WTT Blog - Tagged with diet

Plant invasions and trout rations: the sequel

Posted on January 07, 2019

Plant invasions and trout rations: the sequel

It's a great pleasure to welcome back Alex Seeney to the WTT Blog. Just over 18 months ago, he was one of the first of the early career researchers to contribute a post (The riparian invasion: salmonid friend or foe?) about their ongoing science. Well, Alex is now Dr Alex (congratulations) and has returned with an update which I have been eager to see. I well remember some work by Sally Hladyz on how invasive rhododendron can severely impair stream functioning; her work demonstrated that the plant supplied poor leaf litter quality and blocked out the sun, subsequently depressing decomposition rates and algal production rates meaning less food for inverts. Do balsam and knotweed exert similar influences? Over to (Dr) Alex.....

Invasions by non-native species are reported as one of the greatest threats to global biodiversity, and the invasion of riparian ecosystems by invasive non-native plants (INNP hereafter) presents a common and difficult challenge for river and fishery managers.

Low flows and salmonid rivers: an update

Posted on July 14, 2017

Low flows and salmonid rivers: an update

Jess Picken was the first to contribute to our new series of guest blogs in which she outlined plans for her PhD. And clearly, she has been busy! She is back with an update already...

To recap on my previous post, numerous studies have reported that low flow reduces the density of salmonids within streams. What is not so well-known is what, or how, other parts of the salmonids’ ecosystem are also affected by low flow. Riverflies and other aquatic macroinvertebrates make up a large proportion of juvenile salmonid diet, which is subsequently reflected in salmonid growth rate, condition and survival. Understanding how the availability of these macroinvertebrates changes with reduced summer flow is important to help conserve fish species of high UK and European importance.

My life at the moment... macroinvertebrates down the microscope!

Impacts of low flows on salmonid river ecosystems

Posted on March 22, 2017

Impacts of low flows on salmonid river ecosystems

In the first of a new series from students actively involved in research relevant to wild trout, Jessica Picken from Queen Mary University of London summarises the aims of her PhD working with the Game & Wildlife Conservation Trust and with CEFAS.

Climate change is considered to be the most critical disturbance imposed on natural systems on a global scale. Climate models predict that average temperatures in the UK will increase over the course of the next 50 years with the greatest warming in the south of England during summer months, and that annual average precipitation will reduce. However, the reduction in precipitation is expected to be more pronounced during summer than winter, whereas extreme winter precipitation is expected to become more frequent. In other words, there is likely to be an overall shift towards drier summers but wetter winters.

Diet interactions of brown trout and perch at Malham Tarn

Posted on July 01, 2015

Diet interactions of brown trout and perch at Malham Tarn

It is believed that brown trout and perch were introduced into Malham Tarn by the Cistercian monks in the 12th century. Further stocking of brown trout for recreational fishing started around 1860, continuing off and on until 1994 when the National Trust pushed for a more natural brown trout fishery. Indeed stocking ceased in 2001 and, since 2002, a strict catch and release policy for all fish has been in place.

A few years ago, Jon Payne, now working for one of the fisheries teams at the Environment Agency, looked at the life history and growth rates of brown trout in Malham Tarn and showed very rapid growth compared to other European populations. OK, it’s a limestone lake so the underlying nutrient base for productivity is good, but the elevation and location might suggest pretty harsh growing conditions for fish.