The rise and fall of the NE Atlantic blue whiting (Micromesistius poutassou)

Abstract

Abstract:The Northeast Atlantic blue whiting (Micromesistius poutassou) stock has undergone striking changes in abundance in the last 15 years. The stock increased dramatically in the late 1990s due to a succession of eight unusually strong year classes and dropped again equally dramatically after 2005 when the recruitment collapsed to former levels. The North Atlantic subpolar gyre has previously been shown to have a strong influence on the behaviour of this stock: synchronous changes in the gyre and recruitment suggest a causal linkage and the possibility of forecasting recruitment. A range of mechanisms are reviewed that may explain these observed changes, with two major candidate hypotheses being identified. One hypothesis suggests that the large mackerel (Scomber scombrus) stock in this region may feed on the pre-recruits of blue whiting, with the spatial overlap between blue whiting and mackerel being regulated by the subpolar gyre. Alternatively, variations in the physical environment may have given rise to changes in the amount, type and availability of food for larvae and juveniles, impacting their growth and survival and therefore recruitment. It was not possible to draw firm conclusions about the validity of either of these hypotheses: nevertheless, forecasting recruitment to this stock may be possible in the future if the underlying mechanisms can be resolved.

Effect of intra‐specific competition, surface chlorophyll and fishing on spatial variation of gadoid's body condition

“…While Merluccius merluccius and Phycis blennoides invest energy in body weight from the very early recruit stage consistent with previous studies (Saborido-Rey and Kjesbu 2005), Micromesistius poutassou does not increase in body condition until they reach the juvenile stage, which reveals a strategy to maximize length growth rather than weight to reduce the chance of being predated by maximizing swimming capacities (Payne et al 2012). These ontogenetic differences in the trade-off in allocation of the surplus energy support that investigating the effect of density-dependent and density-independent mechanisms over different life-stages may veil the real contribution of these variables (e.g., Lloret et al 2002, Sandeman et al 2008.…”

Effects of interactions between fish populations on ecosystem dynamics in the Norwegian Sea – results of the INFERNO project

“…The abundance of blue whiting increased until 2004, and the range of the horizontal distribution expanded in a northwesterly direction during this period. Strong year classes of mackerel from 2001 and 2002, together with increasing temperatures, resulted in an increased number of mackerel in the Norwegian Sea (Payne et al 2012;Utne et al 2012a). Furthermore, there were rather substantial changes in the migration pattern of herring during the study period and thus high interannual variability in horizontal overlap between the species.…”

The Sub-Polar Gyre Index – a community data set for application in fisheries and environment research

“…More recently, marine ecologists have reported changes in the ecosystem associated with changes in circulation in the North Atlantic and particularly the sub-polar gyre region (e.g. Hátún et al, 2009a, b;Payne et al, 2012).…”