Quantifying discard potential in the North Sea using spatial biodiversity and fisheries-dependent data to benefit the Scottish demersal fleet

Scotland is committed to reducing the catch of unwanted fish species to support sustainable fishing practices. From 2019 onwards Scottish and other European fishing boats will be unable to discard unwanted catch of species that are managed through setting total allowable catches. Instead, skippers must deliver their unwanted catch to port, a regulatory requirement known as the Landings Obligation. The highly mixed community of fish living in the North Sea makes it difficult to reduce unwanted bycatch and discarding without considerable adjustments to day-to-day fishing practices.

Spatial selectivity, such as establishing temporary closed areas where fishing is not permitted for a defined period of time, has previously been used in the North Sea and other regions to avoid catching unwanted fish. Effective spatial selectivity requires highly resolved spatial information about the potential for catching unwanted species and undersized commercially targeted fish.

Fishing impacts on biodiversity has been widely investigated. However, under the Landings Obligation, biodiversity of the fish community now has consequences for fishing. Locations that are characterised by consistently high diversity could be expected to have greater potential for discarding, particularly where commercial species are also abundant and fishing activity is high.

Spatial gradients in biodiversity of the North Sea faunal communities have been well-studied using data collected by research vessel surveys (Greenstreet and Piet 2008; Reiss et al 2010). The implications of spatial gradients in biodiversity for sustainable fishing practices, including discard reduction, have not been previously been considered.

The aim of this PhD project is to develop novel metrics for quantifying the discard potential of the North Sea taking into account relevant factors including background levels of diversity in the fish community, spatial distribution of quota species, spatial distribution of fish below minimum conservation reference size, regulatory restrictions (e.g., closed areas, TACs and choke species), and the distribution of the fishing fleet. Discard potential will be spatially resolved to the level of ICES statistical rectangle (http://marine.gov.scot/information/ices-statistical-rectangles-and-areas) which are approximately 30 nautical miles by 30 nautical miles in size. These spatially resolved representations of discard potential will then be compared to data describing actual discarding that are collected by the observer programme coordinated by Marine Scotland Science and the Scottish Fishermen’s Federation (SFF), and CCTV data collected by Marine Scotland Compliance.

The project will liaise with the fishing industry through regular meetings with SFF, particularly in assessing their needs for spatial information. There is also potential for the project to inform delivery of the Marine Strategy Framework Directive given that biodiversity is Descriptor 1 of the qualitative descriptors defining Good Environmental Status.

The project offers highly interesting work at the interface of ecology, fisheries science and fisheries. The results will be relevant to addressing current challenges in fisheries management, reduce unwanted fishing mortality and improve fisheries efficiency. With the importance of fishing to Scottish economy and society, considerable public interest in this topic can be expected.

The training budget will also allow for specialised training in the use of fisheries data, for example the courses offered by ICES in Copenhagen (http://www.ices.dk/news-and-events/Training/Pages/default.aspx ). As visual presentation of fisheries data is a central element, training in GIS and infographics is also relevant.