A Comparison of Reproductive Performances in Young and Old Females: A Case Study on the Atlantic Bluefin Tuna in the Mediterranean Sea

In the Mediterranean Sea, a demographic substructure of the Atlantic bluefin tuna Thunnus thynnus has emerged over the last decade, with old and young individuals exhibiting different horizontal movements and spatial–temporal patterns of gonad maturation. In the present study, histology and molecular reproductive markers were integrated with the gonad-specific mir-202 gene expression and ovarian localization to provide a comprehensive picture of the reproductive performances in young and old females and investigate the role played by the mir-202 during gonadal maturation. During the reproductive period, old females (>100 kg; 194.6 ± 33.9 cm straight fork length; 11.3 ± 2.7 years old) were found to have greater reproductive performances than younger females (<80 kg; 139.3 ± 18.8 cm straight fork length; 8.4 ± 1.1 years old) according to gene expression results, suggesting a prolonged spawning season, earlier arrival on spawning grounds and/or better condition in older females. The mir-202-5p showed no global changes; it was abundantly expressed in granulosa cells and faintly present in the ooplasm. On the other hand, the mir-202-3p expression profile reflected levels of oocyte maturation molecular markers (star, lhr) and both histological and molecular (casp3) levels of follicular atresia. Overall, old females exhibited greater reproductive performances than younger females, likely reflecting different reproductive dynamics linked to the physical condition, habitat usage and migratory behaviour. These results highlight the importance of preserving large and old females in the context of fishery management. Finally, the mir-202 appears to be a good candidate to regulate the reproductive output of this species in an autocrine/paracrine manner through either stage- or age-dependent processes.

Download Full-text

Regional variation in the otolith chemistry of age‐0 atlantic bluefin tuna from nurseries in the mediterranean sea

Journal of Applied Ichthyology ◽

10.1111/jai.14174 ◽

2021 ◽

Author(s):

Anna Traina ◽

Enza Quinci ◽

Igaratza Fraile ◽

Isik K. Oray ◽

Haritz Arrizabalaga ◽

...

Keyword(s):

Mediterranean Sea ◽

Regional Variation ◽

Bluefin Tuna ◽

Otolith Chemistry ◽

Atlantic Bluefin Tuna ◽

The Mediterranean

Download Full-text

Surfacing and vertical behaviour of Atlantic bluefin tuna (Thunnus thynnus) in the Mediterranean Sea: implications for aerial surveys

ICES Journal of Marine Science ◽

10.1093/icesjms/fsaa083 ◽

2020 ◽

Vol 77 (5) ◽

pp. 1979-1991

Author(s):

Robert Klaus Bauer ◽

Fabien Forget ◽

Jean-Marc Fromentin ◽

Manuela Capello

Keyword(s):

Mediterranean Sea ◽

Fork Length ◽

Bluefin Tuna ◽

Aerial Survey ◽

Thunnus Thynnus ◽

Survey Period ◽

Atlantic Bluefin Tuna ◽

Aerial Surveys ◽

Gulf Of Lion ◽

Nw Mediterranean

Abstract Atlantic bluefin tuna (Thunnus thynnus) (ABFT) frequently engage in surface basking and foraging behaviour that makes them detectable from afar. This behaviour is utilized for the development of fisheries-independent abundance indices based on aerial surveys, although changes in the surface-feeding dynamics of ABFT are not yet accounted for. We investigated the daytime surfacing behaviour of ABFT at different temporal and vertical resolutions based on 24 individuals (117–158 cm fork length), tagged with pop-up archival tags in the Gulf of Lion, NW-Mediterranean Sea between 2015 and 2016. The results suggest that ABFT remain usually <2 min continuously within the visible surface (0–1 m) during daytime. ABFT presence in the 0–1 and 0–20 m layers varied over time and between individuals but showed a seasonal decline towards autumn with the breakdown of thermal stratification. Furthermore, the rate of surfacing events was highly correlated with the time spent in the 0–20 m layer. Geolocation estimates confirm a strong site fidelity of ABFT during the aerial survey period (August–October) in the Gulf of Lion. Our results support the choice of the survey region and period, but related indices should account for the seasonality of ABFT surface behaviour [i.e. the time spent in the 0–20 m layer.

Download Full-text

Comparative Assessment of the Reproductive Status of Female Atlantic Bluefin Tuna from the Gulf of Mexico and the Mediterranean Sea

PLoS ONE ◽

10.1371/journal.pone.0098233 ◽

2014 ◽

Vol 9 (6) ◽

pp. e98233 ◽

Cited By ~ 22

Author(s):

Jessica M. Knapp ◽

Guillermo Aranda ◽

Antonio Medina ◽

Molly Lutcavage

Keyword(s):

Gulf Of Mexico ◽

Mediterranean Sea ◽

Bluefin Tuna ◽

Comparative Assessment ◽

Reproductive Status ◽

Atlantic Bluefin Tuna ◽

The Mediterranean

Download Full-text

Electronic Tagging of Atlantic Bluefin Tuna (Thunnus thynnus, L.) Reveals Habitat Use and Behaviors in the Mediterranean Sea

PLoS ONE ◽

10.1371/journal.pone.0116638 ◽

2015 ◽

Vol 10 (2) ◽

pp. e0116638 ◽

Cited By ~ 27

Author(s):

Pablo Cermeño ◽

Gemma Quílez-Badia ◽

Andrés Ospina-Alvarez ◽

Susana Sainz-Trápaga ◽

Andre M. Boustany ◽

...

Keyword(s):

Habitat Use ◽

Mediterranean Sea ◽

Bluefin Tuna ◽

Thunnus Thynnus ◽

Atlantic Bluefin Tuna ◽

The Mediterranean ◽

And Behaviors ◽

Electronic Tagging

Download Full-text

Spatial–temporal pattern of bluefin tuna (Thunnus thynnus L. 1758) gonad maturation across the Mediterranean Sea

Marine Biology ◽

10.1007/s00227-008-0955-6 ◽

2008 ◽

Vol 154 (4) ◽

pp. 623-630 ◽

Cited By ~ 48

Author(s):

Gilad Heinisch ◽

Aldo Corriero ◽

Antonio Medina ◽

Francisco J. Abascal ◽

Jose-Miguel de la Serna ◽

...

Keyword(s):

Mediterranean Sea ◽

Temporal Pattern ◽

Bluefin Tuna ◽

Gonad Maturation ◽

Thunnus Thynnus ◽

The Mediterranean

Download Full-text

Spatio-temporal population structuring and genetic diversity retention in depleted Atlantic Bluefin tuna of the Mediterranean Sea

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.0908281107 ◽

2010 ◽

Vol 107 (5) ◽

pp. 2102-2107 ◽

Cited By ~ 72

Author(s):

Giulia Riccioni ◽

Monica Landi ◽

Giorgia Ferrara ◽

Ilaria Milano ◽

Alessia Cariani ◽

...

Keyword(s):

Genetic Diversity ◽

Mediterranean Sea ◽

Population Size ◽

Effective Population Size ◽

Large Population ◽

Bluefin Tuna ◽

Effective Population ◽

Microsatellite Variation ◽

Atlantic Bluefin Tuna ◽

The Mediterranean

Fishery genetics have greatly changed our understanding of population dynamics and structuring in marine fish. In this study, we show that the Atlantic Bluefin tuna (ABFT, Thunnus thynnus), an oceanic predatory species exhibiting highly migratory behavior, large population size, and high potential for dispersal during early life stages, displays significant genetic differences over space and time, both at the fine and large scales of variation. We compared microsatellite variation of contemporary (n = 256) and historical (n = 99) biological samples of ABFTs of the central-western Mediterranean Sea, the latter dating back to the early 20th century. Measures of genetic differentiation and a general heterozygote deficit suggest that differences exist among population samples, both now and 96–80 years ago. Thus, ABFTs do not represent a single panmictic population in the Mediterranean Sea. Statistics designed to infer changes in population size, both from current and past genetic variation, suggest that some Mediterranean ABFT populations, although still not severely reduced in their genetic potential, might have suffered from demographic declines. The short-term estimates of effective population size are straddled on the minimum threshold (effective population size = 500) indicated to maintain genetic diversity and evolutionary potential across several generations in natural populations.

Download Full-text