Oysters

I would guess that almost every known sea creature has been tasted at some time, except perhaps the Box jellyfish and Brain coral. Bread, butter, pepper, salt, tomato sauce and specimen A. Most fish are edible. Most crustaceans, kina, some sea squirts, turtles and sea anemones and almost all molluscs are on the menu. I’ve tried a range of them. Coming in at 327 in the ranking is the kina. There is disagreement about the top spot but only by people who have never actually tried oysters, or perhaps they are just looking for a fight.

Auckland Rock Oysters

We, the public, rarely get to see an oyster in its true majesty. The largest are skimmed off by ‘the trade’ for their own consumption and rascally fish and chip merchants cut any half decent one into fractions before battering them.

You can get your own by puddling around knee deep in estuaries and harbours at low tide and you can find larger ones washed ashore after rough weather, often with a sea tulip attached. They last well, sealed in the shell – often a week or more – unless some walrus or carpenter beats you to them. As a last resort you can buy one or get acquainted with an oysterman.

Oysters are best raw and best opened by yourself. This way you’ve earned it, you know it’s fresh and your enemies haven’t had a chance to poison it. Listen for that little squeal when you bite into one.

The term ‘oyster’ is applied to several different groups of bivalves of a flattened and irregular shape. The best known one is probably the pearl oyster, quite unrelated to the Bluff oyster. Pearl oysters produce nacre, a form of calcium carbonate, which lines the inside of the shell and coats grit trapped within it. This sometimes forms a perfect pearl.

Many shellfish produce pearls with the largest coming from the Giant clam.

In New Zealand we have three food oysters: the Auckland rock oyster, Pacific oyster and Bluff oyster. Once it was believed there were more but most of the discounted species are synonymous with the Bluff oyster. Huge fossil oysters with shells 8cm or more thick are found at Springhills, Southland, but for all their bulk, there wouldn’t have been much oyster in them.

Fossil Oysters from Springhills

Oysters were harvested, bottled and exported as early as 1830, the first food exports from New Zealand. There were extensive beds in Port Adventure which were accessible at low tide. Small vessels would be grounded and the oysters shovelled aboard.

Oysters are protandrous, being males first and then female. They produce copious eggs, only a few of which survive to become oysters. As in most species, vastly more eggs than required are produced. Nature is an enormous restaurant and 99.99% of all eggs and larvae are eaten. Oysters, like almost all bivalves, are filter feeders. They generate a current and trap minute food particles.

All is not joy in oysterdom. We constantly worry whether the quota may be too large. A protozoan parasite, Bonamia sp., has had a serious effect on oyster numbers since about 1985. Pacific oysters are in the news as there as been a big die-off of juvenile specimens in Northland oyster farms. Let’s hope its not a new disease!