RESEARCH





THE SALMON SCALE SAMPLING PROGRAM IN THE CURRANE CATCHMENT

For the last two years the local ghillies have supported us with the taking scale samples from the salmon they catch on Lough Currane. 2016 saw a many more samples taken than in 2015, with over sixty separate samples collected over the year.

The following is taken from the 2016 report on scale samples:
A sample of sixty scales were sampled from the rod catch on Lough Currane during the 2016 angling season. The first scales were collected on the 18th January and sampling continued up to the 29th July. The first salmon captured on Currane was also the first fish to be recorded in Ireland in 2016.
Anglers and angling guides sampled scales from captured fish on lough Currane and stored them in paper envelopes recording the date, length, weight and general condition of individual fish. Some anglers commented if fish were of hatchery origin from fish that were missing its adipose fin while some samples had useful information missing such as date of capture or length or weight.
The scales from the rod catch were used to predict the life histories of Salmon in the Cummeragh. Scales were washed and prepared on glass slides prior to been run through a digital scanner where age interpretation was predicted. The camera zoom was set between 30 and 40 times depending on size of scale to make it easier to interpret the summer and winter periods on each scale.
This was the second year in succession an effort was made by anglers and guides on Lough Currane to take scale samples from rod caught fish and develop a greater understanding of the current life history trends in the population. The data gathered allowed for a general analysis to be performed from the rod catch. The first spring salmon was captured in mid-January with captures tapering of during late May. The average length of 2SW Salmon captured was 72cm. One sample aged as 2SW was only 59cm in length, appearing to be an outlier on the graph but this is also not unusual in current trends. In 2015, a similar analysis showed “undersized” multi sea winter fish appearing in the Currane analysis. This is further confirmed from Delphi fishery in Co. Mayo where it is not unusual for 2SW salmon to return in 4lbs range. There was another fish aged as a 3SW during the study, this fish measured 78cm in length with a weight of 10.75lbs. It would normally be expected that the weight of a 3SW salmon would be in excess of 16 or 17lbs. Perhaps, this is further evidence of the struggles salmon are currently facing in the marine phase of their life cycle as a result of climate change or diminishing food source.