Plattform Platform	Reise-Nr. Cruise-No.	Zeitraum Period	Projekt Project	Arbeitsgebiet Working area
Solea	732	21.03.2017 - 30.03.2017		North Sea German Bight

Fahrtleiter Chief Scientist	Institut Institute	Auslaufhafen Port of departure	Einlaufhafen Port of return	Stationskarte Station map	Schiffsroute Trackchart
Stepputtis Daniel	Thunen-Institut fur Ostseefischerei	Cuxhaven	Cuxhaven

Ziel der Reise / Objectives of Cruise:

Solea 732: This fishery is a small and regional coastal fishery. Nevertheless, it is the most important German fishery - based on the economic revenues. The standard gears in this NorthSea-shrimp fishery are beamtrawls with a Bobbin-Groundrope. A standard beamtrawl (8m width) has around 36 bobbins. These bobbins have two duties: a) the bobbins guide the net over the bottom and b) they startle shrimp to jump off the bottom. Unfortunately, the bobbins also stimulate other bottom living species, such as flatfish spe-cies. Usually, those unwanted animals are caught and discarded - a point of criticism. An-other critical point is the bottom contact of the bobbins, which potentially harm the sea bot-tom and requires additional energy. To omit the bobbins (or at least to reduce their number), other ways to stimulate the shrimp have to be found - ideally only the shrimp. One option is the usage of electrical fields. Our Belgian colleagues developed the shrimp-pulse beam trawl, using a pulsed electrical field, optimized for shrimp (5 stimuli per second). This shrimp-pulse trawl was intensively studied in Germany with focus on changes on catchability. The consequences of these pulsed electri-cal fields on other marine organisms were investigated in Belgium and the Netherlands. So far, no negative influence on such organisms was found. Nevertheless this fishing method is discussed critically in relation to potential negative effects of electric field (whereas, it is often not distinguished between shrimp-pulsetrawl and sole-pulsetrawl). During SO732, we want to investigate whether it is possible to efficiently catch with the shrimp-pulsetrawl us-ing reduced pulse parameters (pulse duration and number of pulses). These experiments at sea are based on Lab-experiments, which were conducted in October 2016 in Ostende – and have shown good results. Additionally, the ROV (remotely operated vehicle) will be deployed after fishery at selected days. To deploy the ROV, the vessels need to be anchored.

Messungen / Measurements