Plattform Platform	Reise-Nr. Cruise-No.	Zeitraum Period	Projekt Project	Arbeitsgebiet Working area
Walther Herwig III	WH352	05.03.2012 - 30.03.2012		North Sea Western North Sea English Channel

Fahrtleiter Chief Scientist	Institut Institute	Auslaufhafen Port of departure	Einlaufhafen Port of return	Stationskarte Station map	Schiffsroute Trackchart
Keyl Friedemann	Institut fur Seefischerei der VTIG Hamburg	Bremerhaven	Bremerhaven	Karte Map

Ziel der Reise / Objectives of Cruise:

Cruise objectives: - study the biotic and abiotic conditions of the habitats of whiting (Merlangius merlangus) and other demersal species, andthe influence of relevant factors on their distribution and abundance, - provide samples for the analysis of the trophic position of whiting considering size and sex, - study the hydrography of the western North Sea, particularly with respect to the inflow of North Atlantic water, - take samples to analyse the genetic structure of North Sea whiting to differentiate potential relevant subunits of the population, - hydroacoustic recordings of demersal and pelagic fish, - deploy and test the towed underwater vehicle TRIAXUS for continuous oceanographic and seabed sampling - sampling of ichthyoplankton and zooplankton The survey area covered the western North Sea from the Shetland Islands to the Channel laid out mostly perpendicular to bathymetry and coast with approximately 20 nm distance between stations. The favorable conditions allowed to extend the original cruise plan with 7 to 9 transects to a total of 10 transects with lengths between 40 and 180 nm. The main target species, whiting, was found in high quantities and in its complete size range that will allow conducting the planned trophic and genetic analyses. Samples of cod and grey gurnard were taken for the analysis of their trophic positions and possible competition with whiting. Preliminary results show that size structure and composition of demersal fish assemblages, epibenthic communities as well as their biodiversity as expected change with depth, latitude, water masses and distance to river runoff. The samples taken by GOV and beam trawl during the cruise will allow quantitative analyses on the influence of these factors on the communities. The hydroacoustics sampling that covered large parts of the cruise will allow for estimates of the distributions of most abundant pelagic and demersal fish species along the transects. Hydrographic information obtained from CTD and water samples taken support the analysis on the North Sea demersal communities and the trophic system. Oceanographic data for physical (temperature, salinity), chemical (oxygen) and biological (chl-a) parameters were taken as intended on all fishing stations. The anticipated continuous nighttime sampling of hydrography, particle counts and seabed mapping with CTD, LOPC and sidescan sonar respectively mounted on the underwater tow vehicle TRIAXUS was not successful. After malfunction of the vehicle for yet unknown reasons during the second deployment phase which led to bottom contact, it was decided not to deploy the TRIAXUS again during the cruise. The alternative nighttime sampling program for ichthyoplankton and zooplankton with the MIK provided additional data for the understanding of trophic links between the primary production (PP) in the water column and bottom feeders. Fluoresence measurements during the CTD tows and remote sensing data will allow assessing PP; the chl a-analysis conducted on board will support the validation of the satellite data.

Messungen / Measurements