A method to convert the hydroacoustic survey estimates of small pelagic biomass from a February/March 2024 survey to equivalent biomasses that might have been surveyed in November 2023, for use in 2024 fisheries management advice

A hydroacoustic survey of the small pelagic biomass off the South African coastline is due to be conducted in February/March 2024 in lieu of the cancelled November/December 2023 survey. This document considers the timeseries of historical ratios of November : March biomasses corresponding to these surveys from the most recent full stock assessments. Based on these assessments, the early 2024 survey estimates of biomass for anchovy, sardine west of Cape Agulhas, sardine east of Cape Agulhas and round herring could be multiplied by factors of 0.98, 0.88, 1.07 and 0.97 respectively to adjust the biomass to correspond to late 2023 for use in fisheries management advice for 2024. However, lower ratios should additionally be considered given the variability in these ratios and, particularly for sardine and round herring, the assumption herein of no fishing at the start of the year.