Expedición Internacional Vaquita Marina 2015: Conservation and Abundance

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The International Recovery Team (CIRVA) met in December, 2015 to learn preliminary results about the survey and consider other key elements needed to save vaquitas including enforcement and development of alternative fishing gear. The short report is now available (English, Spanish).


Vaquita population and abundance 13 May 2016 300x185
Decline in the numbers of vaquitas (from CIRVA VII report)

Abundance and trends: Historical abundance of the vaquita is unknown, but genetic evidence indicates that the population was never large (Rojas-Bracho et al., 2006). The first precise estimate of abundance was obtained from a cooperative Mexican-American survey conducted in 1997 that sampled the entire geographical range of the species and estimated there were 567 individuals (95% CI 177-1073; (Jaramillo-Legoretta et al., 1999). Early acoustic work between 1997 and 2008 indicated a decline (Jaramillo-Legoretta & Rojas-Bracho, 2008).  These data agree with population estimates based on the 1997 visual abundance estimate, combined with the increased number of pangas in the area, the estimated kill rate from bycatch in gillnets and potential vaquita population growth rate (Jaramillo-Legoretta et al., 2007). A second Mexican-American survey was conducted in 2008 and estimated total vaquita abundance to be 245 animals (CV = 73%, 05% CI 68-884) (Gerrodette et al. 2011).  The 2008 estimate was 57% lower than the 1997 estimate, an average rate of decline of 7.6%/year.  The 2008 research also gathered data to allow design of a passive acoustic monitoring program using a device that detects vaquita events called a CPOD.  The acoustic monitoring program uses a grid of 48 CPODs inside the Vaquita Refuge.  The Refuge covers about 50% of vaquitas’ distribution but could not be monitored due to loss of the CPODs to active fishing (both gillnetting and trawling).  Results indicated a 67% decline in acoustic activity in the sampled area, for an annual rate of 31% (CIRVA VI Report, in IWC/66/Rep01(2015), Annex L).  Simple models suggest that in 2015 there are fewer than 100 vaquitas remaining.

  Vaquita Netted 300px
  Vaquita entangled in gillnet set for totoaba, ca. 1992 (Cristian Faesi, copyright Omar Vidal)

Interaction with Fisheries: Coincident with the recognition of the vaquita as a new species was the realization that individuals were being incidentally taken in small scale and industrial commercial fisheries (Norris & Prescott, 1961). From around the mid-1930s (Brownell, 1982) to the mid-1970s (Flanagan & Hendrickson, 1976), the most important fishery in terms of vaquita by-catch was the gillnet fishery for totoaba, Totoaba macdonaldi, a large fish up to 2 m in length and can exceed 100 kg in weight that is endemic to the Gulf of California.  Despite the closure, many vaquitas continued to die in illegal totoaba nets (Vidal 1995 and see details of the early totoaba fishery in Rojas-Bracho and Taylor 1999). This fishery was officially closed in 1975 because of severe overfishing (the species is on the Mexican Endangered Species list, listed as CITES Appendix I (1976), added to the U.S. Endangered Species list (1979) and is listed (1986) by the IUCN Red List as Critically Endangered). Even following closure of the totoaba fishing, many vaquitas died in both illegal fishing (Vidal 1995) and some in an experimental fishery (see summary of early levels of vaquita kills in totoaba nets in Rojas-Bracho and Taylor 1999).  Since that time, and perhaps before, it has become known that vaquita are incidentally caught in gillnets set for shrimp and fish. D’Agrosa et al. (2000) found that some level of vaquita bycatch is known to occur in most, if not all, types of gillnets used in this area. The small scale gillnet fisheries in the northern Gulf of California generally involve the use of boats known as pangas which are (mainly) fiberglass, outboard-powered boats 6-8 meters long crewed by two or three local men (Vidal et al., 1994). The gillnet fishery is highly dynamic due to a combination of environmental variation, market factors and overexploitation (Rojas-Bracho et al., 2006). Much of the market for fish is domestic. Species targeted include corvina Cynoscion othonopterus, mackerels (sierra, Scomberomorus sierra; also S. concolor), chano (Micropogonias megalops), sharks (including Carcharhinus spp., Sphyrna spp., Rhizoprionodon spp. and Mustelus spp.), and skates and rays (including Myliobatis spp., Rhinobatus spp., Dasyatis brevis, Mobula spp.). The high-value shrimp fishery in the northern Gulf includes a large industrial trawling fleet as well as the pangas that fish with gillnets. The product, especially fresh-frozen shrimp, is consumed locally or exported to the United States (Rojas- Bracho et al., 2006). 

Carlos Navarro with Totoaba and Vaquita 300px
  Totoaba and vaquita killed in gillnet fishery for totoaba (Photo taken ca. 1991-1992, Omar Vidal)

Illegal fishing for totoaba has greatly increased in the past few years and is a great menace to the vaquita.  As in previous years, vaquitas have died in nets set for totoaba.  In addition to the meat, this endangered fish is prized for its swim bladder, which is exported to China where it is used as an ingredient in soup and believed to have medicinal value. Thousands of swim bladders are dried and smuggled out of Mexico, often through the United States. The remainder of the fish is left to rot on the beach. Fishermen receive up to $8,500 for each kilogram of totoaba swim bladder, equivalent to half a year’s income from legal fishing activities.

Threat assessment: Rojas-Bracho & Taylor (1999) examined whether four hypothesized factors constituted threats that could place the vaquita at risk of extinction.  The putative threats and conclusions about their importance are: (1) habitat alteration from reduced flow of the Colorado River does not currently appear to be a threat because ecosystem productivity (nutrient levels and chlorophyll) remains high in vaquita habitat and vaquitas examined after dying in fishing nets appeared to be feeding normally (ie., they were not emaciated); (2) pollutant loads in tissues of bycaught animals are low and available data show that pollutants pose no threat to the survival of the remaining population; (3) reduced fitness from inbreeding depression and loss of genetic variability are unlikely to pose high risk currently, though risk will increase if' vaquitas remain at low abundance over long periods of time; and (4) mortality resulting from fisheries bycatch poses high risk because deaths in nets far exceed possible replacement by births. The authors note that short term management should not be hindered by uncertainty in estimating the magnitude of these threats, and primary conservation efforts should be directed toward immediate elimination of incidental fishery mortality.  These conclusions have been repeatedly confirmed by CIRVA, the International Committee for the Recovery of the Vaquita (CIRVA 1997, 1999, 2004, 2012, 2014, 2015).  Recent research focused on vaquita and productivity of the Northern Gulf has corroborated CIRVA´s conclusion: this region has remained a healthy system at the level of primary producers in spite of the possible lack of supply of nutrients by the Colorado River.  The small size of the population of vaquitas is not due to the collapse of its ecosystem.

Bycatch estimates: Gillnets for fish and shrimp cause incidental mortality (bycatch) of  vaquitas.  The only published study that estimates bycatch is from 1993–94 and refers to El Golfo de Santa Clara, one of the three main fishing ports (D’Agrosa et al., 2000).  The authors estimated that 39 individuals were killed per year (95% CI 14–93) using combined data from observers and interviews with fishermen. Assuming a similar rate of mortality from the port of San Felipe, the extrapolated estimate of incidental mortality for the two ports was 78 vaquita killed per year in 1993 (D’Agrosa et al., 2000), which is well above what would be sustainable for this species (D’Agrosa et al., 2000; Rojas-Bracho et al., 2006).

Alternative Small Shrimp Trawl 300px
Small-type trawl approved in NOM 002 to replace gillnets. Numbers refer to design features to reduce bycatch of turtles and fish. Courtesy of WWF-Mexico.

Conservation Efforts:  Working alongside scientists and non-governmental agencies, the Government of Mexico has taken a number of actions over the years that were intended to eliminate gillnets from the region and to protect the vaquita.  Among these efforts are the designation of a Biosphere Reserve (The Upper Gulf of California and Colorado River Delta Biosphere Reserve, a UNESCO World Heritage Site) in 1993 and, in 2005, the establishment of a Vaquita Refuge, where all commercial fishing (including gillnets) is banned in core vaquita habitat.  In 2008, the Government introduced the Species Conservation Action Plan for Vaquita (PACE Vaquita ), a comprehensive protection and recovery effort which includes a program to encourage fishermen to switch to fishing gear that does not threaten vaquitas.  Despite the investment by the Government of Mexico of more than $40M USD, these actions may have slowed, but did not stop, the decline of the species (Rojas-Bracho and Reeves, 2013).  The Government of Mexico continued to make forward progress in reducing gillnets in vaquita habitat by adopting regulations (NOM 002) to switch all shrimp gillnetting to small-type trawls over a 3 year period.  They also formed a Presidential Commission for the recovery of vaquitas.

Following the reporting of results from the acoustic monitoring program that revealed the dramatic decline in the species from 2011 onwards, CIRVA recommended an emergency gillnet ban throughout the range of vaquitas before the opening of shrimp season in September 2014.

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Participants in the CIRVA V meeting that led to recommending an emergency ban of gillnets throughout the range of vaqutias.

The 5th meeting of CIRVA followed the initial results of the decline from acoustic monitoring.  The international recovery team recommended:

  1. CIRVA strongly recommends that the Government of Mexico enact emergency regulations establishing a gillnet exclusion zone (Fig. 2) covering the full range of the vaquita - not simply the existing Refuge - starting in September 2014.
  2. CIRVA recommends that the Government of Mexico provide sufficient enforcement to ensure that gillnet fishing is eliminated within the exclusion zone.
  3. CIRVA recommends that all available enforcement tools, both within and outside Mexico, be applied to stopping illegal fishing, especially the capture of totoabas and the trade in their products.
  4. CIRVA recommends that a clear statement of the resources of PROFEPA and its resources in the Upper Gulf of California is needed, along with information on all co-operative enforcement efforts of other agencies.
  5. CIRVA recommends increased efforts to introduce alternatives to gillnet fishing in the communities that will be affected by enforcement of the exclusion zone.
  6. CIRVA strongly recommends that the acoustic monitoring program continue indefinitely, with strong financial support, in order to determine whether mitigation efforts are indeed working.

The Government of Mexico responded with a two-year emergency gillnet ban with compensation to the fishermen and related industries and increased enforcement efforts with the Navy in charge.  The new program was launched in San Felipe by President Peña Nieto in April of 2015.  As part of this program SEMARNAT is supporting a new cooperative survey (with Southwest Fisheries Science Center, NOAA Fisheries) to get the most precise abundance estimate possible at the start of this program.

President Pena in San Felipe 325px Defender Enforcement Boat 325x263px
President Peña Nieto announces the 2-year emergency gillnet ban with the Navy in charge of enforcment. New Defender enforcment vessel in background. (Photo Barb Taylor) Defender enforcment boat (Photo Barb Taylor)

The 6th CIRVA meeting in the spring of 2015 learned that the decline had been even worse than indicated by early results.  Their recommendations were:

  1. CIRVA strongly recommends that the Government of Mexico follow up on its enactment of emergency regulations establishing a gillnet exclusion zone by immediately initiating the process of making the ban permanent.
  2. CIRVA recommends that the Government of Mexico maintain its strong commitment to interagency enforcement.
    Fixed Trap Launching 200px
      Fish traps being tested by WWF-Mexico and INAPESCA as an alternative to gillnets for catching fish (Photo Barb Taylor)
  3. CIRVA recommends that the Government of Mexico increase enforcement, including night-time surveillance, to ensure that all gillnet fishing is eliminated within the exclusion zone.  Possession and transportation of gillnets should be prohibited both at sea and on land.
  4. CIRVA recommends that the efficacy of the enforcement efforts for the current ban be monitored and commends the Government of Mexico for having entered into a collaboration that involves third-party monitoring.
  5. CIRVA recommends that all available enforcement tools, both within and outside Mexico, be applied to stopping illegal fishing, especially the capture of totoaba and trade in their products.
  6. CIRVA recommends that increased efforts be made to develop and introduce alternatives to gillnet fishing in communities affected by enforcement of the exclusion zone.
  7. CIRVA recommends that, in accordance with Mexican Standard 002 published in June 2013 mandating the stepwise substitution of alternative gear for shrimp gillnets, the Government of Mexico announce that shrimp gillnets are now permanently banned.
  8. CIRVA recommends that issuance of permits for legal non-gillnet fishing be expedited.
  9. CIRVA strongly recommends that the acoustic monitoring program continue indefinitely, with adequate financial support, to determine whether mitigation efforts are working.

Satellite view of the northern Gulf of California with the vaquita distribution shown by yellow crosshatching.  The gillnet exclusion zone for the 2-year ban is within the area bounded by the red line.  The Vaquita Refuge, which remains a no fishing zone, is outlined in blue.  Note the correspondence between the vaquita distribution and the muddy water that results from strong currents stirring up the muddy bottom resulting from deposits laid down by the outflow of the Colorado River.

Legal Status: The International Union for the Conservation of Nature (IUCN) has placed the vaquita in the Critically Endangered category. Both the Mexican Official Standard NOM-059 and the U.S. Endangered Species Act list the vaquita as Endangered. Under the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) the species is listed in Appendix I.

Citations

Brownell, R. L., Jr. 1982. Status of the cochito, Phocoena sinus, in the Gulf of California. In: Mammals in the Seas, volume IV: Small Cetaceans, Seals, Sirenians and Others. Selected Papers of the Scientific Consultation on the Conservation and Management of Marine Mammals and their Environment (Ed. by J.G. Clark), pp 85-90. FAO Advisory Committee on Marine Resources Research. Working Party on Marine Mammals. Food and Agriculatural Organization of the United Nations, Rome. 

CIRVA (Comite Internacional Para la Recuperacion de la Vaquita/International Committee for the Recovery of the Vaquita). Scientific Reports of: First Meeting, 25–26 January 1997; Second Meeting, 7–11 February 1999; Third Meeting, 18–24 January 2004; Fourth Meeting, 20-23 February 2012; Fifth Meeting, 7-11 July 2014; Sixth Meeting, 22 May 2015.  Available at http://www.iucn-csg.org/index.php/downloads/ The previous link is a link to non-Federal government web site. Click to review NOAA Fisheries disclaimer

D’Agrosa, C., Lennert-Cody, C.E. and Vidal, O. 2000. Vaquita bycatch in Mexico’s artisanal gillnet fisheries: driving a small population to extinction. Conservation Biology 14: 1110-1119. 

Flanagain, C.A. and Hendrickson, J.R. 1976. Observation on the commercial fishery and reproductive biology of the totoaba, Cynoscion macdonaldi, in the northern Gulf of California. Fishery Bulletin 74: 531-544.

Gerrodette, T., Taylor, B. L., Swift, R., Rankin, S., Jaramillo‐Legorreta, A. M., and Rojas‐Bracho, L. 2011. A combined visual and acoustic estimate of 2008 abundance, and change in abundance since 1997, for the vaquita, Phocoena sinus. Marine Mammal Science, 27: 79-100

Jaramillo Legorreta, A. M., and Bracho, L. R. (2008). Passive acoustic assesment of vaquita. Paper SC/60/SM3 presented to the IWC Scientific Committee.

Jaramillo-Legoretta, A.M., Rojas-Bracho, L. and Gerrodette, T. 1999. A new abundance estimate for vaquitas: first step for recovery. Marine Mammal Science 15: 957-973.

Jaramillo-Legoretta, A.M., Rojas-Bracho, L., Brownell, R.L., Jr., Read, A.J., Reeves, R.R., Ralls, K. and Taylor, B.L. 2007. Saving the vaquita: immediate action not more data. Conservation Biology 21: 1653-1655.

Norris, K.S. and Prescott, J.H. 1961. Observations on Pacific cetaceans of Californian and Mexican waters. University of California Publications in Zoology 63: 291- 402. 

Rojas-Bracho, L. and Taylor, B. 1999. Risk factors in the vaquita. Marine Mammal Science 15 (4): 974-989.

Rojas-Bracho, Reeves, R.R. and Jaramillo-Legoretta, A. 2006. Conservation of the vaquita Phocoena sinus. Mammal Review 36: 179-216.

Rojas-Bracho, L. and R. Reeves. 2013. Vaquitas and gillnets: Mexico’s ultimate cetacean conservation challenge. Endangered Species Research. Vol. 21: 77–87.

Vidal, O. 1995. Population biology and incidental mortality of the vaquita, Phocoena sinus.  International Whaling Commission SC/42/SM24 (Revised).

Vidal, O., Brownell, R.L. Jr. and Findley, L.T. 1999. Vaquita, Phocoena sinus (Norris and McFlarland, 1958). Pp. 357-378 in S. H. Ridgway, and R. Harrison, eds. Handbook of Marine Mammals (Volume 6: The Second Book of Dolphins and the Porpoises). Academic Press, London.


Last modified: 6/14/2016