Plattform Platform	Reise-Nr. Cruise-No.	Zeitraum Period	Projekt Project	Arbeitsgebiet Working area
Alkor	AL585	23.01.2023 - 31.01.2023	WINTER COD 2021-25	Mecklenburg Bight Baltic Sea Kiel Bight Fehmarn Belt

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

Ziel der Reise / Objectives of Cruise:

The western Baltic cod stock is currently in distress, which is largely associated with several years of only low recruitment success. The reasons for these several years of low recruitment are not understood sufficiently so far. However, there are indications for a (potentially climate-induced) shift in spawning phenology shifting spawning activity (peaking usually in March) to an earlier time, probably causing mismatch of cod larvae and zooplankton food and thus leading to a poor larval survival. This cruise was the third out of five proposed cruises in the framework of the Winter cod 2021-25 cruises of the IMF, which aim to investigate the early winter spawning activity of western Baltic cod. For this purpose, Ichthyoplankton samples and cod samples were taken on a for-defined station grid. Cod samples are used to investigate maturity stages and condition of adult cod. Plankton samples are especially analysed on the occurrence of cod eggs and larvae. Results are used to identify whether there is an early-winter spawning activity of western Baltic cod, and furthermore, if there are spatial difference in cod spawning activity between the different parts of the Belt Sea (i.e. Little Belt, Great Belt, Kiel Bight, Fehmarn Belt & Mecklenburg Bight).

Messungen / Measurements