Boxplots showing levels of explanatory variables determined to significantly explain survival to 28 d for fish that survived 7 d and had recorded metrics on surgical wounds.

Results are for estimated fitted values from a linear mixed effects model evaluated by AIC. Boxplots of the fitted estimated survival values show median values surrounded by a box of the 25th to 75th percentiles (i.e. interquartile range) with whiskers at the outlying values, which are 1.5 times the interquartile range extended from the median.</p

Nonparametric Kaplan‑Meier estimated mortality for replicates 1–8 pooled across treatments.

Nonparametric Kaplan‑Meier estimated mortality for replicates 1–8 pooled across treatments.</p

a. Antimicrobial chemicals for aquatic or fishery use by product name with active ingredients, concentration/duration of recommended application, and FDA‑approved species, life stage, and usage.

b. Relevant literature on fish applications by chemical.</p

Number of fish tagged by treatment and date.

In an attempt to develop more effective surgical implantation methods for fish, surgical incisions typical of those made for implanting micro-acoustic transmitters into the peritoneal cavity were evaluated on a weekly basis for healing progression using a suite of metrics. Additionally, four chemicals were evaluated at concentrations commonly used in aquaculture for their ability to prevent surgical site infection and thus to promote incision healing and survival. Chemical treatments included hydrogen peroxide (25, 50, and 100 mg l-1), salt (10 and 30 ppt), Argentyne (1:1, Argentyne:water), and PolyAqua (1/2 tsp 36 l-1). For all study fish, the presence of two intact sutures seven days post-surgery (generally associated with good suturing technique) was negatively correlated with survival. A generalized linear mixed effects model indicated that suture presence, increasing tagging temperature, and the presence of foreign material on sutures decreased survival by 0.56, 0.72 and 0.60 respectively. Conversely, evidence of suture tearing and increasing fork length at tagging increased survival by 0.24 and 0.17. The antiseptic treatments tested promoted neither faster healing of surgical incisions nor higher survival for fish held for 28 days compared to a reference group and two of the chemicals may be contraindicated for prophylactic use at published doses. These findings underscore the need for researchers to adopt a decidedly cautious approach to planning and interpretation of study outcomes that rely on telemetry tagging, carefully considering the study subjects, potential effects of the techniques used, and implications of the environmental conditions experienced.</div

Average survival for subyearling Chinook salmon (<i>Oncorhynchus tshawytscha</i>) held at Bonneville Dam by treatment (all replicates combined) at 7, 14, 21, and 28 d.

Average survival for subyearling Chinook salmon (Oncorhynchus tshawytscha) held at Bonneville Dam by treatment (all replicates combined) at 7, 14, 21, and 28 d.</p

a. Mixed Linear Effects modeling results (GLMM, using a logit link function) for 28 d survival.

Random-effects covariates included in all models were replicate tagging days and surgeons. Fixed-effect covariates tested against survival were: Treatment, fork length, weight, water temperature at tagging, presence of foreign material (0,1), sutures (0,1,2), suture tearing (0,1), inflammation or ulceration at suture site (0,1,2), and healing at suture site (1,2). See Table 1 for the full list of post-incision metrics. For 28-d survival we evaluated models at three stages: Variable at time of tagging, incision metrics after 7d for survivors, and 2 –way interactions among covariates. Only models with delta AIC values within approximately 2 units from the best model were included in the table, although the process included all subsets as possible models. b. Final GLMM linear mixed model.</p

S1 Fig -

Examples of select metrics used to evaluate progression of healing including a.) suture tearing b.) presence of foreign material c.) inflammation associated with suture entrance/exit sites d.) ulceration at suture entrance/exit sites e.) incision apposition 50% of incision length. (TIF)</p

List of metrics used to evaluate incision site healing for dip study fish that survived the 24‑h post‑tagging recovery period and transport to the Bonneville fish facility.

List of metrics used to evaluate incision site healing for dip study fish that survived the 24‑h post‑tagging recovery period and transport to the Bonneville fish facility.</p

Rank among surgeons based on percentage mortality for study replicates 1–8.

Mean and overall rank scores are also listed; a lower ranking corresponds with higher mortality. (DOCX)</p

Nonparametric Kaplan-Meier estimated mortality for treatments pooled across replicates 1–8.

The mortality curves for the three peroxide treatments were very similar, therefore they were pooled for this analysis. The two salt treatments were also pooled due to having very similar mortality curves.</p