Plattform Platform	Reise-Nr. Cruise-No.	Zeitraum Period	Projekt Project	Arbeitsgebiet Working area
Walther Herwig III	WH465	02.03.2023 - 23.04.2023		NW Atlantic (Limit 40?W)

Fahrtleiter Chief Scientist	Institut Institute	Auslaufhafen Port of departure	Einlaufhafen Port of return	Stationskarte Station map	Schiffsroute Trackchart
Hanel Reinhold	Thunen-Institut fur Fischereiokologie	Bremerhaven	Bremerhaven

Ziel der Reise / Objectives of Cruise:

The primary objectives of the survey were the investigation of distribution and abundance of leptocephalus larvae with focus on the European and American eel and to further characterize the hydrography of the spawning area of these species. The study also aimed at better understanding the influence of abiotic factors on potential eel spawning sites and on the distribution of eel larvae. Together with the results of the 342nd, the 373rd and the 404th voyage of the Walther Herwig III in 2011, 2014 and 2017, respectively, as well as the 41st voyage of RV Maria S. Merian in 2015, this cruise aimed at delivering insights into possible changes of the leptocephalus abundance and assemblage in the Sargasso Sea and to shed light on the influence of varying hydrographic conditions on the distribution of eel larvae. For this purpose, all caught leptocephalus larvae were sorted from the catch, identified, measured and preserved. In addition, gut and tissue samples were taken for gut content and virus analyses and depth-stratified catches with an IKMT-MultiNet were conducted to record diurnal changes in the depth distribution of early developmental stages. The scientific work started after reaching the first station (at 67?W 31?N) on March 23 and continued south along a latitudinal transect in steps of 1? or 0.5?, depending on catch efficiency. After ending the first transect at 67?W 22?N, the second transect started at 64?W 19?N with one intermediate station between the two transects. The distance between the transects was 3? longitude. Last station was at 64?W 31?N.

Messungen / Measurements