Here at FiveRivers, we’re proud to provide a full range of fish passage solutions, including design, installation and monitoring.
Where possible, we will aim to remove existing structures completely, however there are alternate options available for when this is not possible, such as naturalised fish bypass channels; technical fish passes (i.e Larinier); and non-technical fish passes, such as rock ramps, pre-barrages and low-cost recycled baffles.
We work in line with the Environment Agency’s Fish Pass Manual to ensure that the most appropriate and cost-effective solutions are used at each point, providing passage for multiple fish species where possible.
FiveRivers are a top choice for environmental services in the UK, and we are pleased to act as both a designer and contractor for your project. What’s more, we’re perfectly positioned to liaise with regulatory bodies in order to obtain fish passage approval and environmental permits.
What are fish passages?
A simple way to think about fish passages is to envision a ladder which allows aquatic species to move with greater ease from location to location. While certain species, such as salmon, are able to jump upstream, smaller fish may not be able to travel in the same way and therefore may be restricted in their ability to reach their habitat. Eels, too, are particularly vulnerable due to their catadromous life history. Fish passages provide a means for fish species to fully utilise available habitat and complete their life cycles.Talk to an expert
Why are fish passages important?
Some fish species spawn in freshwater and spend most of their lives out at sea, others have the opposite strategy. Barriers can drastically impact these two groups, blocking off access to complete vital life stages. Other fish species spend their whole life in freshwater, but still move significantly throughout catchments at different life stages. By cutting off fish passage we are fragmenting our fish populations, and making them less resilient.
Fish passage improvements are key technique in the catchment managers toolbox to improve Water Framework Directive status. Under specific legislation such as the Eels (England and Wales) Regulations 2009 there may also be a requirement to improve passage for a single species.Talk to an expert
How do fish passages work?
There are many different techniques to improve fish passage depending on the specific site conditions, and species of fish present. No.1 on this list is full removal of the barrier, as well as improving fish passage with will also reduce impoundment and improve sediment flow. This is not always possible or desirable, at which point we look at the toolkit of available options.
Next we favour a ‘nature-like’ fish pass approach, this maybe involve by-passing a structure with a naturalised channel or creation of a ramp (e.g. low cost baffles, rock ramp) to allow fish to traverse an obstacle. Sometimes we need a more engineered approach and will develop a pool or baffle type system within a constrained channel built on the structure.Talk to an expert