Calamari choreography.

Squid has become a favorite of foodies and fishermen in recent years, as stocks of cod and other marine fish have crashed from overharvesting (SN: 2/22/97, p. 124). Worldwide, the chewy, tentacled cephalopods are the third most lucrative catch from the sea, behind shrimp and tuna.

Squid are generally caught near shore, which is where they breed. To help keep populations thriving, researchers have been studying the squid's reproduction, which involves behavior as strategic as the strutting competitions of many land animals.

Large male squid initiate the main action at dawn. They begin slowly swimming in a large circle about 200 meters across--the length of a couple of football fields, says Roger T. Hanlon of the Marine Biological Laboratory in Woods Hole, Mass. Occasionally thousands, but usually tens or hundreds, of other shimmering squid, both male and female, join in.

Hanlon and his colleagues from South Africa and Canada used radio transmitters to track the movements of eight squid over 2 weeks at a breeding area off South Africa.

The transmitters pinpointed the speed and placement of the squid during the "nuptial dance," the researchers report in the April Biological Bulletin. "It looks chaotic at first, then you realize they're in pairs," says Hanlon. The circling males pass packets of sperm to females that have been drawn into the swirl.

"It's like a busy airport," says Hanlon. "There's lots of circling going on, with a couple occasionally coming in to land."

Land, in this case, is the seafloor, where the female with her attendant male deposits the fertilized eggs. Whether the dance partner is actually the source of the sperm isn't clear. Smaller "sneaker" males frequently cut in and pass off sperm to paired females; some females also carry sperm from earlier, offshore matings. Hanlon is beginning DNA analyses to determine paternity and whether the circling, sneaking, or offshore-mating tactic is best.

South Africa has begun regulating the catch of squid to preserve the near-shore breeding areas. The United States does not yet, says Hanlon, although fisheries managers are watching for warning signs of decline in the increasingly popular catch.