So today was an exciting day for me and the children of three local primary schools. They took a delivery of some very special eggs to look after for the next 4 weeks.
Not only is Loch Leven internationally important for the wildfowl that make it home but throughout its history it has been renowned for its fish. One in particular – the Loch Leven Brown Trout Salmo trutta levensis is famed throughout the world for its deep pink flesh colour and silvery colouration, its flanks lack the red spots of some other forms.
Eggs – more properly known as ‘ova’ from Loch Leven trout have travelled the world from Loch Leven to be stocked into rivers and stillwaters around the globe from North America to New Zealand.
The Loch Leven Fishery now prides itself in being a self sustaining wild brown trout fishery. It is the life cycle of a natural wild fish in Loch Leven which the pupils will be learning more about. To guide them through this they are fortunate to be able to tap into the lifetime of expertise from recently retired fishery manager Willie Wilson.
So the first part is to take delivery of the eggs or ‘ova’. Willie and I dropped by the schools earlier in the week to set up the tanks, refrigeration units and aerators and the pupils were able to learn about the first stages of the trout lifecycle.
Perhaps most people will be more familar with the famous life cycle of a Salmon. And the lifecycle of the Loch Leven trout in some respects is not that dissimilar to that of the Salmon.
I find it simplest to use the analogy that to a Loch Leven brownie the loch is its freshwater ocean, and home for much of its life. Each year ( and usually in more than one season) around October or November as the burns swell with autumn rain the mature trout make their way up into the highest reaches of the catchment to spawn.
Here they create a gravel nest known as a redd and in this the eggs are laid. It is at this stage the kids are getting the eggs to care for. Our eggs come from a hatchery supplied with Loch Leven ‘levensis’ Trout eggs some years ago and although Loch Leven once had its own hatchery this is no longer the case.
The kids now take on the responsibilty for monitoring the temperature in the tank – a nice cool 5C is perfect (given the loch has been frozen solid for the last week they’ll be glad of the warmth!) and ensuring that there is always a supply of oxygen to the tank.
During the next 4 weeks the eggs will begin to hatch out. At this next stage they are called alevins and they are just discernable as fish but comical ones with their large eyes and yolk sac stomachs. They are able to sustain themselves from the yolk sac for some weeks but as this runs out the urge to find food draws them out and they emerge from the gravel.
It is at this stage in around a months time we will go back into the school and release the alevins. But more on that to come in few weeks time………..
If you want to find out even more about Trout and Salmon in Scotland then check out the SNH Scotlands Nature Blog https://scotlandsnature.wordpress.com/2015/01/30/species-of-the-month-trout/