Category Archives: Alevins

Alevins, North Walls, Trout life cycle

North Walls School alevins released in the Ore Burn

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I’m delighted to publish this report which Cameron Stout, the Class 2 teacher at North Walls emailed me. It was written by his pupils for the April issue of The Blether, “the newsletter of the community of Hoy and Walls” and when reading it, we can tell how much enthusiasm and commitment went into the project:

Brown trout fry, ready to be released by Levi in the Ore Burn

Away back at the beginning of Term 3 (January), Class 2 got some trout eggs from Jim Erskine so that we could take part in the Troot in the Shed project. Everyone was very excited about it since some of us did a similar project a few years ago and we were really looking forward to taking part in it again.

First of all we had to prepare a tank in the shed – the shed is best because it is at a cooler temperature. If the eggs and baby fish (alevins and fry) get too warm it can kill them.

We put the eggs in the tank carefully. We had to watch in case the eggs went white. That meant they had died. We were fortunate though, because not many of them died. Out of our total of 300, only about 40 didn’t survive. We think it’s possibly because they had to make an extra journey across to North Walls on the boat.

We had to check on the eggs frequently, recording the air temperature and water temperature, and whether any had died. If they had, we had to remove them from the tank within 24 hours.

As they grew, we noticed that their yolk sacs started to shrink. The yolk sac contains the food that they use when they are first hatched. At this stage, they are approximately 1.5cm in length.

They were very small and their eyes looked gigantic. They wriggled in the corners of the tank – probably trying to hide among the stones.

There is a microscope in the science room so we used that to examine them closely. It was fascinating to see them so close up.

When they got older, their colour turned darker and we noticed that their yolk sacs had almost disappeared. At that stage they start being called fry and they come up to the surface to look for food.

Almost at the end of the project we took a walk to the Ore Burn to release them. Everyone had a shot of scooping out a net with between 5 and 20 in it, and transferring them to a bag of burn water that we had at the ready. The reason we do that is so that there is not too big a change of temperature, and so that they do not fall in from too high a height.

We took great care handling the troot as they were very small.

Now that they are in the burn, the survivors will probably stay under the brig until they’re a bit bigger and then they will head to the sea.

We learnt about life cycles and we can now compare the trout life cycle to the human life cycle and other parts of nature.

We would like to say thank you to Mr Erskine and the Orkney Trout Fishing Association for preparing the whole project and involving us in it. We hope to do it again.

Craig scooping the alevins before release in the Ore Burn

Alevins, Stronsay, Trout life cycle

Stronsay pupils release their fry into the Meikle Water

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Double click on picture for full-size view

Spring was in the air on March 28th when the time had come to release the alevins hatched at the Stronsay School. The island was bathed in sunshine and the surface of the Meikle Water was hardly broken by a gentle breeze from the east.

The 200 odd young trout hatched at the Stronsay School were carried in a basin to the edge of the loch and then transferred into plastic pouches to allow every pupil to release a dozen fish each.

It was a good opportunity to learn about the wildlife with which our trout would be sharing their new habitat: we realised that the tiny alevins would need to be extra careful as many predators such as mergansers, herons, cormorants, eels, otters and even some of the bigger trout wouldn’t mind a little fishy snack! Our alevins would have a more modest diet for the first year, consisting mainly of daphnia, midges at various stages of development, freshwater shrimps and insects.

Pupils gently released the fry in the vicinity of weed beds to provide them with enough cover from predators, after checking the loch water temperature (3⁰C) was as close as possible to the water in which  the alevins had been transported  (4⁰C), in order to avoid thermal shock.

A big thank you to Mrs. Evans who accompanied the children and also to Steve, our janitor who supervised the pupils’ visits to our hatchery on a daily basis over the last couple of months.

Check the video clip by copying and pasting in this link in your browser:

Mr.P

Alevins, North Walls

Alevin photographs from North Walls

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This is a little email I received from some of the North Walls pupils along with some photos they took:

Hello,
Recently our teacher took some alevins out of the tank to examine them under the microscope and take pictures of them. But before we took the shots we gave them clove oil to stop them swimming about whilst we were taking the pictures.
Sorry we haven’t written to you for a while because we’ve been a busy class. We’ll send Mr. Pietri more pictures. All the swimmers are fine. Thank you we will try to keep you updated.
Adele, Andrew and Mia

Alevins, Dounby Primary

Burn of Hourston stocked by Dounby Primary

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Malcolm, briefing the Dounby pupils

The project ran very smoothly at Dounby Primary this session and last year’s disaster when all the alevins died shortly after hatching was soon forgotten!

The pupils managed to follow their small trout through all the stages, from ova, eyed ova, sac fry and eventually alevins. Malcolm Thomson, very kindly, was overseeing the project with the school and on Friday 15th March, he and Mr. Forsyth led a group of very keen youngsters to the nearby Burn of Hourston to release the alevins. The receiving water which we applied for was originally the Burn of Netherborough and the Burn of Hourston was a last minute switch which made sense from a transport point of view, but the stocking consent had to be sought before we could go ahead.  I would like to thank Marine Scotland who were very flexible with the application to release our fish; after a couple of phone calls and an email, we received permission the same day to proceed with the release in the new water.

The burn was a bit coloured but there was  a gravel shelf along the edge where the youngsters could release their fish and watch them for a few moments before they disappeared.

Malcolm also  did a kick sample, literally, stirring the gravel bed and sweeping through with a fine mesh net to collect invertebrates hidden amongst the gravel and to observe them closely, an activity which captivated the children!

The pupils were very keen to run the project again and they may even have an opportunity to attend an electro-fishing session which Malcolm is considering running in April/May in Orphir.

Well done to everybody for looking after the alevins so well. Looking forward to next year already!

Mr.P

Alevins, Sanday

Sanday School release their alevins into Bea Loch

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Release of fry into Bea Loch, Sanday (Click for full view)

This year, the Sanday ova took a lot longer to hatch because of a slightly delayed transfer from the Kirbister hatchery to the school and due to the very cold spell of weather in February/March. In fact, it wasn’t before March 7th (more than 2 weeks later than last year) that the alevins started hatching. The advantage of hatching ova in very cold water (an average of 4.6°C on Sanday this year) is that the mortality stays very low (4 casualties for over 150 ova)  but the downside is that the alevins haven’t quite reabsorbed their yolk sacs by the time we need to release them, before the Easter holidays.

This year, the most noticeable improvement on release day was undeniably the weather! While in March 2012, we had been battling against a westerly gale and released the alevins facing a mini-tsunami, this time, the Bea Loch was bathed in bright sunshine with a distinctive taste of spring and a gentle breeze from the east.

While Mr. Thorne, the Sanday ranger and Mr. Pietri headed for the loch with the alevins and transferred them in small bags for the pupils to release, the Primaries from Room2  and the secondary 1s, accompanied by Mrs. Butler, Mrs. Cawthorne, Mrs. Muir and Mrs. Thomson walked from the school to the loch.

As the last arrangements were made to release the fry, Mr. Thorne gave a little introduction regarding the loch environment and the challenges our fry would possibly meet in the future: mergansers, herons, cormorants, otters, eels without forgetting the bigger trout lurking in the depths…

Then, it was time to part with our alevins,  let them disappear amongst the weeds in the shallows and wish them good luck!

A big thank you to all the staff from the school who helped with the project, to the Sanday ranger Mr. Thorne  and to the Orkney Trout Fishing Association for providing the ova.

Mr.P

Alevins, St.Andrews Primary, Trout life cycle

St.Andrews fry released in the Burn of Quoykea

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On Tuesday 19th March, the time came to let the small trout go into the Burn of Quoykea, situated within walking distance of the school. Led by Mr. McIntosh, their teacher and Sandy Kerr from the Orkney Trout Fishing Association, who very kindly supervised the project, the Primary 7 pupils were very enthusiastic and knowledgeable, as Sandy’s presentation back in January was still very fresh in their minds. The little burn, in spite of its diminutive size,  remains a crucial watercourse for the reproduction of Orkney sea-trout in the East-Mainland and bringing young people by the burn raises awareness about the importance of its role in the local biodiversity.

Actually, the pupils may well be back in the summer, as Sandy offered to give an electro-fishing demonstration in order to monitor the health and growth of the alevins.

In the meantime, let’s hope the weather improves and that the warmer water brings our fry plenty of food!

Thank you to everybody who helped to make the project happen.

Mr. P

Alevins, Kirkwall Grammar School, St.Andrews Primary

Project still running at St.Andrews!

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Mr.Ewing and Mr.McIntosh releasing the new batch of alevins.

After the very sad news we received last week from St. Andrews Primary, where all the alevins died over the week-end, the Troot in the Shed team and the Orkney Trout Fishing Association were on the case right away! Sourcing some alevins was the a priority as  so much work had already been put in by the pupils, their teacher Mr. McIntosh (see the posters below) and Conrad the janitor. Mr. Ewing came up with the quickest solution and arranged to transfer some of the Kirkwall Grammar alevins to the St.Andrews tank in order to keep the project going and provide the children with the experience of seeing the alevins slowly turn into miniature trout and eventually releasing them into the nearby Burn of Quoykea.

Over 100 alevins made the trip from KGS to St.Andrews and after measures were taken to prevent alevins from being sucked up by the pump, the tank was buzzing with life again!

Mr.P

Click on picture for full screen view!

Alevins, North Walls, ova / eggs

Troot activities at North Walls!

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These are the beautiful photos I received  yesterday from North Walls. Adele, Andrew, Ben, Cameron and Molly to name but a few, explained how they used the data from their mini-hatchery to produce graphs during maths classes and how they managed to take those great shots by using a microscope linked to a laptop. Details of alevins are very difficult to capture but the North Walls pupils, thanks to a very clever use of ICT have managed to produce these during a science class.

Apart from studying the alevins closely, they’ve also done a very good job at looking after their ova as they only lost about 10 since the project  started.

Congratulations to them and their current  teacher Ms Allen!

Photos taken by the North Walls pupils.
Alevins, General info, ova / eggs, St.Andrews Primary

WARM WEATHER WARNING

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After the St. Andrews incident which wiped out all the alevins, and some concerns from other schools regarding the rise in water temperature caused by a few warm sunny days, Mr. Erskine, who has been overseeing the project on Hoy, has come up with a few simple steps to cool down the tank and prevent water quality from deteriorating; here they are:

KEEPING THE TANK WATER TEMPERATURE LOW

Ideally, the tank temperature should be less than 7C and never allowed to exceed 10C.

On sunny days, the shed temperature will be higher than the outside air temperature, due to heat transfer from the walls and roof. Opening the shed door and windows will keep the tank temperature down. Wetting the shed floor and the sides of the tank will also help. Windows which are not facing North should be kept shaded from the sun.

If the temperature is very high, ice made from bottled or burn water could be added to the tank, keeping it as far away from the ova or alevins as possible. The pump should be kept running to avoid water much colder near the ice.

To calculate the amount of ice needed:

Measure the length and breadth of the tank and the depth of water in centimetres.

Multiply length X breadth X depth to obtain the volume of water in cubic centimetres.

Then, assuming that the ice is at freezer temperature of -18C:

Divide the volume by 98 to calculate the weight of ice in grams needed to lower the water temperature by 1C.

For example:

V = L x B x D

= 60 x 40 x 20

= 48000 cubic centimetres

48000 / 98 = 490

Add 490 grams of ice to lower the temperature by 1C.

Once all the ice has melted, another batch could be added. Try to lower the temperature in 1C stages to avoid thermal shock.

Alevins, General info, Kirkwall Grammar School, Trout life cycle

KGS release their alevins in the Wideford Burn (Inganess)

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The KGS pupils and their teacher releasing the alevins in the Wideford Burn.

It was on March 18th that Mr. Ewing and his dedicated team from KGS met at Inganess Beach to release the  alevins they hatched in the school shed. Spring was in the air and it was a glorious day which seemed just perfect to set the small trout  free in the crystal clear water of the Wideford Burn. This burn not only holds a small population of  brown trout but is also one of the main spawning burns for our migratory sea-trout.  

However, what should have been a great start for the small trout ended in a rather tragic way when last Monday night, merely a week after the fish were released, we were alerted about a severe case of pollution in this very burn. Most if not all of the fish population in the Wideford Burn was wiped out and the source of the pollution is still being investigated. This is a serious blow to the environment but also  to our project as we were planning to come back in June or September to monitor the growth of our trout using electro-fishing equipment.  

One of the casualties of pollution at the Wideford Burn (27/03/12).