River fish research
For his PhD Twan has been doing research on river fish in the Netherlands. The aim of his work is investigating the environmental effects on the abundance of juvenile rheophilic fish species floodplain waters in the Dutch part of the River Rhine (IJssel, Waal and Nederrijn/Lek). A variety of techniques are used to answer his research questions. Twan started his PhD in July 2017 and will continue his work, funded bij Rijkswaterstaat Oost-Nederland, until 2021.
Caribbean shark research
Since 2013 Twan has been doing research on fish communities and sharks in Dutch Caribbean waters, first as a student and later as project assistant of the Save our Sharks project. With stereo Baited Remote Underwater Video (sBRUV) surveys, satellite tagging and acoustic surveys research is done on spatial and temporal abundance of Caribbean sharks in the waters surrounding Aruba, Bonaire, Curaçao, Saba, St Eustatius and St Maarten.
underwater camera research
Twan works a lot with Stereo Baited Remote Underwater Video surveys (sBRUVs), which is a noninvasive method to study various aspects of fish communties. He conducted a base-line fish survey on the Saba bank, which is a first step towards effective protection. He also developed robust, quantifiable objectives and reference points for conservation (and fisheries) in order to be able to evaluate the performance of management actions.