to mount such an effort in
VaquitaCPR was not intended as a substitute for
the broader socio-economic solutions needed to con-
serve the marine wildlife of the Upper Gulf of Califor-
nia. It was an emergency measure initiated in the
face of the extreme decline of the vaquita despite a
suite of legislative, enforcement, and development
actions intended to stem this decline. The goal of sal-
vaging some individuals and protecting them until
their habitat was gillnet-free was ambitious and at -
tempted only to buy time as an alternative to extinc-
tion. The field effort was complex, and there was no
previous experience, or luxury of time, to guide
refinements of the methods.
Ultimately, the political attractiveness of Vaquita -
CPR appears to have contributed to enhanced in situ
measures and greater media focus on the plight of
the vaquita, but the species continues to teeter at the
very brink of extinction (Crosta & Sutherland 2017).
Global awareness of the plight of the vaquita has
been bolstered, and continues to drive the cycle of
efforts invested in net retrieval within the vaquita
Endang Species Res 38: 11–27, 2019
refuge. In the end, the efforts of VaquitaCPR did not
compromise funding or the implementation of other
conservation actions.
VaquitaCPR followed the failure of efforts over
the past few decades to find alternatives to the use
of gillnets in the Upper Gulf. Those efforts to find
legal solutions were complicated, slow and difficult,
with conflicts arising between the fishing commu-
nities and those seeking to conserve vaquitas. The
sudden, unexpected emergence of the illegal
totoaba fishery sidelined any normal societal efforts
to meet the goals of vaquita conservation, biodiver-
sity protection, and socio-economic viability in the
upper Gulf of California. The rapid decline of the
vaquita stands as an important lesson on the vul-
nerability of critically endangered species to sudden
changes in threats and highlights the need for
longer-term contingency planning well before a
species reaches such critical levels of conservation
Acknowledgements. Manuscript authorship represents the
management team for this project. We thank the entire
VaquitaCPR field team and all those who worked alongside
us in San Felipe (G. Alker, J. Allen, S. Amozurrutia, J.
Antrim, D. Bader, L. Ballance, A. Barleycorn, J. Barlow, A.
Blancaforte, A. Borilla, D. Breese, S. M. Burton, S. Calderan,
V. Cendejas, K. Coughlin, R. Daniels, J. Danoff-Berg, M.
Dire, K. Danil, J. Dunham, B. Duryee, W. Elsen, J. C. H. Fer-
nandez, J. Filamor, L. Fish, K. Forney, E. Franks, J.
Gilpatrick, M. Gizowski, AC Ü, S. Hanson, K. Harding, A.
Henry, S. Higgins, R. Holland, K. Kreuger, T. Jefferson, C.
Lamendola, C. LeBert, K. Loflin, B. Lopez, J. Malloy, R. Mar-
tinson, J. McDaniel, J. Meegan, S. Mesnick, W. Musser, M.
Nájera, J.V. Ocampo, C. Oedekoven, H. Ohara-Quesada, R.
Olds, R. Pitman, M. Ponce Amaya, T. Pusser, V. Resendez, H.
Rico, I. Rodriguez, J. Rodriguez, P. Rodriguez, M. Rohr, J.C.
Salinas, B. Sarmiento, M. Schaaf, D. Schreher, A. Smith, J.
Smith, S. Stevenson, E. Vasquez, I. Vomend, B. Weisman, S.
Yin, N. Young, GSD; H. Nollens, C. Parry, R. Rivera, and T.
Romano for blood sample analyses; T. Robeck and N. Sted-
man for examination of ovarian tissue; O. Ryder and M.
Houck for tissue archiving; and A. Hall, J. Urban, N. Gales,
J. McBain, and R. R. Reeves for serving on the IRP. Six fish-
ermen were highly efficient managing deployments of
acoustic detectors. We thank CIRVA for their advice and
guidance throughout this effort. All animal handling was
conducted under permit no. SGPA/DGVS/07534/17. Va -
quita sample collection, shipping and international transport
was conducted under MMPA permits nos. 18786-02 and
19091; and CITES permits MX90273, 17US082589/9 and
17US774223/9. Public communication efforts were led by
Secretaría de Medio Ambiente y Recursos Naturales
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Proofs received from author(s): December 19, 2018
... Mark−recapture using photographic identification is another method to estimate population size. Photographic identification of vaquitas began in 2008 (Jefferson et al. 2009), and opportunistic photographs were obtained during the 'VaquitaCPR' (CPR: conservation, protection, recovery) effort in 2017 (Rojas-Bracho et al. 2019a) and during a dedicated effort to obtain a vaquita biopsy on 24−28 September 2018. Although no within-year photo-recaptures were obtained, this survey provided photographic matches to photographs from 2017 that showed vaquitas could calve annually , and a minimum of 6 animals seen on a single day helped inform the 2018 population size estimate ). ...
... We present no data on finfishing activities because vaquita visual research takes place in the fall during shrimp season, outside the finfish season. We observed no gillnetting inside protected vaquita areas in 2008(Gerrodette et al. 2011, Taylor et al. 2017, Rojas-Bracho et al. 2019a. In contrast, substantial gillnetting was observed within the ZTA in both 2019 and 2021, and fishers did not attempt to disguise their illegal activity (for examples of numbers and locations of boats see Rojas-Bracho et al. 2019b. ...
... During the 2017 attempts to capture vaquitas (Rojas-Bracho et al. 2019a), animals were seen to actively avoid nets, and one animal from the entangled pair of vaquitas was observed to briefly become entangled and escape from the net. The other entangled vaquita later died from capture myopathy (Rojas-Bracho et al. 2019a). Post-mortem examination of the 15 yr old female killed in that attempt revealed multiple linear scars and fluke/fin notches typical of healed previous entanglement injuries ( Rojas-Bracho et al. 2019a). ...
Full-text available
In 2018, it was estimated that fewer than 20 of Mexico’s endemic vaquita porpoise Phocoena sinus remained, and the species was declining by 47% yr ⁻¹ . Entanglement in gillnets is the sole threat to the species, and since the last population size estimate, gillnetting has increased in the small area where most vaquitas remain—a 12 × 24 km area in the Gulf of California near San Felipe, Mexico. We conducted research efforts in 2019 and 2021 in that area to estimate the minimum numbers of adults and calves and look for any signs that vaquitas are unhealthy. Through expert elicitation, we estimated between 7 and 15 unique individuals were seen in 2019 and 5-13 were seen in 2021. Calves were seen in both years, and all vaquitas appeared healthy. Population projections from the last full survey indicated that more vaquitas have survived than expected. We suggest that these surviving adult vaquitas may have learned to avoid entanglement in gillnets. These vaquitas and their calves provide hope that the species can survive. However, given the high levels of illegal gillnetting and the theft of equipment which hindered our monitoring efforts, and with only around 10 individuals remaining, survival can only be assured if vaquita habitat is made gillnet-free.
... Extraordinary efforts to assess and save the vaquita have included aerial and boat surveys, passive acoustic techniques, and captive care (Barlow, Fleischer, Forney, & Maravilla-Chávez, 1993;Taylor & Gerrodette, 1993;Barlow, Gerrodette, & Silber, 1997;Jaramillo-Legorreta, Rojas-Bracho, & Gerrodette, 1999;Jaramillo-Legorreta et al., 2007;Jaramillo-Legorreta et al., 2019;Rojas-Bracho et al., 2019). Despite such efforts, results have been deceptive because no effective actions have been implemented to eliminate bycatch mortality (Bobadilla, Álvarez-Borrego, Avila-Foucat, Lara-Valencia, & Espejel, 2011;Morzaria-Luna et al., 2013). ...
Introduction: Despite extensive science-based conservation policy recommendations, with fewer than 20 individuals remaining, the vaquita (Phocoena sinus) -endemic to the Gulf of California- is the world’s most endangered marine mammal due to incidental catch in fishing nets and whether it can recover is unclear. Objective: Assess expectations for vaquita over the next two decades. Methods: We identified factors affecting the vaquita, constructed life tables, derived demographic parameters for different scenarios and conducted a population viability analysis using stochastic age-structured matrix Leslie models. Results: Analytical results indicate that the vaquita net growth rate is particularly sensitive to juvenile survival. We find that intensive, ongoing bycatch in gillnets used to poach totoaba (Totoaba macdonaldi) over the past decade brought the vaquita population to its current critically low size. Currently this seems to be exacerbated by demographic stochasticity and a potential Allee effect. Conclusions: If totoaba poaching is eliminated immediately, demographically, vaquita can recover; its long-term survival will depend on its uncertain genetic status, although a recent study found encouraging results in this regard.
... p-value for smooth term < 0.001. dolphins with congestive heart failure (Smith et al., 2012) and one mature vaquita porpoise (Phocoena sinus) that developed pulmonary edema secondary to capture myopathy (Rojas-Bracho et al., 2019). However, we considered pulmonary edema unlikely in most BB dolphin cases given the lack of additional clinical findings to support this diagnosis. ...
Full-text available
The Deepwater Horizon (DWH) disaster resulted in large-scale contamination of bays, sounds, and estuaries in the northern Gulf of Mexico, home to multiple stocks of common bottlenose dolphins (Tursiops truncatus). Inhalation, aspiration, ingestion, and dermal absorption of oil and its toxic components were all considered possible routes of exposure for dolphins living within the oil spill footprint. To determine if dolphins were adversely impacted, catch-and-release health assessments were performed in heavily-oiled Barataria Bay (BB), Louisiana, and in Sarasota Bay (SB), Florida, a comparison site with no DWH oil contamination. Initial studies were conducted as part of a Natural Resource Damage Assessment (2011-2014) and follow-on studies were performed between 2016-2018 with support from the Gulf of Mexico Research Initiative. Ultrasound was used to evaluate the dolphins’ pulmonary health, including the presence/absence of pleural effusion, nodules, masses, consolidation, and alveolar interstitial syndrome (AIS). When present, AIS was further graded by severity (mild, moderate, or severe) and distribution. Based on the presence and severity of abnormalities, each dolphin was given an overall lung disease score (normal, mild, moderate, or severe). Normal to mild scores were considered within expected limits for a wild population, therefore the prevalence of normal-mild versus moderate-severe scores was compared between the oiled and unoiled sites. Separate analyses were conducted for dolphins alive in 2010 (and in BB, presumably exposed to DWH oil), and those born after 2010. For the dolphins alive in 2010, temporal trends were also examined using generalized additive models (GAMs). Results showed a strong difference (p=0.000357) in moderate to severe lung disease between the two sites for dolphins alive in 2010, but no significant difference (p=0.6745) between the sites for dolphins born after 2010. In BB dolphins, the prevalence of moderate to severe lung disease did not decrease in the years after the spill, and in fact, potentially worsened (p=0.0644 for trend over years), with the highest prevalence (0.61) being in 2018. Moderate to severe AIS remained a persistent finding in BB dolphins, and several animals had a pattern of AIS that was more severe ventrally than dorsally, with evidence of chronic, progressive disease states.
... All samples were collected as dead strandings, except for the vaquita and one common bottlenose dolphin that died from directed and incidental capture, respectively. 26 All nonbycatch BC samples were decomposing (SI Table 1), and blubber tissue could not be separated from muscle tissue. Thus, all analyzed BC samples contained both blubber and muscle tissues, except for the vaquita and single Table 2). ...
Coastal reintroduction sites for California condors (Gymnogyps californianus) can lead to elevated halogenated organic compound (HOC) exposure and potential health impacts due to the consumption of scavenged marine mammals. Using nontargeted analysis based on comprehensive two-dimensional gas chromatography coupled to time-of-flight mass spectrometry (GC×GC/TOF-MS), we compared HOC profiles of plasma from inland and coastal scavenging California condors from the state of California (CA), and marine mammal blubber from CA and the Gulf of California off Baja California (BC), Mexico. We detected more HOCs in coastal condors (32 ± 5, mean number of HOCs ± SD, n = 7) than in inland condors (8 ± 1, n = 10) and in CA marine mammals (136 ± 87, n = 25) than in BC marine mammals (55 ± 46, n = 8). ∑DDT-related compounds, ∑PCBs, and total tris(chlorophenyl)methane (∑TCPM) were, respectively, ∼7, ∼3.5, and ∼148 times more abundant in CA than in BC marine mammals. The endocrine-disrupting potential of selected polychlorinated biphenyls (PCB) congeners, TCPM, and TCPMOH was determined by in vitro California condor estrogen receptor (ER) activation. The higher levels of HOCs in coastal condors compared to those in inland condors and lower levels of HOC contamination in Baja California marine mammals compared to those from the state of California are factors to consider in condor reintroduction efforts.
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River cetaceans are particularly vulnerable to anthropogenic impacts due to their constrained ranges in freshwater systems of China, South Asia, and South America. We undertook an exhaustive review of 280 peer-reviewed papers and grey literature reports (1998−2020) to examine the current status of knowledge regarding these cetaceans and their conservation. We aimed to better understand the scale of threats they face, and to identify and propose priority future efforts to better conserve these species. We found that the species have been studied with varying frequency and that most of the research on threats has focused on habitat degradation and fragmentation (43%, mainly driven by dams and extractive activities such as sand mining and deforestation), and fishery interactions (39%, in the form of bycatch and direct take). These threats occur across all species, but more information is needed, primarily on quantifying the population impacts as a basis for designing mitigation measures. Other threats identified include pollution, vessel collisions, traditional use, and poorly managed tourism. Emerging methods such as environmental DNA and unmanned aerial vehicles are described for studying these species. Promising conservation interventions include cetacean-specific protected areas, natural ex situ protection, community-led conservation, and education programmes. However, transnational political will is required for a step change towards broad-scale protection in freshwater environments. In addition, we propose in creasing capacity building, developing management plans, working closely with fishing communities, enhancing public awareness, expanding regional collaborations, and diversifying funding.
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Human use of oceans has dramatically increased in the 21st century. Sea turtles are vulnerable to anthropogenic stressors in the marine environment because of lengthy migrations between foraging and breeding sites, often along coastal migration corridors. Little is known about how movement and threat interact specifically for male sea turtles. To better understand male sea turtle movement and the threats they encounter, we satellite-tagged 40 adult male sea turtles of four different species. We calculated movement patterns using state-space modeling (SSM), and quantified threats in seven unique categories; shipping, fishing, light pollution, oil rigs, proximity to coast, marine protected area (MPA) status, and location within or outside of the U.S. Exclusive Economic Zone (EEZ). We found significantly higher threat severity in northern and southern latitudes for green turtles (Chelonia mydas) and Kemp’s ridleys (Lepidochelys kempii) in our study area. Those threats were pervasive, with only 35.9% of SSM points encountering no high threat exposure, of which 47% belong to just two individuals. Kemp’s ridleys were most exposed to high threats among tested species. Lastly, turtles within MPA boundaries face significantly lower threat exposure, indicating MPAs could be a useful conservation tool.
Cetacean rehabilitation is always a big challenge, especially when it involves species that there exists little information about. Pontoporia blainvillei is one of those species. Although much information about its biology is published, franciscana’s rehabilitation and maintenance in captivity is still a big concern. Most live stranded animals consist of newborns, victims of bycatch, and they survive only for a few hours or days. All efforts to rehabilitate stranded animals need to be done. A single success will immensely contribute to the conservation of species since it is the best manner to collect data about species behavior, physiology, and biology.
This chapter offers some personal thoughts and reflections on strategies taken to manage human activities and limit or lessen their impacts on whales, dolphins, and porpoises. OverkillOverkill in one form or another, whether by targeted hunting or by accidental mortality from entanglementEntanglementin fishing gearFishing gearor vessel strikesVessel strike, has been the main driver of cetaceanCetacea/cetaceanspopulationPopulation declines, and measures taken to prevent or strictly limit the killing have proven to be the best ways to achieve conservationConservationand recoveryRecovery. The cessation of commercial whalingCommercial whaling, for example, occurred in the nick of time for some of the large whales. However, the numbers of North Atlantic and North Pacific right whalesRight whale, North Atlantic had been driven so low by whalingWhaling that ongoing mortality caused by other human activities has been enough to keep those species on the brink. Although the Yangtze River dolphinYangtze River dolphin, baiji (baiji) has gone extinctExtinct and efforts to save the vaquitaVaquita have fallen short, some progress has been made at buying time for Yangtze finless porpoisesYangtze finless porpoise through a combination of ex situEx-situmanagementManagement and fishery closures; and for large whales, through disentanglementDisentanglement programs and initial attempts to control ship traffic. The long-term dedication of exceptional people who function as ‘champions’ of the animals is often an essential ingredient for successful conservationConservation. It should never be assumed that the task of conservingConserving cetaceans is one that can be completed, with needed actions taken only once. Rather, the actions must be at least overseen and monitored and, if and when necessary, repeated again and again.
People have held marine mammalsMarine mammals captive for public displayPublic display for centuries, and the history of peoples’ engagement with free-ranging marine mammals has an even longer history. Currently, most concern is expressed over keeping cetaceansCetacea/cetaceans captive, rather than other marine mammals, so cetaceans are the focus of this chapter. Conservation and animal welfareAnimal welfare arguments against catching free-ranging cetaceans have gained traction in many countries in recent decades. Few nations now have live-captureLive capture industries. The reasons for and against maintaining captive cetaceans continue to be debated. While some countries have banned keeping cetaceans captive for entertainmentEntertainment, the industry is growing in others, particularly China. As standards for captive husbandry in some of these new operations are poor, survivalSurvivaland welfareWelfare there remain problematic. In some other nations, conditions for captive cetaceans have improved markedly, and captive dolphins live at least as long as their free-ranging conspecifics. The recent extinctionExtinction of the baijiBaiji and dire conservationConservation situation of other small odontocetes have led to a call for new thinking on the possible role of ex situ conservationEx situ conservation measures. For this, the veterinary and husbandry skills developed for captive cetaceans can play a role in integrated conservationConservation programs. There is a continuum of interactionsInteractionwith cetaceansCetacea/cetaceans, from remote observation of free-ranging animals, through engagement with dolphins that seek human interaction, semi-natural reservesSemi-natural reserves used in the conservationConservation programs, to cetaceans kept in indoor pools far from the ocean. The development of oceanic sanctuariesSanctuary/ies to house cetaceans formerly held in entertainmentEntertainment facilities adds to this continuum, and allows more options for integrated conservationConservation. As humanity’s understanding of the complexity of the lives of cetaceans has improved, our ethicalEthical stance on some aspects of maintaining them in captivityCaptivity has shifted. At the same time, our need to engage the public with conservationConservation messaging, and to manage the welfareWelfare of free-ranging cetaceansCetacea/cetaceans injured by human actions, has also grown.
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The vaquita (Phocoena sinus) is the most endangered species of cetacean in the world, with an estimated global population of less than 150 individuals. The species is listed as Critically Endangered by the IUCN, and is on the U.S. and Mexican endangered species lists. It is expected that the population will dwindle to extinction if management solutions (primarily the removal of gillnets from the species' range) are not implemented in the next couple of years. The lack of high-quality photographic images of living vaquitas has been a serious impediment to conservation efforts for the species. This project aimed to obtain the first such images and to evaluate the potential for using photo-identification to study the species. Twenty surveys were conducted in the northern Gulf of California between 2 and 30 October 2008. We observed 13 groups of vaquitas and several dozen high-quality images were obtained, which are currently being used for conservation and education purposes. We were also able to identify six individuals from natural markings, although two of these may not possess markings suitable for long-term identification. Based on the small sample, an estimated 24-31% of adult vaquitas possess long-term markings, and thus photo-identification appears to be a valid technique for use with this species. All photographed individuals appeared healthy, with no evidence of malnutrition, and several calves were observed. Future planned work will include long-term photo- identification studies to examine aspects of the species' life history, movements, social organization, and health status. Through these efforts we hope to increase the prospects for the species' long-term survival.
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Quantifying intraspecific variation in movement behaviour of marine predators and the underlying environmental drivers is important to inform conservation management of protected species. Here, we provide the first empirical data on fine-scale movements of free-ranging harbour porpoises (Phocoena phocoena) in their natural habitat. Data were obtained from six individuals, tagged in two areas of the Danish North Sea, that were equipped with Global Positioning System (GPS) and dive recorder units (V-tags). We used multi-model inference and model averaging to evaluate the relative importance of various static and dynamic environmental conditions on the movement characteristics: speed, turning angle, dive duration, dive depth, dive wiggliness (a proxy for prey chasing behaviour), and post-dive duration. Despite substantial individual differences in horizontal and vertical movement patterns, we found that all the tracked porpoises responded similar to variation in environmental conditions and displayed movements that indicate a higher likelihood of foraging behaviour in shallower and more saline waters. Our study contributes to the identification of important feeding areas for porpoises and can be used to improve existing movement-based simulation models that aim to assess the impact of anthropogenic disturbance on harbour porpoise populations. Electronic supplementary material The online version of this article (10.1007/s00227-018-3346-7) contains supplementary material, which is available to authorized users.
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Harbour porpoises Phocoena phocoena are common in continental shelf areas of the North Atlantic, but little information is available on their occurrence outside coastal areas. In this study, 30 harbour porpoises were actively caught in West Greenland and instrumented with satellite transmitters to document their seasonal movements and diving behaviour. The porpoises displayed long-range oceanic movements within the North Atlantic, especially during winter/spring where they moved over areas with water depths >2500 m. While offshore, 2 females demonstrated an average maximum dive depth of 248 m, with the deepest dive reaching 410 m. This behaviour is in contrast to 71 porpoises tagged in Danish waters of the North Sea which did not leave the continental shelf but showed a preference for areas with shallow waters year round, even when at the edge of the continental shelf where greater depths were available. Six tags from Greenland transmitted long enough (up to 3 yr) to demonstrate extensive movements and strong site fidelity to the tagging site in West Greenland the following summer. This study documents that harbour porpoises use oceanic habitats and can dive to depths that enable mesopelagic foraging, while repeatedly demonstrating summer site fidelity to coastal areas.
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The vaquita is a critically endangered species of porpoise. It produces echolocation clicks, making it a good candidate for passive acoustic monitoring. A systematic grid of sensors has been deployed for 3 months annually since 2011; results from 2016 are reported here. Statistical models (to compensate for non-uniform data loss) show an overall decline in the acoustic detection rate between 2015 and 2016 of 49% (95% credible interval 82% decline to 8% increase), and total decline between 2011 and 2016 of over 90%. Assuming the acoustic detection rate is proportional to population size, approximately 30 vaquita (95% credible interval 8–96) remained in November 2016.
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The number of Mexico's endemic porpoise, the vaquita (Phocoena sinus), is collapsing primarily due to bycatch in illegal gillnets set for totoaba (Totoaba macdonaldi), an endangered fish whose swim bladders are exported to China. Previous research estimated that vaquitas declined from about 567 to 245 individuals between 1997 and 2008. Acoustic monitoring between 2011 and 2015 showed a decline of 34%/year. Here, we combine visual line transect and passive acoustic data collected simultaneously in a robust spatial analysis to estimate that only 59 (95% Bayesian Credible Interval [CRI] 22–145) vaquita remained as of autumn 2015, a decrease since 1997 of 92% (95% CRI 80–97%). Risk analysis suggests that if the current, temporary gillnet ban is maintained and effectively enforced, vaquitas could recover to 2008 population levels by 2050. Otherwise, the species is likely to be extinct within a decade.
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For threatened and endangered species, translocations have been widely used to mitigate multiple sources of mortality that threaten population recovery. Although numerous Hawaiian monk seals Neomonachus schauinslandi have been translocated for a variety of purposes, few monk seal translocations have addressed the problem of prey limitation. To assess the efficacy of using translocations to mitigate reduced prey availability, 12 weanling monk seals were translocated with pre-release health screening and post-release monitoring. Specifically, the health, foraging behavior, habitat use, and survival of translocated seals were compared with those of 17 monk seals resident to the release site. There was little evidence of infectious diseases in translocated and resident seals, although Chlamydophila abortus antibodies and enteric bacteria were detected in many individuals. Translocated and resident weanling seals also demonstrated similar diving, movements, and habitat use, whereas resident adult seals had greater variability in foraging patterns. First-year survival for translocated weanlings (50%, n = 12) and non-translocated weanlings at the donor (31%, n = 36) and recipient sites (69%, n = 16) was related to weaning body size, with larger individuals having greater survivorship. These results supported 3 main conclusions that have important consequences for future translocation and population recovery efforts: (1) there was minimal risk of exposing seals to novel infectious diseases as a result of translocation; (2) individuals translocated with limited foraging experience rapidly adapted to their post-release environment; and (3) translocation for the purpose of mitigating prey limitation is a viable and important conservation tool for Hawaiian monk seals.
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The vaquita (Phocoena sinus) is the world's most endangered marine mammal with ≈245 individuals remaining in 2008. This species of porpoise is endemic to the northern Gulf of California, Mexico, and has historically suffered population declines from unsustainable bycatch in gillnets. An illegal gillnet fishery for an endangered fish, the totoaba (Totoaba macdonaldi), has recently resurged throughout the vaquita's range. The secretive but lucrative wildlife trade with China for totoaba swim bladders has probably increased vaquita bycatch mortality, but by an unknown amount. Precise population monitoring by visual surveys is difficult because vaquitas are inherently hard to see and have now become so rare that sighting rates are very low. However, their echolocation clicks can be identified readily on specialized acoustic detectors. Acoustic detections on an array of 46 moored detectors indicate that vaquita acoustic activity declined by 80% between 2011 and 2015 in the central part of the species' range. Statistical models estimate an annual rate of decline of 34% (95% Bayesian Credible Interval -48% to -21%). Based on preliminary acoustic monitoring results from 2011-2014 the Government of Mexico enacted and is enforcing an emergency 2-year ban of gillnets throughout the species' range to prevent extinction, at a cost of $74 million USD to compensate fishers. Developing precise acoustic monitoring methods proved critical to exposing the severity of vaquitas' decline and emphasizes the need for continual monitoring to effectively manage critically endangered species. This article is protected by copyright. All rights reserved.