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For those whom might want to try Manila clam gardening without using protective netting or mesh grow out bags you can get decent results by just using seed. The results will not be as productive but does offer the alternative of not having to deal with maintaining netting or bags on the beach. Try larger seed around 6000 micron screen or even larger if you can get it. Not all beaches are amenable to this....especially ones that have large populations of Cancer gracilis crab offshore. Try out a small patch first on your beach as a test.

Is it possible to grow manila clams in grow bags similar to the method used for growing oysters? It seems that this would be a great way to give ultimate protection to the clams from all predators and also make harvesting as simple as reaching in to a bag free of sand and particulate. I guess what I really am asking is: do the manila clams absolutely need to be in substrate to thrive and grow?

You can grow the clams in the same grow bags as the oysters, however you must dig down and have the bags in the sand. So to answer your question, yes, the manila clams do need to be in the substrate in order to survive and grow, so while the bag method does work and is a good way to keep your clams safe from predators, it may end up being more work than just a predator net over the top of them. It really comes down to what you prefer!

Thanks j-hop for the quick response!

No problem, good luck with your shellfish garden!

I have a 100% mortality rate from seed clams placed under netting the first week in July. Wha??

BD

Sorry to hear about your mortality. Here are a few questions to help people give you some good advice.
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• Where is your beach located?
• Did you find dead clams? If so, where they just open and empty or were they crushed?
• Is there a lot of algae on your net?
• What size netting do you use?
• How did you sample your garden plot?
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The good news is that it is very common for commercial growers to think they have lost their crop, only to find a few months later that they actually did survive. If you have not tried this already, I would get some small hardware cloth and make a screen frame for sifting sand. This is a good way to count both live seed and dead clam shells. With some information on how they died we can work on avoiding it next time.

Thanks for the reply. The clams appear to have grown about double, then die. They are whole, but full of sand. The beach is on Vashon on Colvos Passage. We have a wide tidelands - over 300' at minus tide and the sand is fine. I bought the netting at the Bow nursery - I think it is 1/4". We have had a normal seaweed-deposit season, and very little over the test areas. We have many geoducks, a few razors and a few more butters. If there is any good news here, it is that the butters like the protective netting.

BD

Manila clams won't survive on a sandy beach like that. It's an extreme rarity to find them occurring naturally in sand habitats in Puget Sound. You can probably grow them in bags with gravel on a sandy beach. But by themselves even with netting they just won't work in sand. As you stated, the good news is that the netting increased the survival of Butter clams on your tidelands. Just watch out for Moon snails when those Butters get to around 30 mm in shell length or slightly bigger. I've observed great survival with experimental Butter clam seed plants right up until the Butters got to that shell length then it was almost like the snails were waiting for dinner to be ready.The Razors on your beach are likely Jack Knife clams a relative of the Razor clam that occurs on our coast. Occasionally Razors can be found on the west side of Whidbey Island but haven't been found anywhere else.