Mackerel are fast-swimming, streamlined fish belonging primarily to the family Scombridae, a group that also includes tuna and bonito. These pelagic species inhabit temperate and tropical seas globally, often migrating long distances in massive schools. They are highly valued in commercial fisheries around the world due to their abundance and nutritional content. Mackerel are indeed classified primarily as carnivores.
Defining Mackerel’s Dietary Status
Mackerel are categorized as carnivores because their diet consists almost entirely of other marine animals. This classification distinguishes them from herbivores, which consume plants, and omnivores, which consume both.
Mackerel are often described as both planktivores and piscivores, reflecting the different types of animal matter they consume. Planktivores feed on plankton, including small crustaceans and larvae drifting in the water column. Piscivores are fish-eating animals that specialize in preying on other fish.
The Atlantic mackerel (Scomber scombrus), for example, exhibits a diet that shifts based on its life stage, location, and prey availability. Younger mackerel feed more heavily on plankton, transitioning to a greater proportion of fish as they grow larger. This varied diet firmly establishes the mackerel as a carnivore.
The Primary Prey and Feeding Methods
The wild diet of mackerel is highly diverse and depends on the species, season, and geographical location of the population. Their primary food sources include small crustaceans, mollusks, and smaller fish. For example, calanoid copepods are often the most important contributor to the diet of Northeast Atlantic mackerel during feeding migrations.
Common prey items include euphausiids (krill), amphipods, shrimp, squid, and the larval stages of invertebrates. Larger mackerel species, such as the King mackerel (Scomberomorus cavalla), are voracious feeders that regularly consume small schooling fish like sand eels, herring, and capelin. Mackerel employ an opportunistic strategy, consuming the most dominant and abundant prey available.
Mackerel employ two distinct methods to acquire prey. They engage in filter feeding for the smallest organisms, swimming with their mouths open to strain plankton through specialized gill rakers, acting like “living colanders”. For larger prey, they switch to active hunting and school predation. Using their speed and streamlined bodies, they actively pursue and capture individual fish and squid.
Mackerel’s Role in the Ocean Food Chain
Mackerel occupy a position as mesopredators within the marine food web. They are middle-level consumers that prey on smaller organisms while also being preyed upon by larger ones. Their consumption of zooplankton and small fish helps regulate the populations of these lower trophic levels.
As a forage fish, mackerel serve as a crucial energy conduit, transferring biomass from lower levels of the food chain up to apex predators. They are a significant food source for larger marine animals, including tuna, sharks, porpoises, dolphins, and seals. Their tendency to swim in large, dense schools makes them a reliable target for these larger hunters.
The health and abundance of mackerel populations are closely linked to the overall stability of the ecosystem. A decline in mackerel stock can impact the species that rely on them for sustenance. They are a foundational component of the marine ecosystem, supporting life at higher trophic levels.