Atka Mackerel

Pleurogrammus monopterygius

The Atka mackerel (Pleurogrammus monopterygius) is a species of greenling in the family Hexagrammidae. Adults reach up to 56 cm with an elongated body displaying distinctive dark vertical bars on a lighter background, ranging from olive-green to golden-brown. Males during spawning develop bright yellow coloration. This species inhabits rocky reefs, kelp forests, and offshore areas at depths of 0-575 meters in the northern Pacific, from the Sea of Japan to the Aleutian Islands and Gulf of Alaska. Atka mackerel are schooling fish that form large aggregations near rocky substrates. Males are nest guarders, defending egg masses deposited on rocky surfaces by multiple females and turning bright yellow during this period. They feed on zooplankton, small fish, and invertebrates. This species is ecologically significant in the Aleutian Islands ecosystem, serving as important prey for Steller sea lions, seals, and seabirds.