Diving and Photographic Techniques for Observing and Recording Salmon Activities

Abstract

Techniques have been developed for underwater observation and photographic recording of salmon activities that are useful in various kinds of behaviour studies. Scuba divers can approach salmon sufficiently closely under some conditions to permit clear observation. From tests made both above the surface and under water, an exposure chart has been prepared for salmon photography in rivers. Two examples are demonstrated. Colour film can be used, with appropriate filters, to render underwater objects in the colours they would have in air, or to give them untrue colours that assist in differentiating them from their background.