Can you actually believe that the attitude to the grayling once varied very much and many fly fisherman ignored this member of the salmonids? Even nowadays the grayling is sometimes regarded as a neglected noble fish. Maybe ignorance towards this beautiful fish lead to the decline in population and as a consequence in many areas the grayling is endangered. For the latest status visit the website of the International Union for Conservation of Nature and Natural Resources (IUCN) or visit directly the sites for Thymallus thymallus and Thymallus arcticus, respectively.
It seems as if only the French admired the grayling right from the beginning and so wrote Izaak Walton in his famous book The Compleat Angler ”..., and they [the French] value the Umber or Grayling so highly, that they say he feeds on gold; and say, that many have been caught [...], out of whose bellies grains of gold have been often taken.“
Be that as it may be, the fish being a member of the family of salmonidae is my personal favourite and I would like to present a short -very short- natural history of that magnificent fish.
„The grayling, Thymallus thymallus, is a charming and beautiful fish...“
Norman Maclean
Trout and Grayling – An angler´s natural history
Thymallus has a rough time facing in many countries an increasing numbers of predators (e.g. cormorants or goosanders) and a deterioriation in habitat quality. Therefore societies were founded to protect the grayling against further harm and to represent the grayling´s rights to intact natural habitats. By promoting the graylings interests not only the fish will be helped, but the whole ecosystem ”stream“. In 2006 the first international grayling conference was organized at the University of York (England) by The Grayling Research Trust and the Grayling Society. Additionally, the species Thymallus has been listed in the „Red List“ of the IUCN.
Directly related to the grayling population´s welfare is the issue of ”catch and release“. Scientific studies have verified that a selective removal of older bigger fish has a negative effect on that species´ population. Larger graylings will lay more eggs of better quality, their offspring will have a better vitality, etc. In short: the fittest grayling population will be spawned from larger individuals. So, for the benefit of all: next time you have caught a trophy grayling show him your honour by releasing him.
Just in the spirit of Lee Wulff who more than once expressed: „A good game fish is too valuable to be caught only once.“
Sometimes even a grayling needs to see a doctor. There are indeed some diseases and pests that are luckily all harmless to the fisherman.
A major influence on grayling populations once had the so called ulcerative dermal necrosis (UDN) which is often accompanied with the fungus Saprolegnia parasitica. Bacteria will have a feast and without question such an infected fish is going to die...
To name only a few other: furunculosis caused by Aeromonas-bacteria, infective pancreatic necrosis as a result of a virus infection or Ich, which occurs when grayling have been infected with the protozoan Ichthiophthirus multifilis. But let us not dwell on this subject too long for it is not very appealing.
The graylings diet is quite diverse and you might be surprised at the variety of nourishment that might have found his way into a graylings stomache. The freshly hatched grayling (alevin) feeds on his yolk sac, but after this food source is utilised the grayling starts feeding on microplankton and is termed now fry. The microplankton consists mainly of midge larvae. Growing bigger, graylings just expand their menu and add other larvae and nymphs to their list. As an adult the grayling will feed on insects that are highly abundant. Thus there are seasonal fluctuations in the prefered prey. Nevertheless the top five lists mayflies (larvae, duns, spinners), midges (larvae, pupae, adults), sedge or caddis flies (larvae, pupae, adults), stoneflies (larvae, nymphs, adults), beetles and ants.
Additionally grayling are not averse to eating fish eggs and small fish. In fact the bigger the grayling grows the more he displays tendency to a predatory feeding behavior: ichtyophagy. It is also know that graylings in Scandinavia hunt lemmings! Mikko Halonen from Finnland has written a nice aricle about this behaviour and his lemming fly (sopuliperho) in Fly Fishing & Fly Tying (June 2010).
The grayling´s spawning season usually begins as early as April and continues in Northern regions as late as July. During this period the female grayling lays up to 36.000 eggs into a redd, which the male grayling tries to fertilize by releasing his milt on them. It is essential for the survival of the eggs and sperms that the water temperature is about 8 (± 4) degrees Celsius.
After 2 to 4 weeks from an egg (once 3 millimetres in diameter) an grayling alevin (12 to 18 millimetres) will emerge from the gravel. By winter they have reached up to 180 millimetres. After only three years grayling can reach a body length between 30 and 40 centimetres, due to faster growth compared to e.g. trout.
The grayling´s maximum size is usually 50 centimeters, weighing up to 1 kilo. However, there are reports about graylings weighing more than 3 kilos (caught in a Swedish lake), even 6.7 kilogramms (caught 1956 in a Finnish lake). At an average the body length is about 30 centimeters. The main reason why there are only so few graylings that grow beyond these figures may be because they are short lived and often do not celebrate their 7th birthday.
Grayling prefer fast-flowing clear rivers and streams, that are rich in oxygen. River sections should have a steady flow and a solid ground, therefore grayling can often be found over stretches with gravel, where they hide between weed growth. Water temperature is ideally not lower than 4 degrees and not higher than 18 degrees Celsius.
A river can be divided into regions or zones, where the region that has all the above mentioned characteristics is known as the grayling zone. In some areas of northern Europe grayling can also be found in lakes.
As mentioned before, the grayling belongs to the salmonidae and has its own subfamily of thymallinae, which means there are different species of grayling. According to scientific lists there can be as many as 39 (!) graylings, but only four of have been considered as confirmed. Firstly, there is the European grayling (Thymallus thymallus, Linnaeus 1758) and secondly, the arctic grayling (Thymallus arcticus, Pallus 1776). Thirdly and fourthly, the Kosogol grayling (Thymallus nigrescens, Dorogostajskij 1923) and the Mongolian grayling (Thymallus brevirostris, Kessler 1879). All other graylings are likely to be subspecies, e.g. the Kamchatka grayling (Thymallus arcticus mertensi, Valenciennes 1848), but you will also note a certain discordance within the grayling´s systematics and only genetic studies of all grayling species will shed light on the grayling´s real ancestry.
In 2007 a new grayling species has been found and described from the Amur river basin. This new low Amur grayling has been named Thymallus tugarinae sp.. This species has been earlier equated with the Amur grayling Thymallus grubii (Dybowski 1869) from the rivers Onon and Ingoda. It differs from other representatives of the genus in body colouration, pattern on the upper fin, and certain morphological characters. For more details see: Journal of Ichthyology, 2007, Vol. 47, No. 2, pp. 123-139 (download PDF). The latest grayling subspecies which has been described in 2009 was the yellow-spotted grayling Thymallus grubii flavomaculatus ssp..
The given name grayling, as the german word ”Äsche“ (from ash), obviously refers to the body colour , being of grayish-blue. Other names you will see are ombre commun or oumbre and umbra in France, sometimes umber in Great Britain, temolo the Italians call it, Scandinavians prefer to call the grayling stalling in Denmark, harjus in Finnland, harr in Sweden and Norway. In the Netherlands it was given the nice name vlagzalm and when the Japanese talk about grayling they speak of グレイリング.
Whereas the scientific name thymallus comes from the Latin word thymus and has to do with the fact, that graylings quite often have a fragrance that nicely scents like thyme.
When the grayling is spoken of more colloquially you will hear expressions like the gray lady, the lady of the river or the lady of the lake (here quite often the arctic grayling is meant!).