Accumulation of butyltin compounds in cobia Rachycentron canadum raised in offshore aquaculture sites

Butyltin residues (monobutyltin, MBT; dibutyltin, DBT; tributyltin, TBT; tetrabutyltin, TeBT) in the sea water and in the cobia (Rachycentron canadum) from aquaculture sites located offshore of Penhu island, Taiwan, were collected and quantified. The average concentrations of MBT, DBT, TBT and TeBT in sea water were n.d.—28 ± 3, 4.0 ± 0.6–88 ± 13, n.d.—43 ± 4, and n.d.—7 ± 1 ng l− 1, respectively. The total butyltin (sum of MBT, DBT, TBT, TeBT) residues in the skin, dorsal muscle, ventral muscle, dark muscle, and liver of the cobia were in the range of 72 ± 12–2270 ± 85, 79 ± 11–688 ± 33, 82 ± 14–1715 ± 104, 93 ± 13–803 ± 47, and n.d.—52,745 ± 252 ng g− 1 (wet weight), respectively. Although in this study in most cases, the highest concentration of total butyltin residues was found in liver or skin, in some cases, the highest concentration was found in muscle tissue. The crude lipid content in the skin, dorsal muscle, ventral muscle, dark muscle, and liver of these cobia was in the range of 7.9 ± 0.1–28 ± 1%, 11.7 ± 0.8–29 ± 1%, 11.5 ± 0.3–44 ± 3%, 24.2 ± 0.4–48.4 ± 0.4%, and 55.7 ± 0.1–87.7 ± 0.4% (wet weight), respectively. The concentrations of crude lipid content, and the concentrations of total butyltin residues in these tissues were not correlated.