Artisanal data-limited fisheries in Tanzania. Photo: Thomas Mildenberger

PhD defence about improvement of management procedures for data-limited fish stocks

Wednesday 27 Jan 21



J. Rasmus Nielsen
DTU Aqua
+45 35 88 33 81

On 11 February 2021, Tobias Mildenberger, DTU Aqua, will defend his PhD thesis. The defence can be watched online.

To ensure sustainability of fisheries resources, reliable management procedures are required. The procedures must be capable of adequately assessing the current exploitation status of fish stocks and predicting future stock development under various exploitation scenarios. 

The assessment of stock status and the resulting management advice, however, may be complicated by a lack of available and informative data, as well as a high degree of uncertainty. This uncertainty typically arises from natural variability, sparse and inaccurate data collection, incorrect model structure, and the parameter estimation process. Uncertain management advice may lead to a risk of overfishing.

Through his PhD study, Tobias Mildenberger, has worked on improving the robustness and effectiveness of data-limited management procedures by evaluating and advancing state-of-the-art assessment methods, as well as accounting for the estimated uncertainty in the management advice. This was done with simulation frameworks that allow for the validation and evaluation of existing and novel management procedures by analyzing their impact on simulated stock and fisheries dynamics. 

Overall, Tobias Mildenberger concludes in his PhD thesis that biased and imprecise stock assessment methods, in combination with harvest control rules that do not account for uncertainty, compromise the robustness and effectiveness of management procedures. Further, he states that the sustainable management of data limited fisheries will not only rely on comprehensive guidelines on the application and implementation of assessment methods, but also on the further development of stochastic models and effective harvest control rules that propagate the estimated uncertainty into management advice.

About the PhD defence

Tobias Mildenberger willl defend his PhD thesis "Towards sustainable fisheries: Improving the robustness and effectiveness of management procedures for data-limited fish stocks” on Thursday 11 February 2021 at 14:00 (CET) via Zoom. Find link to Zoom in the box below.


  • Principal supervisor: Professor J. Rasmus Nielsen, DTU Aqua
  • Co-supervisor: Senior Researcher Casper Willestofte Berg, DTU Aqua
  • Co-supervisor: Researcher Alexandros Kokkalis, DTU Aqua
  • Co-supervisor: External Consultant Martin Wæver Pedersen


  • Professor Anders Nielsen, DTU Aqua
  • Scientist Alexander Kempf, Johan Heinrich von Thünen Institute, Institute of Sea Fisheries, Germany
  • Chief Fisheries Science Adviser Carl O'Brien, Centre for Environment, Fisheries and Aquaculture Science, UK

Chairperson at defence

  • Professor Ken Haste Andersen, DTU Aqua
Learn more

A popular science summary of the thesis can be downloaded here 

A copy of the thesis is available by e-mail on request. Please contact Karin Stubgaard,

Link to Zoom and guidelines for attending the defence

It is possible to attend Tobias Mildenberger’s defence on Zoom using this link:

Please, enter the meeting 10 minutes prior to the defence proceedings are scheduled to start.

All participants are muted per default, but we ask you to double check that both camera and microphone are turned off at all times.

There will be instructions regarding the proceedings in the beginning of the defence.