The Pacific halibut is a very large fish that lives in the north Pacific Ocean and the second largest flatfish in the world, behind only the closely related Atlantic halibut (Hippoglossus hippoglossus). Reaching lengths of 8 feet (2.4 m) and weights of 500 pounds (230 kg), the Pacific halibut is a large predator near the top of the north Pacific food web.
Like all flatfishes, Pacific halibut have both of their eyes on the same side of their heads, and they live on the seafloor, lying on their blind side, with their eyes facing the open water column. This species is one of several “righteye flounders,” with both eyes on the right side of the head. Amazingly, when they hatch from their eggs, Pacific halibut resemble normal fishes, with an eye on each side of the head. As they mature, the bones on the left side of the skull grow significantly faster than on the right side, so the left eye and nostril slowly migrate to the right side. The jaws, however, do not change significantly, so the adults bite sideways, from right to left.
Pacific halibut are large, active predators and eat a variety of medium-sized fishes and invertebrates. Because they reach such large sizes as mature adults, few species attack and eat them. Pacific halibut spawn in groups in deep water at the edge of the continental shelf. They spawn by a method known as broadcast spawning, where several females and males release their eggs and sperm into the water column at the same time. This method increases the likelihood that the eggs will become fertilized and decreases the chances of predation by egg predators.
The Pacific halibut is highly desirable table fare and supports large commercial fisheries throughout its range. Though it has been targeted commercially for more than 100 years, the species is generally thought to be well managed, and scientists do not currently believe it to be a conservation concern.
Oceana joined forces with Sailors for the Sea, an ocean conservation organization dedicated to educating and engaging the world’s boating community. Sailors for the Sea developed the KELP (Kids Environmental Lesson Plans) program to create the next generation of ocean stewards. Click here or below to download hands-on marine science activities for kids.