The King Mackerel, Scomberomorus cavalla, is a highly migratory and fast-swimming predatory fish found along the Atlantic coast and throughout the Gulf of Mexico. These sleek, torpedo-shaped members of the Scombridae family have annual movement patterns dictated by water temperature and food availability. Understanding the King Mackerel’s diet is important for appreciating its role as a top predator in coastal marine ecosystems. Its feeding habits reflect its speed and ability to opportunistically target abundant prey populations.
The Primary Menu: Small Pelagic and Coastal Fish
The foundation of the King Mackerel’s diet consists almost entirely of small, schooling forage fish, which provide the bulk of their caloric intake. These predators focus on species that group tightly in the mid-to-upper water column, making them accessible targets for a high-velocity attack. The most frequently consumed prey items include various members of the herring and sardine families.
Specific examples of this primary menu are Atlantic menhaden (pogies) and the Spanish sardine, which form massive, dense schools that King Mackerel easily exploit. Threadfin herring and cigar minnows are also highly targeted species, especially in nearshore coastal waters. Larger King Mackerel readily consume small blue runners and mullet, demonstrating a preference for the largest available schooling fish.
Dietary studies show that the local population of small, schooling fish heavily influences the mackerel’s menu. For instance, the Atlantic stock consumes a high percentage of anchovies, while the Gulf of Mexico population exhibits greater diversity in its fish intake. Adult King Mackerel typically consume fish between 3.9 and 5.9 inches in size, maximizing the energy gained from each capture.
Invertebrate Supplements and Opportunistic Feeding
While small fish are the staple, King Mackerel are opportunistic carnivores that supplement their diet with various invertebrates. These non-fish items become important when primary forage fish schools are less numerous or during certain migratory phases. This secondary diet provides necessary nutrients and moisture.
Squid is a common, high-value invertebrate prey consumed by King Mackerel of all sizes. They also consume various species of shrimp, especially penaeid shrimp, which are often encountered in coastal and nearshore environments. Analysis of stomach contents shows that invertebrates typically make up a much smaller percentage of the adult diet compared to fish.
Juvenile King Mackerel rely more heavily on smaller invertebrates as they grow, transitioning from a planktonic diet. Young fish consume small crustaceans, copepods, and other minute organisms that are easily captured. This feeding flexibility allows the species to thrive across a wide range of marine environments.
Predatory Tactics and Environmental Influences on Diet
The King Mackerel is built for speed, with a streamlined, fusiform body that allows bursts up to 40 miles per hour during a pursuit. This high-velocity strike is the core of its predatory tactic, enabling it to rapidly close the distance on schools of baitfish. Their low mass-specific bite force is offset by the high pressure generated by their razor-sharp, laterally compressed teeth.
These teeth are used not for crushing, but for slicing and disabling larger prey with a quick swipe. Anglers often refer to this behavior as a “cut-off,” noting that the mackerel frequently attacks the tail section of a baitfish first. The King Mackerel’s preference for this high-speed, slicing attack dictates that it targets fast, soft-bodied prey rather than hard-shelled or slow-moving bottom dwellers.
Environmental factors like water temperature primarily influence the King Mackerel’s diet, as they prefer warm waters and rarely enter areas below 68°F. Their seasonal migration along the coast is a direct response to tracking the movement of warm water and the schools of baitfish that follow those currents. Geographical location also influences prey availability, leading to slight regional differences in diet composition.