Oceanic sharks are captured incidentally by swordfish and tuna high seas fisheries. At first, mahi-mahi were mostly bycatch in the tuna and swordfish longline fishery. A fletch is a large boneless fillet of halibut, swordfish or tuna. There are important tuna, sardine, swordfish and European anchovy fisheries. These include the swordfish, marlin, tuna, and some sharks. Other predators include tunas, sharks, swordfish, sea turtles and penguins. Some 14 aircraft were destroyed&colon; five Blackburn Sharks, five Fairey Swordfish, and two Fairey Albacore. The Alboran Sea also hosts important commercial fisheries, including sardines and swordfish. The marlins are perciform fish, most closely related to the swordfish and Scombridae. Among marine mammals, killer whales sometimes prey on adult swordfish. Occasional sightings are made of whales, sunfish, swordfish and turtles. Chinese paddlefish are also commonly referred to as "Chinese swordfish", or "elephant fish". Another notable characteristic is the elongated bill, resembling that of the swordfish and other marlins. Specialized lures made specifically for trolling swordfish use plastic glow sticks. Fully adult swordfish have few natural predators.