Yesterday, Friday, 18th March, Orphir Primary released their fry into the burn which runs through the school ground.
A big thank you to Mr Erskine for sending me the following report so promptly and well done to the children and their teachers!
“The Swanbister burn was at quite a low level this morning; just right for the Orphir Primary School troot release The children were surprised how many alevins were in their tank, well hidden amongst the gravel. The sharp corners and curved sides of the tank made capture of the very frisky alevins difficult, but the pupils persevered and eventually 65+ peedie troot were transferred to the basin and carried up to the burn. All 24 pupils got the chance to move a few alevins into a polythene bag and release them into the burn.
The fish tank was very small and no outside shed was available, so the Orphir P4 – 7 pupils did well to keep the water temperature low and do frequent water changes to achieve a very high survival rate. Only about 80 ova were delivered to the school and most of the mortalities occurred while the ova were being transported or the following day. The temperature only reached 10 C on 1 day and the tank water pH stayed quite close to a neutral 7.
As well as learning about the brown trout life cycle, the Orphir pupils also :
- Used a digital microscope linked to a computer to see the embryo development inside an ovum.
- Observed some of the small invertebrates preyed on by Orkney troot including gammarus shrimp, corixa and pebble cased caddis.
- Learned about the migration of sea trout from Scapa Flow through Stenness into the Harray burns and the predators they have to try to avoid.
- Learned how to recognise brown trout, sea trout and salmon.
- Examined fly tying materials and a range of angling equipment used by the Orkney troots’ most formidable predators…“