During recent years, massive jellyfish congregations have appeared along the Northeast U.S. coast, in the Gulf of Mexico, in the Mediterranean, in the Black and Caspian Seas, and in South-East Asian coastal waters.

“Dense jellyfish aggregations can be a natural feature of healthy ocean ecosystems, says Dr Anthony Richardson of the University of Queensland, but a clear picture is now emerging of more severe and frequent jellyfish outbreaks worldwide.”

A new study by Richardson and his colleagues at the University of Miami, Swansea University and the University of the Western Cape, presents convincing evidence that these massive jellyfish populations are supported by the release of excess nutrients from fertilisers and sewage, and that fish populations depleted by over-fishing no longer are capable of keeping them in check.

“Fish normally keep jellyfish in check through competition and predation but overfishing can destroy that balance,” Dr Richardson says. “For example, off Namibia intense fishing has decimated sardine stocks and jellyfish have replaced them as the dominant species. Mounting evidence suggests that open-ocean ecosystems can flip from being dominated by fish, to being dominated by jellyfish. This would have lasting ecological, economic and social consequences.”

In addition to this, the distribution of many jellyfish species may extend as a response to global warming and an increased water temperature could also favour certain species by augmenting the availability of flagellates in surface waters.

The study, which was lead by CSIRO Climate Adaptation Flagship, has been published in the journal Trends in Ecology and Evolution.

You can find more information about CSIRO Climate Adaptation Flagship here:

450 pound blobs filling up the Sea of Japan

The changing ecosystems affect a long row of different jellyfish species, but some of the most spectacular jellyfish congregations observed during recent years have involved the Nomura jellyfish (Nemopilema nomurai) living in the Sea of Japan (Also known as the East Sea). This colossal species, which can reach a size of 2 metres* across and weigh up to 220 kg**, is also present in the Yellow Sea as well as in the rest of the East China Sea.

After becoming a major problem in the region, the Nomura jellyfish population is now combated by a special committee formed by the Japanese government. Killing jellyfish or ensnaring them in nets will however only prompt these animals to release billions of sperm or eggs; aggrevating the problem rather than reducing it. Coastal communities in Japan have started to harvest jellyfish and sell them as a dried and salted snack, and students in Obama, Fukui have started making jellyfish cookies and jellyfish-based tofu.

* circa 6 feet 7 inches

** circa 450 pounds

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.

Credit: NMFS File Photo

Russia has proposed a five year long ban on fishing sturgeon in the Caspian Sea, News.com.au reports. According to non-governmental organisation Caviar Emptor, the Beluga Sturgeon population has declined by 90 percent during the last 20 years. Russia has suggested that all countries bordering the Caspian should impose a ban and that the ban should last for at least five years. According to Andrei Krainy, head of Russia’s state fisheries agency, Russia is ready to ban even scientists from fishing sturgeon in the Caspian Sea. The Caspian Sea is home to roughly 90 percent of the total sturgeon population. The sturgeon is primarily fished for its caviar eggs, a world-famous delicates.

You can read the full article here: http://www.news.com.au/story/0,23599,23444657-1702,00.html

The Caspian Sea is an enormous body of water without any outflows. Its coastline is shared by Russia, Iran, Azerbaijan, Kazakhstan and Turkmenistan. Its salinity is about 1.2%, while the average salinity of the ocean is 3.5%. The Caspian Sea is fed by over 130 rivers, including the famous Russian river Volga which is the largest river in Europe in terms of length, watershed and discharge. The Caspian Sea is home to several endemic species of fish, such as the Caspian roach and the Caspian white fish (also known as Kktum). The Caspian Sea is also where you will find the Caspian seal, one of very few seal species that live in inland waters instead of living in the ocean.