Population Surveys on the River Avon and Tributaries – August 2011
FDSFB were able to provide their biologist, Dr Joanne Girvan, for three days in early August 2011 to electro-fish various tributaries and selected areas in the main Avon, in an attempt to update historic records of the fish population in the Avon catchment.
Electro fishing uses a portable generator to pass a low voltage electric current into the water using a metal hoop. The hoop is swept back and forth across the river, and upstream for ten to twenty minutes, stunning any fish or eels present. Normally the time scale allows a 25 to 30 yard stretch of water to be sampled. Any stunned fish are netted and placed in containment tanks. Fish are then recorded by species, by numbers present, and by their length. Scale samples are also taken.
The three Clubs had electro-fished areas of the Avon in the past, and the intent was to resurvey these areas and to also investigate fish populations in the primary Avon tributaries to provide base information for use in any future pollution incidents.
On the first day, three sites were chosen and fished on the Logie Water, which runs from Armadale to Westfield. The first site, approximately 100m above the WWTW at Westfield, only produced two 8” fish, but both salmon parr. No other fish were found. The area sampled was approximately 8x25m. The second site was on the Coulston Burn about 200m above the weir at the old paper works site at Westfield. This burn runs from Bathgate and has suffered from low levels of dissolved oxygen for years. The area sampled was approximately 1x30m and surprisingly only produced five stone loaches. No other fish were found, stressing the polluted nature of the burn. A final site on the Logie north of the B8028 between Armadale and Westfield, produced five adult trout of around 8”. Again no other trout of any year class were found. However the Logie was determined to be healthy and to be suitable for future stocking.
Two days later, after some rain, electrofishing commenced on the Mains Burn at Homebase in Linlithgow. This Burn had been stocked about 4 years ago by LAC with fed fry. The 1x25m area sampled produced 21 trout between 1.5” and 9” in length and several sticklebacks. This represented several year classes and showed that the burn is healthy.
The last site sampled was within the main village at Whitecross about 4 years ago by LAC with fed fry. The 1x25m area sampled produced 21 trout between 1.5” and 9” in length and several sticklebacks. This represented several year classes and showed that the burn is healthy.and gathered quite a crowd of interested villagers of all ages. The burn was around 6” deep and a 1mx20m area produced around 28 trout and four eels. Again several year classes were present.
It had been hoped to find salmon parr in both the Mains and Manuel Burns but none were found. However we now have updated information on both these important spawning burns and base line information on the Logie.