Totoaba (Totoaba macdonaldi)
 Totoaba (Totoaba macdonaldi) Photo: Gene Kira, mexfish.com  | |
Did You Know? · The totoaba is the largest species within its genus, growing to over 6 feet (1.8 m) long and weighing over 200 pounds (91 kg). | |
Status
ESA Endangered - throughout its range
Taxonomy
Kingdom: Animalia
Phylum: Chordata
Class: Actinopterygii
Order: Perciformes
Family: Sciaenidae
Genus: Totoaba
Species: macdonaldi
Species Description
The totoaba is a large marine fish and is the largest species within its family Sciaenidae. They have been measured at over 6.5 feet (2 m) and can weigh over 220 pounds (100 kg). Adults mainly feed on large crabs and sardines, and juveniles feed on small fish and small benthic organisms, such as amphipods, shrimp, and crabs.
Schools of adult totoaba migrate northward in the winter along the east coast of the Gulf of California to the Colorado River delta and remain there for weeks before spawning in the spring. Adults then migrate back south along the west coast for the rest of the year. Juveniles remain in the upper Gulf of California for two years before beginning this migration pattern. They begin reproducing after another 4 years for females and 5 years for males. It is believed that they can live up to 25 years (Cisneros-Mata et al., 1994).
Habitat
They inhabit mainly the upper half of the Gulf and the first 75 feet (23 m) of the water column. The Colorado River delta is the totoaba's spawning and nursery area; it provides the warm, low salinity necessary for spawning that is not found elsewhere in the Gulf. Water temperatures in this area during the spawning season range from 14°C-26°C (57°F-79°F) (Cisneros-Mata et al., 1994).
Distribution
The totoaba is one of many "endemic" species found only in the Gulf of California, Mexico.
Population Trends
No survey of the totoaba population has been conducted since the fishery was banned in 1975. Before 1975, abundance was measured in terms of annual catch. See Threats below.
Threats
The construction of the Hoover Dam in 1928 was the largest of a series of diversions of the Colorado River and severely limited water flow downstream into the Gulf of California. The United States agreed to allow about 10% of its prior annual output to enter the Gulf, which is at least 1.5 million acre feet of water. With the addition of more dams along the Colorado River, little or no water has been flowing into the Gulf of California since the late 1960s. This lack of freshwater disrupts salinity levels as well as input of sediments and nutrients important to totoaba's spawning and nursery habitat. In addition, the lack of water input from the Colorado River has led to a drastic increase in water temperature, further impacting the totoaba's normal spawning cycle (Kellogg, 2004).
During spawning seasons when totoaba migrate and aggregate in the shallower waters at the mouth of the Colorado River, totoaba become easily accessible to commercial and sport fishermen. Totoaba were initially fished for local consumption, but an increase in demand for the export of the fish triggered the growth of the industry. Juvenile totoaba were also taken as by-catch in shrimp fisheries in the upper region of the Gulf. In 1946, a peak of about 2,864,340 pounds (1,299,240 kg) of totoaba filets was exported to the United States. This increase in demand and the improvement in fishing equipment led to the severe decline of the population. Catch decreased from 2,000 metric tons (4,409,245 lbs) in 1942 to 300 metric tons (661,385 lbs) in 1958, and then to 58 metric tons (127,870 lbs) in 1975 (Cisneros-Mata et al., 1994).
Conservation Efforts
Attempting to protect totoaba during their period of reproduction, Mexico instituted a closed season beginning in 1940 on the totoaba fishery between March 20 and May 1. Despite this effort, the totoaba population continued to decline, which lead to the complete closure of the fishery in 1975 and the designation of a reserve zone at the mouth of the Colorado River. However, poaching and incidental taking of the totoaba were still widespread. Thus, in 1993, the Mexican government decided to expand the reserve zone and improve enforcement to ensure the protection of both the totoaba and vaquita, an endangered marine mammal endemic to the same area.
The totoaba was listed in 1976 on Appendix I of the International Convention on Trade in Endangered Species of Fauna and Flora (CITES) , prohibiting the importation of the species into the United States, except for the purpose of scientific research. It was also listed in 1986 as endangered on the IUCN Red List .
Regulatory Overview
The totoaba was listed as endangered in 1979 under the Endangered Species Act (ESA).
Key Documents
(All documents are in PDF format.)
| Title | Federal Register | Date |
|---|---|---|
| ESA Listing Rule | 44 FR 29480 | 05/21/1979 |
- U.S. Fish and Wildlife Service Totoaba Species Profile
- IUCN Totoaba Information
- Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) Species Database Totoaba Information
- Miguel A. Cisneros-Mata, Louis W. Botsford, James F. Quinn. 1997. Projecting Viability of Totoaba Macdonaldi, a Population with Unknown Age-Dependent Variability [pdf] Ecological Applications: Vol. 7, No. 3, pp. 968-980
References
- Cisneros-Mata, M. A., G. Montemayor-Lopez, and M. J. Roman-Rodriguez (1994). Life history and conservation of Totoaba macdonaldi. Conservation Biology, 9 (4), 806-814.
- Kellogg, B. (2004). The dam controversy: Does the Endangered Species Act apply internationally to protect foreign species harmed by dams on the Colorado River. Journal of Transnational Law and Policy, 13(2), 447-474.
