There is only one species of swordfish, Xiphias gladius. This nonschooling fish roams temperate and tropical seas worldwide and is hunted by more than 30 nations. Swordfish  harvesting is governed by the International Commission for the Conservation of Atlantic Tunas. U.S. Atlantic fishermen operate under a strictly enforced ICCAT quota, but not all ICCAT nations observe their quotas. Swordfish grow to over 1,000 pounds but average 50 to 200 pounds. Most are caught by longline, the rest by gillnet and a very small amount by harpoon. The fishery is conducted at night (except the harpoon fishery). The best catches from the longline fleet come on the full moon, when nights are bright and swordfish are feeding heavily. Thus, the best catches occur during the final quarter of the moon. The opposite is true for gillnet fisheries. The darker the night, the better the fishing (because sword-fish can’t see the net). Generally speaking, longlined fish are considered the best. Frozen-at-sea swordfish, known as “clipper,” is often a high-quality product and less expensive than fresh sword, which can be less fresh than FAS.