7/12/2021

time: 3:00 pm

air temp: 78 F

water temp: 65 F

tide: rising

conditions: muggy, calm


It's been an interesting few weeks on the farm lately - some new-to-me challenges, and some regular old mid-summer craziness to manage. My seed arrived as anticipated just about a month ago, and in that time its gone from itty-bitty 3mm to almost triple the size.

Left fingers - 3mm babies, June 16. Right fingers, the 8-9mm babies, July 12.

Yesterday I finally got around to grading all those little babies, to sort out the smaller ones from the bigger and send them back out into the water in more appropriately sized gear. For whatever reason, the smaller oysters especially seem to do better and grow faster when they are grouped together with other slower growers. And, the more size grading I do now, the easier it is for me to keep track of and manage the crop as it grows. The smaller oysters went back into a couple nursery boxes to do some catching up, and the bigger ones went into 4mm mesh bags. It won't be long before I have to come back around and divide them into twice as many bags!

Sponge treatment: 6 min dip in concentrated salt-water solution, followed by a 1 hour minimum air dry.

The newer challenge that I've been working out has been the discovery of my first really problematic pest on the farm. It was only a matter of time before I had to deal with something along these lines. Cliona celata is a shell-boring sponge species that can be found up and down the east coast and is often a problem for oyster farmers like myself. While it's not exactly a predator of the oysters themselves, this sponge can become a big issue if let be because of how it makes it's home. Through a chemical reaction, it bores it's way into the shell material of oysters and clams and creates these maze-like galleries within the layers of the shell, where it then lives and grows. This boring and tunneling action causes the oyster's shell to become very thin and brittle, and because the sponge almost always seems to target in the hinge area of the shell, the affected oysters are more challenging (and sometimes impossible) to shuck without it turning into a crumbly mess of shell bits and orange sponge tissue.

Drying.

You can bet that I did as much research as I could on possible treatments as soon as I discovered an oyster with indications of cliona present, as well as lots of sampling on the farm to try and get a sense of which oysters and how many were affected. The good news here was that it just seemed to be my oldest year class that had signs of it (only about half of the total farm), and maybe only 6-7% of those oysters with obvious sponge presence. Because this is the time of year that cliona reproduces, though, I wanted to act quickly in treating things in the event that this infection was only just getting started. The treatment solution I landed on came from a well-documented study from Canada that was most importantly one that I could pretty easily conduct on my boat. Simply put, I submerged the oysters in their gear into a concentrated salt brine solution for six minutes, and then laid them out around the boat for at least an hour to dry. Nice hot sunny weather helped to speed the drying along, and after about two and half long days of this, I managed to get everything dipped and dried.

All back in the water after the end of a long dip day.

Circling back a week or so later, I was pleased to see that oysters with obvious sponge presence now have obvious signs of very very dead sponge. This was hard to tell, but I learned to notice that what little bits of sponge I could see through it's bore holes had gone from the usual bright orange color to black. I bashed up a few badly affected oysters to really be positive, and sure enough, dead sponge. My oysters seem to have survived the treatment well, by and large. There were a few casualties here and there where they must have accidentally gulped some of the brine solution, but those losses seem worth it to know that I've stopped this problem from progressing.


As stressful and dooming as it felt to make this discovery this month, at the end of the day, I'm glad it happened. It was a good test run for me on doing a widespread pest treatment on the farm, and it will make any future issues feel much less daunting to deal with.

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