Difference between revisions of "Sensory, behavioural barriers (electricity, light, sound, air-water curtains)"

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[[category:Downstream fish migration measures]][[category:Measures]]
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[[category:Downstream fish migration measures]][[category:Measures]][[Category:Needs improvement]]
  
 
=Introduction=
 
=Introduction=

Revision as of 11:04, 24 October 2019


Introduction

Fish are deterred by a series of measures, including flashing lights, noise, air bubbles and electrical power. This can be used to control fish from dangerous migration routes, such as intake for turbines. The measure initially only works if the fish has alternative migration routes, for example escape routes and safe bypasses. The guiding impact can be improved with attraction measures such as increased water flow to a bypass (repulse and attract). Common for repulsion measures is that they usually only work for parts of migrating fish, that they work less well by flooding and are selective in terms of species and sizes. Fish may also be accustomed to deterrence measures over time, so that they get lower efficiency.

Design varies between the methods and refers to the literature below. The most important deterrence methods are:

  • Electric screens
  • Strobe light
  • Bubble curtains
  • Acoustic deterrence, e.g. BAFF (bio-acoustic fish fence), which is a perforated tube located below the surface that emits sound and compressed air, which will act as a repellent on fish.

Promising results have been obtained with various experimental behavioural screens in laboratories or on test sites. However, not many prototype installations have been evaluated. Furthermore, the technology has not met the expectations and the results obtained in field applications have been much less reliable than those obtained under controlled conditions (EPRI, 1986) (Kynard, et al., 1990), (EPRI, 1994), (Gosset, et al., 1999), (Therrien, et al., 1998) (Travade, et al., 1999), (Larinier, et al., 2002), (Bau, et al., 2008). Furthermore, their scope of application is otherwise limited to low flow velocities (<0.3 m/s).

Care should be taken when using behavioural barriers, especially since manufacturers of these products have a high marketing interest to promote the use of their technology and may deliberately overestimate their effectiveness (Larinier, et al., 2002).

Methods, tools, and devices

During planning

During implementation

During operation

Classification table