WTT Blog - Tagged with fish population

As WTT Conservation Officers, we are asked to make assessments on what is good and bad habitat for trout populations based upon visual observation and expert judgement; this is the basis of a typical Advisory Visit Report. If we had the time and resource, we'd look to the fish themselves to tell us! In this latest blog from current researchers, Jess Fordyce from the University of Glasgow Scottish Centre for Ecology and the Natural Environment outlines how an understanding of the genetic diversity within a catchment can inform more efficient management strategies for safe-gaurding trout populations.

The brown trout, Salmo trutta, is an extremely diverse species in terms of behaviour, physiology, genetics and morphology. Brown trout can adopt a range of life-history strategies which include freshwater residency in rivers and/or lakes, or anadromy – the movement from fresh to saltwater and back again (ie sea trout). The diversity of brown trout in terms of genetics and morphology was the focus of my PhD which was funded by an EU project called IBIS (Integrated Aquatic Resource Management Between Ireland, Northern Ireland and Scotland) and the Atlantic Salmon Trust. My study site was the Foyle catchment which is a large dendritic (branching) system with an area of around 4500km2 located in both Ireland and Northern Ireland. This catchment is managed by the Loughs Agency. Like other catchments across Britain and Ireland, sea trout numbers have been sharply declining over the last few decades. Therefore, it is important to understand the genetic population structuring of brown trout (the pattern of genetic variation) and which environmental factors shape such structuring. From this information, it is possible to detect exactly which populations contribute significantly to the production of sea trout and hence provide focused management.

Just a couple of weeks ago, I posted the news article entitled ‘Where have the rivers gone?’

A typical British summer has since dropped a deluge of rain across much of the countryside, and with it, will wash away any thoughts of droughts and painfully low flows from most people’s minds. It’s exactly the same with flooding:-

Typical! Not two weeks after completing my round-up for the Science Spot in Salmo trutta, the annual glossy WTT publication that our members receive, an interesting paper on IMWs (Intensively Monitored Watersheds) lands on my desk. While not exactly on topic, it includes interesting snippets that would have embellished my article. However, as I wrote in the Salmo piece, the means by which knowledge is transferred nowadays means: I can (and have already) tweeted about this paper (but not included any precis or personal view of its content); I can (here, now) blog about it and impart some detail; or I can sit on it for 12 months and tell you all about it in the 2017 issue of Salmo!

IMWhats? In the Pacific Northwest, a vast tract of land with a very loosely defined boundary but it’s roughly 67 times the size of Wales if you’re interested in that sort of thing, there are at least 17 IMWs. They are an attempt to test the effectiveness of a broad range of stream restoration actions for increasing the freshwater production of anadromous salmon and steelhead and to better understand fish–habitat relationships. This is no mean feat, and the paper by Bennet and his colleagues reports on the lessons learned so far.