Abstract
This report describes the results of field work in the Princess Amalia Wind Farm (in Dutch: Prinses Amaliawindpark, or PAWP). The field work meets the requirements of the Monitoring and Evaluation Programme, which is part of the Wbr-permit of the wind farm. The objective is to determine if the wind farm functions as a refugium for demersal fish. PAWP is expected to act as a refugium because fisheries are excluded in the farm area since 16 October 2007. It is expected that larger and older individuals as well as species sensitive to fisheries would have a better chance to survive, which would result in an increase in numbers and larger individuals. The methods and design of the field work were decided upon by PAWP and the government and follow closely the protocols of the IMARES statutory task beam trawl surveys. The two beam trawls used were similar to the gear used in the IMARES Sole Net Survey (SNS). One beam was rigged with a SNS type net (mesh size 40 mm, rigged with four tickler chains) while the other beam was rigged with a net used in the Demersal Fish Survey (DFS, mesh size 20 mm, rigged with one tickler chain and bobbin rope). Following the protocols, twelve tows were performed in the wind farm. At each location this resulted in two samples: one SNS-net and one DFS-net. These catches were compared to data collected by the regular SNS and DFS survey in the surrounding area over the past 10 years (2004-2013). The spatial distributions of the two statutory surveys differ from the location of the wind farm. The positions of the DFS were closer to shore. For the SNS a limited number of stations was close to the farm, these were used in the analyses as SNS subset (SNS-close), which contains a maximum of two tows a year. Data analyses were performed on the number of species caught, the total catch per hectare and the numbers per hectare of a number of target species (sole, plaice, dab, turbot, flounder, brill) and nontarget species (solenette, scaldfish, greater sandeel and striped red mullet). In total 27 fish species were caught in 24 samples, all of which were also caught in the surrounding statutory surveys. The total catch, species richness by tow and the abundance of the analysed species were very similar to the catches in the surrounding surveys. The length range of the species was similar to the SNS and DFS, but the length frequency distribution differed. The catches in PAWP had a lower number of small fish and a larger number of larger fish compared to the SNS catches. A part of this is due to the offshore position of PAWP compared to the total SNS set, however the differences were still visible compared to the SNS-close subset. The overall impression is that fish species composition is equal inside to outside the wind farm. The expectation that larger and older individuals would have a better chance to survive and so increase in size and numbers, might be supported for the species analysed in this project.