TOTOABA: CHARACTERISTICS, HABITAT, REPRODUCTION, BEHAVIOR - BIOLOGY - 2024

The totoaba (Totoaba macdonaldi) is a marine fish that is part of the Sciaenidae family. It is endemic to the Gulf of California, in Mexico, where years ago, its populations were abundant. Currently, as a result of overfishing and the destruction of its habitat, this species is in danger of becoming extinct.

Its body is elongated and compressed, being able to measure almost two meters. In terms of weight, it is usually about 100 kilograms. Regarding the coloration, it is golden, but some species may have a dark gray-blue tone.

Totoaba. Source: CICIMAR / CONABIO Ichthyological Collection

This fish, in its adult state, is benthic, living near the seabed of the Gulf of California. In contrast, the juveniles live in the delta of the Colorado River, in shallow waters.

On the other hand, the Totoaba macdonaldi is a carnivorous animal. Its diet is based on shrimp, crabs, squid, crabs and small fish, such as anchovies and anchovies.

characteristics

Size

When the totoaba is one year old, it measures about 7.5 centimeters and at four years it reaches 91.5 centimeters. At eight years of age, when it is ready to reproduce, it has a length of 183 centimeters. Regarding the maximum sizes, experts have reported species from 193 to 198 centimeters.

In relation to weight, it can reach 100 kilograms. These dimensions make the Totoaba macdonaldi one of the largest species of the Sciaenidae family, together with the Chinese bahaba (Bahaba taipingensis).

Body

The body is covered by ctenoid scales, characterized by having ridges, projections and notches. In addition, these have the peculiarity that they grow as the fish develops. Thus, uneven and seasonal bands are gradually added, called rings, which can be used to calculate the age of the animal.

The Totoaba macdonaldi has a compressed, elongated and ellipsoid shape. Both ends, the tail and the head, are narrower than the center of the body. The swim bladder of this fish has, in particular, two very long lateral appendages, which are extended backwards.

The coloration of the species is golden, although occasionally the dorsal area may be slightly bluish or deep gray. The fins have a much darker hue than the rest of the body. With regard to juveniles, they differ from adults because they have several dark spots in the dorsal-lateral area.

Gills

Between 9 and 10 gill rakers are located on the lower branch of the first gill arch. Also, the preopercle is smooth. This structure is a laminar bone that is located in the fin. Its main function is to cover and protect the gills (operculum).

Fins

The dorsal fin is characterized by having a pronounced cleft, but this does not divide it into two parts. This structure has 24 to 25 radii. In relation to the anal, it has a short base and is formed by 7 or 8 smooth rays. This fin has two spines, the second of these being large, robust and highly visible.

Both fins lack scales on the upper part, however, they have a thin, scaly sheath at the base.

As for the tail, in adults it is doubly truncated and has slightly protruding middle rays. In contrast, in youngsters, it is pointed in shape and the middle rays are very elongated.

Head

The head of this fish has a pointed shape. Its eyes are of moderate size and the mouth is large, set obliquely. As for the lower jaw, it is slightly prominent. At the base of this structure are three pairs of pores.

Regarding the teeth, the totoaba lacks canines. The mouthparts located on the outer row of the upper jaw are tapered and enlarged. At the end of this jaw there are some pointed teeth.

As for the lower jaw, the inner teeth are slightly larger than those of the outer row.

In this video you can see the morphology of the totoaba:

Migrations

Changes in the distribution of this species are associated with two important ecological factors: salinity and water temperature. These movements of the fish give rise to annual migrations.

One of these is done to get away from the warm waters, typical of the northern coast of the Gulf during the summer months. This causes the this fish to take refuge in cold and deeper waters.

In this sense, in the San Felipe region, in Baja California (Mexico), this species is not present in the months of July, August and September. This is due to the high temperatures of the water. Thus, the animal goes to cold areas, removed from the coast. Experts estimate that the return to shallow waters occurs in October.

The other migration is influenced by salinity. This very important element in the development of eggs and larvae, since the female goes to the mouth of the Colorado River to mate.

Consequently, variations in the properties of the water cause the female to need to go to another habitat to lay her eggs.

Habitat and distribution

The Totoaba macdonaldi is endemic to the eastern Pacific, found exclusively in the north and center of the Gulf of California, in Mexico. Thus, on the eastern coast, its distribution ranges from the mouth of the Colorado River to the Fuerte River.

Relative to the western coast, the fish lives from the Colorado River to Coyote Bay. The highest population density occurs in the northern part of the Gulf of California, in the areas near Puerto Peñasco, Santa Clara and San Felipe.

In this species there is a differential distribution, taking into account the state of development of the animal. Thus, the females head to the Colorado River for spawning. Therefore, in this body of water the eggs and larvae abound. Regarding the young, they stay in the areas near the river delta.

On the other hand, adults are found scattered throughout the habitat. Thus, during the months of January to March, they present a greater abundance in the northern region. However, from June to October, the population density decreases, especially in the western Gulf.

Taxonomy

-Animal Kingdom.

-Subreino: Bilateria

-Filum: Cordate.

-Subfilum: Vertebrate.

-Infrafilum: Gnathostomata.

-Superclass: Actinopterygii.

-Class: Teleostei.

-Superorden: Acanthopterygii.

-Order: Perciformes.

-Suborder: Percoidei.

-Family: Sciaenidae.

-Gender: Totoaba.

-Species: Totoaba macdonaldi.

State of conservation

The totoaba populations are declining significantly. Therefore, the IUCN has included this species within the group of animals that are vulnerable to extinction.

- Threats

Poaching

For decades, the Totoaba macdonaldi has been overfished, specifically for its meat and swim bladder. Both are considered a delicacy in Chinese cuisine.

Furthermore, the swim bladder is eventually used in non-verifiable treatments for fertility, some skin diseases and circulatory problems.

In this way, for years, this species was the basis of the commercial fishing industry and sport fishing that took place in the Gulf of California. Overfishing of adults caused that in the period from 1942 to 2007, the decline of this fish was more than 95%.

At present, the fishing pressure on juveniles still continues. This is due to the shrimp trawl fishery in the upper Gulf of California.

Habitat destruction

Studies carried out by various environmental institutions indicate that the diversion of the Colorado River has created a serious environmental problem in the area. In this sense, the brackish water ecosystems, located in the extreme north of the Gulf of California, have been converted into a hypersaline environment.

In this way, there is a loss of freshwater flow to the delta, which drastically alters the nesting area of ​​Totoaba macdonaldi.

- Conservation actions

In 1975, the Mexican government declared a ban on totoaba fishing. In addition, this species is part of the List of endangered species in Mexico (PROY-NOM-059-SEMARNAT-2000). Likewise, since 1976 the Totoaba macdonaldi was included in Appendix I of CITES.

On the other hand, the United States National Marine Fisheries Service added it to the group of animals in danger of extinction, under Federal registration 44 (99): 29478-29480.

However, despite the controls, illegal fishing for this species continued for several years. In 1990, efforts were resumed, decreeing the spawning area as a national reserve. However, there are no data that outline the recovery of the fish.

This video talks about how the nets cause the death of totoabas and about their relationship with the extinction of the vaquita porpoise:

Feeding

- Nutritional regimen

The Totoaba macdonaldi is a carnivorous animal that feeds on crabs, crabs and shrimp of the genus Penaeus. In addition, it includes small fish in its diet, belonging to the Gobiidae family. Some of their favorite prey are the Gillichthys mirabilis and the Gobionellus sagittula.

It also consumes anchovies (Cetengraulis mysticetus) and anchovies, with a certain preference for the olive ridley (Anchoa mundeoloides). However, specialists point out that 63% of the prey are crustaceans and 20% are larvae and small young fish.

On the other hand, juveniles tend to feed on a wide variety of invertebrates, such as shrimp, amphipods, and crabs. As for the adults, they feed mainly on large crabs, small squid and sardines.

- Digestive system

Oral cavity

This first part of the digestive system is associated with the capture of the prey. In the case of the totoaba, the teeth are designed to catch and hold the animal to be ingested, not carrying out any crushing action on it. This species does not have salivary glands, failing that it has mucous glands.

Pharynx and esophagus

The pharynx acts similar to a filter, since it prevents water particles from passing into the gill filaments.

As for the esophagus, it is a wide and short tube. Its walls are thick, which allows it to expand, thus allowing the passage of food. In addition, this organ is made up of mucous cells, responsible for lubricating the internal surface, thus facilitating the movement of food through it.

Stomach

The stomach is large and its walls can be distended. In this way it makes possible the entry of large dams.

This structure is made up of a glandular region, where gastric juices are secreted, such as hydrochloric acid, which contributes to digestion. The rest of the organ is aglandular. The outlet of the stomach into the intestine is limited by the pylorus.

Intestine

This organ is tubular in shape, whose length can be equal to the total length of the fish's body. Its function is to complete the digestive process, which was started in the stomach. In addition, in the intestine, nutrients and water are absorbed.

Between the pyloric area of ​​the stomach and the proximal foregut are tubular appendages called the pyloric cecum. These fulfill the function of increasing the absorption surface of the processed organic compounds.

Year

The anus is located at the terminal end of the intestine and constitutes the exit orifice to the outside of the organic waste that was not processed during digestion.

Reproduction

The male of the Totoaba macdonaldi matures sexually at 6 years of age, while the female does so at 7 or 8 years. In appearance, there are no traits that allow differences between the sexes. However, in the reproductive season, the female exhibits a bulging belly.

The mating stage begins at the end of February or in the first weeks of March, and can last until June. Specialists point out that the maximum spawning peak occurs in the month of May.

At the time that the female has to spawn, she goes to the region that borders the mouth of the Colorado River. Studies indicate that it lays eggs only once a year.

Regarding the amount of eggs deposited, it could be associated with the physical characteristics of the female.

Thus, a female weighing 20 kilograms and measuring 1.18 meters can lay 15,395 eggs, while another with a body mass of 70 kilograms and a length of 1.8 meters lays approximately 46,192 eggs.

Behavior

The adults of this species group together, forming schools. They do this during the pre-reproductive period, starting in February, and during the mating stage.

On the other hand, the Totoaba macdonaldi is capable of emitting a sound similar to that of a drum. This is produced by the vibration of the swim bladder. This internal organ is full of gases, which makes it function as an resonance chamber.

This, together with the specialized muscle group associated with the bladder, produces a sound similar to the croaking of a toad. The fish emits it to communicate with its conspecifics.

References

1. Findley, L. (2010). Totoaba macdonaldi. The IUCN Red List of Threatened Species 2010. Recovered from iucnredlist.org.
2. Wikipedia (2020). Totoaba. Recovered from en.wikipedia.org.
3. Juan Antonio de Anda Montañez (2013). Final report * of Project HK050 Health status and conservation status of the population (s) of totoaba (Totoaba macdonaldi) in the Gulf of California: an endangered species. Recovered from conabio.gob.mx.
4. Aquaculture industry (2020). Aquaculture and conservation of totoaba: hope for the conservation of an endangered fish. Recovered from com
5. Arely Eliam Paredes Martínez (2018). Description of the gonadogenesis and identification of the period of sexual differentiation of Totoaba macdonaldi. Recovered from repositorioinstotucional.mx.
6. Joaquin Arvlzu and Humberto Chavez (1972). Synopsis on the biology of the totoaba, Cyoosoion macdonaidi Gilbert, 1890. FAO. Recovered from fao.org.