The importance of bivalves to estuarine ecosystems is well known and documented in the scientific literature. Repatriation of clams has been established as a viable means of aiding in ecosystem restoration. Unfortunately, this work is time and labor intensive requiring large amounts of funding to be impactful. The need to find novel approaches to clam restoration has arisen to optimize restoration dollars while accelerating ecosystem restoration. Blue Ocean Quest in collaboration with the SJRWMD and the University of Florida have experimented with a novel approach leveraging native clam reproductive strategies to deliver millions of juvenile clams to restoration sites via heavy lift drone. This approach negates aquaculture techniques of growing adult clams and repatriating with cover nets. Trials of aerial dispersal indicates the mean survival of clams was 33.6% (±8.0%). This can be accomplished for approximately one third of the cost of clam repatriation via the traditional methods.
The traditional method for clam restoration has been to raise clams in the nursery to a size of 15-25 mm then out-plant them at a density of up to 50 clams per square feet and covered with protective cover netting for a period of 1 to 2 years. The theory is that the clams will spawn, and the larvae released into the water column to then be carried by the tides and eventually settle on the bottom to continue the life cycle.
The heavy-lift drone approach is accomplished through a patented device attached to the drone that deploys clam seed. The clams are 2 to 3 mm in size and are deployed in a homogenous manor at a density of approximately 20/sq ft or 1,000,000 per acre. Once the clams are deployed, they bury into the bottom and complete the life cycle. This mimics what occurs in nature with the early stages of life protected in a nursery. A scientific study of this method has shown a 33% survival rate after 8 months. Predation is expected and welcomed as it naturally feeds the food web and helps restore the fisheries.
Using the survival rate that has been observed, an economic comparison of the traditional method vs the drone seeding method can be made. With an expected outcome of 1,000,000 clams of 15 to 25 mm in size being introduced into the IRL, the total cost using the traditional method is $88,500 vs the Drone seeding method cost of $29,300. This results in a saving of $59,200 or 67% using the drone method as opposed to traditional.