Abstract
To catch flatfish, in particular sole and plaice, tickler chain beam trawling has been traditionally employed. This fishing strategy has the following drawbacks: (1) Catching efficiency and selectivity are relatively low; (2) Fuel costs are very high owing to the combination of high vessel speed and high drag; (3) The overall environmental impact is considerable (combination of bottom disturbance, CO2 production and the release of pollutants). These problems make ticker chain fishing no longer viable (economically as well as environmentally). To partially tackle these issues, electrical fishing techniques have been employed, resulting in a substantial reduction in fuel costs and bottom disturbance compared to the traditional technique. However, the EU has now banned this efficient and promising technique. This project aims to develop new catching techniques for sole and plaice that substantially reduce the problems of the tickler chain technique in terms of catching efficiency, without employing electrical fields for capture. To achieve this, we will study the capture avoidance behaviour of sole and plaice, including escape swimming and burrowing in response to a range of mechanical stimuli that could be implemented in the next generation fishing gear. We will study this in especially designed tanks, using multi-camera high-speed videography in combination with automated tracking techniques. Based on the acquired knowledge of the escape behaviour, we will design new gear with novel stimuli with the following design goals: (1) high catching efficiency and low bycatch, (2) low bottom disturbance, and (3) relatively low required vessel speed. In a next step, we will build prototypes of the new gear and test these in a semi-field situation and optimize the design based on experimental outcomes and theoretical inferences. Selected prototypes will form the starting point for the industry to build the next generation fishing gear.
Netherlands