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Among the many fish species commercially exploited since prehistoric times, Atlantic bluefin tuna (Thunnus thynnus) is one of the most economically significant, having left an indelible imprint on several civilizations including the Phoenicians, Greeks, and Romans. Here, we describe our efforts to identify tuna specimens among the remains of 345 fish vertebrae and bones in several large collections from the Atlantic Ocean, Mediterranean Sea, and Black Sea, dating from the Late Iron Age (2nd century BCE) to the early 20th century (1911–1927). Unfortunately, ancient fish specimens are often mislabelled, which can cause a great deal of confusion among zoologists. Protocols were developed and optimized to overcome the unique challenges related to the compromised integrity of genetic material preserved in ancient bones. Three DNA isolation protocols were compared to maximize yields, and as reported for other faunal remains, a silica spin column‐based method was proven most effective. Endogenous DNA was successfully extracted from the majority of bones and amplified using polymerase chain reactions (PCRs) and an assortment of four primer pairs targeting nuclear (internal transcribed spacer) and mitochondrial sequences (cytochrome oxidase subunit 1 and control region). Protocols targeting mitochondrial markers were more successful than those focused on nuclear targets. Due to the restricted length of the extracted DNA molecules, character‐based keys containing diagnostic nucleotide substitutions were defined and used to identify 231 samples to genera, of which 171 were identified to species level. The success rate of assignment of specimens to species level varied between location and collection, reflecting variation in DNA preservation between different sites and environments. The methods detailed herein can be used to identify other ancient fish specimens and provide information about historical human diets, trade, species distribution, and biodiversity. The same tools can be applied to the analysis of processed food items with highly damaged DNA. [ABSTRACT FROM AUTHOR]

The growth of bluefin tuna ( Thunnus thynnus ) in the North-eastern Atlantic and Mediterranean was analysed using the back-calculation of the dorsal fin spine annuli. Spines from a total of 2678 bluefin tuna, collected from 1984 and 1990–2010, were analyzed. The specimens ranged from 45 to 287 cm straight fork length (SFL). Both linear and power regression functions showed a significant relationship between spine radius and SFL, but power function fitted better than linear (SFL = 42.978R 0.884 , r 2 = 0.98), as also was found in previous studies when a wide range of sizes was available. Two back-calculation equations were used to obtain the back-calculated SFL, Fraser-Lee and Body Proportional Hypothesis (BPH), showing similar results. The Von Bertalanffy growth parameters obtained with the selected BPH model were: SFL = 349.5(1 − e −0.086( t +0.814) ). Back-calculated lengths and growth parameters showed similarities with those from previous literature. [ABSTRACT FROM AUTHOR]

Abstract: The salted and dried product of tuna roe (bottarga) is a seafood characteristic of the Mediterranean area and exported all over the world. Samples of bottarga from bluefin tunas (Thunnus thynnus, L.) caught in the southwest Mediterranean sea were analysed. The samples were characterised by high content of marine wax esters (55–67mol% of lipid classes), of docosahexaenoic (22:6 n-3, 25w%) and oleic (18:1 n-9, 19w%) fatty acids. Cholesterol was detected as 7–9w% of lipids. Free fatty acids, index of lipid hydrolysis, represented 32–39mol% over total fatty acids. Among metabolites, nutrients as taurine, nicotinamide and β-alanine, were found. The microflora comprised staphylococci, enterococci (2.2 log10 CFU/g) and lactic acid bacteria (3 log10 CFU/g). The food-borne pathogens Staphylococcus aureus, Listeria monocytogenes and Salmonella spp. were not detected. These findings indicate tuna bottarga as valuable source of nutrients. [Copyright &y& Elsevier]

Abstract: Aquaculture of bluefin tuna in Mediterranean coastal waters has generated growing concern about the negative environmental effects. In the present isotopic study we examined the dispersal and fate of organic matter derived from a Mediterranean tuna farm in the surrounding environment. An overall enrichment in the heavy nitrogen isotope was found in the feed and in farmed tunas, indicating the input of isotopically traceable organic matter in the system. Waste was clearly traceable in the water column up to 1000m from the cages, while only slight accumulation occurred in the sediment just below the cages. Waste was isotopically shown also to contribute to the diet of demersal and benthopelagic wild fish collected around the cages. As a result, waste undertook multiple pathways. In the water column its was diluted and dispersed due to hydrodynamism, which prevented great accumulation of aquaculture-derived organic matter in sediments. In addition, biological constraints such as benthopelagic and demersal fish further prevented organic matter accumulation through the benthic trophic route. [Copyright &y& Elsevier]

Gordoa, A., Olivar, M. P., Arevalo, R., Viñas, J., Molí, B., and Illas, X. 2009. Determination of Atlantic bluefin tuna (Thunnus thynnus) spawning time within a transport cage in the western Mediterranean. – ICES Journal of Marine Science, 66: 2205–2210.For the first time, tuna spawning in a transport cage being towed from the western Mediterranean spawning ground to a fattening facility off the coast of northeastern Spain was examined during the 2008 fishing season. Daylight and night surface plankton samples were collected using bongo nets located in front of and behind the transport cage. The results for the different time intervals revealed clear and massive nocturnal spawning from 03:00 to 05:00, when the rear bongo was completely jammed with eggs (up to 250 000–300 000 eggs per 1000 m3). Egg size and morphology were consistent with the features of Thunnus thynnus eggs, and identification was confirmed by genetic analysis. Microscopic examination showed the eggs to be in the very early developmental stages. Spawning took place every night over the entire journey. The study showed that neither captivity nor handling/environmental changes along the route inhibited T. thynnus spawning to a very precise biological clock. The study also revealed the diel temporal concurrence of T. thynnus spawning and jellyfish larvae at the sea surface. [ABSTRACT FROM PUBLISHER]

Long-term time-series of bluefin tuna catches from ancestral Mediterranean and Atlantic trap fisheries are presented and analysed. The trap is a passive gear, little modified for centuries, that catches bluefin tuna Thunnus thynnus during their annual spawning migration. These features, together with preliminary analyses, lead us to suggest that long-term fluctuations in trap catches could reflect those in true abundance if they vary in the same manner all around the western Mediterranean and adjacent Atlantic. To test this hypothesis, we investigated 54 time-series more than 20 years long (the longest ones spanning four centuries) of trap catches along the western Mediterranean coasts of Italy, Sicily, Sardinia, Tunisia, Spain, and Morocco, and the adjacent Atlantic coasts of Spain, Portugal, and Morocco. Trends and cycles were identified using Eigen Vector Filtering and spectral analysis, and the synchrony between short- and long-term fluctuations in trap catches was studied with the modified correlogram of Koenig and Knops. The magnitude of fluctuations in trap catches is large, periods of great abundance being up to seven times bigger than those when abundance was low. More interesting was the occurrence of 100-year-long periodic fluctuations as well as 20-year cycles. These medium- to long-term fluctuations, representing more than 50% of the total variability in the time-series, were synchronous all around the western Mediterranean and adjacent North Atlantic. In contrast, short-term variability was synchronous at a local scale only. It is argued that long-term fluctuations in trap catches could be considered as a proxy for those of true abundance, and a synthetic time-series has been computed to depict them. Biological and ecological processes that could cause such long-term fluctuations are also discussed. [ABSTRACT FROM PUBLISHER]