As the River Ayr has been suffering from poor juvenile stocks for the last few years, we have been researching possible causes for this problem for some time. In order to determine what life stages are most affected, we decided to plant egg boxes out at key points across the catchment to pinpoint any areas that are failing. This may well tie up with our chemistry and conductivity research that Natalia and others have assisted with since September.
We placed 100 salmon eggs in each box and then buried them in artificially constructed redds. Each box is marked with a trailing string to help us relocate the box when we return in the spring to determine egg survival. We had planned to do this on the day that the eggs were stripped from the fish as they are fairly tough at that point but unfortunately high water prevented this. This was the first opportunity since the fish were stripped about two weeks ago to carry out the planting however the eggs are now very susceptible to any vibration and die quickly from the least knock. We counted eggs into polythene bags filled with water and then floated them in a bucket of water.
This method reduced the chance of damaging the eggs however some did die off. They very quickly turn white and these were removed and replaced with health eggs at the time of planting.
Helen and my daughter Katie braved a very cold but lovely day to help and we completed 17 sites across the upper catchments. Some are in polluted areas and others are in areas where water quality is excellent to act as controls. We won’t know the results for a couple of months.
Hopefully we will gain valuable data from this trial and an understanding of how inputs can affect this lifestage.