– It started in September. We have now received many reports that some have been observed along the coast, says researcher Tone Falkenhaug at the Institute of Marine Research. The autumn has offered a sharp increase in the number of sightings of the pearl gannet along the coast. There have been many sightings, especially in western Norway and in Trøndelag. But the jellyfish has been observed along almost the entire coast, says the researcher. The jellyfish burns in the same way as a normal burning jellyfish, and is particularly dangerous for farmed fish, says Falkenhaug. – When this long colony hits a physical object, such as a fish net, it will split into smaller pieces. It then passes through the meshes in the cage. But it burns just as strongly even if it is broken up. Tone Falkenhaug at the Institute of Marine Research has, among other things, researched jellyfish. Photo: Erlend Astad Lorentzen / Institute of Marine Research As a small community – This is a type of colony jellyfish. This means that there are many individuals living in a colony, where each individual is specialized in different tasks. The colony forms a long pearl-like chain, says Falkenhaug. In other words, the jellyfish is not one creature, but a colony of many small individuals. Falkenhaug says that the individuals must work together to survive. They have different tasks in the colony, and together they make up a small community in a way. – They are so specialized that they depend on each other. Some are tasked with catching food, while others are responsible for reproduction. Still others ensure that the colony has momentum and swims forward, and some to buoyancy. So it’s a fascinating creature. The jellyfish is not one animal, but a colony consisting of many small individuals that all have different roles. Simply a small community! Photo: Erling Svensen / Marine Research Institute Facts about the pearl jellyfish Latin name: Apolemia uvaria Is a so-called colony jellyfish that can be up to 30 m long and is a few cm thick. It looks like a pearl necklace. Belongs to the nettles (cnidaria), and has strong nettle venom that can harm fish. The colony is pelagic and drifts with the ocean currents, and can occur throughout the water column from the surface to a depth of 1,000 metres. The species is widespread in the Pacific, Mediterranean and Atlantic oceans. Previous reports from blooms in 1997 and 2001 indicate that the jellyfish occur in highest concentrations at the far end of the coast. Source: The Norwegian Institute of Marine Research 600 tonnes of fish died In two previous years, pearl corals have led to the mass death of farmed fish. In 1997, the species killed 12 tonnes of salmon, while as many as 600 tonnes died in 2001, according to the Norwegian Institute of Marine Research. – This is particularly true of the fish involved. But we can hope there won’t be any such incidents this year, says Falkenhaug. Wild fish will probably just avoid the jellyfish by swimming away, but farmed fish cannot, which have a little less room to frolic. In the “Dugnad for the sea” portal, a submitter writes that the jellyfish has been observed in several places around and outside Vannøy in Troms. In the web portal owned by the Marine Research Institute, everyone can register their observations of life in the sea. Observations of jellyfish on the portal Dugnad for the sea since 1 September. A majority of these are Perlesnormanet. Photo: Skjermdump/Dugnad for the Sea In Rana in Nordland, several Pearl Normans have been observed just a few hundred meters away from the Buktodden breeding facility. Tom Eirik Aasjord, who is the managing director of Nova Sea, which owns the breeding facility in question, says they are ready if the jellyfish should come dangerously close. – We have detailed contingency plans for such threats. If such a jellyfish should get into the cage, or we discover them before they reach the facility, we will be able to move the fish temporarily, for example. – We can also take other measures if there are many threats nearby. Aasjord is not immediately concerned, although jellyfish have been observed at the facility. – We are monitoring the situation, he says. The jellyfish can be up to 30 meters long. Photo: Erling Svensen / Havrforskningsinstituttet Coming with the ocean currents However, it has been a long time since the jellyfish has caused major damage to farmed fish. Last year at the same time, a similar pattern was seen with many observations. – It is believed to be linked to the influx of Atlantic water masses. This is a species that is widespread in many of the world’s oceans, and particularly in the Atlantic. Then perhaps the jellyfish will follow the warm ocean currents that come in along the coast, says Falkenhaug. But why there is a lot in some years and less in other years is not known. Falkenhaug has a clear appeal to people who may observe the jellyfish: – Report it to “Dugnad for the ocean”. There you can report observations of various interesting creatures along the coast.
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