Maintaining food production while sustaining productive ecosystems is among the central challenges of our time, yet, it has been for millennia. Ancient clam gardens, intertidal rock-walled terraces constructed by humans during the late Holocene, are thought to have improved the growing conditions for clams. We tested this hypothesis by comparing the beach slope, intertidal height, and biomass and density of bivalves at replicate clam garden and non-walled clam beaches in British Columbia, Canada. We also quantified the variation in growth and survival rates of littleneck clams (Leukoma staminea) we experimentally transplanted across these two beach types. We found that clam gardens had significantly shallower slopes than non-walled beaches and greater densities of L. staminea and Saxidomus giganteus, particularly at smaller size classes. Overall, clam gardens contained 4 times as many butter clams and over twice as many littleneck clams relative to non-walled beaches. As predicted, this relationship varied as a function of intertidal height, whereby clam density and biomass tended to be greater in clam gardens compared to non-walled beaches at relatively higher intertidal heights. Transplanted juvenile L. staminea grew 1.7 times faster and smaller size classes were more likely to survive in clam gardens than non-walled beaches, specifically at the top and bottom of beaches. Consequently, we provide strong evidence that ancient clam gardens likely increased clam productivity by altering the slope of soft-sediment beaches, expanding optimal intertidal clam habitat, thereby enhancing growing conditions for clams. These results reveal how ancient shellfish aquaculture practices may have supported food security strategies in the past and provide insight into tools for the conservation, management, and governance of intertidal seascapes today.
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.
