Natural mortality and the need to thin out the larvae to proper densities should leave about 25 million eyed larvae ready for setting. Under good conditions 200 million eggs can result in 100 million or more early-stage larvae, which require 2,600 gallons (10,000 L) of treated water. As a rule, ten average females produce about 200 million eggs. Spawning oysters is the first step in the production of spat. Because of the rich array of organisms in Gulf of Mexico waters, mechanical filtration down to 1 ?m with UV treatment can assist in successful spawning and larval production. Mechanical filtration is usually done with a pressurized sand filter, cartridge filters for smaller volumes, or fine-mesh bags. Large-scale operations and “low-tech” or “back yard” facilities may forgo UV treatment but will use some mechanical filtration. Water used for spawning, mixing eggs and sperm, and growing larvae is typically filtered mechanically and treated with ultraviolet radiation. Good water quality is essential to successful hatchery production (see Site Selection) but even high-quality water must be treated to remove unwanted organisms. Another larger space with special lighting, separate from the main hatchery, is needed to grow larger volumes of algae. If algal cultures are to be produced, there must be a clean room with special lighting for starting cultures. Aeration throughout the hatchery is supplied by an appropriate size blower, overhead PVC piping, vinyl tubing, and good quality air stones. Shallow rectangular tanks with drain pipes provide nursery space for juvenile oysters. 4) that can handle the maximum expected water flow helps keep water off the floor. Drain pipes make it convenient to drain water and sieve larvae. Tanks for larval production are circular, generally 250 gallons (946 L) or larger, and have center drains and sloping or conical bottoms. Treated sea- water is then suitable for larval and algal production. The plumbing is designed with a water filtration and treatment system consisting of some combination of rapid sand filters, cartridge filters, activated carbon, ultraviolet (UV) sterilization or pasteurization (Fig. Oyster farms may also reduce wave energy and help protect vulnerable shorelines.Īs oyster aquaculture grows, so will the food and water quality benefits to the Chesapeake Bay.ĭownload the final aqualcuture study report and addendum.Small cartridge and ultraviolet sterilizer filter system for treating seawater. For every 100,000 oysters grown and harvested annually, six pounds of nitrogen and phosphorus pollution are removed from the Bay. The data indicate that the oyster aquaculture industry can help to restore water quality in our rivers and bays. The growers graciously allowed us to work in and around their operations as we collected data to quantify aquaculture's influence on water quality and ecosystem health.Īfter sampling and studying environmental variables at each of the four oyster farms including water currents, water clarity and chemistry, and sediment type (and the creatures that live in it), our research indicates that oyster aquaculture is a low impact way of producing animal protein. We worked with VIMS and four oyster growers-Big Island Aquaculture, Chapel Creek Oyster Company, Lynnhaven Oyster Company and White Stone Oyster Company-on this two-year study. With that decline, the Bay has lost the oysters’ capacity to filter sediment and algae and remove nitrogen and phosphorus-harmful pollutants in excess-from the water. Wild oyster populations in the Chesapeake Bay have declined to less than 1% of their historical numbers.
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