New insights into behavioural ecology of European seabass off the West Coast of France: implications at local and population scales

Abstract

From 2010 to 2012, 246 data storage tags were deployed on European seabass in the Iroise Natural Marine Park, a marine protected area (MPA) off west Brittany, France. A return rate of 14.6% associated with long time series of data provided new information on fish ecology (e.g. maximum experienced depth greater than 225 m, temperature range 6.80–21.87°C). Depth and temperature series were used to infer individual migration using an innovative hidden Markov model (HMM) especially developed for seabass geolocation. Reconstructed fish tracks revealed that seabass is a partially migratory species, as individuals exhibited either long-distance migrations towards the Bay of Biscay or the Celtic Sea, or residency behaviour in the Iroise Sea. Fidelity to summer feeding areas and to winter spawing areas was demonstrated. These results suggest that the population is spatially structured. The Iroise Sea is likely a mixing zone for different stocks or sub-populations, and may also shelter a resident population. At the population scale, such findings may impact ICES stock assessment and the resulting decisions from EU managers. At the local scale, conservation action could be taken by MPA managers. Besides, this study demonstrates the high potential of archival tags for investigating multi-year behavioural patterns such as site fidelity to offshore spawning areas.

The spatial scale of dispersal revealed by admixture tracts

“…Our numerical estimations seem consistent with previous population genetics studies demonstrating the existence of a genetic structure between western and eastern Mediterranean populations using allozymes (Allegrucci, Fortunato, & Sbordoni, 1997), microsatellite markers (Bahri-Sfar, Lemaire, Hassine, & Bonhomme, 2000;Quéré et al, 2012), and SNPs (Souche et al, 2015). These results are also in line with the suspected philopatric behavior of the European sea bass (Bahri-Sfar et al, 2000;Castilho & Ciftci, 2005;de Pontual et al, 2019). Nevertheless, since we only used two sampling loca- , 2000).…”

Food availability modulates the combined effects of ocean acidification and warming on fish growth

“…1700 µatm). The 15 °C treatment included larval rearing at 15 °C while juveniles experienced naturally fluctuating thermal conditions between 15 and 18 °C (natural, seasonal differences reflecting ambient summer conditions in the Bay of Brest 77,78 , http://marc. ifremer.fr/en/results/temperatureand_salinity/mars3dchannel_bay_of_biscay_mode/(typevisu)/map/(zoneid)/ sudbzh#appTop]).…”

Horizontal and vertical movements of starry smooth-hound Mustelus asterias in the northeast Atlantic

“…The more we learn about the movement, spatial distribution and stock structure of commercially important fish species, the more it becomes clear that some nominal stock units don’t always capture the underlying dynamics of the population [ 1 – 4 ]. For instance, in the waters surrounding the British Isles, numerous species (including Atlantic cod Gadus morhua , European seabass Dicentrarchus labrax and European plaice Pleuronectes platessa ) have been shown to exhibit metapopulation-like stock structures made up of several semi-discrete sub-populations [ 5 – 7 ]. These sub-populations often converge on particular locations (e.g.…”

“…These sub-populations often converge on particular locations (e.g. for spawning or foraging) and are subsequently dispersed at other times of the year [ 5 – 7 ]. Consequently, such sub-populations may demonstrate unique space-use patterns [ 4 ], display differing fine-scale foraging and spawning strategies [ 8 – 10 ] and exhibit variable rates of growth and maturation [ 11 ].…”