4 In Trial

Oyster Trial Update – 2017

Abair! That is the season over already, where did it all go? Time for an oyster trial update.

Well 2017 was a really busy year given that we have actually started building the farm now but in the background the trial oysters have been continuing to grow and it is time for an update on how things have gone with them this past year.

In regard to the weather, in this part of Scotland it has been another odd year, almost a reverse image of last year. This time spring was very mild and relatively dry and we had a terrific early spell of sunshine and warmth in the first part of the summer. Then things seemed to stall and low pressure and after low pressure rolled off the Atlantic bring wet and cool conditions throughout the rest of the summer; apparently the jetstream had moved south and this is what caused the deterioration in the weather.

Unfortunately this continued into the Autumn and September and October were dreadful, with continual rain joined by increasing wind speeds and a further drop in temperature. The loch itself has at times been pitch black in colour with all the fresh water running in and this has done the oysters no favours in the backend. As a result I think we can safely say that the growing season ended early this year.

We have two types of oyster, Pacific (Rock oyster – Crassostrea gigas) and Native (European Flat – Ostrea edulis), on our trial site and the first observation that can be made is that again both have grown successfully this year which has been very encouraging as this was one of the key goals of the trial.

The Pacifics…

At this point for our Pacifics (Rock oyster – Crassostrea gigas) the average size is ~100mm x 65mm x 30mm (length, width, depth) with an average weight of ~128g after three full growing seasons. This is a size increase of ~10% across the year and a weight increase of ~50%. Of course there are a spread of sizes with the batch so care has to be taken when considering these values but in general it can be seen that a change can be seen in the development of the pacific oysters. They have now passed through the primary stage of rapid shell growth and are now in a more mature stage where weight gain is the more apparent.

Trial Pacific Oysters - Size

Trial Pacific Oysters – Size

Trial Pacific Oysters - Weight

Trial Pacific Oysters – Weight

Visually the shells continue to hold onto the teardrop shape as opposed to the flute shape and this continues to support the thesis that the BST basket design causes the Pacific oysters to rumble thus developing the teardrop shape. This is reflected in the fact that the oysters pass Width / Length and Depth / Length ratio tests that have used in Alaska to estimate the quality of the oyster shape.

As an aside we are using these helpful ratios as a quality metric for our farm and plan to continue using them for our commercial stock as well. We shall use them to make key decisions in regard to stocking densities and line heights. At this point we would also be amiss not to mention the excellent ‘Alaska Oyster Growers Manual’ by Raymond RaLonde available here. Of course we live in Scotland not Alaska but there are parallels that can be drawn and this is an excellent resource for any oyster farmer. So a deserved hat tip to these guys in Alaska and I doubt if they ever thought they would end up helping someone so far away as us.

As such we are very happy with the progress of the Pacifics. Using the BST system we have managed to produce oysters, a significant portion of which, shall be ready for harvesting after two seasons. In fact at this point many of the Pacific oysters are simply too big and are taking up too much farm space, and we hope to sell many of these shortly once we gain a classification from the Council.

The Natives…

Turning to the Native oysters (European Flat oyster – Ostrea edulis), our average size is ~64mm x 55mm x 15mm (length, width, depth) with an average weight of ~42g after three full growing seasons. This is a size increase of ~15% across the year and a weight increase of ~78%.

Trial Native Oysters - Size

Trial Native Oysters – Size

Trial Native Oysters - Weight

Trial Native Oysters – Weight

As expected the Natives are now behind the Pacifics in terms of weight and size but the Natives are much more regular and lack the wide size range evident in the Pacifics. A similar trend to the Pacifics can be seen in the Natives in that it appears that they are also starting to move into a stage where weight gain is becoming more apparent than shell growth.

We had expected more growth from the Natives in the past year but 2017 seems to have been a bad year for them. We have noted previously that our Natives respond more slowly than the aggressive Pacifics and tend to put on shell and weight in small steady amounts throughout the summer and as such the poor weather from June onwards seems to have knocked them back.

Having said that we have still succeeded in producing a clutch of Native oysters at the size: Number 4 (Petit) on the French Belon oyster size scale after three full seasons which has to be good all things considered.

And how do they taste?

Well they taste great of course! We did a sample a couple of weeks ago and here are our notes.

Pacifics: Deep plump creamy coloured meat, initial taste is big and fruity followed by a pleasant cucumber finish.

Natives: Light brown coloured meat, initial taste is of sweet salty brine followed by a very pronounced metallic “coppery” finish.


Therefore in summary, some ups, some downs but mostly ups and as such we are delighted with how the oyster trial is progressing / has progressed. It gives us that much needed confidence that this project can and will work!

On the farm works, they continue and we have a busy year ahead as there are loads more posts to install. We are also currently busy trying to a boat railway build as well as a grader.

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    Brad Mcallister
    26th November 2018 at 12:24 pm

    Excellent blog you have got here.. It’s hard to find quality writing like yours these days.
    I honestly appreciate people like you! Take care!!

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