Pelagic seascape ecology for operational fisheries oceanography: modelling and predicting spawning distribution of Atlantic bluefin tuna in Western Mediterranean

Abstract

The ecology of highly migratory marine species is tightly linked to dynamic oceanographic processes occurring in the pelagic environment. Developing and applying techniques to characterize the spatio-temporal variability of these processes using operational oceanographic data is a challenge for management and conservation. Here we evaluate the possibility of modelling and predicting spawning habitats of Atlantic bluefin tuna in the Western Mediterranean, using pelagic seascape metrics specifically designed to capture the dynamic processes affecting the spawning ecology this species. The different seascape metrics applied were processed from operational oceanographic data products providing information about the temporal and spatial variability of sea surface temperature, kinetic energy and chlorophyll a. Spawning locations were identified using larval abundances sampled in the Balearic Sea, one of the main reproductive areas for this species in the Mediterranean Sea. Results confirm the high dependence of bluefin tuna spawning ecology on mesoscale oceanographic processes while providing spawning habitat maps as a tool for bluefin tuna assessment and management, based on operational oceanographic data. Finally, we discuss the coming challenges that operational fisheries oceanography and pelagic seascape ecology face to become fully implemented as predictive tools.

Accounting for ocean connectivity and hydroclimate in fish recruitment fluctuations within transboundary metapopulations

“…Finally, a more efficient use of the environmental information generated by ocean models and observing systems is required to pursue the fast development of “operational fisheries oceanography” (Alvarez‐Berastegui et al. ). Besides the abundant research dedicated at including climatic influences in long‐term projections of fish production (Rice and Browman ), a new paradigm should focus in those oceanographic and climatic processes that considerably affect short‐term predictions, which are the relevant scales for management purposes.…”

Does upwelling intensity determine larval fish habitats in upwelling ecosystems? The case of Senegal and Mauritania

“…The joint locations are known as ‘knots’ (Wood, ). The number of knots was limited to k = 3 for the smoother SST, SAL, bottom depth and CUI sst to avoid overfitting of the model (Alvarez‐Berastegui et al., ).…”

Challenges for Sustained Observing and Forecasting Systems in the Mediterranean Sea

“…The Mediterranean Sea has also been identified as an important anthropogenic carbon pool where the column inventory is much higher than in the Atlantic (Álvarez-Berastegui et al, 2016;Schneider et al, 2018). This is due to its intrinsic physico-chemical characteristics, in which warm and highly alkaline waters are prone to absorb high amounts of CO 2 from the atmosphere and transport it to deep waters via a number of convective areas.…”

“…The recovery of the Eastern Atlantic bluefin tuna population during the last decade, after a long period of continuous and alarming decrease, is a successful example of how science and operational oceanography can trigger advances in the sustainability of fisheries and species conservation. At SOCIB, the combination of hydrodynamic models, remote sensing and in situ data has enabled the development of techniques for predicting both the spawning and larval habitat distribution, and the survival rate of the egg and larvae in the Balearic Sea (Álvarez-Berastegui et al, 2016;Reglero et al, 2018). These novel predictive capabilities have been applied to the standardization of larval abundance indices used to evaluate the trends of adult tuna populations during the last two decades (Ingram et al, 2017;Álvarez-Berastegui et al, 2018a), and to integrate environmental variability into the short-term forecasting of the survival of larvae and the derived immature individuals.…”