Quantifying benthic impacts and recovery from trawling; developing a risk assessment tool for the Marine Stewardship Council

Trawling can be a damaging fishing practice, but considering its importance for global food security we need to balance environmental conservation with food provision. We are developing a tool to quantify and assess the... [ view full abstract ]

Trawling can be a damaging fishing practice, but considering its importance for global food security we need to balance environmental conservation with food provision. We are developing a tool to quantify and assess the benthic impacts of trawling against a defined conservation objective. The Marine Stewardship Council recognises and rewards sustainable fishing practices, through its global certification and eco-labelling program; this tool is being developed primarily to help assess fisheries against the MSC Standards for eco-certification.

The tool applies a simple risk assessment method to estimate the status of seabed habitats. The relative benthic status (RBS) of seabed habitats is calculated using a grid cell approach; the resulting distribution of RBS scores across the area indicates the overall status of a habitat or region. The predicted time to recover to a threshold RBS score indicates the sustainability of the fishery.

To calculate RBS with the tool, users input maps of fishing intensity and habitat type. Depletion and recovery parameters can be derived from a global meta-analysis of trawling studies, or related to the penetration depth of a fishing gear. The tool requires relatively few parameters and thus may be applicable in data-limited fisheries.

A data degradation exercise has illustrated how the perceived benthic impacts of a fishery can be sensitive to the data inputs (e.g. habitat data resolution). We also need to understand the sometimes-counterintuitive incentives that may be unintentionally created with such a tool. These represent important considerations when developing tools to assess fisheries against a common standard.