Beneath the Surface > August 2014 > Thursday Analysis Update - 07.08.2014

Thursday Analysis Update - 07.08.2014
Firstly my apologies for not posting anything for a while but between vacations and training courses I've not had any new material to post.

That changed last week; Eric and I spent Tuesday and Wednesday processing juvenile salmon gathered from the River Carron during an electrofishing survey on the 3rd and 4th of April. Below are pictures of all the fish processed over these two days as an illustration of the size of the task:

(Note: some of these fish look to have damaged fins but this may well be an artifact of thawing these frozen specimens.)
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For a larger image of this picture click here.

In all 336 fish were lengthed and weighed, and had scale and tissue samples taken. And this isn't even the end of the process! Now all of this information has been gathered, it needs to be processed.

Over the next few months the scales will be read as part of the stocking investigation to allow us to determine the age ranges of the Carron population. The length data will be combined with electrofishing data collected over many years to try to map the distribution of juveniles in the river. Examination of this length data may also be able to shed some light on how many age classes co-exist in the river at a given time; by looking for distinct groups of sizes and comparing the findings to the literature we can estimate the range of ages present in the river.

Finally, the tissue samples will be used to look at the genetics of the fish in river. This will allow us to determine what proportions of the juveniles found in river surveys are of completely wild origin, which have been stocked from the hatchery and what proportion (if any) are a mix of the two.

Watch for these results over the coming months...
Posted: 8/12/2014 4:50:15 PM by Matthew Curran | with 0 comments


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