Plattform Platform	Reise-Nr. Cruise-No.	Zeitraum Period	Projekt Project	Arbeitsgebiet Working area
Solea	824	27.06.2023 - 12.07.2023	NHAS	ICES-Subarea IVb Skagerrak Kattegat North Sea ICES-Subarea IVc

Fahrtleiter Chief Scientist	Institut Institute	Auslaufhafen Port of departure	Einlaufhafen Port of return	Stationskarte Station map	Schiffsroute Trackchart
Schaber Matthias	Thunen-Institut fur Seefischerei	Cuxhaven	Cuxhaven

Ziel der Reise / Objectives of Cruise:

The survey was part of an international hydroacoustic survey providing information on stock parameters of small pelagics (Acoustic Survey in the Skagerrak and Kattegat, the North Sea, West of Scotland and the Malin Shelf area, HERAS) coordinated by the ICES Working Group of International Pelagic Surveys (WGIPS). Denmark, Ireland, the Netherlands, Norway and Scotland also participated in the survey. In general, this survey provides the most important fisheries independent contribution to the assessment of herring stocks in the North Sea, Western Baltic Sea, Skagerrak/Kattegat as well as areas west of Scotland and the Irish Sea. The total survey area largely covers ICES Divisions 27.3.a, 27.4.a, 27.4.b and 27.6.a. Altogether, 1137 nautical miles of hydroacoustic transects were covered, which is for the second consecutive year substantially less than planned. Initial delays and premature termination of the survey led to the loss of a week of survey time. This ultimately led to the repeated non-coverage of stratum 131. Accordingly, the survey area could not be covered as planned. The distribution of backscatter values allocated to clupeid fishes in general followed the observations made in previous years, with highest concentrations of schools in the southwestern stratum 51 and notable registrations in the southeastern German Bight (stratum 61). In the northern coastal stratum 71, overall NASC values registered were lower than in the previous year, with again most detections of clupeid aggregations towards the western boundary of that stratum. To allocate biological information to echorecordings and for the collection of biological samples, 28 fishery hauls were conducted. As in the previous years, sprat contributed the bulk biomass to total catch weight and had -together with mackerel and herring- the most frequent occurrence in the hauls. Herring mostly co-occurred with sprat in mixed schools. Herring catches were -despite the even further reduced coverage- higher than those in the previous year, and herring was widely distributed in the area. Sardines and anchovies were caught only on occasion and in relatively small quantities.

Messungen / Measurements