Report of the Workshop on Including Socio-Economic considerations into the Climate-recruitment framework developed for clupeids in the Baltic Sea (WKSECRET)

Recruitment–environment relationships for five distinct Baltic Sea herring stocks in‐habiting the areas of the Western Baltic (WBH), the Main Basin (MBH), the Gulf of Riga (GRH), the Bothnian Sea (BSH) and the Bothnian Bay (BBH) and for the Baltic sprat stock (BS) were developed and tested in two previous workshops held in 2007 and 2008 (WKHRPB and WKSSRB; ICES 2007 and 2008) and published in Cardinale et al. 2009. A number of hydro‐climatic and biological predictors were tested for their effect on recruitment. In previous analyses, temperature was determined to be an im‐portant predictor for four of the stocks (MBH, GRH, BSH and BS). However, spawn‐ing stock biomass was the major factor explaining recruitment for GRH and BS while weight‐at‐age of the spawners and spawning stock biomass as those are highly corre‐lated were important predictors of MBH recruitment. For 2 (i.e. MBH and BSH) out of 5 stocks for which complete zooplankton data were available, food supply was also a significant  predictor,  suggesting  that  changes  in  climate  and/or  food  web  structure  may indirectly affect herring recruitment via prey availability for the recruits or spawners. The results emphasized both similarities and differences in the main regu‐lators of recruitment dynamics for the different stocks that should be taken into con‐sideration in the development of area‐specific management strategies thorough the Baltic  Sea  basin.  Further,  it  calls  for  a  thorough  analysis  of  the  effects  of  climate  change on productivity of Baltic herring and sprat stocks in the medium term.