Phocoena sinus

http://dx.doi.org/10.2305/IUCN.UK.2017-2.RLTS.T17028A50370296.en

Scope: Global

Language: English

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Taxonomy

Assessment Information

Geographic Range

Population

Habitat and Ecology

Threats

Conservation Actions

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Taxonomy [top]

Kingdom	Phylum	Class	Order	Family
Animalia	Chordata	Mammalia	Cetartiodactyla	Phocoenidae

Scientific Name:

Phocoena sinus Norris & McFarland, 1958

Common Name(s):

English	–	Vaquita, Gulf Of California Harbour Porpoise, Gulf Of California Porpoise, Gulf Porpoise
French	–	Marsouin Du Golfe De Californie

Taxonomic Notes:

Genetic (Rosel et al. 1995) and morphological (Brownell et al. 1987) data suggest that Vaquitas are most closely related to porpoises in South America. Genetic data suggest divergence from two sister taxa (Burmeister’s porpoise, Phocoena spinipinnis and spectacled porpoise Australophocaena dioptrica) in the Pleistocene (i.e., at least 2.5 million years ago).

Assessment Information [top]

Red List Category & Criteria:	Critically Endangered A2a+4d; C1+2a(ii); D; E ver 3.1
Year Published:	2017
Date Assessed:	2017-07-20
Assessor(s):	Rojas-Bracho, L. & Taylor, B.L.
Reviewer(s):	Reeves, R. & Jaramillo-Legorreta, A.
Facilitator/Compiler(s):	Lowry, L., Chiozza, F., Pollock, C.M.
Justification: The Vaquita qualifies for listing on the IUCN Red List as Critically Endangered based on criteria A2a, C1, C2a(ii), D, and E. The generation time for the Vaquita is estimated as 10 years (Rojas-Bracho and Taylor 1999, Taylor and Rojas-Bracho 1999), therefore three generations is approximately 30 years. Criterion A2a: The best estimate of total population size is from 2016: posterior mean = 33 (median = 27, 95% credible interval (CRI), 8 to 96) (Comité Internacional para la Recuperación de la Vaquita, CIRVA 8, 2016). [Throughout this assessment, reports of CIRVA are cited by number [chronological sequence] and year.]. The estimated number of Vaquitas in 1997 was 567 (95% confidence interval (CI), 177-1,073; Jaramillo-Legorreta et al. 1999). Thus, in approximately two generations, the population declined by 94%, which is a direct observation and is clearly greater than 80% over three generations. The main threat (entanglement in gillnets) is known and could be reversible but has not ceased. Criterion C1: The total population in 2017 numbered around 30, so clearly the number of mature individuals is fewer than 250 and the decline in a single year was around 50% (CIRVA 8, 2016) and therefore the reduction exceeds 25% in one generation. Criterion C2a(ii): The total population numbers around 30, so clearly the number of mature individuals is fewer than 250, there is a continuing observed decline, and all mature individuals are in one subpopulation. Criterion D: The total population numbers around 30, so clearly the number of mature individuals is fewer than 50. Criterion E: Projections of the 2015 population abundance using the observed rate of decline resulted in extinction being likely (>50%) within 10 years (a single generation) (Taylor et al. 2016). This analysis was acknowledged to underestimate risk but still clearly meets the criterion to exceed a 50% probability of extinction within three generations (30 years).
Previously published Red List assessments:	2008 – Critically Endangered (CR) 2007 – Critically Endangered (CR) Download assessment 1996 – Critically Endangered (CR) Download assessment 1994 – Endangered (E) Download assessment 1990 – Endangered (E) Download assessment 1988 – Vulnerable (V) Download assessment 1986 – Vulnerable (V) Download assessment

Geographic Range [top]

Range Description:

The Vaquita is known to occur only in the northern Gulf of California, Mexico, mainly north of 30º45'N and west of 114º20'W (Gerrodette et al. 1995). The area of highest remaining numbers is centred at Rocas Consag, some 40 km northeast of the town of San Felipe, Baja California.

The Vaquita is endemic to the upper quarter of Gulf of California. Its extent of occurrence (EOO) and area of occupancy (AOO) (core area) is approximately 3,000 km².

Countries occurrence:

Native:

Mexico (Baja California, Sonora)

FAO Marine Fishing Areas:

Native:

Pacific – eastern central

Additional data:

♦ Estimated area of occupancy (AOO) - km2:	2000	♦ Continuing decline in area of occupancy (AOO):	No
♦ Extreme fluctuations in area of occupancy (AOO):	No	♦ Estimated extent of occurrence (EOO) - km2:
♦ Continuing decline in extent of occurrence (EOO):	No	♦ Extreme fluctuations in extent of occurrence (EOO):	No
♦ Number of Locations:	1	♦ Continuing decline in number of locations:	No
♦ Extreme fluctuations in the number of locations:	No
♦ Lower depth limit (metres):	50

Range Map:

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Population [top]

Population:

There have been three complete surveys for Vaquitas, resulting in abundance estimates as follows: in 1997 abundance was estimated to be 567 (95% CI, 177-1,073; Jaramillo-Legorreta et al. 1999); in 2008 abundance was estimated to be 245 animals (95% CI, 68-884; Gerrodette et al. 2011); and in 2015 abundance was estimated to be 59 (95% CRI 22-145; Taylor et al. 2016). These three abundance estimates revealed a catastrophic population decline has been occurring. Past (1997-2007) and ongoing acoustic monitoring programs (2011-2017) provide additional datasets that also document this catastrophic decline (Jaramillo-Legorreta 2008, Jaramillo-Legorreta et al. 2016). Using the 2015-2016 acoustic monitoring data and the 2015 abundance estimate, the species was likely to number only about 30 individuals as of November 2016 (posterior mean = 33, median = 27, 95% CRI: 8 to 96; CIRVA 8, 2016) and will likely be extinct within a decade.

As noted above, between 1997 and 2008 Vaquita numbers declined by an average of 7.6%, from an estimated 567 to 245 animals. The acoustic monitoring program between 1997 and 2007 also independently estimated an average decline rate of 7.6%/year. This decline was consistent with mortality rates estimated by D’Agrosa et al. (2000) and plausible growth rates estimated by Gerrodette and Rojas-Bracho (2011). Between 2008 and 2015, Vaquita numbers declined from an estimated 245 to only 59 animals. Separately, a passive acoustic monitoring program from 2011 through 2015 estimated Vaquita abundance was declining by 34%/year (95% Bayesian CRI, -48% to -21%; Jaramillo-Legorreta et al. 2016) over that time period. Additional acoustic monitoring between 2015 and 2016 revealed the annual average decline was -49% (95% CRI = -82% to +8%).

The only demographic data for Vaquita relevant to maximum net productivity rates come from Hohn et al. (1996). Interbirth interval was estimated to be 2 years based on inspection of ovaries of a limited number of adult females. This differs from the 1-year interval typical of other porpoises. A modelling exercise (Gerrodette and Rojas-Bracho 2011) used the Hohn data plus data from Harbor Porpoises (Phocoena phocoena) (Moore and Read 2008) and arrived at a posterior mode of 3.8%/year (95% CRI, 1.5 to 7.8%). In a population modelling exercise using data on fishing effort, 1997 abundance, and passive acoustic monitoring (1997-2007), it was estimated that historic population level of Vaquita previous to its capture in fishing activities could have been about 5,000 individuals (95% credible interval 2,088-10,697) (Jaramillo-Legorreta, 2008). This implies that current population level could be less than 1% of the historic level.

Current Population Trend:

Decreasing

Additional data:

♦ Number of mature individuals:	18	♦ Continuing decline of mature individuals:	Yes
♦ Extreme fluctuations:	No	♦ Population severely fragmented:	No
♦ No. of subpopulations:	0
♦ Extreme fluctuations in subpopulations:	No	♦ All individuals in one subpopulation:	Yes

Habitat and Ecology [top]

Habitat and Ecology:	The Vaquita lives in a relatively shallow (<50 m), turbid and dynamic marine environment (Vidal 1995, Rojas-Bracho and Jaramillo-Legorreta 2002). Vaquitas feed on a variety of demersal or benthic fishes, squids, and crustaceans. They have been observed singly and in small groups of up to 8-10 individuals (mean = 2), but many such groups can be loosely aggregated over several km².
Systems:	Marine
Continuing decline in area, extent and/or quality of habitat:	Unknown
Generation Length (years):	10
Movement patterns:	Not a Migrant

Threats [top]

Major Threat(s):	Mortality in gillnets of various mesh sizes has long been recognized as the most serious and immediate threat to the Vaquita's survival (Vidal 1993, 1995, Reeves and Leatherwood 1994, IWC 1995, Rojas-Bracho and Taylor 1999, Rojas-Bracho et al. 2006). The only available estimates of the Vaquita bycatch rate are 39 (using one method) and 84 (using a different method) animals killed per year by boats from a single port (D'Agrosa et al. 2000). This alone would represent 7 or 15%, respectively, of the estimated total population size (Rojas-Bracho and Jaramillo-Legorreta 2002). Other potential threats that have been suggested, but that appear not to be significant risk factors at present, include inbreeding depression, pesticide exposure and ecological changes as a result of reduced flow from the Colorado River (Taylor and Rojas-Bracho 1999, Brusca et al. 2017).

Major Threat(s):

Mortality in gillnets of various mesh sizes has long been recognized as the most serious and immediate threat to the Vaquita's survival (Vidal 1993, 1995, Reeves and Leatherwood 1994, IWC 1995, Rojas-Bracho and Taylor 1999, Rojas-Bracho et al. 2006). The only available estimates of the Vaquita bycatch rate are 39 (using one method) and 84 (using a different method) animals killed per year by boats from a single port (D'Agrosa et al. 2000). This alone would represent 7 or 15%, respectively, of the estimated total population size (Rojas-Bracho and Jaramillo-Legorreta 2002). Other potential threats that have been suggested, but that appear not to be significant risk factors at present, include inbreeding depression, pesticide exposure and ecological changes as a result of reduced flow from the Colorado River (Taylor and Rojas-Bracho 1999, Brusca et al. 2017).

Conservation Actions [top]

Conservation Actions:	An International Committee for the Recovery of the Vaquita (Comité Internacional para la Recuperación de la Vaquita, CIRVA) was established in 1997 and has developed many recommendations over its nine reports (current through July 2017). The most consistent and important recommendation is to permanently ban the manufacture, possession, or use of all gillnets on land or sea throughout the range of Vaquitas. In June 2017, a permanent ban was published in the Mexican Federal Register that made the use or transport of gillnets illegal, with exemptions for two fish species (Curvina, Cynoscion othonopterus, and Pacific Sierra, Scomberomorus sierra). Night fishing was banned and legal entry (departure from land) and exit (landing) points were restricted. Since many of these provisions were temporarily in place from 2015-2017 and illegal fishing continued to occur at high rates, better compliance and enforcement are essential and it remains to be seen whether this will be forthcoming. CIRVA also recommended that as many Vaquitas as possible be removed into protective sanctuary as quickly as possible. An international team (VaquitaCPR) was formed to carry out this effort. The first attempt to capture and maintain Vaquitas is planned for autumn 2017. The Vaquita is listed on Appendix I of the Convention on International Trade in Endangered Species.

Conservation Actions:

An International Committee for the Recovery of the Vaquita (Comité Internacional para la Recuperación de la Vaquita, CIRVA) was established in 1997 and has developed many recommendations over its nine reports (current through July 2017). The most consistent and important recommendation is to permanently ban the manufacture, possession, or use of all gillnets on land or sea throughout the range of Vaquitas. In June 2017, a permanent ban was published in the Mexican Federal Register that made the use or transport of gillnets illegal, with exemptions for two fish species (Curvina, Cynoscion othonopterus, and Pacific Sierra, Scomberomorus sierra). Night fishing was banned and legal entry (departure from land) and exit (landing) points were restricted. Since many of these provisions were temporarily in place from 2015-2017 and illegal fishing continued to occur at high rates, better compliance and enforcement are essential and it remains to be seen whether this will be forthcoming.

CIRVA also recommended that as many Vaquitas as possible be removed into protective sanctuary as quickly as possible. An international team (VaquitaCPR) was formed to carry out this effort. The first attempt to capture and maintain Vaquitas is planned for autumn 2017.

The Vaquita is listed on Appendix I of the Convention on International Trade in Endangered Species.

Citation:	Rojas-Bracho, L. & Taylor, B.L. 2017. Phocoena sinus. The IUCN Red List of Threatened Species 2017: e.T17028A50370296. http://dx.doi.org/10.2305/IUCN.UK.2017-2.RLTS.T17028A50370296.en. Downloaded on 10 March 2018.
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