A fish blog.com

In spite of the cold and windy weather we have had the last weeks in the southwestern par of Norway, some keen recreational fishermen manage to arrange fishing trips. The photos below were sent me by Jon Henneli. A couple of days ago he was out fishing on deep water – using long lines.

Fishing on deep water is always exciting, and in addition to cod and haddock you can see a halibut on the photo above. Catching halibut on long line is very exciting. The shimmer of the white belly is visible long before the halibut reaches the surface. To Jon the halibut is a very valuable and special fish. Though he likes to go fishing and to harvest from the sea, he feels a great responsibility for what he is doing. Knowing the problems concerning the halibut stock in the southern part of Norway, he chooses to release every halibut he gets.

He places a tag in the halibut. By tagging and recapturing tagged halibut he hopes that we will get valuable information about the growth and migration of the halibut in the area. He has tagged a lot of halibut earlier, often cooperating with Thorstein Halstensen. Every halibut they catch are released, hopefully to live long lives; growing and reproducing.

Jon and his friends did not return empty handed. Above you can see two of the biggest cod. Even on cold and wet days a fishing trip gives a lot of pleasure and excitement – and some excellent seafood.

The freshwater pearl mussels (Margaritifera margaritifera) live to be over 100 years old. Some scientists claim that its maximum age is about 200 years. This gives the mussel a lot of opportunities to reproduce, but in the Northern Europe most populations of freshwater pearl mussel is classed as either “extinct”, “endangered” or“vulnerable”. The mussel is dependent on the presence of fish (mainly trout and salmon) as hosts for its larvae. Polluted rivers may not damage the mussel population, but it may have an negative influence on the fish they are so depended on.

A couple of years ago a friend of mine told me he had found a strange mussel in a stream. It appeared to be a freshwater pearl mussel. He saw a couple of other mussels in the same stream, but they were all big and old. This sad fact supports the situation in United Kingdom were it is believed that many populations have not produced young for over 30 years.

We reported the found of freshwater pearl mussels to the local authorities. They were not aware of this population, and they would examine the location the next summer. On my island (in the southwestern part of Norway) there are now two known populations of freshwater pearl mussels.

In most rivers in Norway it is now hard to find these mussels. 100 years ago thousands of pearl mussels were harvested each year. The search for the pearls was almost an industry in some rivers. Now there are no commercial interest for the pearl mussel in Norway, and the mussel is protected by law (from 1993). Still reports indicate decline in every known population.

This fish is not bigger than your little finger. It lives for only 3 years and its maximum length is 8 cm. The pearlside (Maurolicus muelleri) is not a threatened nor a rare fish but you may not have seen it before. This fish is found on waters down to 1500 meters depth. If you study the photo above you will see a “row of pearls” between the jaws and the anal fins.

Its seize makes it impossible to catch with a fishing rod or a net, and most species are therefore caught with fine-meshed trawl. The photo below shows three pearlsides and a blue withing.

To determine the age of the fish, scientists use otholits (small, bony stones in the brain of the fish). The otholits of a pearlside is of course very small. Below you see what the otholits look like through a mircoscope. Growth lines in the otholits tells how many summers and winters (years) the fish has lived.

In late March 2003 the Norwegian research vessel Johan Hjort left Bergen (Norway), heading west. Its mission was to examine the blue withing stock on the spawning grounds west of Ireland.

After 7 days of sailing the crew started talking about a strange sound outside. Engines, pumps, fans and wind made a lot of noise, but one sound did not fit in. Three men started searching outside, and on the second floor they found “the sound”. A cat was hiding in a corner behind a winch drum. The poor cat was thin, wet, cold and dirty. The men gave the cat a shower, washing off oil and dirt from its fur.

The crew gave the cat everything a scared and hungry cat could want. After washing up, drying and eating, the cat slept…. and slept..

When the cat was found the vessel was far out in the Atlantic ocean – not far from the rocky islet Rock All – west of Ireland. The cat was therefore called Rockey. The story was soon known in Bergen, and it did not take long to find the owner of the cat. The cats’ real name was Sebastian and he had (of course) been missing for over a week. The cat still had to wait three more weeks before he could meet his owner.

The cat was never alone on the research vessel. Rockey got all the attention he could dream of, and it is not bad being a friend of the chef. A couple of times Rockey got to see the crew and the scientists working outside. Below you can see Rockey on a trawl bag filled with blue withing – an endless supply of food for a cat.

Rockey did not like the noise outside. He preferred being indoors; eating fillets, sleeping and being the main attraction on board. He had his own bed on board, but Rockey preferred the sofa – or a lap.

Rockey returned safely to Bergen, and it was a moving moment when he finally met his owner. This was the last time Rockey explored boats in the harbor. All photos: Øyvind Tangen (The Norwegian Institute of Marine Research).