SARF044: Assessment of the impacts and utility of acoustic deterrent devices

Start Date: 1st March 2008   
End Date: 31st August 2009
Main Contractor(s): University of St Andrews
Other Sponsor(s): The Crown Estate

Objectives

1. Measure the degree of disturbance and exclusion caused by commercial and widely used ADD devices on cetaceans over a range of time scales and over spatial scales from 10s m to 10s Kms. We will explore this by conducting a series of controlled experiments and test at least two widely used devices with contrasting acoustic outputs.

2. Investigate effects on porpoises at greater spatial and temporal scales by estimating the relative abundance of porpoises (based on acoustic data) and analysing this with respect to ADD occurrence, from data collected over five years during regular surveys in the Hebrides.

3. Assess, through interviews and analysis of existing log books, how ADDs are used on a representative sample of Scottish salmon farms. Assess how their use affects the pattern of seal attacks at fish farms.

4. Collect data directly from salmon farms during episodes of 'seal attack' and make observations of the effects of ADDs as part of management activities 5. Suggest guidelines for best usage based on these data and their analysis.

Summary

The use of ADDs in Scottish fish farms has become controversial due to a perceived acoustic impact on cetaceans. Uncertainties about the extent to which ADDs are effective in minimising seal damage also remain. This study proposes to examine the extent to which porpoises are affected by different ADD models, and specifically under different duty cycles. We will also use existing acoustic data collected over five years from the West Coast to examine how porpoise distribution is influenced by ongoing ADD use. In collaboration with the industry we will use daily records from farms where ADDs have been used to collate descriptive information on the effectiveness of otherwise of ADDs. We will on an opportunistic basis deploy acoustic and video equipment around the pens of a salmon farm where seal attacks are ongoing to try to understand more about the nature of such attacks, while also testing the effectiveness of ‘triggers’ used by one of the manufacturers as indicators of seal attack. Finally we will use the results of this work to elaborate guidelines for best practice use of ADDs.