WTT Blog - Tagged with ecosystem functioning

Stocked fish or native invader?

Posted on August 17, 2017

Anyone with an interest in rivers or lakes and the life within them, be it from a conservation, management, or angling perspective (and of course those three are not mutually exclusive) will be aware of invasive non-native species (INNS), the impacts they may cause in certain situations, and the importance of biosecurity. Ecologists with a particular interest in invaders differentiate between non-native (i.e. those species introduced beyond their original distribution range, a pertinent example being pink salmon) and native invaders (referring to species that add to existing or establish new populations within their native range). The artificial stocking of salmonids into waterbodies is one such example of the deliberate introduction of native invaders, to allegedly enhance commercial and recreational fisheries, as well as for conservation purposes in some instances. The evidence accruing as to the benefits of this approach makes interesting reading.

In 2016, Buoro and colleagues used the global-scale introductions of salmon and trout as a robust biological model (i.e. lots of studies with plenty of data to analyse) to investigate the ecological effects of changing intraspecific (within species; e.g. stocking farmed brown trout in to rivers containing wild brown trout populations) and interspecific (between species; e.g. stocking rainbow trout into lakes with Arctic char) diversity. The enormity of the dataset collated from the literature allowed them to look at various levels of organisation which introduces a lot of complexity. However, the take home message was that, overall, introduction of native invaders resulted in stronger ecological effects than those associated with changes in interspecific diversity caused by non-native species.

Workshop on developing river monitoring for citizen scientists

Posted on September 15, 2015

On behalf of WTT, I recently attended a workshop coordinated by Dr Murray Thompson (a former MSc student of mine), the aim of which was to brainstorm on how to extend and develop river monitoring of restoration projects, particularly for citizen scientists. The workshop was generously supported by Ross Brawn, a good friend and supporter of WTT. The discussions were wide ranging and there were some interesting viewpoints raised by the various contributors (from the Environment Agency, Wildlife Trusts and Rivers Trusts, academia, consultancies, the River Restoration Centre etc).

Why? Well, in the limited number of cases where monitoring (to determine whether the restoration has achieved what it set out to do) is actually considered, then the cost of that monitoring typically is a part of an already limited restoration budget. Funding before and after sample collection, particularly in the longer-term, is not always available. However, the lack of coordinated standardised restoration monitoring has led to a paucity of knowledge about the effectiveness of restoration projects. Where monitoring has been undertaken, the sampling methodologies used were often originally conceived to detect pollution but may be incompatible for detecting ecological recovery.