Having a British base for SMRU Consulting Europe means some of us are a bit preoccupied with the weather. And sometimes it even affects our jobs. Visually detecting animals in low visibility conditions can be challenging – and that affects our ability to monitor populations and mitigate impacts. So how do we improve detection performance in low visibility?
About the weather
Fog, rain, high sea state, sun glare or the lack of light reduce the effectiveness with which anyone can visually detect an animal. As such visual methods are restricted to daylight hours and relatively good weather conditions.
However, industrial projects and naval operations offshore are often required to monitor their operational area for the presence of marine mammals. So, what happens in bad weather and/or at night?
Overcoming low visibility limitations
With our colleagues from the Sea Mammal Research Unit, Marine Ecological Research, the Centre for Research into Ecological and Environmental Modelling, Ocean Environmental Consulting, Alfred Wegener Institute and Prove Systems Ltd we reviewed which monitoring methods are suitable for low vis marine mammal monitoring and compared their strengths and weaknesses.
What low visibility detection methods are available to us?
- Passive acoustic monitoring, detects an animal’s vocalisations using hydrophones (underwater microphones).
- Active acoustic monitoring, sound pulses are emitted into the water and acoustic reflections from an animal are received by hydrophones.
- Thermal IR (infrared imaging), uses an electro-optical imaging sensor to detect temperature differences between the body or the exhalation of the warm blooded marine mammal and that of the surrounding environment.
- RADAR, radio or micro-waves, can be emitted into the air and echoes from the animal’s body, its exhalation, or from disturbance on the sea surface are picked up by receivers.
These systems are usually supervised by a trained human operator who makes the final judgement on animal detection.
The review highlighted that no method’s single performance suits all species and environmental conditions. However, using complimentary systems in parallel is recommended to increase the probability of an animals detection but to also decrease the probability of false alarms.
Read all about it
Anyone clicking on this link before December 27, 2017 will be taken directly to the final version of our Marine Pollution Bulletin article “Comparing methods suitable for monitoring marine mammals in low visibility conditions during seismic surveys” on ScienceDirect. No sign up, registration or fees are required – simply click and read.
Let us know what you think.