Feeding ecology of Sardina pilchardus larval stages

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Cell cycle analyisis of brain cells as a growth index in larval cod at different feeding conditions and temperatures

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First recording of a bathypelagic deep scattering layer in the Bay of Biscay

Acoustic meso- and bathypelagic studies are scarce in the Bay of Biscay but increasing over the last years. This study provides a description of seasonal and bathymetric variation in the distribution of the main scattering layers. We combine acoustics and hydrographic information from four surveys carried out in 2015 in the southern Bay of Biscay. Water mass properties as well as mixing processes studied through optimum multiparameter (OMP) analysis provided information on the physical seascape. This study reports for the first time a bathypelagic deep scattering layer that was detected in autumn (1300–1500 m) and winter (800–1200 m) and did not present a daily migration pattern. Migrant deep scattering layers and non-migrant layers, stronger at 18 and 38 kHz respectively, are two separate entities with distinct spatial and seasonal dynamics. Migrant layers vary in number and intensity with primary production while the main non-migrant layer (400–800 m depth) is constant in intensity throughout the year. Non-migrant layers seem to locate at horizontal water mass boundaries with increased stratification.Versión del editor3,26

Vertical distribution and aggregation patterns of krill (Crustacea: Euphausiacea) in the Bay of Biscay: interannual and seasonal variability

The recent collapse and recovery of the anchovy population in the Bay of Biscay raised the need to assess environmental influences on the mortality of juvenile stages, in particular the impacts of predation by tunas. Stomachs of 1354 albacore and 579 bluefin tunas were collected in several zones of the Bay of Biscay and adjacent waters in the summers of 2004–2007 (period of depletion in anchovy population) and of 2009–2010 (period of recovery). Among different years, average daily consumption of anchovy (when present in diet) varied between 6.7 and 26.5 individuals (max. 118) per day and predator for bluefin tunas, and between 4.8 and 15.5 (max. 103) for albacore. Anchovy consumption by tunas appeared to have an important interannual, seasonal, and geographical variability. Juvenile anchovy were absent from both albacore and bluefin tuna diets until early August in all years. They were also absent from albacore diet outside the inner Bay of Biscay (core area of anchovy) in 2004–2007, whereas they were present up to the most northwestern part of the Bay in 2010, which supposes a higher exposure to predation in the period of recovery. On the other hand, the absence of albacore in the inner Bay of Biscay since 2008 tends to reduce predation impacts. Anchovy appears to be a significantly more important prey for bluefin tuna than for albacore, particularly in the case of age‐1 bluefin tunas. No significant relationship was found between tuna size and anchovy consumptio