Comparison of two tagging techniques for Sarpa salpa: external attachment and intraperitoneal implantation

For a given species in a particular environment, the success and the harmlessness of transmitter attachment appear to be highly specific. As no information was available for the tagging of the strepie, Sarpa salpa, a suitability study of attachment techniques was needed. Two types of transmitter attachments were investigated: (1) externally, placed on the back of the fish below the dorsal fin by means of two threads sutured through the dorsal musculature, and (2) internally, in the peritoneal cavity. Twenty-five fish were monitored over a 14-d period for survival, surgical healing, injury occurrence and post-tagging behaviour. Even though we observed a 100% survival rate for both groups, with no noticeable buoyancy or swimming alteration, findings from this study indicate that both groups of tagged fish were affected by the presence of the transmitter in different ways. Fish with an external transmitter were chronically affected, incurring physical impact, whereas the surgically-implanted fish exhibited short-term tagging effects (less than 36 h), attributable to surgery effects, and were not subject to fouling on transmitter or wound chafing. Moreover, they appeared to recover quickly with no indication of long-term effects. Based on the findings of this study, the use of the surgical implantation method for Sarpa salpa is recommended.