bob_G

Some cultivated shellfish biology

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I found a few old photos on my phone I took when I grew shellfish for the town.

 

The first three are quahogs. The tiny quahogs in the first photo are around 12-17mm, and about three months old.  They need to reach at least 12mm before release to have a good chance for survival.   When I received those quahogs in June, they were all between 1-1.5mm.

The ones in that photo still have another month to go, so they'll be in fine shape.  By the time I planted them, the majority will be 20mm, with some reaching an extraordinary 25mm!  I planted those in mid October. The water was still warm enough for them to dig into the sand. Plus there was still enough active phytoplankton around for them to feed. 

Please note the tiny red lines on the shells.  Those are the genetic markers of a southern notada strain. Virtually all northern cultivated quahogs are hybrids. A cross between a northern quahog, and the faster growing southern notada.  Northern quahogs are notoriously slow growers. However they are very disease resistant to our local shellfish diseases.  Southern notadas grow much faster than their northern counterparts. Therefore, by cross breeding the two, you get a quahog which is still disease resistant, and grows at a fast rate.

As you can see in the second photo. That is a mature notada that I grew and harvested in Monument Beach. It was probably 3.5 years old.  Note the almost decorative red markings all over the shell. A classic notada characteristic.

The last photo is of two quahogs I grew from seed, and planted in Buttermilk Bay. Note the orange. paint at the base of their shells. I painted that, and that's how big they were upon release. About 25mm.  I used to paint about 10% of my shellfish to monitor their growth.  Also recreational shell fishermen around town would call me to say they found them, and this provided me with further information I could use down the road.

 

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The next photos are my oysters. The oysters in that photo are the same age as the quahogs. About three months old, and from diploid stock.

Oysters are extraordinarily fast growers. I took possession of the oyster seed when they were between 1.1.5mm in length.  About the size of a grain of sand.  As you can see, they are about 50-75mm, three times the size of the quahogs. 

From there, I would place the oysters in floating pouches, about 300 per pouch. When the growing season would end in October, I'd sink them, to winter them over.  In the spring we'd raise all the pouches and float them until the following Oct. By that time they would be mature, with almost all reaching the 3" minimum legal size limit.  The ones in the last photo are 4" long, 16 months old, and beautiful quality. An oyster that one could easily fetch $1-2.

 

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Can you distinguish the hybrid, Northern, or Southern quahogs by taste? Or is it entirely a matter of water temperature and the plankton varieties they've eaten?

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30 mins ago, Joe G said:

Bob......I think it's notata not notada.     ;)

 

Also, where did you folks buy your oyster seed?  ARC?   

Yup, you're right Joe. Typed it on my phone and didn't notice the error.

 

The oysters didn't come from ARC, but the quahogs did.  The oyster seed came from Muscongus Bay Aquaculture in Maine.

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You have to wonder, with the current mindset on exotic/invasive species, whether introducing a non-native species (notata) would be something that would be acceptable today.  I fully understand they’ve been used for seed for quite a while, but with ocean temperatures rising and other environmental factors, whether this will prove to be an error.  
 

“Anticipated Problems
A list of future problems that are destined to confront the Massachusetts shellfish farming industry includes:
1. The genetics of farmed animals relative to wild animals: Because the commercial shellfish hatcheries have developed a specific genetic phenotype that results in distinctive shell markings ("notata" clams), hatchery reared quahogs are easily identified. This is result- ing in a growing awareness of the contribution of hatchery reared shellfish to wild popula- tions. The contributions of notata clams comes both from municipal restocking programs using hatchery reared clams and from the larval production of cultured clams that are spawn- ing in the growing beds prior to harvest. Regardless of the source, the question will inevita- bly be asked as to what is the impact of hatchery-selected strains of shellfish on wild shellfish population genetic diversity.”

 

https://scholarworks.wm.edu/cgi/viewcontent.cgi?article=2117&context=reports

 

 

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1 hour ago, Jonesy02719 said:

You have to wonder, with the current mindset on exotic/invasive species, whether introducing a non-native species (notata) would be something that would be acceptable today.  I fully understand they’ve been used for seed for quite a while, but with ocean temperatures rising and other environmental factors, whether this will prove to be an error.  
 

“Anticipated Problems
A list of future problems that are destined to confront the Massachusetts shellfish farming industry includes:
1. The genetics of farmed animals relative to wild animals: Because the commercial shellfish hatcheries have developed a specific genetic phenotype that results in distinctive shell markings ("notata" clams), hatchery reared quahogs are easily identified. This is result- ing in a growing awareness of the contribution of hatchery reared shellfish to wild popula- tions. The contributions of notata clams comes both from municipal restocking programs using hatchery reared clams and from the larval production of cultured clams that are spawn- ing in the growing beds prior to harvest. Regardless of the source, the question will inevita- bly be asked as to what is the impact of hatchery-selected strains of shellfish on wild shellfish population genetic diversity.”

 

https://scholarworks.wm.edu/cgi/viewcontent.cgi?article=2117&context=reports

 

 

Boy, I don't know how to reply to this?

Notata quahogs have been around Cape Cod for decades.  But you do have a point.

I'll only speak to the situation in Bourne. We have no quahog grants in Bourne. So the notata quahogs grown in upwellers are grown strictly to augment the sometimes beleaguered wild stocks.  

From my observations, the annual infusion of cultured quahogs definitely help conserve the wild stocks.   In addition, we've documented it over and over, the notata stocks I grew, are spawning. We've found numerous notata seed and littleneck in areas where none were ever planted. 

One potential benefit of notata stock is as follows. Notata are a southern quahog strain. They thrive in southern waters. The waters in the south are warmer on average that our waters up north.  If our local waters were to warm a couple degrees due to climate change, would this help notata stocks to thrive?

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I get notatas on occasion where I do 99% of my quahogging, and that area has never been stocked or seeded (according to the shellfish warden).  So it would stand that they do naturally spawn.  However, the numbers I’m seeing don’t make it appear like they are numerous or taking over.  
 

I was just giving it some thought seeing as people are paying more and more attention to species (of all kinds) that are moving in or out of their natural range due to human influence and climate changes.

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Fairhaven stocked them striped quahogs a couple years ago and open the area this year. It was sweat filling a basket in 20 min with little necks. By the end of summer they were gone and I had to work for them in other spots. (natives)Talk with the shellfish warden and he loves them and will be using them again.

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15 hours ago, BrianBM said:

Can you distinguish the hybrid, Northern, or Southern quahogs by taste? Or is it entirely a matter of water temperature and the plankton varieties they've eaten?

Brian,

As far as taste, they're indistinguishably. On the half shell or over pasta they look and taste great.

However despite the fact that notatas look more presentable on a plate, they do posses a slight flaw.   

Their shells are slightly thinner that that of their northern quahog cousins.  The slightly thinner shell in no way impacts the notata's ability to survive and thrive in the wild.  But where it does manifest itself is in the half shell, raw bar market.  

When being opened, the shell in about one in five break. They simply crack. This is especially the case if the quahogs are refrigerated for a couple days, and the shells lose some of their water content.  

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Really appreciate the experience and knowledge being shared here

I too wondered what those markings on some clams were, and the growth on the painted shells……etc..

Thanks

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