Severe winter conditions improve recruitment success of blue whiting (Micromesistius poutassou), a temperate water fish species, in the NW Mediterranean sea

Nursery areas of Micromesistius poutassou and Sardina pilchardus unveil their reproductive strategies in the northwestern Mediterranean Sea

“…However, the deep cascading event detected in 2018 (Figure 4h) could have contributed to sink and displace blue whiting larvae out of the shelf‐slope front reducing their survival chances. In this line, Mir‐Arguimbau et al (2022), from the analysis of the otolith microstructure of flue whiting recruits, demonstrated that the survival of individuals born during the cascading event and intense vertical mixing of 2018 was very low. However, the high primary productivity resulting of the intense vertical mixing (Estrada et al, 2014; Marty & Chiavérini, 2010) would enhance the growth and survival of individuals born after these events (Mir‐Arguimbau et al, 2022).…”

“…These production pulses mainly occur after episodes of strong vertical mixing (Estrada, 1966; Salat et al, 2002) but can also result from intense precipitation events, as those detected in 2017. This would explain the observed high surface chlorophyll‐a over the shelf waters in 2017, despite this year was one of the mildest winters of the decade (Mir‐Arguimbau et al, 2022). By contrast, in 2018, the observed surface chlorophyll‐a over the shelf would only be dependent on vertical mixing, as typical in winter.…”

“…Sardine spawning is highly dependent on local primary production over the coastal areas that, in turn, depends on the strength of the winter or the occasional rain storms that may partially compensate the lack of nutrients at surface, because of the vertical stability. Blue whiting spawning takes place over the upper slope aimed at ensuring that their larvae will be retained by the shelf‐slope front and that juveniles will be able to take advantage of the late winter bloom in the open sea, when the stabilization process begins in late winter‐early spring (Mir‐Arguimbau et al, 2022). In the NW Mediterranean, severe winters are characterized by cold water and strong vertical mixing that enhances surface productivity over the continental shelf and the intensity of the late‐winter phytoplankton bloom in the open sea (Estrada et al, 2014; Marty & Chiavérini, 2010).…”

“…In the NW Mediterranean, severe winters are characterized by cold water and strong vertical mixing that enhances surface productivity over the continental shelf and the intensity of the late‐winter phytoplankton bloom in the open sea (Estrada et al, 2014; Marty & Chiavérini, 2010). Recent studies have evidenced that severe winter conditions improve the recruitment success of blue whiting (Mir‐Arguimbau et al, 2022). Climate trends for the NW Mediterranean show a warming trend along with a decline in precipitation (e.g., Alpert et al, 2002; Vargas‐Yáñez et al, 2017).…”

The role of oceanographic conditions and colony size in shaping the spatial structure ofPyrosoma atlanticumin the NW Mediterranean Sea

“…Although in both years the sampling was conducted in February, in 2017, the abundance of small–medium (≤6.9 mm) colonies was very high, the largest registered in the Mediterranean ( Andersen and Sardou, 1994 ; Granata et al ., 2020 ). This exceptional abundance might be related to an earlier development of spring conditions and the subsequent seasonal phytoplankton bloom in 2017 in comparison with 2018 ( Mir-Arguimbau et al ., 2022 ). The life history traits of P. atlanticum , with short generation times and rapid growth, could allow for a rapid population increase during suitable trophic conditions associated with the seasonal production bloom ( Alldredge and Madin, 1982 ).…”