DREAMER-1 Cruise, RV Sarmiento de Gamboa

DREAMER-1 Cruise (29SG20170313) carried out on the Research Vessel Sarmiento de Gamboa in 2017The European hake, Merluccius merluccius L., is one of the most important economical fisheries in the North-East Atlantic that also plays a key role in the marine ecosystem. After the implementation by the EU of various recovery plans for both stocks, the spawning biomass has recently recuperated, after more than two decades under the security limits. However, recruitment remains highly variable, and in the case of the Southern stock (SS) still decreasing. The overall objective of the project is to analyze the causes that determine hake recruitment with special attention to the demographic and environmental causes and focusing in particular in the seasonal differences in the spawning pattern (SS hake shows two spawning peaks, in late winter and late spring-summer), larval distribution, trophic dynamics of larvae, seasonal differences in recruitment and connectivity patterns between stocks. To achieve these objectives the project will carry out two research surveys, in March and June 2017 within the main hake spawning area, between Cape Finisterre and Eo estuary. The main goals of the surveys are to determine the distributional pattern of hake larvae and the factors determining the observed pattern (climatic, oceanographic and foraging) and collecting biological samples in several life stages: from larvae to young of the year recruits. March survey (DRE0317) was divided in two legs. The first one aimed to characterize environmental conditions and larval abundance along 18 transects orthogonal to the coast, covering the whole research area, and summing 114 fixed stations. Each transect was drawn every 8 nautical miles, while the stations within transect was separated every 4 nm. In each station it was performed an oblique Bongo (60 cm, 500 m mesh size), a vertical pairovet (60 and 150 m) and a CTD profile to estimate hake larval abundance, ichthyoplankton community, micro and mesozooplankton and oceanographic parameters, respectively. In addition during this leg an ODI (Ocean Drifter Iridium) buoy with a 50 m drogue was released. The second leg aimed to catch hake postlarvae using IKMT and MIK nets and young of the year recruits using bottom trawl fishing gears (BACA and GOV). An image from every hake larvae collected was recorded and each larva was individually frozen at -80ºC. All other plankton material was preserved in either formalin or in 96º EtOH. A full biological sampling was conducted for juveniles, including measuring size and weight, and removal of otoliths, gonads, stomach and a muscle tissue piece, as well an estimation of the size frequency. A large number of recruits were additionally frozen for later analysis in the laborator