Oyster seed collection

Seed Collection

Oysters reproduce by releasingĀ their eggs and spermĀ into the waters around them. Some of these eggs and sperm combine to formĀ larvae. These larvae are free-swimming for a few weeks as they grow and develop. At a later stage of development, they begin sampling surfaces in search of somewhere suitable to attach. They are attracted to calcium-rich materials such as oyster shells.

Oyster life cycle diagram

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The usual collection technique is to coat a collector with a calcium-rich material. The collector is then suspended in the water at a timeĀ coincidingĀ with when the oyster larvae are ready to attach to a suitable surface. If timed correctly, oyster larvae will attachĀ and begin to grow a shell. The collectors remain in the water for weeks or months to allow the oyster seed (baby oysters) to grow to about Ā 6mm or larger in size.

Here are two different types of seed collectors

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After theĀ collectorsĀ are brought to shore, the oysters are removed, washed, sieved by size, and placed in tanksĀ to grow in ideal conditions to the size of a quarter or larger. This seed is then placed in growth units on the farm.

Collection of naturally occurring oyster seed in no way impacts wild oysters. It is a proven technique commonly used on most oyster farms. Incidentally, aĀ female oyster can produce up to 58,000,000 eggs annuallyā€¦multiply that number by the vast number of oysters in the harbour and the number of larvae available is astronomical! We are interested in collecting only a very tiny fraction of this huge number.Ā In fact, our farm is likely to increase wild oyster populations because oysters on our farm will add to the seed production of the entire harbour.

The process of seed collection does not involve disturbing, touching or removing wild oysters in the harbour.

Growth Units

The growth units we plan to utilize have been developed to improve upon several issues not addressed byĀ gear commonly used on off-bottom farms throughout North America. Most relevant to our farm from the perspective of other stakeholders is the issue of visual profile.Ā OurĀ units are black in color, curved in shape, andĀ floatĀ only a few inches above the water's surface. They will tend to blend in rather than stand out. Observers will see a pattern on the water, but it will be far less noticeable than other gear options. Furthermore, the distance to the nearest homes is Ā½ km so this pattern will be even less noticeable.

Harvesting

After the seed oysters have been on the farm grow sites for about three years, they will be of market size, 3ā€ in length. At this point they will be removed from the grow sitesĀ and taken to shore.

Cleansing

To prepareĀ oysters from Antigonish Harbour forĀ market they must first be cleansed.Ā This can be done in two ways. One method isĀ to transport the oysters to an approved lease siteĀ to be left submerged for three weeks. This allows the oysters toĀ purgeĀ any harmful contaminants. This technique is calledĀ "relay"Ā and is a common approach in preparing oysters for consumption.

The secondĀ suitable technique is called depuration which, simply put, allows the oysters toĀ purgeĀ any harmful contaminantsĀ inĀ controlled conditions. The local company, Bio-Novations, markets depuration systems and we hope to use their technology as our system for preparing our product for market.

Packing / Shipping

The remaining steps to prepare the product for market areĀ grading by size and shape, packing the product in shipping boxes, storing the product in refrigerated cold storage, and shipmentĀ to clients. None of these tasks involveĀ any processing. There are no treatments applied beyond washing with seawater.

Scientific Articles

For further reading please see theĀ links below toĀ relevant scientific journal articles.Ā 

Thanks to Chen Shuhan for reference