Despite their size, ocean sunfish are docile, and pose no threat to human divers. Injuries from sunfish are rare, although a slight danger exists from large sunfish leaping out of the water onto boats; in one instance, a sunfish landed on a 4-year-old boy when the fish leaped onto the boy’s family’s boat. Areas where they are commonly found are popular destinations for sport dives, and sunfish at some locations have reportedly become familiar with divers. The fish is more of a problem to boaters than to swimmers, as it can pose a hazard to watercraft due to its large size and weight. Collisions with sunfish are common in some parts of the world and can cause damage to the hull of a boat, or to the propellers of larger ships, as well as to the fish.
The flesh of the ocean sunfish is considered a delicacy in some regions, the largest markets being Taiwan and Japan. All parts of the sunfish are used in cuisine, from the fins to the internal organs. Some parts of the fish are used in some areas of traditional medicine. Fishery products derived from sunfish are forbidden in the European Union according to Regulation (EC) No 853/2004 of the European Parliament and of the Council as they contain toxins that are harmful to human health.
Sunfish are accidentally but frequently caught in drift gillnet fisheries, making up nearly 30% of the total catch of the swordfish fishery employing drift gillnets in California. The bycatch rate is even higher for the Mediterranean swordfish industry, with 71% to 90% of the total catch being sunfish.
The fishery bycatch and destruction of ocean sunfish are unregulated worldwide. In some areas, the fish are “finned” by fishermen who regard them as worthless bait thieves; this process, in which the fins are cut off, results in the eventual death of the fish, because it can no longer propel itself without its dorsal and anal fins. The species is also threatened by floating litter such as plastic bags which resemble jellyfish, a common prey item. Bags can choke and suffocate a fish or fill its stomach to the extent that it starves.
Many areas of sunfish biology remain poorly understood, and various research efforts are underway, including aerial surveys of populations, satellite surveillance using pop-off satellite tags, genetic analysis of tissue samples, and collection of amateur sighting data. A decrease in sunfish populations may be caused by more frequent bycatch and the increasing popularity of sunfish in human diet.