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Director’s Debrief #5: Spawn!

By Susannah Black
January 20, 2016

I hope everyone stayed warm and safe this weekend and had an opportunity to get out and enjoy all this snow. Cold weather means two things for BOP: things are beginning to heat up in the hatchery and the oysters at our partner restaurants are at their best.

As the water cools each fall the metabolism of Eastern Oysters slows. Oysters use the fall to build a store of glycogen within their soft tissue. This sugar nourishes the oyster throughout the cold winter and allows them to hibernate once the water temp falls below 50̊ F. It also tastes delicious. Oysters in the northeast are at their plumpest and sweetest as the water passes this critical threshold. Gradually throughout the winter, these stores are exhausted. Oysters stop pumping water and feeding, their heart rate slows and by the time spring rolls around and the water gets back up above 50˚, their meats are generally thinner and they’ve lost that sweetness. In a typical year, this peak flavor happens in November. It was so warm this fall that the water in New York Harbor did not fall below 50̊ until the end of December. If you’re a fan of oysters from the northeast, now’s the time to hit the raw bar.

Billion Oyster Birthday: BOP celebrates Robina at Crave Fishbar, a recently-added restaurant partner.

Billion Oyster Birthday: BOP celebrates Robina with an oyster platter at Crave Fishbar, a recently-added restaurant partner.

January is also the start of our hatchery season. Recently, wild oysters, harvested from the mouth of the Bronx River were brought into the lab for conditioning. By warming the water we are able to trick the oysters into thinking it is spring. Over the course of two weeks, they will begin to grow and produce their gametes. During this time, the temperature in their tanks is tightly regulated and we change the water and clean out the tanks daily to maintain water quality. Oysters that are ready to spawn are said to be ripe. It’s impossible to evaluate how ripe without killing the oysters, so we follow strict timing, feeding and temperature protocols to improve our chances of a successful spawn. When the oysters are ready (and the temperature in their tanks is the same as it would be in the Harbor at the end of July), they’re are moved to the spawning trays where a series of rapid temperature changes will stimulate spawning. Eggs are collected, counted and fertilized and then added to the larvae tanks for rearing.

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Jeremy with broodstock ready for spawning.

We repeat this process every week or two depending on how well the larvae are doing. Oyster larvae are incredibly sensitive to changes in water chemistry and temperature. We work hard to maintain these throughout each larval cycle, but it’s a real challenge given the variation in the Harbor and our limited ability to treat the Harbor water we use in our system. We will be working this spring to make some much-needed improvements to our water intake and heating system. With these in place we will be able to prevent pathogens from entering the lab through the intake system.


In the Lab

Our first spawn is happening today. Stay tuned for more developments as the hatchery season progresses.