Performance Assessment of Suture Type, Water Temperature, and Surgeon Skill in Juvenile Chinook Salmon Surgically Implanted with Acoustic Transmitters

—This study assessed performance of seven suture types in subyearling Chinook salmon Oncorhynchus tshawytscha implanted with acoustic microtransmitters and held at two water temperatures (128C and 178C). Nonabsorbable (Ethilon) and absorbable (Monocryl) monofilament sutures and nonabsorbable (Nurolon and silk) and absorbable (Vicryl, Vicryl Plus, and Vicryl Rapide) braided sutures were used to close incisions in Chinook salmon. When differences existed among suture types, tag and suture retention were generally highest for monofilament sutures. Wound inflammation and ulceration were generally lower for Ethilon and Monocryl than for most of the braided sutures. In this study, Nurolon (braided) often resulted in low wound inflammation and ulceration, although suture retention was poor. Generally, fish held in 128C water had more desirable postsurgery healing characteristics (i.e., higher tag and suture retention; lower incision openness, wound inflammation, and ulceration) at 7 and 14 d postsurgery than fish held in 178C water. On days 34 and 63, tag retention remained high among fish in 128C water, while suture retention decreased dramatically in both water temperatures. We found a significant effect of surgeon on tag and suture retention, wound inflammation and ulceration, and incision openness. Surgeons in this study were initially thought to have similar surgical proficiency based on their extensive previous experience. However, surgeons who had received feedback on their previous surgical technique performed better in this study. Results indicate that surgical training (i.e., feedback) and perhaps aptitude, rather than surgeon experience alone, may be as important as suture type in influencing the retention of sutures and tags. The overall results support the conclusion that Monocryl is the best suture material for closing incisions created during surgical implantation of acoustic microtransmitters in subyearling Chinook salmon. Future research should include testing different suturing patterns and knotting techniques as well as the number of knots required for different incision lengths. Biotelemetry research involves attaching a device that emits an acoustic or radio signal from a tagged individual to a receiving system (Winter 1996). Ideally, the attachment or presence of a transmitter should not affect the behavior or survival of tagged fish, allowing inferences from a sample of tagged fish to a population of interest. However, there is evidence that biotelemetry devices can indeed affect fish behavior, growth, and survival (Lucas 1989; Moore et al. 1990; Robertson et al. 2003; Brown et al. 2006). Therefore, studies using this technology must aim to minimize this effect. Acoustic transmitters are often implanted into the peritoneal cavity of study fish, and incisions are closed with suture material. Ideal suture material should maintain adequate tensile strength and knot security until the surrounding tissue integrity has returned. The suture material should (1) have minimal interference with the healing process, (2) resist bacterial contamination, and (3) elicit minimal foreign body reactions (Lin et al. 1996; Roush 2003). Although suture materials have been studied extensively for use in human and veterinary medicine (Lin et al. 1996; Roush 2003), comparatively little effort has been focused on suture performance in fish (Thoreau and Baras 1997; Wagner et al. 2000; Hurty et al. 2002; Jepsen et al.