Modifications of unmanned aerial survey on spawners of pacific salmons in the rivers of Sakhalin and Khabarovsk Regions

Abstract

Two modifications of unmanned aerial vehicle (UAV) survey on spawners of pacific salmons are examined for certain rivers in Sakhalin and Khabarovsk Regions. The route survey along the rivers was tested to evaluate its applicability for the salmons counting in prespawning and spawning aggregations. Poor suitability of such approach was found for some of surveyed rivers. For these rivers, an alternative approach was proposed, as a localized UAV survey with shooting video over contrast background, like tower videocounts widely used in North America. This kind of survey can be easy adopted for many rivers of southern Sakhalin due to their spatial proximity, transport accessibility, and rather dense population in this area. Detailed technical recommendations for the UAV counting on observation transects are provided and limitations for this approach are shown. The route UAV survey allows to make inventory of the salmon spawning grounds and to evaluate the spawning efficiency, whereas the local UAV survey solves a narrower task for operative fishery regulation as counting the spawners escapement to rivers.

Keywords

• unmanned aerial vehicle
• observation transect
• video survey
• spawners abundance
• pacific salmon
• sakhalin
• khabarovsk region