Plattform Platform	Reise-Nr. Cruise-No.	Zeitraum Period	Projekt Project	Arbeitsgebiet Working area
Alkor	AL588	01.03.2023 - 10.03.2023		Baltic Sea

Fahrtleiter Chief Scientist	Institut Institute	Auslaufhafen Port of departure	Einlaufhafen Port of return	Stationskarte Station map	Schiffsroute Trackchart
Mollmann Christian	UNI HAMBURG	Kiel	Kiel

Ziel der Reise / Objectives of Cruise:

This cruise was conducted as part of the teaching schedule of the Bachelor of marine ecosystem and fisheries science programme of the University of Hamburg. The cruise aimed to teach students in commonly used scientific methods, gears and working procedures of fisheries science and biological oceanography onboard of a research vessel. This included zooplankton and ichthyoplankton sampling using BONGO and multi-closing nets, investigation of size and species distribution of the fish fauna by using bottom trawl sampling and angling and investigating prevailing hydrographic conditions using CTD probes. Initial sample analyses and subsequent sample archiving were taught to the students in particular in the context of the continuation of the Belt Sea ichthyoplankton sampling time series of the University of Hamburg. This ichthyoplankton time series as well as supplementary sampling of adult cod at selected stations served to investigate the late-winter spawning activity of western Baltic cod in the Belt Sea (ICES SD 22) and complemented sampling efforts on the reproductive biology of western Baltic cod internationally coordinated by the University of Hamburg, GEOMAR, University of Aarhus and the Danish Technical University. During the cruise AL588, spawning cod were found in the Kiel Bight, the Mecklenburg Bight, the Fehmarn Belt, the Little Belt and the Great Belt. In addition, first analyses of BONGO net samples revealed the presence of cod larvae in all sampled subareas, with most larvae observed in the Kiel Bight and only a few cod larvae in the Mecklenburg Bigth. The observation of a relatively high proportion of cod in the late spawning and post-spawning stages could be an indication that March, which in the past was designated as the main spawning season for western Baltic cod in the area, now tends to reflect the late spawning phase of cod.

Messungen / Measurements