Greater trevally is a large and strong fish belonging to the species of ray-finned fish and the order of horse mackerel. Due to its large size, the trevally is often called the giant horse mackerel, as it is similar to this commercial fish in appearance and meat quality, but it is much larger in size. But the big trevally is distinguished not only by its outstanding size, but also by its great strength, as well as its social behavior, which changes several times during its life. In this article, we will talk in detail about the big trevally, its lifestyle, diet and reproduction.
Species origin and description
It can rightly be argued that the quaranx is one of the few antediluvian creatures that have come down to us from the era of dinosaurs with minimal changes. Ichthyologists claim that the large trevally, as a species, was formed about 60 million years ago and has practically not evolved since then.
Paleontologists have found the skeletons of the caranx in residual deposits, at a depth of up to 8 meters, which corresponds to the time of the Cretaceous period. For the first time, ossified remains were discovered as early as 1801, and since then, such finds have been very common. In its current form, the fish was described in the middle of the 19th century and noted in the multi-volume work of Carl Linnaeus. I must say, despite the past 200 years, the fish has not changed at all and therefore its description has not become outdated at all.
Video: Big trevally
A unique feature of the large trevally is a strongly flattened and vertically elongated torso. In addition, a special notch on the back, where both upper fins are removed, can be considered a difference from other fish. Their fish removes (or releases) depending on the strength of the sea current or during the hunt, when it is necessary to quickly maneuver.
As a rule, the average size of the trevally is about 70-80 centimeters, and the weight fluctuates around 30 kilograms. The largest size of the caught fish was 124 centimeters, and the weight exceeded 65 kilograms. Despite the fact that the trevally is large, it is a shallow fish and it does not dive to a depth of more than 100 meters, preferring to live at a depth of 20-30 meters.
Appearance and features
If unique features such as retractable fins and a highly elongated body are common to all trevally, the appearance varies depending on the type of fish.
Currently, 16 types of trevally are distinguished, but only three deserve special mention, as they stand out from the general background.
- Golden trevally. In its appearance, it is a medium-sized fish. Its length does not exceed 40 centimeters, and its weight is rarely more than 3 kilograms. In its habits and way of life, it is no different from the rest of the species. The main difference is the bright golden coloration, which makes this fish very spectacular at depth. Moreover, golden trevally is often placed in aquariums, as it is a beautiful, compact and unpretentious fish.
- Senegalese trevally. The smallest representative of the family. As it is not difficult to guess from the name, this fish lives off the coast of Senegal. The size of her body is about 30 centimeters, and the weight does not exceed 1.5 kilograms. The peculiarities of the species include the fact that the body of the Senegalese trevally is very flattened from the sides. The head is completely triangular in shape. Unlike all other trevally, the Senegalese belongs to the schooling species of fish.
- Six striped trevally. Medium sized fish. As a rule, the length of the body of this trevally is about 35-40 centimeters, and the weight does not exceed 5 kilograms. A feature of this fish is an unusual color, three stripes on each side. In appearance, the six-striped trevally is most similar to the aquarium barb.
Where does the big trevally live?
The trevally lives exclusively in warm oceans and tropical seas. Therefore, in Russia this fish is practically not known, and even in restaurants it is a rare dish. The bulk of the trevally population lives in the Red Sea, the western Atlantic Ocean and off the coast of Africa.
In countries such as Thailand, Indonesia, the Philippines and Malaysia, trevally is considered an ordinary dish, as the fishermen of these states are fishing for this fish on an industrial scale. But off the coast of Senegal, fishing for this fish is very moderate, since the local variety of trevally is not large in size and is not considered a valuable breed for fishing.
Another important condition for the habitat of the trevally is a comfortable depth. These fish do not rise above 5 meters from the surface, but also do not fall below 100. They spend most of their lives at a depth of 30-50 meters, where they feel most comfortable. In addition, these fish like to live in quiet lagoons, where there are no high waves and the sea is almost always calm. They do not move far from the coast, preferring to hunt in coastal waters.
The inhabitants of the Hawaiian Islands have a special relationship with the large trevally. They consider him a warrior fish, which not everyone can catch. For a long time, the trevally symbolized male strength and valor, and women were forbidden to eat the meat of this fish.
What does the big trevally eat?
I must say that the big trevally is an active predator. It occupies a fairly high place in the food chain of warm seas, second only to sharks and moray eels. Moreover, if these fish are single and hunt solo, then the trevally is a schooling fish. Currently, it is the large trevally that makes up 75% of all predatory fish in the Gulf of Mexico and the western Atlantic Ocean. The main diet of trevally is another fish that is inferior to them in size. Moreover, they hunt with equal success both predators and herbivorous fish.
In addition, jacks eat:
In addition, large fish are able to hunt young dolphins and even young turtles, whose shell has not yet completely hardened. The method of hunting these fish is also interesting. If necessary, they easily combine into large flocks of 300-500 individuals and are able to drive large schools of fish. Moreover, the hunting of quaranxes is not chaotic. There are dominant individuals in the pack that control the hunting process and manage the pack.
With this tactic, large fish act as hunters, and small trevally work as beaters. With this tactic, the prey has no chance to escape, and the surrounded schools are almost completely destroyed.
Interesting fact: There are cases when large flocks of trevally attacked even dolphins and killed young animals. As a rule, jacks hunt at dusk, before nightfall, and during the day they prefer to bask at a safe depth.
Features of character and lifestyle
A unique feature of the great trevally, as a species, is that its behavior changes several times during its life. In the first year of life, these fish stray into large flocks. Thus, it is not only easier for them to hunt and get food, but it is also much easier to defend themselves against large predators. There are documented facts that large flocks of trevally managed to fight off even tiger sharks.
When hunting in a pack, the great trevally show a coordinated interaction. Fish are divided into hunters and beaters, and do not leave their prey any chance. However, pack leaders don’t care about all of their members. Everyone tries to snatch as much of the prey as possible and it often happens that small individuals remain hungry. After the onset of puberty, the great trevally prefers to hunt alone. The fish grows to a considerable size and is able to cope with almost any prey alone.
The big trevally, like any predator, has its own territory. As a rule, the fish chooses its hunting grounds in the water area with a radius of several kilometers. This is enough for large predatory fish to feed themselves. Due to the peculiarities of vision, the great trevally sees best in the twilight and goes hunting at dusk. The trevally shows the greatest activity in the late evening and calms down after midnight.
Interesting fact: By its nature, the large trevally is a fairly aggressive fish that does not tolerate strangers on its territory and attacks other marine life that are smaller.
Social structure and reproduction
This fish species has sexual dimorphism. It is expressed in the color of the quaranks. Males are colored dark gray or black, while females are much lighter. Because of these features, there are no problems in determining the sex of mature individuals. The reproduction of a large trevally depends entirely on the temperature of the water. I must say that this fish is extremely thermophilic, and if the sea water is somewhat colder than the norm, then the trevally may completely skip several breeding cycles.
Under favorable climatic conditions, this fish is able to lay eggs 2-3 times a year. At a moderate water temperature, the trevally will acquire offspring only once a year. Parents from a large caranx are unimportant. Females lay several million eggs, males fertilize them. In the future, they do not care about the fate of the offspring and the fry are left to themselves. About 80% of all eggs and fry die in the first weeks of life. They are food for most fish and marine life and are often eaten along with plankton.
After the fry have grown up and are able to swim in the water column on their own, and not by the will of the current, they try to hide from predators in the shade of jellyfish or in the waters of coral reefs, where dangerous predators do not live. After 2-3 months, the young begin to stray in a flock in order to hunt more efficiently and defend themselves from large predators. Already at the 8th month of life, the trevally reach a significant size and are themselves a danger to most fish in tropical latitudes
Natural enemies of the big trevally
The large trevally does not have many natural enemies. This fish occupies one of the leading places in the food chain in tropical seas. Only sharks and moray eels can hunt medium-sized trevally, and even these born predators do not threaten large fish. The main danger threatens the big trevally in action. Fry, and even more so eggs, are completely defenseless, since parents absolutely do not care about the fate of their offspring.
The eggs of the trevally move along with the plankton, and they are eaten by all the inhabitants of the seas that feed on plankton. Hatched fry can already avoid predators, but by and large are also defenseless against attack. They try to stay close to natural hiding places, atolls and coral reefs. In addition, trevally fry hide in the shade of jellyfish and large fish.
The greatest danger to the caranx is people. The fact is that this fish is commercial and it is caught both with the help of trawls and spinning rods and fishing rods. In Hawaii and Thailand, there are special fishing tours where tourists are offered to catch blue marlin and large trevally and personally feel how strong this fish is in its native element. But pollution of coastal waters poses a significant threat to both adult fish and fry. Poisoned water kills or seriously injures the trevally and prevents the fry from growing.
Population and species status
Despite the fact that there is a year-round commercial fishing for the big trevally, nothing threatens the fish population. According to the estimates of scientific ichthyologists, there are more than a billion individuals of the trevally, and every year the population remains the same. Since 2015, the authorities of Thailand and Indonesia have introduced quotas for the catch of this fish, which has allowed to restore the number of trevally. It is planned that from 2020 fishing quotas will be removed, and this will save the waters of the Gulf of Thailand from too many predators.
The greatest damage to the quaranx, as a species, was brought by an oil spill in the Gulf of Mexico. Within six months, the number of fish decreased by 10%, which became a real threat to the population. However, the breakthrough of a deep-sea well caused damage to all living organisms living in the bay. In addition to their natural habitat, trevally thrive in aquariums around the world. Most often there you can find a golden or diamond trevally. These fish are distinguished by their attractive coloration and are very pleasing to the eye.
Karanks breed well in an artificial environment, and the absence of dangers and natural enemies has a great effect on the survival of offspring. As practice has shown, in artificial reservoirs, under human supervision, up to 95% of the total number of fry survive. At present, nothing threatens the population of the big trevally, and this fish remains a valuable commercial breed in warm seas and oceans.
The big trevally is an active predator, but this does not make it less beautiful and graceful in the deep sea. This is an excellent commercial fish species, reminiscent of the habitual horse mackerel and is served in all fish restaurants in tropical countries and exotic islands.