Compilation of processed and validated data of mesozooplankton along the St Helena Bay Monitoring Line (SHBML) (now under the Integrated Ecosystem Programme: Southern Benguela (IEP:SB)) on the Algoa, Voyage 091, from 05 to 08 February 2001. This includes the validated flow, processed counts and validated ship`s information. This is ready for analysis by a user. This is a long-term monitoring line conducted off the coast of Elands/St Helena Bay on the west coast of South Africa. SHBML started in 2000 as a BENEFIT-driven project on "shipboard monitoring" which linked with similar lines run in Namibia and Angola. The aims were to obtain seasonal and interannual information on the hydrology and productivity of the area. It was incorporated under the IEP:SB in 2013 consolidating a long-term, multi-decadal time-series (from 1951 onward) of information for this important region and has continued monitoring in the form of the IEP:SB. The programme is a multi-disciplinary, collaborative and capacity building platform undertaking relevant science, including updating technology, with the aim to develop ecosystem indicators that can be used to effectively monitor and understand the Southern Benguela. These include physical, chemical, planktonic, microbial, seabird, marine mammal, benthic and pollution (plastic) ecosystem indicators as required by ecosystem-based management regarding the following priorities: ocean warming, ocean acidification, trophic functioning, pollution and water quality. It is an on-going monitoring programme. The Supplementary Information linked to this data is currently embargoed - contact Keshnee Pillay (KePillay@environment.gov.za) for more information.