A case study of anchovy diurnal migration patterns in Teluk Bakau, Bintan Regency, Riau Island, Indonesia

Abstract

Teluk Bakau is an area of water on the shore of Bintan Regency where the people make their livelihoods through fishing. There is now a lot of data showing a decline in catches, but it is unclear why this is happening. Changes in migratory patterns are regarded to be one of the primary reasons. The daily diurnal migratory pattern of anchovies is assumed to correspond with the movement of plankton. Anchovies are a type of tiny fish larvae whose life cycle is tied to plankton. It is possible to see microorganisms by converting the mean volume backscattering strength (MVBS) value into a measure of anchovy quantity and presence. Anchovy diurnal vertical migration was discovered using Diel Vertical Migration (DVM) measurements, which also revealed that the fish were in the MVBS range of -40 dB to -60 dB (e.g. FL: 5–10 cm). The migration of anchovies seen by ADCP shows they typically move towards the surface in the afternoon and that their numbers generally expand until night. Along with this an increase of anchovies, a lot of plankton has been rising to the surface. The presence of an anchovies moves into deeper waters in the early morning, and until daytime, they are decreasingly abundant. An indication that anchovies are increasingly plentiful and more present is in the afternoon