Measuring the in situ tilt orientation of fish and zooplankton using stereo photogrammetric methods

Acoustic‐derived estimates of fish and zooplankton numerical and biomass density rely on knowledge of the sound scattered by an individual, known as target strength (TS). An important, but difficult to measure, factor in determining TS is the tilt orientation of animals in relation to the insonifying acoustic wave. Underwater stereo‐camera systems can provide in situ tilt measurements for fish and zooplankton. We describe a protocol to remove...