This study deals with important methodology issues that affect age estimates of eastern Atlantic bluefin tuna Thunnus thynnus using dorsal fin spines. Nearly 3800 spine sections were used from fish caught in the north‐east Atlantic Ocean and western Mediterranean Sea over a 21 year period. Edge type and marginal increment analyses indicated a yearly periodicity of annulus formation with the translucent bands (50% of occurrence) appearing from October to May. Nucleus vascularization seriously affected specimens older than 6 years, with the disappearance of 40–50% of the presumed annuli by that age. An alternate sectioning location was a clear improvement and this finding is an important contribution to the methodology of using this structure for ageing the full‐length range of eastern T. thynnus. Finally, there were no significant differences between the coefficients of von Bertalanffy growth model estimated from mean length at age data (L_∞ = 327·4; k = 0·097; t₀ = −0·838) and those estimated from the growth curves accepted for the eastern and western T. thynnus management units.

Proepicardial/epicardial‐derived cells are the main origin of the early embryonic coronary vascular bed. In vivo coronary vasculogenesis, which is a fast‐occurring event, can be mimicked in vitro by culturing proepicardial tissue in different ways. The in vitro vasculogenic model presented in this study (a proepicardial suspension culture assay) partially reproduces coronary vascular development from its cellular precursors, a process known to be highly dependent on cell migration, cell differentiation, cell adhesion/sorting, and tissue fusion phenomena. The main aim of this study is to study the triggering signals and the cellular dynamics that regulate the differentiation of proepicardial cells into the angioblastic/endothelial lineage and their in vitro vasculogenic potential. Our results indicate that hanging drop‐cultured proepicardia, which have an intrinsic vascular potential, behave like self‐assembling cell aggregates or spheroids that can fuse to give rise to complex vascularized 3D structures. We believe that these self‐assembling cell aggregates are an optimal choice to study the differentiation of coronary angioblasts, as well as a good method to reproduce vascular development in vitro. Finally, we propose the proepicardium as a suitable cellular source for vascular tissue engineering. Anat Rec Part A, 288A:700–713, 2006.

The shape of sagitta otoliths was used to compare individuals of little tunny (Euthynnus alleteratus) harvested on board commercial fishing vessels from the coastal areas along the Eastern Atlantic, including the Mediterranean Sea. Fish sampling and selection was designed to cover possible seasonal changes and tuna size. The research encompassed both morphometric and shape analyses of left sagittal otoliths extracted of 504 fish specimens. Four shape indices (Circularity, Roundness, Rectangularity, and Form-Factor) were significantly different between two groups, showing a statistical differentiation between two clear spatial units. The degree of divergence was even more pronounced along the rostrum, postrostrum, and excisura of the generated otolith outlines between these two groups. One group corresponds to the samples from the coastal areas in the Northeast Temperate Atlantic and Mediterranean Sea (NETAM Area) and a second group from the coastal areas off the Eastern Tropical Atlantic coast of Africa (ETA Area). This study is the first to use otolith shape to differentiate tunas from separate spatial units. These results could be used to re-classify previously collected samples and to correct time series of data collected.

Background: The bullet tuna (Auxis rochei) is an epipelagic fish with a worldwide distribution that is highly targeted by fisheries. Genetic diversity and population genetics are good indicators of population structure and thus, essential tools for fisheries management. Knowing which factors (biotic and abiotic) might be shaping such structure is crucial for management plans. In the present study, we assessed the population structure of the bullet tuna in the western and central Mediterranean Sea. Methods: We used two types of genetic data: the mitochondrial DNA control region and seven microsatellite loci. The analysis of 431 sequences with a length of 386 bp from the mtDNA CR and the results from 276 individuals were genotyped by seven microsatellite loci. Results: Both types of markers coincided in showing significant genetic differences between an Iberian Peninsula–Strait of Gibraltar stock in comparison with a North African stock. Conclusions: We argue that this differentiation pattern is likely caused by reproductive strategies such as coastal spawning, larval retention, and natal homing behavior. These results should endorse the implementation of management plans for a resource that currently is not being managed. Thus, to ensure sustainability, these new policies should consider the presence of at least two genetically identified stocks.

Integrative approaches that investigate trophic ecology drivers provide knowledge to explore and predict changes in food‐web dynamics under contrasting scenarios of global change. However, there are few studies that analyse the relationship between environmental factors and trophic interactions and that additionally consider other human stressors such as fisheries. Here, we use Bayesian Stable isotope mixing models to study the trophic ecology of a widespread pelagic predatory fish, the swordfish (Xiphias gladius), in the western Mediterranean Sea and the adjacent Atlantic waters. We explore the relationships between dietary estimates and biological, environmental and anthropogenic drivers using generalized additive models (GAMs). GAMs are used to develop spatial predictions of present prey consumption and, as a prospective exercise, to project changes in prey consumption under different future climate change scenarios. Overall, we found that swordfish diet varied as a response to changing environmental conditions, particularly to varying sea surface temperature (SST), mixed layer depth (MLD) and chlorophyll‐a concentration (Chl); and to fishing pressure. Fish consumption was related to SST and MLD. Squid consumption was related to SST, with the greatest contributions observed in swordfish of intermediate lengths. Squid had a higher contribution to swordfish diet around the Canary Islands and the western Mediterranean Sea, while gelatinous organisms were more consumed around the Gulf of Cádiz. The consumption of gelatinous organisms was higher in smaller swordfish and in areas with lower productivity. Our prospective exercise suggested different diet alterations under contrasting future global change scenarios. For the first time, we provide quantitative evidence of how large‐scale, spatial–temporal patterns in fishing pressure and environmental conditions can shape the diet of swordfish. Our study presents useful results to assess the diet of this predator and highlight how incorporating trophic interactions into projections can improve our understanding of future distributions.