Unfortunaetly no photos exist of live sea grayling in the wild. This photo is of grayling in a river. 

Grayling biology  To top

Swedish name: Harr  (havslekande harr)          
Finskt namn: Merikutuinen harjus
English name: Sea grayling
Latinskt namn: Thymallus thymallus        

Geographical distribution
Originally grayling are found in freshwater all over the northern hemisphere. However, has it only been documentated from the Gulf of Bothnia that the fish also spawns in the ocean, more spesifically in the Kvarken area.

The grayling is easily recognized by its great dorsal fin and that it has got the small dorsal fin, typical for the salmonoids, on the back of its tail. The fish smells like thyme, that is also described by its latin name Thymallus thymallus, which precisely means thyme. The grayling can exceed a length of 60 cm and has got a documentated max weight of 3.5 kg.

Biology
The grayling lives in cold, clear and oxygenized rivers, streams and lakes, and are even found in brackish water. Its prey is a mix of insects, crustaceans and fishes. The sea grayling is both day and night active. It spawns in April – May in very shallow water. The grayling is a popular fish among sports fishermen. Since it likes to hunt for insects close to the surface it is often caught by fly casting but can also be caught by hook and line. Until the beginning of the 1960 grayling was fished commercially and it is recognized as a tasteful fish to eat.
What is so extraordernary about the grayling described in this project, is that it spawns in the ocean, which has not been observed anywhere else in the world
 

Reproduction To top
The graylings choice of habitat during spawning is well documented in running waters (ex. Gönzi 1989, Nykänen 2004). There are also descriptions from the Baltic Sea of spawning grounds in the Kvarken. (Enholm 1937, Hurme 1966).
Trough interviews

Watch live fry in the Kvarken!

local fishermen have marked out spawning grounds in the Kvarken and fishery related to these areas. ( for example Sven Lundberg, Erik Åvik, Anton Björkman, Are Söderblom, Helmer Westergård, Harri Österqvist).
 

The information concerning the grayling’s biology found in the literature is mostly similar to each other. Below you’ll find some examples:

-The spawning occurs in early spring, shortly after the ice has melted.

-The temperature during spawning is between 4 -10 ° C.

-The spawning occurs in shallow water, and in running water it often happens that the dorsal fin and the back of the fish sticks out of the water.

-The spawning always occurs on bottoms free of vegetation.

Information about whether the grayling digs spawning holes or not varies a lot. Some literature states that it does not dig spawning holes at all and that the eggs fall into cracks between rocks and pebbles, others claim that the grayling digs the fish eggs into the sediment.

One specie - two origins  To top

By comparing genetic information from DNA a group of Finnish, Russian and Swedish scientists found that the grayling of Northern Europe mainly derives from two genetic strings (1). The populations of Sweden, Norway, Denmark, Poland and Germany are of the same origin, whereas the populations of Finland, Russia and Estland had a different origin, see the figure below. The differences are distinct and there is almost no overlap at all.

The figure gives an overview of the results made from studies of the grayling in northern Europe. The black dots represents grayling that during the ice age probably was settled south of Scandinavia and the grey dots resembles the grayling coming from the East (modified after Koskinen et. al 2000.).

(1) Koskinen M. T. , E. Ranta,
J. Piironen, A. Veselov, S. Titov, T. O. Haugen,
J. Nilsson, M. Carlstein and C. R. Primmer. Genetic lineages and postglacial colonization of grayling (Thymallus thymallus, Salmonidae) in Europe, as revealed by mitochondrial DNA analyses. Molecular Ecology (2000) 9, 1609–1624. The”historical gene” which was used for this study derives from the cells mitochondria, so called mitochondrial DNA. What is so unique about this DNA is that it is only inherited by the females. Due to this, it is impossible to changed or “contaminate” it with the DNA from males that derive from other areas. The DNA are inherited from female to offspring without any changes except from if it undergoes mutations.

The explanations to the different origins of the grayling are probably found during the period of the last ice age. The ice evolved approximately 70000 years ago and had its maximum ice coverage around 20 000 years ago, when it extended all the way down into northern parts of Germany. When the ice cover started to withdraw 10 000 years ago it was possible for the grayling to return to the areas which until recently had been covered in snow and ice. Likely the immigration that gave rise to the Swedish – Norwegian lineage came from the south, whereas the for fathers of the Finnish/Russian lineage immigrated from the East.