Integrating moored acoustic instruments into vessel-based fish stock assessments
The Lake Victoria fishery supports more than 35 million people in the East African Community (EAC – including Kenya, Uganda and Tanzania). EAC fisheries research institutes collect lake-wide acoustic data (during daylight) each year to estimate fish stock biomass, which is vital for sustainable management and economic resilience in the EAC. The analysis of this ship-based acoustic data is limited temporally since the acoustic survey is only done twice per year, around September and March. Since the vertical distribution of fish biomass in the Lake shifts between September and March as the Lake becomes stratified, there is a need to collect data with higher temporal coverage to understand the changes occurring on a daily and seasonal basis.
We collected multi-frequency echosounder data using an acoustic mooring (Acoustic Zooplankton Fish Profiler, AZFP), which was deployed for a 4-month period in Lake Victoria. AZFP data was analysed at a workshop carried out immediately after recovery of the instrument in mid-February 2020. Results from this analysis will support fish stock assessment (e.g. through quantification of seasonal shifts in biomass) and feed into ecological models (e.g. by parameterising vertical distribution of biomass). Data collected will also be linked with 20 years of historical vessel-based acoustic data (that provide high spatial resolution) and likely feed into fisheries management, e.g. in planning of future stock assessment surveys.