It is essential from both the consumer perspective and the environmental sustainability aspect, to delve more deeply into the specific traits and conditions of fish reared in a pisciculture setting. Among the many factors that affect the latter, one of the most important is the cycling of chemical compounds in intensive rearing systems. For this reason, we analysed the stomach contents and trace metal levels (cadmium, copper, chromium, lead, and zinc) in the muscles of several fish species that aggregate around mid-Adriatic cages of reared Atlantic bluefin tuna (Thunnus thynnus), attracted by the organic leftovers found in farmed waters. The metals were also analysed in samples of reared bluefin tuna, fish species used as tuna feed (baitfish), and their non-farm-associated counterparts. Finally, to better follow the dietary relationships and metal-acquisition pathways, we also analysed the stable isotopes.

The results revealed that wild fish consume a great deal of trophic resources deriving from the cages, mainly in the form of baitfish remains. The isotopes suggest the reared tuna consume high levels of herring baitfish (Clupea harengus), there is an increased trophic level for the wild omnivorous bogue (Boops boops), and this decreases for the carnivorous garfish (Belone belone). No significant differences in metal concentrations were detected between farm-associated and non-farm-associated wild fish, with the exception of the zinc levels in bogue, which were in lower concentrations in specimens aggregating around the farm. Most importantly, the concentrations of trace metals in the tuna, baitfish (sardine, Sardina pilchardus, and herring), and wild fish (garfish and bogue) did not exceed the recommended limits established by European legislation. However, the cadmium values in the garfish, bogue, and sardine were close to, but not over the legal limit value. The reasons behind these results and their potential consequences should be further investigated, although there is only a moderate degree of concern with regard to the metal content of fish stocks captured in the area under study.

从消费者的角度和环境可持续性方面来说，至关重要的是要更深入地研究在养鱼场养殖的鱼类的具体特征和条件。在影响后者的众多因素中，最重要的因素之一是集约化饲养系统中化合物的循环。因此，我们分析了在大西洋蓝鳍金枪鱼（Thunnus thynnus）的亚得里亚海中部网箱附近聚集的几种鱼类的肌肉中的胃含量和微量金属水平（镉，铜，铬，铅和锌）），被养殖水域中的有机剩菜所吸引。还分析了养殖蓝鳍金枪鱼，用作金枪鱼饲料的鱼种（诱饵鱼）及其与农场无关的对虾中的金属。最后，为了更好地遵循饮食关系和金属获取途径，我们还分析了稳定同位素。

结果表明，野生鱼消耗了大量来自网箱的营养资源，主要是饵料残骸的形式。同位素表明，饲养的金枪鱼消耗大量的鲱鱼饵鱼（Clupea harengus），野生杂食性鲍鱼（Boops boops）的营养水平增加，而食肉性fish鱼（Belone belone）则减少。农场相关和非农场相关野生鱼之间的金属浓度均未检测到显着差异，但鲍格中的锌含量除外，锌的浓度在农场周围聚集的标本中较低。最重要的是，金枪鱼，饵鱼（沙丁鱼，沙丁鱼pilchardus）中的微量金属浓度和鲱鱼）和野生鱼（大蒜和鲍鱼）均未超过欧洲法律规定的建议限制。但是，鱼，鲍鱼和沙丁鱼中的镉含量接近但未超过法定限值。尽管对研究区域捕获的鱼类种群的金属含量只有中等程度的关注，但应进一步调查这些结果背后的原因及其潜在后果。