River Rottnan in winter

Johan Watz, Olle Calles, Niclas Carlsson, Teemu Collin, Ari Huusko, Jörgen Johnsson, Anders Nilsson, Johnny Norrgård and Daniel Nyqvist recently published the paper “Wood addition in the hatchery and river environments affects post-release performance of overwintering brown trout” in the journal Freshwater Biology.

In the abstract, the authors write:

“1. Habitat structural complexity affects the behaviour and physiology of individuals, and responses to the  environment can be immediate or influence performance later in life through delayed effects.

2. Here, we investigated how structural enrichment, both pre-release in the hatchery rearing environment and post-release in the wild, influenced winter growth and site fidelity of brown trout stocked into side channels of a regulated river.

3. Experiencing structural enrichment in the rearing environment during 3 months in autumn had no pre-release effect on growth, but a delayed positive effect after release during the subsequent winter. Moreover, trout recaptured in wood-treated sections of the side channels had grown more than trout recaptured in control sections. Wood enrichment in the side channels also increased overwinter site fidelity.

Johan Watz at the field site.

4. These results show that adding structure during a relatively short period may alter growth trajectories, and adding wood to side channels is a cost-effective method to enhance winter habitat carrying capacity for  juvenile salmonids in regulated rivers.”

Access the paper here.

Teemu Collin tracking trout at the field site.

 

Dead wood in a side channel of the river.

 

River Rottnan.

Haydn Washington, Guillaume Chapron, Helen Kopnina, Patrick Curry, Joe Gray and John Piccolo recently published the paper “Foregrounding ecojustice in conservation” in the journal Biological Conservation.

In the abstract of the paper, the authors write:
“Justice for nature remains a confused term. In recent decades justice has predominantly been limited to humanity, with a strong focus on social justice, and its spin-off – environmental justice for people. We first examine the formal rationale for ecocentrism and ecological ethics, as this underpins attitudes towards justice for nature, and show how justice for nature has been affected by concerns about dualisms and by strong anthropocentric bias. We next consider the traditional meaning of social justice, alongside the recent move by some scholars to push justice for nature into social justice, effectively weakening any move to place ecojustice centre-stage. This, we argue, is both unethical and doomed to failure as a strategy to protect life on Earth. The dominant meaning of ‘environmental justice’ – in essence, justice for humans in regard to environmental issues – is also explored. We next discuss what ecological justice (ecojustice) is, and how academia has ignored it for many decades. The charge of ecojustice being ‘antihuman’ is refuted. We argue that distributive justice can also apply to nature, including an ethic of bio-proportionality, and also consider how to reconcile social justice and ecojustice, arguing that ecojustice must now be foregrounded to ensure effective conservation. After suggesting a ‘Framework for implementing ecojustice’ for conservation practitioners, we conclude by urging academia to foreground ecojustice.”

You can access the full paper here.

Daniel Nyqvist, Jonas Elghagen, Marius Heiss and Olle Calles recently published the article “An angled rack with a bypass and a nature-like fishway pass Atlantic salmon smolts downstream at a hydropower dam” in the journal Marine and Freshwater Research.

In the abstract, the authors write:

Hydropower dams disrupt longitudinal connectivity and cause fragmentation of river systems, which has led to declines in migratory fish species. Atlantic salmon smolts rely on intact longitudinal connectivity to move downstream from rearing habitats in freshwater to feeding grounds at sea. Smolts often suffer increased mortality and delays when they encounter hydropower plants during their downstream migration. Currently, there are few examples of downstream passage solutions that allow safe and timely passage. We assessed the performance of two passage solutions at a hydropower dam, namely, an angled 15-mm rack with a bypass and a large nature-like fishway. The performance of these new fish passage solutions was evaluated by tracking radio-tagged Atlantic salmon smolts as they encountered the facilities. The radio-tagged smolts passed the dam 9.5 h after release (median) and exhibited a dam-passage efficiency of 84%, with passage rates increasing with body length. Fish passage occurred through both the rack bypass and the naturelike fishway. The passage efficiencies were 70–95% for the rack bypass and 47% for the nature-like fishway. The new fish passage facilities resulted in improved passage conditions at the site, confirming that angled racks with bypasses as best practise solutions for downstream passage, but also that large nature-like fishways may act as downstream passage routes for salmon.

Access the paper here, or contact any of the authors.