The totoaba or totuava ( Totoaba macdonaldi) is a species of marine fish endemic to the Gulf of California in Mexico. It is the largest member of the drum family Sciaenidae
Distribution and habitat
Although the totoaba population has declined due to nearly 50 years of overfishing, they have maintained their historical distribution range across the Gulf of California, inhabiting the northern part of the Gulf, the south of La Paz, the west of Baja California Sur, and the east of Mármol, Sinaloa.
Interestingly, the genus
Totoaba appears to have had a slightly wider range on the western North American coast in prehistoric times; a
fossil otolith assigned to the extinct species
Totoaba fitchi is known from the Oclese Sand Formation in Kern County, California, suggesting that it reached as far north as there during the late part of the
Early Miocene.
New studies have indicated a possible expansion in range for the living totoaba population from their historical southern limit of west Bahía Concepción and east in the mouth of the El Fuerte River, Sinaloa to more southward bound areas such as in the Bay of La Paz and off Mármol.
The totoaba use different habitat areas of the Gulf for their ontogenetic migratory pattern which consist of pre-recruits, juveniles, pre-adults, and adults.
The totoaba habitats consists of either brackish or marine waters depending on their life stage. They mainly inhabit coastal areas, but have been found in rocky reef areas. Their water depth ranges from 1 to 70 meters, and temperature ranges from .
Species description
While there is no formal compilation of the color, shape, or other characteristics besides size and weight of the totoaba, a website dedicated to the photography and species information of Mexican fishes has compiled a cohesive enough species description of the totoaba. The totoaba can reach a size of up to and weight of .
The totoaba coloration is silvery with darker fins and a light belly.
There is no sexual dimorphism between the males or females.
The juveniles tend to be spotted in comparison to the adults, specifically having a spotted second dorsal fin.
The totoaba have an elongated compressed fusiform body shape with a terminal oblique mouth and lower jaw that projects slightly.
The totoaba has two dorsal fins with a clear separation between them. The anterior dorsal fin is a spinous portion, and the posterior dorsal is a soft-rayed portion providing balance, maneuverability, and protection. Its pectoral fins are located towards the head of the fish right behind the operculum and are exceedingly long with the pelvic fins located right beneath it. Its anal fin is located before the peduncle and its caudal fin most closely resembles a
truncate shaped tail.
Life cycle
The totoabas' weight and size makes it the largest species in the drum family,
together with the similar-sized
Chinese bahaba (
Bahaba taipingensis) and meagre (
Argyrosomus regius).
The totoabas' diet consists of
Actinopterygii and
. A recent study done in 2023 has used
metabarcoding for the first time to identify a more specific diet for wild totoaba. The study found 11 species of prey consumed by the totoaba:
Pacific anchovy (
Centengraulis mysticetus), flathead grey mullet (
Mugil cephalus), bigeye croaker (
Micropogonias megalops),
northern anchovy (
Engraulis mordox),
ocean whitefish (
Caulolatilus princeps),
milkfish (
Chanos chanos), and
Pacific sardine (
Sardinpos sagax).
Crustaceans known as
krill from the
Euphausiidae family were also identified.
This more in depth understanding of diet allows for a better understanding of dietary needs for
aquaculture feed considerations, biodiversity, trophic relationships, and ecology. It is important to note that discovering the diet of the totoaba has proven difficult because their diet varies depending on the life stage it's in. However, in juveniles examined in 1972, they found
amphipods,
crustaceans, and juvenile fishes (
Micropogon sp.,
Mugil cephalus, and
Leuresthes sardina) so although limited by size the diet if the juveniles is comparable to the diet of the adults.
Totoaba are long-lived and may live up to 20–25 years, but sexual maturity is usually not reached until females are seven years old and males are six years old.
Environmental threat
The diversion of water from the
Colorado River within the United States leaves little or no
fresh water to reach the
river delta, greatly altering the environment in the delta, and the
salinity of the upper Gulf of California. The flow of fresh water to the mouth of the Colorado since the completion of the
Hoover Dam 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.
Changes in salinity cause the response of physiological processes to change which can impact the survival of a population by affecting growth and reproduction. With the loss of the freshwater flow from the Colorado River, salinity in the delta is usually 35
Per mille (about 35 g
Sodium chloride/L) or higher; it ranges from (practical salinity unit) at the head of the Colorado River to 20 psu in the delta.
While this alteration has been considered one of the reasons for totoaba population decline since historically the totoaba have been considered an
Estuary-dependent species that use the Upper Gulf of California for
spawning, new studies done in 2023 have indicated that the totoaba continue to use the modified breeding grounds.
This suggest that either the totoaba are resilient and adaptable to changes occurring in their natural habitat or migrating to
served other purposes outside meeting breeding conditions.
Regardless this does not mean reproduction success is not impacted but that reproductive activity by adults is not as negatively affected due to environmental changes caused from
.
Each life stage of the totoaba
Osmoregulation differently. Totoaba eggs are
. Their
are
stenohaline able to osmoregulate in salinity levels of 20 to 34 psu, this life stage is the less tolerant to extreme salinity.
Juveniles, on the other hand, can survive in salinity ranging from 5 to 40 psu.
The change in salinity in the habitat of juveniles has not affected their distribution or abundance.
Human threats
Another threat to the totoaba is from human
poaching: the
swim bladder, commonly referred to as "maw" is a valuable commodity, as it is considered a
delicacy in
Chinese cuisine;
the meat is also sought after for making soups. It can fetch high prices – 200 bladders may be sold for $3.6 million at 2013 prices – as it is erroneously believed by many Chinese to be a treatment for
fertility, circulatory, and
skin problems.
The swim bladders are often smuggled to
Hong Kong, where they are illegal, but import screenings are lax, and from there they are sometimes forwarded to the Chinese mainland, where import screenings are stricter.
This trade once focused on the
Chinese bahaba, but as its population became depleted, the trade shifted to the related totoaba.
The illegal totoaba fishery also threatens the
vaquita, a critically endangered
porpoise Endemism to the northern Gulf of California that appears to be doomed to extinction unless the setting of
gillnets in its habitat can be halted.
The totoaba swim bladder is often used for identification more than a morphological description of the fish due to the illegal trade of it. Recent research in 2024 has created a way to identify totoaba swim bladders on-site of legal and illegal trades, that is efficient, convenient, inexpensive, and gives reliable results called real-time fluorescence-based recombinase-aid amplification (RF-RAA).
Helping authorities be equipped to handle the increase in illegal imports and the market regulations surrounding totoaba swim bladders.
Commercial trade
Commercial fishing for totoaba began in the 1920s. The catch reached in 1943, but had fallen to only in 1975, when Mexico protected the totoaba and banned the fishery. Anecdotal evidence suggests that totoabas were very abundant prior to the start of the commercial fishery, but no hard evidence now indicates natural population size. Recent studies indicate that the totoaba population has stabilized at a low level, perhaps a bit larger than when the commercial fishery was banned in 1975. Totoabas are still caught as bycatch in fishing for other finned fish and for shrimp, and in illegal fishing for totoaba directly. Some totoabas are illegally exported to the United States, often misidentified as
white seabass.
The government of Baja California has authorized commercial raising of totoaba in Fish farming.
Conservation status
Formerly abundant and subject to an intensive
fishery, the totoaba has become rare, and was listed by the Convention on International Trade in Endangered Species of Wild Fauna and Flora under Appendix I in 1976.
It is also listed by the International Union for Conservation of Nature as vulnerable,
by
NatureServe as critically imperiled
and under the U.S. Endangered Species Act as endangered in 1979.
Making it illegal to catch totoaba since 1975 when it was placed on the Mexican Endangered Species List.
On 16 April 2015, Enrique Peña Nieto, the President of Mexico, announced a program of rescue and conservation of the vaquita and the totoaba, including closures and financial support to fishermen in the area.
The Chinese trade in totoaba swim bladders has been a primary reason for its decline.[Carrington, D. (16 May 2017). "Chinese appetite for totoaba fish bladder kills off rare porpoise". The Guardian. Retrieved 18 May 2019.] More recently, both Mexican and Chinese authorities have tightened checks and performed raids, resulting in large confiscations and several arrests.[Cannon, J.C. (1 May 2018). "More than 800 totoaba swim bladders confiscated by Mexican authorities in smuggling busts". Mongobay. Retrieved 18 May 2019.][Dasgupta, S. (29 December 2018). "China seizes totoaba swim bladders worth $26 million, arrests 16". Mongobay. Retrieved 18 May 2019.][BBC News (7 March 2019). "China accuses 11 of smuggling totoaba swim fish bladder". Retrieved 18 May 2019.]
The totoaba is suitable for fish farming due to the relative ease of breeding it in captivity and its high growth rate.[Dodd, Q. (27 November 2017). "Saving the totoaba for fun and profit". Hatchery International. Retrieved 18 May 2019.] Although this mainly is done to supply the food market,[Kiy, R. (5 July 2018). "Fourth Release of Totoaba in Baja California Sur: A Unique Alliance Between Government and the Private Sector to Protect a Species at Risk of Extinction". Business Wire. Retrieved 18 May 2019.]
External links
