Description and biology

The totoaba (pronounced tow–TOWA–ba) is a large fish with a compressed body. It can grow to almost 6 feet (1.8 meters) long and weigh about 300 pounds (136 kilograms). It is silvery–blue on the upper part of its body and dusky–silver below. It feeds on a variety of prey, including fish, crabs, shrimp, and other crustaceans.

The totoaba spends much of its life in the deeper waters of the Gulf of California (arm of the Pacific Ocean separating Baja California from the northwestern Mexican mainland).

It spawns (lays eggs) in the shallow, brackish waters (mixture of freshwater and salt water) where the Colorado River empties into the gulf at its northern end. Spawning takes place from mid–February until June.

After hatching, young totoabas remain near the mouth of the Colorado River. After about two years, they migrate south to join the parent population. These fish grow rapidly, reaching a weight of 50 pounds (23 kilograms) after just 6 years. A totoaba may live more than 35 years.

Habitat and current distribution

The totoaba is unique to the Gulf of California. It was formerly found throughout most of the gulf, but is now found only in the extreme northern end. To reach spawning grounds near the mouth of the Colorado River, totoabas migrate north-ward along the eastern coast of the gulf.

After spawning, they return along the western coast to the colder, deeper waters of the gulf. Biologists (people who study living organisms) are unsure of the total number of totoabas in existence.

History and conservation measures

The totoaba, a good–tasting fish, was once hunted in great numbers for food and sport. In the early 1940s, the amount of totoaba taken from the gulf each year totaled just over 2,200 tons (1,995 metric tons). By 1975, the yearly take had fallen to just under 66 tons (60 metric tons).

The decline in the number of totoaba has been caused by overfishing and habitat destruction. Fishermen captured totoabas primarily during their annual migrations.

This diminished the number of fish reaching spawning grounds. In the northern section of the gulf, shrimp boats accidentally trapped and killed up to 90 percent of young totoabas in their shrimp nets.

Dams built on the Colorado River decreased the amount of freshwater reaching the Gulf of California. The water in many spawning areas dried up, while the water in others became increasingly salty.

In 1975, the Mexican government declared a total ban on all fishing of the totoaba. The following year, the fish was placed on Appendix I of the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES; an international treaty to protect wildlife).

This banned all trade of the fish between nations that had signed the treaty. In 1979, the totoaba was listed as endangered under the U.S. Endangered Species Act. Despite all these actions, the totoaba is still thought to be threatened by illegal fishing and accidental catches.