PhD students

PhD projects within the research area Ecosystem based Marine Management.

Katrina BromhallKatrina Bromhall

Title of PhD project

Comparing the benthic impact of different fishing gears in sandy habitats


Ole Ritzau Eigaard, Barry O'Neill and Grete E. Dinesen

Background of project

Fishing with mobile bottom-contacting fishing gear is described as the largest anthropogenic pressure to the seabed. Therefore, this fishery has been subject to debate, particularly when it occurs near, or on, habitats protected under European legislation such as the Habitats Directive and the Marine Strategy Framework Directive. In response, the use of alternative or modified, less damaging fishing gears has been suggested to offer some alleviation; conserving both environmental function and economic sustainability of the fishery. Yet, strong quantitative evidence to support these predictions is lacking.

About the project

The PhD project intends to provide quantitative evidence on the benthic impact of three common demersal fishing gears used in Danish waters. Experimental fishing used in Before-After-Control-Impact studies can reliably determine the one-off mortality of a pulse-fishing event. The advantage of using a BACI, rather than a comparative analysis of historical fishing pressure gradients, is the ability to control for differences in environmental conditions; selection of sites with the same physical characteristics, as well as for differences in time. Therefore, the case studies will assess the effects of different gears in different sandy habitats using experimental fishing (BACI design) and, for the first time, quantify the ecosystem impacts of gears described to be of low environmental impact.


The insight gained is highly relevant and needed for fisheries management, by providing empirical evidence of the broader ecosystem effects of these fishing gears. The output from my PhD has the potential to provide alternative management strategies, such as better gear-differentiated closures, and to support the use of more environmentally friendly fishing practices.

Previous PhD student (since 2020)

Isabella Kratzer 

Gillnet modifications to reduce bycatch of harbor porpoises
Go to DTU Orbit to download thesis

Gildas Glemarec

Bycatch of seabirds in Danish gillnet fisheries – assessing scale and testing mitigation
Go to DTU Orbit to download thesis