Salmon Surprise

The good news is that we still have salmon breeding in the river Sid.

The less good news is that they are restricted to the stretch in town rather than getting to the upper reaches of the river to their preferred breeding sites.

As I reported last week, Environment Agency contractors were electro-fishing in the river below school weir to keep fish safe while the gravel was being dredged. I didn’t have the full results by the deadline for the story, but two days later Jon Trevett sent the details of the catch. Apart from 19 brown trout average size 30cm, there were numerous loach, bullhead, minnows, eels, 18 brook lamprey, and the big surprise 1 salmon parr of 7cm.

A salmon parr is a juvenile fish, the fourth stage in a complicated life cycle. Salmon lay their eggs in winter in a hollow on the river bed and the female then covers them with more gravel. The babies, or alevins, hatch and stay in the protection of the gravel feeding on their yolk sac. When this is exhausted they swim free as 3cm long fry. By the autumn the young fish have grown to be what are known as parr, and are beginning bodily changes to cope with the next big change when they leave the freshwater river and swim out to sea to grow to full adults. When the sea living adults are ready to breed they return to a river, usually the one where they were born navigating by the Earth’s magnetic field and minute chemical symbols detected in the water.

In years gone by salmon frequently bred in the upper reaches of our river system, but numbers have declined for several reasons, the size of school weir is literally the biggest problem. At 3m, it is too big a leap for most salmon.

The presence of the young parr shows that at least some adults have continued to return to the river and they have found gravel good enough for egg laying in the stretch between the ford and the weir. There is a possibility that they have also been breeding in the area below the ford, local fishermen have reported good numbers of migratory sea trout in there, but it hasn’t been electro-fished for parr and so we cannot tell.

Local enthusiasts net fish at the foot of school weir in October and lift them above the weir, but it is several years since an adult salmon was caught. The River Sid Catchment Group is putting together a plan to reduce barriers to the migrating adult trout and salmon and it is hoped a way round school weir can be constructed, but complications with flood prevention are proving difficult. The presence of the salmon, a priority species for conservation, can only help push the project forward.