Fish farms now produce million tons of fish each year around the globe. But octopuses have largely escaped this kind of confined aquaculturing, despite a growing global demand and overfishing. Why? That's the million-ton question.
Based on their brief life cycles, prolific reproduction and efficient metabolisms, octopuses should be ideal candidates for aquaculture. They have short lives, many taking only a year or two to reach full maturity. Females lay thousands and thousands of eggs. And as poikilotherms, they are incredibly efficient at turning calories consumed into body mass.
Groups of scientists and entrepreneurs across the world—from Japan to Australia to Italy to Mexico—have been trying to find a way to rear these finicky creatures from egg to export. And most of them have struggled. But now, one farm has reported success, a move that could help wild populations and researchers alike.
On the Yucatan coast in Mexico, a small cooperative is finally rearing Octopus maya from eggs after a decade of research and unsuccessful attempts, according to news reports. Called Mayab Mollusks, it is still in its infancy, but the group is planning to gear up to larger commercial operations.
Food is one of the trickiest pieces of the cephalopod-cultivation puzzle. "Diet is probably a crucial factor in the success of farming," Guadalupe Villegas Barcenas, a graduate marine sciences researcher at the Autonomous National University of Mexico, told The Yucatan Times. Unlike fish species that are farmed in captivity, most octopus larvae insist on eating live food. This demand can make rearing young octopuses expensive—and often cost-ineffective. Once they mature, they will eat frozen crab or shrimp. O. maya, however, skip this pickier phase and are more apt to consume less costly chum. Mayab Mollusks is developing a specialized blend of crab, squid and other yummy ingredients that the growing octopuses seem to like. Other crucial elements for surviving—and thriving—octopuses include water temperature, salinity and water flow, all of which are carefully monitored to insure the octopuses stay health and keep growing.
To take their octopuses from egg to adult, the researchers allow wild-caught males and females to mate. Once the females lay fertile eggs, these are removed and placed in an "incubator" that mimics the local sea environment where females often brood their clutches. Once the eggs hatch, the young—which in this species skip the smallest larval stage—are moved to a feeding area. Once the octopuses reach a mature weight, they can then be sold at market.
The program was started by the university, which then invited local costal community members to join, as a way to bring in income during the six months each year when the fisheries were closed. Local women, who normally sold fish while men went out to fish, were the first to join in and have been working on the project since 2005.
The knowledge gained from this farming operation could help scientists rear their own octopus specimens, which would in turn produce more controllable research. (Many cephalopod researchers now have to rely on wild-caught specimens of unknown age and life history.) And if other farming operations crop up, it could help relieve some of the ecological pressure in areas in which octopuses have been overfished, such as in Europe, Asia and Africa.
Another group attempting to cultivate octopuses, Fremantle Octopus Company, is based in Perth, Australia. Instead of trying to bring octopus babies through their tenuous early stage, this company is starting out with underweight octopuses—mainly the common Sydney octopus (O. tetricus)—already caught by fishermen (they're calling their process "ocean to plate"). Their next hope is to move to a full life-cycle model.
One other potential obstacle to octopus farming, however, is that unlike many other animals that are currently reared together in large numbers, octopuses cannot be vaccinated against common infections. They have no acquired immunity—a surprising feature we will cover in the next installment.
Illustration courtesy of Ivan Phillipsen