Totoaba
| Totoaba macdonaldi | |
|---|---|
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Actinopterygii |
| Order: | Perciformes |
| Family: | Sciaenidae |
| Genus: |
Totoaba A. Villamar, 1980 |
| Species: | T. macdonaldi |
| Binomial name | |
|
Totoaba macdonaldi (Gilbert, 1890) |
|
| Synonyms | |
|
Cynoscion macdonaldi Gilbert, 1890 |
|
Cynoscion macdonaldi Gilbert, 1890
The totoaba or totuava (Totoaba macdonaldi) is a marine fish, the largest member of the drum family Sciaenidae, that is endemic to the Gulf of California in Mexico. It is the only species in the genus Totoaba. Formerly abundant and subject to an intensive fishery, the totoaba has become rare, and is listed on CITES, the IUCN Red List of Threatened Species, and the Endangered Species Act.
The totoaba can grow up to 2.0 m in length and 100 kg in weight. Their diet consists of finned fish and crustaceans. Individuals may live up to 15 years, but sexual maturity is usually not reached until the fish are 6–7 years old. As totoabas spawn only once a year, population growth is slow, with a minimum population doubling time of 4.5 to 15 years. The totoaba spawn in the Colorado River delta, which also serves as a nursery for the young fish.
The totoaba population is found in two distinct groups. Larval and juvenile stages occupy the Colorado delta, while the adult breeding population lives for most of the year in deeper water towards the middle of the Gulf of California. The adult population migrates to the Colorado delta in April and May to spawn. One-year-old totoabas are metabolically most efficient in brackish water of about 20 parts per thousand (ppt) salinity, a level that occurred naturally in the delta before the diversion of water from the river that occurred in the middle of the 20th century.
The diversion of water from the Colorado River within the United States leaves little or no fresh water to reach the delta, greatly altering the environment in the delta, and the salinity of the upper Sea of Cortez. The flow of fresh water to the mouth of the Colorado since the completion of the Hoover and Glen Canyon dams has been only about 4% of the average flow during the period from 1910 to 1920. This is considered to be a major cause of the depletion of the totoaba population. With the loss of the freshwater flow from the river, salinity in the delta is usually 35 ppt or higher.
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