Totoaba

The Totoaba (Totoaba macdonaldi) is a large drum in the family Sciaenidae and the sole species in its genus, endemic to the Gulf of California, Mexico. It is one of the largest members of the drum family, historically reaching lengths of up to two meters. Totoaba is classified as Critically Endangered by the IUCN due to decades of population decline driven by habitat loss from reduced Colorado River flow and unrelenting illegal fishing pressure targeting its enlarged swim bladder for international trafficking. The species' decline is closely tied to the plight of the critically endangered vaquita porpoise, which is caught incidentally in illegal totoaba nets. Conservation programs, including captive breeding and stricter enforcement, aim to support recovery of wild populations.

Totoaba are identified by their large size and drum-family features:

• Very large, elongated, robust body, silvery with a bluish or grayish back
• Big head and mouth relative to body, with a slightly protruding lower jaw
• No chin barbel
• Deeply forked caudal fin and two separate dorsal fins
• Notably large swim bladder, visible as a swollen midsection in mature fish

Size alone often distinguishes Totoaba from other Gulf of California drums such as Corvina, since adult Totoaba routinely exceed a meter in length, far larger than any other regional sciaenid. Its restricted endemic range to the Gulf of California is also a key identifying clue.

Totoaba are endemic to the Gulf of California, historically ranging throughout the gulf but now concentrated mainly in its northern reaches near the Colorado River Delta. Adults inhabit open marine waters over sand and mud bottoms, while the upper Gulf estuarine zone near the delta serves as a critical spawning and nursery ground. The species depends on brackish, nutrient-rich conditions historically created by Colorado River freshwater inflow, which has been drastically reduced by upstream damming, contributing to habitat degradation. Totoaba tolerate a range of depths from shallow estuarine waters to deeper offshore gulf habitat, moving seasonally between spawning grounds and open water.

Totoaba are migratory, moving seasonally between offshore feeding grounds and shallow estuarine spawning areas near the Colorado River Delta, where adults congregate in large aggregations each spring to spawn. Like other drums, they produce loud drumming sounds during spawning using their swim bladder muscles, and historically these choruses were so intense they could be detected over long distances. The species is a predator of fish and crustaceans, using its large mouth to capture prey in open water. Once abundant, its populations have collapsed due to illegal fishing for its swim bladder and habitat alteration, making it one of the most critically endangered marine fish species, with ongoing conservation efforts focused on population monitoring and habitat restoration.