Close to Nature: Opportunities for Long Term Maintenance of the Fish Population

As part of its duties as an operator of hydropower plants, VERBUND Innkraftkwerke GmbH is implementing comprehensive ecological improvements in the backwater areas at the power plant sites on the river Inn. Being fully completed at the moment are the structuring measures downstream and upstream of the Rosenheim and Wasserburg levels in coordination with the fishing associations, the Lower Nature Protection Authorities in the Rosenheim District Office and, in the case of the Wasserburg backwater area, also with the Higher Nature Protection Authorities of the Upper Bavarian government. The works were carried out in the winter months and were completed at the end of February 2014- before the start of the breeding season for birds and fish. In total, the work will considerably contribute to maintaining and improving the diverse and species-rich "Inn ecosystem".

Georg Loy, Project Manager at the VERBUND Innkraftwerke GmbH says: "What to the untrained eye may seem like an untouched natural paradise, when being ecologically tested to aid in developing measures, actually turned out to be presenting serious shortcomings for fish species, wading birds and plants on the river and mud banks". This was the starting point for a comprehensive package of measures, to generally improve the situation. The results of this was the renaturation work on the river Inn, which encompasses among other things desedimentation, the connecting up of oxbow lakes and also new river bank and oxbow lake structures, the creation of breeding islands for rare birds and spawning grounds for fish and amphibians as well as ecological through-ways (fish bypasses) by 2015.

The Wasserburg fishing association and the Rosenheim fishing industry association were themselves the first to begin with desedimentation from oxbow surfaces and with connecting them up once more to the river Inn. As part of its agreement with the state of Bavaria, VERBUND Innkraftwerke has declared it is prepared to implement further measures starting in 2011 in coordination with all participants. In Wasserburg, the approval process was looked after together with the planners employed by the fishing industry associations and the execution of construction was carried out in an ecologically-friendly way. The implementations in the Attler floodplain were financed by both the fishing associations in Wasserburg and Rosenheim. "We are pleased that we can increase the value of the habitat in the floodplains with comprehensive measures and that we can once more connect a former oxbow for the fish population.", explains Franz Göpfert, First Chairman of the Wasserburg fishing association. The fishing association doesn't only actively encourage the fish population, but also additionally the ecological increase in value of the entire floodplains in this area and in this way are making an active contribution to species protection.

It is important that the river be able to employ its dynamic power relating to ecosystems. In many places downstream from the level of Feldkirchen, at Attel, on the Sendlinger floodplain on the Laimbach and Rott estuary at Wasserburg, VERBUND Innkraftwerke is arranging the renaturation of the riverbank with spawning grounds and spots for young fish and especially current-loving fish species such as, for example, Danube salmon, nase and grayling.

VERBUND Innkraftwerke has created new, special habitats through the renaturation of the straightened riverbank line, up and downstream from the Rosenheim power plant and through the composition of structures similar to oxbows. This will fulfil an important function for different animal and plant species. Shallow water areas with reduced flow represent particularly top quality habitats for young fish and are used by the fish on the river Inn as flood and winter sites. The gravelly areas should serve as possible spawning sites, which are no longer available in the area near the levels. The stone blocks of the rigid bank revetment have meant new structures have been created, which help to protect against erosion and protect the embankment and at the same time fulfil an ecological function e.g. as a habitat for reptiles. It is expected that the area will be once again inhabited by animal and plant species typical of a floodplain area.

"As part of the works carried out in the area of Rosenheim, non-native hybrid poplars will be removed in both areas where measurements are being undertaken!, says Project Manager Georg Loy of VERBUND Innkraftwerken. In this way, trees which are native to the floodplain areas, such as the silver willow can be encouraged back. Up until now, the woodless surfaces have been a refuge for such species, which are colonizing plants and characterise the young stages of floodplain development. They had become rarer in the Upper Bavarian part of the river Inn, due to the limited fluvial dynamics.

The measurement package for the revitalisation was devised in cooperation with the responsible authorities, WWA and the District Office of Rosenheim, the local government of Upper Bavaria, associations, specialist councillors of the fishing industry as well as fishing associations.

VERBUND won the 2013 environmental prize sum of EUR 5000, for its numerous fish-friendly and ecological structural measures on the river Inn in previous year. The prize was awarded in October by the Association of Hunters and Fishermen in the area of Rosenheim. VERBUND in turn awarded the prize money forward to the fishing associations for its youth work.

For more information visit:

www.verbund.com/bg/de/blog/2013/04/02/fische-muscheln-inn-oekologie

www.verbund.com/inn

www.verbund.com/laufkraftwerk