Whales, diverse marine mammals, display a wide array of feeding behaviors. Their diets vary considerably depending on the species, habitat, and prey availability. While many consume small organisms like krill, a significant number of both baleen and toothed whales also eat various types of fish. This flexibility allows them to adapt to different marine environments and seasonal changes in food sources.
Understanding Whale Diets
Whales are broadly categorized into two suborders: baleen whales (Mysticeti) and toothed whales (Odontoceti). This classification reflects fundamental differences in their feeding anatomy and strategies. Baleen whales possess baleen plates instead of teeth, which they use to filter small organisms from the water. Toothed whales, conversely, have teeth and actively hunt individual prey.
Baleen Whales and Their Fish Prey
Baleen whales, characterized by their filter-feeding mechanism, primarily consume vast quantities of small prey. While krill forms a major component for many species, several baleen whales also actively target schooling fish.
Humpback whales, for instance, are known to consume herring, mackerel, capelin, salmon, pollock, haddock, anchovies, and sand lance. They can eat up to 3,000 pounds of food daily and employ a unique hunting technique called bubble-net feeding, where groups of whales work together to encircle fish with bubbles before surfacing to engulf them.
Minke whales, the smallest baleen whales, also exhibit a diverse diet that includes schooling fish. In the Northern Hemisphere, their diet often consists of capelin, herring, cod, mackerel, salmon, sand lance, and anchovies. They use their expandable pleats to take in large mouthfuls of water and fish, which are then sieved through their baleen. Their diet can shift based on seasonal availability, with fish becoming more prominent when krill is less abundant.
Fin whales, the second largest whale species, also incorporate fish into their diet. In northern areas, they frequently consume small schooling fish such as herring and anchovies. These gulp feeders use their throat pleats to engulf large amounts of water and prey, which is then filtered through their baleen.
Toothed Whales: Apex Fish Predators
Toothed whales, a diverse group including dolphins, porpoises, and orcas, are active hunters that use their teeth to capture prey. Fish constitute a significant portion of the diet for many of these species.
Dolphins, for example, eat a wide variety of fish, including mullet, sea trout, flounder, pinfish, pigfish, ballyhoo, spot, toadfish, tuna, herring, sardines, anchovies, mackerel, cod, and saltwater catfish. They often hunt cooperatively and utilize echolocation to locate and pursue their aquatic prey.
Porpoises, generally smaller than dolphins, also primarily feed on schooling fish. Harbor porpoises are known to consume herring, mackerel, cod, sprat, gobies, and sandeels. Their diet can vary geographically and seasonally, often reflecting the abundance of local fish stocks. They tend to forage on small shoaling fish from both the water column and near the seabed.
Orcas, also known as killer whales, are apex predators within the toothed whale group, and their diets vary significantly by ecotype. Fish-eating ecotypes predominantly consume fish. Southern Resident killer whales, for instance, specialize in salmon, with Chinook salmon making up about 80% of their diet due to its high fat content. They also consume other salmon species like coho and chum, and can diversify their diet to include sablefish, arrowtooth flounder, lingcod, Pacific halibut, and big skate. Their hunting strategies are highly sophisticated, involving cooperative efforts within their pods.