A Drain Down Day in the Hatchery!
A top down view of the conicals.
Clam larvae drained onto a sieve.
Counting larvae under the microscope.
Removing post-set shellfish from the floating mesh trays.
Filling buckets with algae for feeding.
Wondering what a typical day in the hatchery looks like during this time of year? Every Monday, Wednesday, and Friday are referred to as “drain down days”. These days consist of draining, cleaning, and refilling all of the tanks in use, as well as checking on the progress/health of the growing shellfish.
An overview of the hatchery.
Drain down days start with the broodstock conditioning tanks. Typically, one tank is left open and already cleaned from the previous drain down day. This tank is filled up with fresh seawater and let come to temperature. Once it reaches temperature, the broodstock shellfish are moved into the new tank, and the old tank is drained, cleaned, and refilled for the next set of broodstock. This is repeated until all the broodstock sets are in new clean tanks.
Next up are the conicals, which are used to hold the larval shellfish. These conicals are drained down onto a sieve (a fine mesh strainer) that catches the larvae. Once the conical is empty, the larvae are brought over to the sink area and placed into a bucket for the time being. The conical is then thoroughly cleaned and refilled with fresh seawater. These steps are repeated for every conical in use. Once all of the larvae have been collected, a sample is brought over to the microscope to count in order to estimate how many total larvae there are. The larvae will also be put through a series of different sieves to sort them by size. Since some shellfish grow faster than others, shellfish of the same size will be put together in the same conical. After all of the conicals are filled with fresh seawater, the larvae are split up and put back.
Along with the conicals, the downwelling tanks need to be cleaned. These are the tanks the post-set shellfish move into once they have either reached a certain size or have gone to set (fallen out of the water column). The shellfish in these tanks sit atop different sized floating mesh screens. The screens are removed from the water and the shellfish are rinsed into a bucket. The screens are cleaned and rinsed and set aside while the downwelling tank is drained, cleaned, and refilled with fresh seawater. Just like with the larvae, the post-set shellfish will also be sorted by size so they can be places back on an appropriately sized mesh.
The downweller tanks filled with shellfish.
After all the tanks have been cleaned and the shellfish put back, its feeding time! The shellfish are fed every day, but on drain down days, they are fed after the tanks have been cleaned so that no algae goes to waste. Feeding concludes the end of a drain down day. All of these steps are repeated every drain down day until the outdoor water temperature warms up and the shellfish are able to be moved outside!