Acronym ECOLATUN
Category
Fisheries
Title Comparative trophic ecology of larvae of atlantic bluefin tuna (thunnus thynnus) from NW Mediterranean and Gulf of Mexico spawning areas Programme Nat. Programme (supported by ESIF)
Instrument (FP6)
Contact Type (FP7)
Strand (Interreg)
NA
Theme (FP7)
Activity Area (FP6)
Regional Area (Interreg)
Action (COST)
NA
Specific Programme (FP7)
NA
Funding source National-European Coordinator Raúl Laiz Carrión Coordinator email NA
Coordinator institution
IEO - Spanish Institute of Oceanography (Spain)
Institutions involved
NA
Start year 2016 End year 2018 Funding (€) € 133,100 Website http://www.ba.ieo.es/en/investigacion/grupos-de-investigacion/greco/proyectos/2132-ecolatun-comparative-trophic-ecology-of-larvae-of-atlantic-bluefin-tuna-thunnus-thynnus-from-nw-mediterranean-and-gulf-of-mexico-spawning-areas-2016-2018 Summary Atlantic bluefin tuna (thunnus thynnus) mainly reproduces in the nw mediterranean sea (med) and the gulf of mexico (gom), which are two highly contrasting sites from a geographic, climatic and hydrographic standpoint. This population segregation has led fisheries assessment managers to categorically differentiate between a western and eastern atlantic bluefin stock. Genetic cross atlantic bluefin population structure exclusively based on larvae of known natal origin from med and gom will be analyzed in this proposal. In addition, the development and implementation of innovative scientific methods such as simultaneous bulk stable isotope analyses and daily growth, together with stomach content analysis of bluefin larvae, will increase the understanding of their early life trophodynamics in relation to environmental stressors. Moreover, compound specific amino acids stable isotopes will be analyzed for bluefin larvae in both spawning scenarios. The composition and structure of the larval fish communities associated to the atlantic bluefin tuna spawning habitats of the med and gom regions will be described and compared. This knowledge will lay the foundations to analyze the influence of selected environmental variables and the surface ocean dynamics on larval fish abundance and diversity.
Predator-prey interactions of bluefin tuna larvae with other co-occurring apex species (top predator larvae) in the med and gom could differ substantially, and the proposed work would fill an important knowledge gap in this respect. The inter-comparison with, medium and small tuna species (auxis rochei, euthynnus alleteratus, katsuwonus pelamis), and other large pelagic species (sphyraena sphyraena and coryphaena hippurus) will provide a solid understanding to the comparative ecology of bluefin tuna larvae in different spawning grounds. Furthermore, it will increase our ability to estimate the amount of the stable isotope of nitrogen of maternal origin in larvae, and then test the capacity of estimating maternal condition and its link to the growth variability of the offspring.
It is generally accepted that larval survival is growth-rate dependent and small variations of the growth rates may lead to significant recruitment oscillations. Slow growth rates during the larval stage may cause high mortality. Otolith microstructure analysis together with ontogenetic development of the growth hormone gene expression (gh) will be analyzed to assess daily growth variability within med and gom areas.
The proposed study will investigate changes in the food sources and the trophic levels of bluefin larvae and how these changes may explain daily growth variability. The expected results will produce novel information on the early life ecology of bluefin from both regions in relation to the trophodynamics that drive specific growth strategies resulting from specific dietary shifts during the ontogenetic development. This research will have direct relevance to current management issues, in terms of definition of stock population units, examining stock-recruit relationships, and for the prediction of observed high recruitment events. In addition, improved understanding of the connections between environmental variability, larval ecology and recruitment processes can inform future management strategies. This is particularly important for bluefin tuna, which has been shown to be highly vulnerable to climate-induced increases in sea surface temperature.
Keywords
Genetic;
Larvae;
Food web;
Tuna;
Fisheries management;
Fish biology;
Fish;
Marine Region
76
Not associated to marine areas
0
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