Spanish mackerel, scientifically known as Scomberomorus maculatus, are fast-swimming predatory fish that migrate according to water temperature and season.
There are two primary stocks of Spanish mackerel, one in the Atlantic and one in the Gulf of Mexico. Another large stock also lives near Northern Australia.
Spanish mackerel are also known as spotted cybium, bay mackerel, spotted mackerel, Spaniard, and simply mackerel.
There are as many as 21 subspecies of Spanish mackerel worldwide in tropical and subtropical waters. They are surface-level fish that stay mainly in the shallows.
Usually confused with juvenile king mackerel, the Spanish mackerel is smaller. Several differences between the two species can help with the identification process.
As fast-growing fish, Spanish mackerel can reach up to 37 inches and weigh as much as 12 pounds over their lifetime.
They can grow as much as 12 inches in one year. Most Spanish mackerel caught tend to be around 12 to 18 inches and weigh only two to three pounds.
The world record for a Spanish mackerel caught in the wild was almost 78 inches in length and weighed approximately 119 pounds. Someone caught it near Fraser Beach, Australia in 2015.
Spanish mackerels have a fusiform, or torpedo-shaped, body that can slice through the water at quick speeds.
Tiny scales cover their bodies, adding to their flexibility and agility in the water. The fork shape of their tails also helps with maneuverability and acceleration.
They have greenish backs with silvery bellies and sides. Their distinct yellow-gold spots are different from the king mackerel and the cero mackerel.
The dorsal fin is also jet black, whereas king mackerels are gray. Along their backs, they have a marked difference in their lateral lines when compared to king mackerel.
Their lines just barely dip below their anal fin, where there is a pronounced dip on the king mackerel. Spanish mackerels have large mouths.
Each powerful jaw has approximately 60 closely spaced spiky teeth that are incredibly sharp. These teeth help them to capture their prey and defend themselves from predators.
The average lifespan of a Spanish mackerel is typically twelve years, although there are records of several fish living as long as 25 years.
They generally prefer to stay in the coastal waters but will occasionally venture out further over seagrass beds.
They typically remain in large schools to hunt and migrate. Spanish mackerel schools can measure 20 miles in length.
Both the female and male mackerel can start reproducing at the age of two. Their spawning season is between April and September at night in the northern hemisphere.
In the Atlantic, they prefer to spawn off the coast of Virginia and North Carolina. In the Gulf of Mexico, they prefer shallow areas.
The females lay their eggs in batches throughout a spawning season, releasing between 500,000 and 1,500,000 eggs.
The fertilized eggs will hatch in as little as 25 hours in warm waters and as much as 120 hours in cooler waters.
Spanish mackerel are tropical and subtropical regional fish. They will stay in warmer waters and follow currents to do so.
They are surface-level fish, meaning they tend to stay near the water’s surface since that is where the warmer temperatures are.
They also prefer open water but will explore deeper areas with seagrass. They will migrate toward shallower waters in the spring for mating.
Spanish mackerel tend to move quickly from one place to the next, serving as a source of frustration to many fishermen. They prefer water temperature at about 68 degrees.
The Atlantic Spanish mackerel can range as far north as New England and as far south as the Florida Keys.
The Gulf of Mexico stock can be found in the northern part of the gulf west of Cape San Blas, Florida in the warmer months and move down toward the tip of Florida in the winter.
Spanish mackerels are piscivorous predators, meaning they eat fish. They mostly prey on small fish like sardines and hunt in groups that chase schools of fish. They are certainly not passive fish that wait for food to come to them.
This species will work together to trap schools of smaller fish into small areas to form tight bundles. Then they will virtually force them out of the water to feed, which is called a feeding frenzy.
Spanish mackerel will mainly prey on herring, sardines, anchovies, mullet, needlefish, and menhaden. They will also feed on small crab, squid, and shrimp to a lesser extent.
They mainly hunt during the early morning and late evening hours; however, they will eat during the day as they find prey. They rarely eat at night, choosing to conserve energy for hunts at first light.
They are opportunistic hunters, meaning if they happen to find a school of their preferred prey any time of day, they will take that moment to feed.
Although, while they are feeding, their predators are also opportunistic and will prey on them at their most vulnerable time.
Spanish mackerel have numerous predators, including tuna, whales, dolphins, sharks, tortoises, and sea lions.
Dolphins and sharks are the predominant predators of Spanish mackerels. Humans have also been a threat to Spanish mackerel, almost fishing them to the point of endangerment.
People consider these feisty fish as great sports fish since they will fight against the line, but this species has made a strong comeback in North America due to federal and state regulations.
Many Gulf and Atlantic states will have mackerel seasons, size or weight minimums, bag limits, and other regulations to keep the population thriving and in check.
Commercial regulations have short windows or seasons. Seasons can close early if the quotas are met early.
NOAA Fisheries and regional councils monitor the regulations. Elsewhere in the world, stocks of Spanish mackerel face severe threats due to commercial overfishing.
Spanish mackerels cannot regulate their body temperature, so they mainly stay in areas with the water temperature right around 68 degrees Fahrenheit.
Waters with this temperature are usually tropical and subtropical. However, with the threat of global warming, Spanish mackerel have been migrating further north into the coastal waters of New England.
In much the same way mackerels hunt their food, pods of dolphins or whales or schools of tuna will encircle mackerel into tight balls, then charge through them to feed.
Similarly, sea lions will force the school into tight balls, but they will pick off the fish on the edges. Sharks will separate fish from the school to attack and feed.
Sharks will disorientate the fish with the striking motions of their powerful tails, causing some to move away from the school instead of with it.
Tortoises will feed on the smaller, immature fish and hatchlings, and pelicans will scoop Spanish mackerel up while they are fishing for food near the surface of the water.
Other threats to Spanish mackerel worldwide include commercial overfishing of their primary prey. Pollution is another threatening factor to the Spanish mackerel population.
Oftentimes, the trash is mistaken as food which will then become lodged in their systems and chokes them. Or they get ensnared in the pieces and die as they struggle to free themselves.
In North America, the Spanish mackerel is not considered to be overfished or in danger of being overfished.
Commercial and recreational regulations and efforts have been effective in stabilizing the population and labeling them as sustainable.
- Spanish mackerel can reach speeds up to 30 miles an hour for short bursts of time.
- Juvenile Spanish mackerel can grow up to 12 inches in one year. After that, they slow their growth to a few inches in a year.
- People can find subspecies of Spanish mackerel as far as the east coast of Africa and to the Middle East in the northern parts of the Indian Ocean.
- Spanish mackerel in the Gulf of Mexico have higher levels of mercury than those in the Atlantic Ocean.
- The first dorsal fin of a Spanish mackerel will have 17 to 19 spines.