Hatchery Tour

Gloucester Point Hatchery

The ABC Gloucester Point hatchery has all the capabilities of any modern bivalve hatchery. At the heart of these operations are the algal-culture facilities where specific strains of unicellular algae are cultured to feed larvae, young spat (recently set oysters), and brood stock (parents for the spawnings). Algae is raised in batch culture, which means that it is progressively transferred from test tubes to 2 liter beakers to 20 liter carboys to 100-200 liter kalwall tubes, and some cultures are transferred to 2000 liter tanks. From these latter-sized containers, ABC researchers can centrifuge the algal suspension into a paste—essentially algal cells in very little water—for long-term storage. ABC provides algal paste to general VIMS users and to a few outside user groups at cost.

What sets the Gloucester Point hatchery apart from any other is the large number of genetically distinct spawns produced each season, a process requiring exceptional diligence from hatchery personnel. A brood stock room holds specific stocks of oysters in temperature-controlled tanks. The water is filtered and food is provided by the batches of algae cultured constantly. In the Spring, the principal function of the brood stock room is to "fool" parent oysters into thinking that it is early spring, and thereby cause them to start maturing sexually that eventually (in 4-8 weeks) leads to mature eggs and sperm. This is done by controlling the temperature of the water and feeding the oysters large quantities of algae. During mid- to late summer, the brood stock room is used principally to hold parents that are already sexually mature. At this time of the year the temperatures that were used to stimulate reproduction (about 22°C) are sufficiently cool to prevent the parents from releasing gametes before hatchery personnel are ready to use them.

The "working" part of the hatchery is the hatchery floor. This is covered by dozens of small white larval tanks, about 200 L in volume. On occasion, small experiments are done in 15 liter "buckets" and larger cultures are accomplished in 1000 to 2000 liter tanks. This procedure differs from commercial hatcheries because of the size and number of larval tanks. In commercial hatcheries, a small number of extremely large tanks typically fill the hatchery floor. Our modus operandi however is the production of many different genetic groups of small volume. From each 200 liter culture we can easily harvest between 10,000 and 100,000 spat under most circumstances, which is a sufficient quantity for field trials or for holding as parents for the next generation. Our operating procedures are similar to other experimental bivalve hatcheries such as those of Rutgers' Haskin Shellfish Research Lab's Cape Shore Breeding Station and University of Maine's I.C. Darling Center's culture facilities.

The larvae pass through their planktonic stage in the hatchery and are "harvested" when they become ready to "set" (metamorphose to a sedentary existence). We manage the setting process in a number of ways depending on the type of evaluation scheduled for the "seed" oysters. After the hatchery, they are kept in an upweller system that contains the seed oysters as discreet genetic entities in containers that allow raw water to pass through them. Raw water pumped directly from the York River contains microscopic algae and other plankton on which the seed can dine.

We are developing the capabilities to hold and experiment with non-native species at our Gloucester Point hatchery. Importing new species is an activity frought with peril connected with the water borne transmission of exotic material. For example, the original importation of brood stock might include diseases in the brood stock itself; hitchhiker species attached to the brood stock such as boring worms, barnacles, or other epibionts; or commensal species living inside the brood stock such as small crabs or any number of other beasts that could dwell inside the shell cavity of a bivalve. Therefore, we have developed the capability to quarantine imports by holding them in static brood stock tanks and treating discharge water to eliminate the risks of holding non-native brood stock. We call this Level One quarnantine. Level One quarantine is very intensive and we are limited in our capabilities to hold significant numbers of Level One non-native brood stock or fewer individuals of various species of brood stocks. We strive to reduce our Level One quarantine activities by producing the next generation of non-native in the hatchery. That is, direct imports are spawned to produce what is called an F1 generation. In the F1 oysters there will be no hitchhikers and there should be no diseases if the parents were realtively healthy. These conditions can be checked by the VIMS pathology group. Provided that the F1 are "clean," the principal concern of quarantine is preventing the F1 from releasing their gametes to the wild. For this we have constructed and are in the process of upgrading a flow-through quarantine system for long term maintenance of non-native brood stocks. This level of quarantine is called Level Two.

When the seed reach plantable size, generally around 8-10 mm, they are parsed out to various field sites for evaluation, testing, or maintenance until they are large enough to breed again.