Dolphinfish

Natural history

A dolphinfish’s body is sleek and long, with a dorsal fin that extends from head to tail. A mature male’s prominent forehead is high and sloping. A mature female’s forehead is less steep. That lunate (forked) tail propels this fast-swimming fish to speeds of 40 miles an hour.

Dolphinfish is a popular menu item. To distinguish it from dolphins, which are mammals, restaurants have popularized its Hawaiian name—mahi mahi.

Conservation

The dolphinfish is an acrobatic, feisty fish popular with recreational anglers. It is sought after by commercial fisheries, which often catch them on longlines. Longlines can be 20 to 69 miles (32 to 111 km) long, with branch lines fitted with large hooks at each end. An average longline places 1,500 to 2,000 hooks in the water at the same time. Unfortunately, longlines attract and kill many types of animals, including sea turtles, seabirds and sharks. This “bycatch” of nontarget species makes longlining a significant threat to ocean wildlife.

Some dolphinfish are sustainably fished, while others are not. Check the dolphinfish recommendations at SeafoodWatch.org to find best choices and good alternatives.

Cool facts

• The dolphinfish lives life in the fast lane. It’s a rapidly growing fish that can grow to a length of over 4 feet (1.25 m) in its first year, and up to 6.5 feet (2 m) in four years.
• The juvenile dolphinfish (as well as several other species of pelagic fish) is attracted to floating kelp mats, boats, sargassum, logs and debris. Since the floating objects don’t provide food or much protection, scientists aren’t sure why this is so.