The Atlantic horse mackerel, or Trachurus trachurus, is a common type of jack mackerel. It’s a popular commercial fish, with the largest catches coming from the Netherlands and Ireland.
However, it’s recently been classified as Vulnerable to extinction due to overfishing. You’ll hear the Atlantic horse mackerel called the European horse mackerel or common scad.
Its favorite habitats are the chilly waters of the East Atlantic and the warmer waters of the Mediterranean Sea.
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The Atlantic horse mackerel has a long, narrow body with a larger head. However, there are a few defining characteristics that allow it to be easily identified, including its color, size, and shape.
The Atlantic horse mackerel is a fairly lightweight fish. You should expect it to weigh about 3.3 pounds or 1.5 kilograms on average.
This fish can vary a bit in length. You’ll usually find that the common scad is about 22-25 centimeters, or 8-9 inches, long. However, it can grow as long as 60-70 centimeters, or 23-27 inches.
There are a few specific physical characteristics that make the Atlantic horse mackerel easy to identify. It has unique coloring, markings, and fin shapes, as well as a lower jaw that nearly reaches its eyes.
The horse mackerel’s color is one of its most striking physical characteristics. It typically has a silver appearance.
However, you’ll see variations around its body. The top of its body is usually a darker gray that can appear bluish-green, while the rest is a bit paler.
This fish’s fins are also quite unique. Its first dorsal fin is tall, with seven spines. The second dorsal fin is longer than the first, and the two fins are separated by a narrow gap.
One of the Atlantic horse mackerel’s identifying characteristics is a sideline that runs the length of its body from head to tail.
This line appears silver or even white and has a high curve near the head that ends at the eye, which is quite large compared to the fish’s body.
Since the Atlantic horse mackerel has such a wide migratory range, the lifespan can vary from place to place.
For example, the oldest mackerel ever found in the southern regions was 24, while the oldest found in the north was 40, indicating the environment could affect how long a mackerel can live.
Reproduction varies for the horse mackerel based on where a school is located. You’ll find that there are stocks of Atlantic horse mackerel spawning throughout most of the year in different areas. The common trends are as follows:
- Western northeast Atlantic stock spawns in early spring
- North Sea stock spawns in the summer
- Mauritania schools spawn in early to mid-winter
- Ireland schools spawn in the summer
Females reach spawning age anywhere from 2-4 years old. They’ll spawn in 5-7 batches of about 140,000 eggs each in each season, and each larva will measure approximately 5 millimeters.
The young will grow with other local schools of fish before moving on when they reach maturity.
Although this fish gets its name from its significant presence in the Atlantic Ocean, don’t let the name mislead you. You can actually find the Atlantic horse mackerel in many of the world’s oceans and seas.
The Atlantic horse mackerel calls the Atlantic and Indian Oceans and the Mediterranean and Black Seas home.
So don’t be surprised if you encounter this fish from the coast of Norway all the way down and around the coast of South Africa.
The Atlantic horse mackerel appears all up and down the Atlantic coast. Still, despite the differing locales, the habitats are relatively similar.
In the winter, you’ll find schools of horse mackerel in shallow waters in the summer or at depths of up to 100-200 meters or 330-656 feet.
The juvenile mackerel tend to frequent deeper waters, while the older fish swim in shallower depths.
However, despite the fish’s wide distribution, most Atlantic horse mackerel catches happen in the North Sea and near Ireland.
All species of mackerel swim in schools, which is also how they hunt their chosen meals. The Atlantic horse mackerel hunts a wide variety of creatures, including other fish, crustaceans, and small ocean creatures.
Since the horse mackerel are carnivorous fish, they tend to go after shrimp, squid, smaller fish, and other crustaceans. However, small crustaceans and bony fish seem to be their most sought-after prey.
Juvenile Atlantic horse mackerel feed on fish and crustacean larvae, and plankton. They shift to hunting larger prey as they mature, including smaller fish such as herring or sardines.
Their sharp teeth make catching small fish and cracking crustacean shells easy. However, since they tend to favor shallow, sandy areas, the older mackerel often focus on crustaceans and other bottom-dwellers.
Horse mackerel are also quite an active fish. Its speed hasn’t been recorded, but it’s very agile and can travel large distances searching for prey.
However, since they tend to hunt in schools, it’s pretty easy to find significant sustenance in the form of small schools of fish in or near their local habitats.
Since mackerel are often most active near sunset, the bulk of their food comes from other sea life that’s active around that time. This also helps protect them from certain air predators, including seagulls and pelicans.
As with most marine animals, the Atlantic horse mackerel has several threats and predators. These include humans, other animals, and environmental threats.
Humans use Atlantic horse mackerel mainly as game fish, but they’re occasionally used as bait, too. This fish is available in fresh, smoked, canned, and frozen forms.
Since the fish has a high commercial value, overfishing has become a large problem in many areas. Because of this, it’s listed as a Vulnerable Species on the IUCN Red List of Threatened Species.
Climate change has shown a slow but steady effect on the living and spawning habits of the Atlantic horse mackerel.
More specifically, as ocean temperatures have risen, the spawning areas have shifted northward into colder and more hospitable waters.
Currently, there’s no indication that global warming has affected the Atlantic horse mackerel’s spawning numbers. However, studies are underway to address potential shifts.
Orca, seagulls, sharks, and large game fish, such as marlin, are the most significant predators to Atlantic horse mackerel in the ocean. These animals are found throughout the typical mackerel habitats.
However, the horse mackerel has adapted ways to limit predatory threats. For example, juveniles better their chances of avoiding these predators by hiding in jellyfish’s tentacles until adulthood. This unique behavior allows the species to thrive in ways others might not.
The other main threat to Atlantic horse mackerel is habitat loss caused by humans, climate change, and other animals.
The loss of habitat will ultimately cause horse mackerel to have fewer places to spawn, feed, and live, making them even more vulnerable to predators and fishing.
Currently, the Atlantic horse mackerel is considered a Vulnerable species, which means it’s in danger of being threatened with extinction.
The increased threat stems from significant overfishing and harvesting off the coast of Mauritania, which has led to a 35-40% decline in the last 30 years. Conservation efforts are underway but haven’t been terribly successful.
- The Atlantic horse mackerel is venomous. Its first dorsal fin has a needle it uses to inject poison into a predator. Fortunately, it poses no risk to humans.
- Atlantic horse mackerel will form schools with other mackerel species or whiting to facilitate safety in numbers.
- The name “horse mackerel” has nothing to do with horses. Instead, it comes from the Dutch “horsmakreel,” which translates to “mackerel that spawns on a horse,” which is a shallow ocean area.
- The scientific name for the horse mackerel, Trachurus trachurus, is derived from the Greek words “trachys” and “oura,” which mean “rough tail.”