|Scientific Name:||Totoaba macdonaldi|
|Species Authority:||(Gilbert, 1890)|
Cynoscion macdonaldi Gilbert, 1890
|Red List Category & Criteria:||Critically Endangered A2bcd ver 3.1|
|Reviewer/s:||Carpenter, K., Polidoro, B. & Livingstone, S. (Global Marine Species Assessment Team)|
This species is endemic to the Gulf of California. Although once considered abundant, this species' population has been decimated since the 1940s due to intensive overfishing and spawning habitat loss from conversion and degradation of the Colorado River Delta. Even though some conservation measures are in place, juveniles are still severely overfished by continued capture in shrimp trawling fisheries. Based on fisheries data available only until 1975, more than 95% decline in this species' population has been estimated over the past three generation lengths (60 years). Although some conservation measures are currently in place, there is still intensive fishing pressure and habitat degredation throughout this species very restricted range. It is listed as Critically Endangered.
|Range Description:||This species is endemic to the Eastern Pacific, and is only found in the central and northern Gulf of California, Mexico. The species spawns in the northernmost part of the gulf in the Colorado River Delta. Historically, it may have also spawned farther south on the eastern side of the Gulf in large river mouths, especially the Rio Fuerte (Gilbert 1890). Sporadic young adults have been reported in sport fisheries in the southern gulf in areas of rocky reefs.|
|FAO Marine Fishing Areas:||
Pacific – eastern central
|Range Map:||Click here to open the map viewer and explore range.|
|Population:||Current population status is unknown. Unpublished data and incomplete fisheries data has only been collected in the 1980s by the Federal Department of Fisheries of Mexico. However, the population of this species, once considered to be very abundant, has been severely reduced since the 1940s by overfishing.|
|Habitat and Ecology:||
This demersal species is found in shallow coastal waters to depths of 25 m. It is one of the largest fishes in the family Sciaenidae, with a maximum reported length of almost two m and weight of 100 kg. This species has an annual spring breeding migration to the shallow, formerly brackish (now hypersaline) waters of the Colorado River delta at the extreme northern end of the Gulf. It feeds on fishes and shrimps.
The generation length for this species is estimated to be 19 years, based on an estimated average age of first reproduction of seven years and a maximum age of 30 years (Cisneros-Mata et al. 1995).
The species has been seriously depleted due to overfishing and habitat alteration. The fish formerly supported an important commercial fishing industry and sport fishery in the Gulf of California. Historically, the majority of the commercial catch was exported from Mexico to the United States, where prices were high. Overfishing of adults occurred primarily during their annual breeding migrations to the Colorado River delta. Peak annual yield in 1942 was 2,261 tonnes, and despite intensified fishing effort and increased gear efficiency, the annual yield exhibited erratic fluctuations and decreased to approximately 58 tonnes in 1975. This represents a more than 95% decline over the past 65 years (1942–2007).
Current heavy fishing pressure continues on juveniles ("machorros," 20-25 cm) due to the active shrimp trawl fishery in the upper Gulf of California. Because of historical and current overfishing, the once maximum size of 200 cm for the species has been greatly reduced.
An Environmental Assessment Study by NOAA and the U.S. Fish and Wildlife Service noted that diversion of the Colorado River has converted the formerly brackish-water habitat, in the extreme northern Gulf of California, into a hypersaline environment, drastically altering the nursery grounds of the Totoaba (Guevara 1990), and altering the life history of the species (Rowell et al. 2008).
A total ban on fishing was declared by the Mexican Government in 1975 and this species was placed on the Mexican Endangered Species List (PROY-NOM-059-SEMARNAT-2000). In 1976, it was placed on the endangered list (Appendix I , threatened with extinction) of the Convention on International Trade in Endangered Species (CITES). In September 1978, the U.S. National Marine Fisheries Service held a workshop to evaluate the biological status of the totoaba, and in May 1979 it was added to the U.S. Endangered Species list, Federal Register 44(99): 29478-29480.
However, illegal fishing for this species in spawning grounds continued for several years after these conservation measures were enacted, and was only brought under effective control in the 1990s. The spawning grounds are in a biosphere reserve established in 1983, and the mesh size of the large gillnets formerly used for its capture have been reduced by half (from 12 inches to six inches). However, there are no data that shows whether the population is recovering. A small size cultivation effort has been in operation in Ensenada, Baja California, for the past few years and some releases into the wild have been conducted, although there is no known benefit to the population at present.
|Citation:||Findley, L. 2010. Totoaba macdonaldi. In: IUCN 2012. IUCN Red List of Threatened Species. Version 2012.2. <www.iucnredlist.org>. Downloaded on 24 May 2013.|
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