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Sustainably Farmed Halibut

(Hippglossus hippoglossus)

Part of our Fish For Tomorrow range

The Wild Halibut
Wild Stocks
Sustainably farmed Halibut
Our Halibut Range
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Wild Halibut

Halibut (Hippoglossus hippoglossus) is the largest of all flat fishes, and can grow up to 300kg, be 4 metres long, and can live for more than 50 years. More commonly, wild fish average 5-10 kg. It is is thick-set and right-eyed (both eyes on the right-hand side of the body). It is found in cold waters of the Atlantic. Spawning occurs during winter and early spring. Atlantic halibut become sexually mature at 10-14 years.

They are a white-fleshed fish which has a fine, full flavour and are delicious pan-fried, poached, steamed or grilled.

Wild Stocks

The Maine Conservation Society (MCS) describes wild Atlantic stocks of halibut as "Overfished, which means it is caught in such high numbers that a sustainable fishery cannot be maintained by the current population size."

Halibut is also assessed by IUCN - World Conservation Union as "Endangered". The advice of MSC is to "Avoid eating".

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Halibut Farming

Rationale

In view of the perilous state of wild halibut, work has been going on since about 1999, to farm halibut. Over the last couple of years, in Shetland, the emphasis has been on developing a sustainable way of farming the halibut, which it is hoped will soon be developed into an organic system. At present there are no organic standards for farmed halibut, but such standards are currently being developed.

This is a pioneering venture, which has made good progress towards becoming an organic system. The principles are being established, and whilst not yet perfect, we believe this type of enterprise should be supported to enable it to develop towards its goals. We therefore describe the system of production "sustainable". It is however recognised by the fish conservation organisation 'Friend of the Sea'.

Habitat

A halibut lives most of it's life on the seabed. In fish farming, a seabed is emulated at the bottom of the enclosures, which has to be rigid and tensioned flat. Unlike salmon the halibut will not rise to feed but prefer to take the pellets from the flat cage bottom .

Young Fish

This stage is entirely conventional at present with all pens being land based in Iceland. Juveniles are hatched and reared from captive fish in Iceland, so there is no impact on wild stocks. Once volume can be increased, this stage can be developed in the UK, and be varied as necessary to comply with possible organic requirements.

Eggs hatch and larvae live off the yolk sac for about 50 days. Their first feed is on live Artemia, which are cultivated at the hatchery. After another 50 days or so, the larvae metamorphose into juveniles when they are transferred to pellet feed. Pellet feed is not to current organic standards and contains whole fish and a portion of trimmings from human consumption (to be organic the entire feed must be from sustainable sources, which in the UK is trimmings). The egg to juvenile stage (5 gms) lasts about 6 months. Juveniles could be transferred to Shetland at this size, but have been kept in Iceland until 100g to 1kg before wellboated to Shetland.

Stocking Density

Sustainably farmed halibut

Halibut are very sociable, and if you put just a few fish in a large cage they tend to lay together. Because of their habit of lying on the seabed, stocking density is calculated on the area of simulated sea bed which is used, not the water column, to reflect the natural behaviour of the fish. Stocking densities are therefore not comparable to salmon, which are based on kg per cubic meter, whilst stocking densities for halibut are based on kg per square meter.

Size at Maturity

Males stop growing at 2 years and weighing about 2kg. These are graded in December to January and are the perfect size for two to share. For the rest of the year the fish are harvest to order.

Pollution

As with all organic fish farming, the Shetland halibut farm aims to produce minimal environmental impact. As a result, the enclosures are in fast-flowing water facing the wide Atlantic. The seabed around the farm area is regularly inspected by the Scottish Environmenatl authorities to ensure there is no sedimentary build-up.

There is currently virtually no way in which the farmed halibut can escape into the wild populations, due to the size of the fish when they enter the enclosures.

Feed

Feed composition for the growing halibut in Shetland is very close to that for organic salmon - with no pigment and low oil content.

Veterinary treatments

No treatments have ever been needed or given to date. There are no known external parasites, such as lice, which are a problem to species such as salmon.