Piero Addis

Determination of Lmax for Atlantic Bluefin Tuna, Thunnus thynnus (L.), from Meta-Analysis of Published and Available Biometric Data

A meta-analysis of the straight fork lengths (herewith abbreviated as L) of 2,458,028 Atlantic bluefin tuna, Thunnus thynnus (L.), taken from 224 scientific publications and unpublished L data from scientific organizations and fishing companies spanning most of the known Atlantic and Mediterranean Atlantic bluefin tuna fisheries dating from 1605 to 2011, give L values ranging from L min = 20 cm and L max = 330 cm. The results indicate that the parameter L ∞ = 318.85 cm of the growth equation used by ICCATs Standing Committee on Research and Statistics Atlantic bluefin tuna assessment group for the eastern stock (Lt = 318.85 [1 – e−0.093 (t + 0.97)]) lies within the confidence limits of the maximum Ls presented in the study: L max = 319.93 ± 11.3 cm, confirming that this equation perfectly fits the biology of the growth of this species. These conclusions are also valid for the equation for the western stock (Lt = 314.90 [1 – e−0.089 (t +1.13)]). The ICCAT Atlantic bluefin tuna database contains numerous records of Atlantic bluefin tuna L outside the biological feasibility, and solutions are provided to recognize and remove these outliers based on the application of fixed values of Fultons condition factor (K) between 1.4 and 2.6 and appropriate L-W relationships to correct this situation in the future.

Amino-modified polystyrene nanoparticles affect signalling pathways of the sea urchin (Paracentrotus lividus) embryos

Abstract Polystyrene nanoparticles have been shown to pose serious risk to marine organisms including sea urchin embryos based on their surface properties and consequently behaviour in natural sea water. The aim of this study is to investigate the toxicity pathways of amino polystyrene nanoparticles (PS-NH2, 50 nm) in Paracentrotus lividus embryos in terms of development and signalling at both protein and gene levels. Two sub-lethal concentrations of 3 and 4 μg/mL of PS-NH2 were used to expose sea urchin embryos in natural sea water (PS-NH2 as aggregates of 143 ± 5 nm). At 24 and 48 h post-fertilisation (hpf) embryonic development was monitored and variations in the levels of key proteins involved in stress response and development (Hsp70, Hsp60, MnSOD, Phospho-p38 Mapk) as well as the modulation of target genes (Pl-Hsp70, Pl-Hsp60, Pl-Cytochrome b, Pl-p38 Mapk, Pl-Caspase 8, Pl-Univin) were measured. At 48 hpf various striking teratogenic effects were observed such as the occurrence of cells/masses randomly distributed, severe skeletal defects and delayed development. At 24 hpf a significant up-regulation of Pl-Hsp70, Pl-p38 Mapk, Pl-Univin and Pl-Cas8 genes was found, while at 48 hpf only for Pl-Univin was observed. Protein profile showed different patterns as a significant increase of Hsp70 and Hsp60 only after 48 hpf compared to controls. Conversely, P-p38 Mapk protein significantly increased at 24 hpf and decreased at 48 hpf. Our findings highlight that PS-NH2 are able to disrupt sea urchin embryos development by modulating protein and gene profile providing new understandings into the signalling pathways involved.

Atlantic Bluefin Tuna (Thunnus thynnus) Biometrics and Condition

The compiled data for this study represents the first Atlantic and Mediterranean-wide effort to pool all available biometric data for Atlantic bluefin tuna (Thunnus thynnus) with the collaboration of many countries and scientific groups. Biometric relationships were based on an extensive sampling (over 140,000 fish sampled), covering most of the fishing areas for this species in the North Atlantic Ocean and Mediterranean Sea. Sensitivity analyses were carried out to evaluate the representativeness of sampling and explore the most adequate procedure to fit the weight-length relationship (WLR). The selected model for the WLRs by stock included standardized data series (common measurement types) weighted by the inverse variability. There was little difference between annual stock-specific round weight-straight fork length relationships, with an overall difference of 6% in weight. The predicted weight by month was estimated as an additional component in the exponent of the weight-length function. The analyses of monthly variations of fish condition by stock, maturity state and geographic area reflect annual cycles of spawning and feeding behavior. We update and improve upon the biometric relationships for bluefin currently used by the International Commission for the Conservation of Atlantic Tunas, by incorporating substantially larger datasets than ever previously compiled, providing complete documentation of sources and employing robust statistical fitting. WLRs and other conversion factors estimated in this study differ from the ones used in previous bluefin stock assessments.

Body Temperature of the Atlantic Bluefin Tuna (Thunnus thynnus L.) in the Western Mediterranean

This study documents body temperature in the Atlantic bluefin tuna (Thunnus thynnus L.) in the Mediterranean Sea and temperature variability caused by the stress of capture. The investigation was carried out in the traditional trap (tonnara) of Isola Piana (Sardinia, W Mediterranean) where body temperature recordings were conducted on free-swimming bluefin confined in the system of nets known as “camere” or chambers. We tracked the body temperature of two bluefin tuna (214 and 191 cm CFL) using a commercial data logger (HOBO U12, Onset Computer Corporation), under two conditions: the pre-fishing phase, when specimens confined in the “camera di ponente” are undisturbed and the fishing phase when bluefin tuna are trapped in the “camera della morte” and undergo the stress of confinement and capture (mattanza). Body temperature increased by about 2°C during the “mattanza”, whereas no temperature variation was exhibited during the pre-fishing phase. The heat transfer coefficient (K), calculated for both bluefin tuna during the “mattanza”, revealed a rapid increase in heat transfer. Additional data on ambient temperature Ta, white muscle Tw (n = 65; 110–287 cm CFL) and red muscle temperature Tr, (n = 249; 107–287 cm CFL) were obtained from live fish during angling operations, and excess body temperature (Tx = Tr–Ta) was calculated. Mean red muscle temperature was 27.6 ± 1.48°C in an ambient temperature of 18.9 ± 0.84°C. The excess red muscle temperature Tx was 8.21–9.10°C, and the red muscle was 2.4 ± 1.78°C warmer than white muscle.

Physiologic Responses to Stress and Changes in Atlantic Bluefin Tuna (T. thynnus) Meat Color During Trap Fisheries Capture and Processing in Sardinia (W. Mediterranean)

This study investigated plasma cortisol, lactate, and glucose as descriptors of hematological stressors; while the RGB color model using the percentage of monochromatic channels Red (Rp), Green (Gp), and Blue (Bp) was used for the analysis of muscular tissue of the Atlantic bluefin tuna, Thunnus thynnus. The experimental design provided a comparison of stressors and color channels Before and After the stress state and the analysis of variability of monochromatic channels for Fresh and Frozen specimens collected at three time intervals. Results showed a rapid accumulation of cortisol levels (from 73.3 ± 9.5 to 148.0 ± 21.2 ng/mL), lactate (from 5.7 ± 2.9 to 17.0 ± 2.2 μmol/mL), and glucose (from 83.5 ± 8.0 to 128.6 ± 19.3 mg/dL; p < 0.05). The colorimetric analysis highlighted that this accumulation did not in fact affect the color variability of muscle. Analysis of variance carried out to test the effects of color variability in Fresh samples showed significant differences for Rp, Gp, and Bp channels (p < 0.05), whereas no differences were found in Frozen samples. Highly significant differences (p < 0.001) were found comparing Fresh and Frozen for Rp and Bp, indicating a drop of these channels under diverse treatments.

Spatial dynamics and mixing of bluefin tuna in the Atlantic Ocean and Mediterranean Sea revealed using next-generation sequencing

The Atlantic bluefin tuna is a highly migratory species emblematic of the challenges associated with shared fisheries management. In an effort to resolve the species’ stock dynamics, a genomewide search for spatially informative single nucleotide polymorphisms (SNPs) was undertaken, by way of sequencing reduced representation libraries. An allele frequency approach to SNP discovery was used, combining the data of 555 larvae and young‐of‐the‐year (LYOY) into pools representing major geographical areas and mapping against a newly assembled genomic reference. From a set of 184,895 candidate loci, 384 were selected for validation using 167 LYOY. A highly discriminatory genotyping panel of 95 SNPs was ultimately developed by selecting loci with the most pronounced differences between western Atlantic and Mediterranean Sea LYOY. The panel was evaluated by genotyping a different set of LYOY (n = 326), and from these, 77.8% and 82.1% were correctly assigned to western Atlantic and Mediterranean Sea origins, respectively. The panel revealed temporally persistent differentiation among LYOY from the western Atlantic and Mediterranean Sea (FST = 0.008, p = .034). The composition of six mixed feeding aggregations in the Atlantic Ocean and Mediterranean Sea was characterized using genotypes from medium (n = 184) and large (n = 48) adults, applying population assignment and mixture analyses. The results provide evidence of persistent population structuring across broad geographic areas and extensive mixing in the Atlantic Ocean, particularly in the mid‐Atlantic Bight and Gulf of St. Lawrence. The genomic reference and genotyping tools presented here constitute novel resources useful for future research and conservation efforts.

Correction: Atlantic Bluefin Tuna ( Thunnus thynnus ) Biometrics and Condition

[This corrects the article DOI: 10.1371/journal.pone.0141478.].