Fig 1.
Acceleration traces depicting a post-release mortality (A) and post-release survival (B).
Temperature, depth, pitch, and tailbeat movements for (A) a blacktip shark that died after release and (B) a sandbar shark that survived capture and release showing typical “yo-yo” diving behavior. The blacktip shark swam for 30 min before settling on the bottom in normal (dorsal side up) posture, and exhibiting erratic tailbeats for approximately five minutes until all movement ceased around 11:20 am. Inset shows a sandbar shark dorsal fin with ADL float package attached (Lear and Whitney 2016 [46]).
Table 1.
Sizes, water temperaures caught, hook times, and acceleration data-logger monitoring periods for all tagged animals.
Table 2.
Species-specific catch numbers, at-vessel mortality (AVM), post-release mortality (PRM), and total mortality rates.
Table 3.
Comparisons of at-vessel metrics between individuals alive and dead at capture, and individuals that survived or died post-release.
Fig 2.
Kaplan-Meier survival curves for the five species of large coastal sharks tagged in the current study.
Traces show the probability of mortality for the first 48 hours post-release for each species (spinner sharks were only monitored up to 31 hours post-release). The majority of mortalities occurred within the first hour post-release, and all mortalities occurred within 12 hours post-release. The error bars at the end of each curve show the 95% confidence intervals of the final estimated mortality rate for each species, calculated using equations set by Goodyear (2002).
Fig 3.
At-vessel and post-release fate percentages of the total catch by species.
Individuals with the fate unknown (released alive but not tagged) were separated into either a predicted post-release mortality or predicted survivor by mirroring mortality rates for individuals with known outcomes. AVM = At-vessel mortality, PRM = post-release mortality.
Fig 4.
Relationships between blood parameters describing the reaction to capture stress experienced by each species of shark.
Linear trendlines are drawn where significant relationships between parameters were determined. Data from all sharks where blood was taken were included in the plots, including from sharks that were at-vessel mortalities (AVM), post-release mortalities (PRM), sharks that survived the capture process (Survived) and sharks which were alive at vessel but with the post-release fate unknown (Unknown). However, only sharks that were alive at the time of capture were used to test significance of relationships between parameters and form trendlines as it was unknown how long AVM sharks had been dead at the time of sampling.
Fig 5.
Decision trees using at-vessel metrics to predict post-release outcomes for (A) blacktip, (B) sandbar, and (C) spinner sharks.