The collection of biometric variables on mussels from the Mar Piccolo of Taranto started in 2004 and is still ongoing. Seventy-five randomly selected mussels are seasonally sampled from three breeding “camera” (five for each camera), at three different distances from the coastline (i.e. land, middle, off shore) (five for each distance). For each specimen, shell length, shell and meat dry weight, and condition index are measured in the laboratory. From 2004 until 2012, the absence of high levels of contamination and of cyclical heat waves allowed sampling only in summer, in one station in the First Inlet (FI) (40°29’28.99”N 17°15’41.85”E). In 2013, due to the increasing PCB contamination in FI, mussels were moved to the Second Inlet (SI) in summer, where contamination remained lower than the legal limits. Therefore, mussels were sampled in FI in spring, and in SI (40°29’22.46”N 17°18’09.15”) in summer. By way of exception, in 2014, two summer samplings were carried out, one in SI and one in the near Mar Grande (40°27’23.93”N 17°14’38.32”E), to assess the commercial suitability of this second site. In 2015, due to the extreme climatic events occurred, an additional winter sampling in FI became necessary. From 2016 onwards, a spring sampling in FI and a summer sampling in SI are routinely carried out.