This year, fishermen in the southern ocean of Australia report seeing more tuna than in 20 years. They report not only bigger catches, but also that the average tuna is about 20% lager than previous years.

Australian Tuna Association chief executive Brian Jeffries says: “There’s a lot more fish out there than there has been in the past 10 years and the fish are bigger in that period.”

This leads some to believe that the tuna population is recovering and that it has been doing so since 2006 when it was discovered that Japanese boats were catching 40,000 tonnes of southern blue fin tuna illegally each year and had been doing so for at least 20 years. The discovery lead to a crack down on Japanese illegal fishing and the illegal fishing in the region has, although still preset, dramatically dropped since 2006.

Is the tuna population in the Southern Ocean starting to recover, or is this just a sign of an imminent collapse – similar to the good years that preceded the cod collapse in the Atlantic? Only the future can tell.

The sea cucumber, which has been an appreciated traditional food item along the coasts of South East Asia for many generations, is now beginning to show up on dinner tables across the globe. The vast majority of the captured sea cucumbers are however still devoured in South East Asia and countries such as China and Japan are big importers of the delicacy.

This time of year, divers canvass the waters of Alaska in search of a particular species of sea cucumber for the export market; the long and warty Parastichopus californicus. Parastichopus californicus, also known as the giant California sea cucumber, has a soft, cylindrical body and can reach a length of 50 cm. The endoskeleton is found right under the leathery yellowish skin and five rows of tube feet extends from the mouth to the anus on the underside of the body.

giant California sea cucumber

In Alaska, sea cucumber catching is strictly regulated and a diver is not allowed to catch more than his or her daily bag limit. When an area opens during the cucumber season, the catchers have seven hours on Monday and four hours on Tuesday to collect their daily bag limit – 2,000 pounds per person. With one sea cucumber weighing 0.5 pounds or less, you can actually catch thousands of cucumbers without reaching your daily limit. Last year, 179 divers participated in the event, which is well below the authorized maximum of 389.

In most cases, only the skin of the cucumber is shipped off to Asia, not the entire animal. Before being exported, the skin is typically boiled and salted until it shrivels and turns black.

Exotic sea cucumber (giant California sea cucumber)

Enokitake Soup with Clams and Sea Cucumber

Ingredients

1.2 kg whole chicken (no skin)

1 large sea cucumber

30 g dried scallops

1 can clams

80 g fresh enokitake (golden needle mushroom)

30 g coriander leaves

salt and pepper

Method

1.) Cut the chicken into pieces. You can remove the bones or leave them, it’s up to you.

2.) Soak the sea cucumber and cut it into big pieces.

3.) Bring 2.5 litres of water to a boil in a pot.

4.) Add chicken, scallops and sea cucumber.

5.) Bring the water to a boil again.

6.) Reduce to low heat and leave to simmer until ingredients are tender.

7.) Add clams and enokitake.

8.) Add salt and pepper to taste.

9.) Bring to a boil.

10.) Place in soap bowls, sprinkle with coriander leaves and serve.

The Caspian Sea has traditionally been the world’s main source of caviar, but pollution and overfishing has caused serious problems for the fish in this enormous lake and yields are dwindling at a worrisome pace. The Caspian crisis is now prompting an increasing number of restaurants and importers to switch to Israeli caviar instead.

Sturgeon in pond – Not the facility talked about in the article

In Israel, Ossetra sturgeon (Acipenser persicus / Acipenser gueldenstaedtii) is commercially farmed at the Kibbutz Dan close to the Lebanese border, using eggs imported from the Caspian Sea. Compared to caviar from the Beluga sturgeon (Huso huso), Ossetra caviar – also known as Osetra or Asetra caviar – is firmer in texture and has the most variety in terms of size, color and flavor.

Kibbutz Dan began their Ossetra project in 2003, when caviar prices skyrocketed and made sturgeon roe even more expensive than before. The idea was not primarily to export caviar, but to satisfy the demands of the large Russian-Israeli population, according to Ben Tzvi at Kibbutz Dan. The location of the sturgeon fish farm is well chosen since it can use water from the snow-fed river Dan, a principal source of the river Jordan.

Under normal conditions, a female Ossetra sturgeon will not become sexually mature until she is around 15 years old, but Israeli biologist Avshalom Hurvitz has managed to make female sturgeons commence egg-laying at an age of just 8 or 9 years.

So, is sturgeon roe really kosher? Since the sturgeon is considered a scale-less fish, it is seen as forbidden food according to traditional Jewish dietary laws. However, according to Berta Levavi-Sivan, a scientist at the Hebrew University and a participant in the sturgeon-rearing project, the sturgeon fish is actually equipped with tiny scales – it is has only been considered a scale-less fish because the scales are too small to bee seen with the naked eye.

According to Korean scientists, brass can be used to make shellfish a safer choice at the dinner table. “We showed that copper ions diffuse out from a brass plate into a fish tank filled with seawater, and within 40 hours the copper killed 99.99% of the Vibrio food poisoning bacteria contaminating the living fish and shellfish,” says Dr Jeong-Weon Huh from the Department of Health Research at the Gyeonggi-do Institute of Health and Environment.

When a brass plate is placed in a tank filled with seawater, copper ions will diffuse out from it and be absorbed by the Vibrio bacteria, causing them to die and fall of infested fish and shellfish. The copper will not only kill bacteria present on the outside of the animal, it will also get into the internal organs and kill Vibrio bacteria there. The dead bacteria will then be flushed out of the animal and sink to the bottom of the tank.

So, is this a safe method? According to Dr Huh¸ any remaining copper ions in the saltwater will be absorbed by sand and polyester filters and leave fish and shellfish suitable for consumption. “By being able to remove the copper ions, we can prevent people from consuming excess copper themselves, but let them safely enjoy any kind of fish, either raw or cooked.”

Raw fish and shellfish forms a major part of traditional Korean cuisine and finding a way of reducing the risk of food poisoning is high on the agenda for the Gyeonggi-do Institute of Health and Environment. Between 2003 and 2006, roughly 12 percent of food poisoning cases in Korea were caused by Vibrio bacteria. According to Korean tradition, the safest way to serve food is in a so called bangzza bowl – a bowl made from a 78% copper and 22% tin mixture. The researchers have now managed to show that this metal mixture emits enough copper ions to kill off nasty microbes like Vibrio bacteria. Using this traditional type of kitchenware might be a feasible way to prevent serious gastrointestinal infections in situations when it is difficult to uphold a high level of hygiene and sanitation.

Dr Jeong-Weon Huh revealed his findings at the Society for General Microbiology’s autumn meeting at Trinity College, Dublin.

When Kate Stoeckle, 18, and Louisa Strauss, 17, collected samples of fish from New York fish stores and restaurants on Upper Manhattan and tested them using the new genetic barcoding method, an astonishingly large portion of the samples turned out to be mislabelled and sold under the wrong name. A sushi restaurant claiming to offer white tuna was for instance serving their guests Mozambique tilapia instead, while another restaurant sold Spotted goatfish from the Caribbean Sea under the name Mediterranean red mullet.

Red Snappers

All in all, Stoeckle and Strauss collected 60 different samples of fish and had them tested at the University of Guelph in Canada. Four samples could not be identified by the genetic barcoding identification technique, but of the remaining 56 samples no less than 14 turned out to be mislabelled. This means that out of 56 samples, a whooping 25 percent were sold under false pretences.

All 14 cases of mislabelled fish consisted of comparatively cheap fish being sold as a more expensive species. It is therefore hard to see how the mislabelling could be the result of honest mistakes by fishermen or middlemen.

Not getting what you pay for as a consumer is however not the only problem with mislabelled fish; a false identity can also be used to sell endangered species to unsuspecting dinner guests. In the Stoeckle and Strauss study, two samples of alleged red snapper did for instance turn out to be endangered Acadian redfish (Sebastes fasciatus). The Acadian redfish has been listed as Endangered (EN) on the IUCN Red List of Threatened Species since 1996.

The study did not unveil the names of the restaurants and fish shops since it could not be determined if they were intentionally misleading their customers or if they had purchased the mislabelled fish in good faith.

Stoeckle and Strauss are both students at New York’s Trinity school.

Raw fish, such as sushi and salmon tartar, is considered a delicacy and is served in restaurants all over the world. Before you decide to make your own raw fish dishes, it is however important to store the fish in the freezer for at least 72 hours prior to preparation. The recommended freezer temperature is -18°C / -0.5° F or colder. A quicker method is to store the fish at – 35°C / -31°F for 15 hours.

If the fish is really large, ideally keep it in the freezer even longer than the recommendations above since it can take some time for the cold temperature to reach all the way into the fish. For really thin fish, e.g. a slice of salmon, a shorter period can be acceptable. The important thing is that the entire fish is deep frozen all the way through.

By freezing the fish, you will kill potentially harmful parasites that may be present inside the flesh. The popular salmon can for instance be infested with Diphyllobothrium latum, a tapeworm capable of taking up residence in the human digestive tract. You don’t want this tapeworm inside you because it will deprive you of nutrients and can for instance cause vitamin B12 deficiency.

Some connoisseurs dislike freezing fish prior to serving it raw and will instead pay meticulous care when preparing the fish. The fish is carefully cleaned out and all specimens that show signs of parasite attacks, e.g. the presence of tiny worms, are discarded. It is also common to slice the fish into really thin slices since this makes it easy to spot parasites. This method should however only be considered by those who have received proper training in spotting parasites and is not as reliable as freezing the fish.