The totoaba (Totoaba macdonaldi) is an endemic fish of the Gulf of California that has attracted global attention due to its critical conservation status and its valuable swim bladder, known as the “buche,” which is highly coveted in the black market. In this scenario, aquaculture offers hope for the conservation of this species.
In this article, we will explore the totoaba in depth, from its characteristics and habitat to the challenges it faces due to illegal trade and the conservation efforts being undertaken to protect it. However, we will highlight the aquaculture practices being implemented to ensure its conservation, but above all, to take advantage of commercial opportunities.
What is the Totoaba?
Taxonomy
The totoaba belongs to the Sciaenidae family and is known for its ability to produce sounds using its swim bladder. Here is its taxonomic classification:
- Domain: Eukaryota
- Kingdom: Animalia
- Phylum: Chordata
- Class: Actinopterygii
- Order: Acanthuriformes
- Family: Sciaenidae
- Genus: Totoaba
- Species: Totoaba macdonaldi; Gilbert, 1890.
- Spanish Name: Totoaba, totuava, corvina blanca, cabicucho
- English Name: Totoaba, totuava
Biological Characteristics of the Totoaba
The totoaba is a large fish that can reach up to two meters in length and weigh more than 100 kilograms. It belongs to the Sciaenidae family and is known for its longevity, potentially living up to 25 years. This fish is an anadromous species, meaning it migrates between the sea and freshwater to spawn.
The totoaba is characterized by its robust, elongated body, with coloration ranging from silver-gray to golden on the belly. Its fins are prominent, and it has a powerful swim bladder, which is the most valuable organ for poachers due to its supposed medicinal benefits.
Habitat of the Totoaba
The totoaba’s habitat is restricted to the Gulf of California, also known as the Sea of Cortez. This marine environment is crucial for its life cycle, especially for the spawning stages that occur at river mouths. The totoaba prefers the shallow, warm waters of the Gulf, where it finds abundant food and suitable conditions for reproduction. In this regard, Hernández-Tlapale et al. (2020) report that Totoaba macdonaldi spends almost half of its time (47%) in a specific depth range, between 25 and 35 meters.
Use of the Totoaba Swim Bladder
The totoaba’s swim bladder, also known as “buche”, is an organ that allows the fish to control its buoyancy. In traditional Chinese medicine, the totoaba’s swim bladder has been used to treat a variety of diseases. Due to this demand, the totoaba’s swim bladder has reached exorbitant prices in the Asian black market, fetching up to $35,000 USD per kilogram.
Traditional Medicine
The “buche” of Totoaba macdonaldi has been used for centuries in traditional Chinese medicine, where it is believed to have health benefits such as improving skin, strengthening the immune system, treating arthritis and hypertension, as well as increasing fertility. These beliefs have fueled illegal trade that endangers the species’ survival.
Despite its high demand, the purported health benefits of the totoaba’s swim bladder are not scientifically proven. Its consumption is more related to tradition and social status than to real medical evidence.
On the other hand, Cruz-López et al. (2023) report that cultivated totoaba swim bladder could be an ideal source for producing high-quality type I collagen and could be considered an alternative to conventional collagen sources or bioactive peptides.
The Totoaba: An Endangered Species
The totoaba is listed as a critically endangered species by the International Union for Conservation of Nature (IUCN). Its population has drastically declined due to overfishing and the illegal trade of its swim bladder. Fishing regulations and bans have not been sufficient to stop its decline.
The Impact of Illegal Trade
The illegal trade of Totoaba macdonaldi’s swim bladder is a lucrative business that has led to intense poaching in the Gulf of California. The bladders are dried and transported clandestinely to Asia, where they can reach exorbitant prices in the black market. Boilevin et al. (2023) highlights that the totoaba trafficking is not just a conservation issue: it is an organized crime operation involving five key actors: poachers, illegal Mexican and Chinese traders in Mexico, and finally, retailers and consumers mainly in China and Hong Kong.
Effects on Marine Fauna
The smuggling of totoaba not only affects this species but also others like the vaquita (Phocoena sinus), a porpoise endemic to the Gulf of California that gets entangled in the fishing nets used to catch totoaba. The vaquita is on the brink of extinction, with fewer than 20 individuals remaining (Cisneros-Mata et al., 2021), and its situation is directly linked to the illegal fishing of T. macdonaldi.
Conservation Efforts
Regulatory Measures
Mexican authorities and international organizations have implemented various measures to protect the totoaba. The Government of Mexico implemented protection measures for this fish since 1975. These include the prohibition of its fishing, the creation of protected marine areas, and the monitoring of critical habitats. However, the effectiveness of these measures is limited by corruption and lack of resources.
Restocking Programs
Aquaculture restocking programs have shown some success in increasing T. macdonaldi populations. These programs breed totoabas in captivity and then release them into the Gulf of California, hoping to restore the natural population. Although promising, these efforts must be accompanied by strict monitoring to prevent the released individuals from being illegally captured.
However, aquaculture practices have enabled the implementation of restocking programs and the emergence of an incipient industry. The company Santomar (formerly Earth Ocean Farms) is currently the pioneer in the production of T. macdonaldi for both restocking and commercial purposes.
How does the totoaba reproduce?
Totoaba reaches sexual maturity between 8 and 10 years of age. Since these fish are not sexually dimorphic, the identification of gravid females candidates for spawning is based on a simple test for the detection of vitellogenin in their blood serum (True, 2012).
Rodríguez-Jaramillo et al., (2023) investigated the reproductive biology of T. macdonaldi and reported that this fish has asynchronous spawning, and arrived at the following conclusions:
- Reproductive Season: In its natural habitat, the peak spawning period for totoaba occurs between February and May, with March being the most active month.
- Maturity Size: Females reach sexual maturity at a larger size (1354 mm) compared to males (1299 mm).
- Fecundity: The average female totoaba carries a significant number of eggs (more than 2.6 million). The relative fecundity, which considers the number of eggs in relation to body weight, was also high.
- Temperature and Egg Size: Although not statistically significant, the study observed a trend where larger eggs were associated with warmer sea surface temperatures.
What does the totoaba eat?
The totoaba is a carnivore that feeds mainly on fish, shrimp, crabs, and other invertebrates in its natural habitat. In captivity, T. macdonaldi is fed with feeds designed to meet the nutritional needs of the fish.
Mroue-Ruiz et al., (2023) reported that in its natural habitat, T. macdonaldi consumed Pacific anchovy (Cetengraulis mysticetus), mullet (Mugil cephalus), bigeye croaker (Micropogonias megalops), northern anchovy (Engraulis mordax), ocean whitefish (Caulolatilus princeps), milkfish (Chanos chanos), and Pacific sardine (Sardinops sagax) and also identified members of the Euphausiidae family (krill).
Nutritional Requirements
Protein
Rueda-López et al., (2011) obtained greater weight growth in juvenile totoaba fed a diet containing 52% protein; however, Minjarez et al., (2012) determined that a diet with 47% crude protein appears to be sufficient for juvenile T. macdonaldi and could serve as a basis for formulating practical feeds.
Madrid et al., (2019) investigated the role of lysine in the diet of juvenile T. macdonaldi and determined that around 19.3 grams per kilogram of dry feed is the optimal level for best growth.
Trejo et al., (2021) investigated the replacement of fish meal (FM) with soy protein concentrate (SPC) in the diet of juvenile T. macdonaldi; determining that replacing up to 45% of fish meal with soy protein did not have negative effects on totoaba metabolism, liver health, or overall well-being (according to a 60-day study). González et al., (2021) indicated that the partial replacement of fish meal with soy protein concentrate produced swim bladders of comparable quality to those of fish fed traditional fish meal diets.
Lipids
Totoaba can tolerate lipid inclusion in its diet from 8% to 22% (Minjarez, 2015); however, Rueda-López et al., (2011) reported that a lipid level of 8.5% is adequate for the growth of juvenile T. macdonaldi.
Lazo et al., (2020) studied the dietary needs of juvenile T. macdonaldi for a specific type of fat, long-chain omega-3 polyunsaturated fatty acids (n-3 LC-PUFA), and concluded that fish fed diets with 1.0% n-3 LC-PUFA grew more (both in weight and length) compared to other groups; in this regard, they recommend that totoaba diets contain between 0.8% and 1.0% n-3 LC-PUFA for optimal growth, survival, and efficient food utilization.
Maldonado-Othón et al., (2020) studied the replacement of fish oil (FO) in the diet of juvenile T. macdonaldi with two types of microalgae meals derived from Schizochytrium limacinum and soybean oil; and concluded that fish fed diets containing microalgae meals showed better growth compared to those fed soybean oil; they also produced a healthier fatty acid profile in the fish, with higher levels of omega-3 fatty acids.
The replacement of 30% fish oil (FO) in the diet of juvenile Totoaba macdonaldi with oils derived from black soldier fly larvae (BSFLO) allows for similar growth rates in fish compared to a diet based solely on fish oil (Maldonado-Othón et al., 2022).
Prebiotics and Probiotics
Villanueva-Gutiérrez et al., (2022) replaced fish meal (FM) with hydrolyzed soy protein (HSP) in diets for juvenile Totoaba macdonaldi, and determined that 15% of the fish meal in the diet can be substituted with HSP without affecting growth, survival, or food utilization or the body indices of the fish.
The use of soy in fish feed can cause enteritis, and scientists are exploring a range of alternatives to combat this negative effect. Fuentes-Quesada et al., (2020) explored the effect of agavin, obtained from agave, in the feeding of Totoaba macdonaldi, and concluded that agavin improves the intestinal health of the fish; while Fuentes-Quesada et al., (2023) reported that fish fed diets containing 1% agavin grew faster, and that the main benefit of agavin is intestinal health due to its prevention of soybean meal-induced enteritis.
In cultivation systems, Olmos et al., (2022) studied the probiotic capacity of Bacilus subtilis 9b to improve the growth and health status of T. macdonaldi fed formulations containing 30% and 60% replacement of fish meal with soy protein concentrate (SPC), and concluded that B. subtilis 9b improved the growth performance of T. macdonaldi, their health status, modulated the gut microbiota, and increased fish resistance to Vibrio harveyi infections.
Feeding Program
Larvae
According to the research results of Mata-Sotres et al., (2015), totoaba larvae can transition from live feed (such as artemia) to prepared microdiets as early as 17 days after hatching, even before their digestive system is fully developed. Similarly, Escárcega (2021) recommends early weaning starting from day 18 post-hatching, using co-feeding with rotifers, artemia, and microdiets as a promising strategy to improve the development and survival of totoaba larvae.
Juveniles
According to the research results of Mata-Sotres et al., (2024), under commercial conditions, juvenile totoaba showed higher food consumption in the afternoons (16:00 hours).
Aquaculture as an Alternative
Totoaba aquaculture has emerged as a viable strategy for its conservation and to meet market demand sustainably. Captive breeding allows for the controlled production of T. macdonaldi, reducing pressure on wild populations and providing a legal source of swim bladders for the Asian market. These initiatives can also contribute to the reintroduction of juvenile specimens into their natural habitat, supporting the recovery of the species.
To date, significant advances have been made in the larval rearing of this fish. In this regard, True (2012) reports that the development of totoaba through metamorphosis during intensive rearing (26°C, 35 gL-1 salinity) lasts between 35 and 50 days, after which juveniles are fed a practical diet.
On the other hand, Larios-Soriano et al., (2023) note that the fertilization of eggs, hatching, and larval growth of T. macdonaldi begin with strict physicochemical parameters of the water, such as temperature (24°C), dissolved oxygen (>6 mg L-1), and salinity (34).
An important aspect for the growth of marine fish is to raise them within the optimal temperature range. Hernández-Tlapale et al., (2020) highlights that in its natural habitat, the totoaba prefers waters in the range of 21-23°C, which can be considered ideal for the growth of T. macdonaldi.
Conclusion
The totoaba is an emblematic example of the challenges faced in conserving endangered marine species. The illegal trade of its swim bladder has pushed the species to the brink of extinction and endangered other species, such as the vaquita. Despite conservation efforts, a long-term solution requires a combination of regulatory measures, repopulation programs, and, most importantly, a change in the demand for illegal products in Asian markets. Protecting the totoaba is crucial not only for the biodiversity of the Gulf of California but also for the health of global marine ecosystems.
On the other hand, aquaculture presents a viable option to reduce fishing pressure on natural populations and to meet the demand of the Asian market for “buches”; however, the farming technology is still in its infancy with many bottlenecks that need to be overcome to ensure sustained growth in totoaba aquaculture.
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