shifts that accompany changes in depth; potential benefits of this include increased visual acuity and reduced response times. Human interactions The porbeagle has very rarely, if ever, bitten swimmers or boats. As of 2009, the International Shark Attack File attributes three bites to this species, one provoked and none fatal, and two on boats. One older anecdote tells of a fisherman who provoked a porbeagle into leaping from the water and tearing his clothes. In another account of a swimmer bitten by a "mackerel shark", the species responsible could easily have been a misidentified shortfin mako or great white shark. Recently in the North Sea, adult porbeagles have been filmed charging at divers working on oil platforms, sometimes even brushing lightly against them without doing harm. These rushes do not appear to have predatory intent and may instead be motivated by curiosity or defense. On 14 May 2018, a porbeagle shark was reported to have bitten a fisherman off the coast of Cornwall, United Kingdom, as it was being returned to the sea. At one time, porbeagles were regarded as nuisances by some commercial fishers because they damaged lighter fishing gear intended for smaller species and took hooked fish from lines. This shark is highly valued as a game fish by sport fishers in Ireland, the United Kingdom, and the United States. It fights strongly on hook-and-line, but does not usually jump into the air like the related shortfin mako shark. Novice anglers often mistake this shark for the mako, which has earned it the affectionate moniker "fako" in New England. The International Game Fish Association keeps records on the porbeagle. Commercial fishing Prized for its meat and fins, the porbeagle has long been under heavy fishing pressure. The meat is sold fresh, frozen, or dried and salted, and ranks among the most valuable of any shark: in 1997 and 1998, it had a wholesale price of 5–7 eur/kg, four times that of the blue shark (Prionace glauca). Most of the demand comes from Europe, though the United States and Japan also import this species. The fins are shipped to East Asia for use in shark fin soup. The remainder of the shark may also be used for production of leather, liver oil, and fishmeal. International trade in the porbeagle appears to be significant, but remains unquantified, as shark products tend not to be reported to the species level, and