Harbour porpoise surfacing in calm, northern water.

The prevalence of ultra short baseline acoustic position systems, also known as USBLs 🔊, is understudied in #EuropeanWaters and its effect on marine mammals 🐋, such as the #harbourPorpoise, is mostly unknown. These systems are used in #geophysicalSurveys and during #trawling fishing activities. 🧵1/6