2.2 Fish, larvae and sea turtles
The injury threshold criteria for fish, larvae and sea turtles used in this underwater sound assessment for impulsive piling are given in Table 2.2. In the table, both peak and SEL criteria are un-weighted. Physiological effects relating to injury criteria are described below (Popper et al., 2014; Popper and Hawkins, 2016):
- Mortality and potential mortal injury: either immediate mortality or tissue and/or physiological damage that is sufficiently severe (e.g. a barotrauma) that death occurs sometime later due to decreased fitness. Mortality has a direct effect upon animal populations, especially if it affects individuals close to maturity.
- Recoverable injury: Tissue and other physical damage or physiological effects, that are recoverable but which may place animals at lower levels of fitness, may render them more open to predation, impaired feeding and growth, or lack of breeding success, until recovery takes place.
- TTS: Short term changes in hearing sensitivity may, or may not, reduce fitness and survival. Impairment of hearing may affect the ability of animals to capture prey and avoid predators, and also cause deterioration in communication between individuals; affecting growth, survival, and reproductive success. After termination of a sound that causes TTS, normal hearing ability returns over a period that is variable, depending on many factors, including the intensity and duration of sound exposure.
Table 2.2: Criteria for onset of injury to fish and sea turtles due to impulsive piling (Popper et al., 2014).
Type of Animal | Parameter | Mortality and Potential Mortal Injury | Recoverable Injury | TTS |
Group 1 Fish: no swim bladder (particle motion detection) | SEL, dB re 1 μPa2s | >219 | >216 | >>186 |
Peak, dB re 1 μPa | >213 | >213 | - | |
Group 2 Fish: where swim bladder is not involved in hearing (particle motion detection) | SEL, dB re 1 μPa2s | 210 | 203 | >186 |
Peak, dB re 1 μPa | >207 | >207 | - | |
Groups 3 and 4 Fish: where swim bladder is involved in hearing (primarily pressure detection) | SEL, dB re 1 μPa2s | 207 | 203 | 186 |
Peak, dB re 1 μPa | >207 | >207 | - | |
Sea turtles | SEL, dB re 1 μPa2s | 210 | (Near) High (Intermediate) Low (Far) Low | (Near) High (Intermediate) Low (Far) Low |
Peak, dB re 1 μPa | >207 | |||
Eggs and larvae | SEL, dB re 1 μPa2s | >210 | (Near) Moderate (Intermediate) Low (Far) Low | (Near) Moderate (Intermediate) Low (Far) Low |
Peak, dB re 1 μPa | >207 |