Marine Stewardship Council Science Series Best practices for managing, measuring and mitigating the benthic impacts of fishing - Part 2

In a previous paper, Review of habitat dependent impacts of mobile and static fishing gears that interact with the sea bed (2014) we offered definitions for benthic habitat, fishing gear and fisheries management and a way of thinking about the challenge of understanding best practices for measuring, monitoring, managing and mitigating benthic impacts of fishing in the context of the MSC’s certification requirements. These informed our review in the previous paper’s classification of habitats and fishing gears and helped us highlight likely variations in benthic impact depending on habitat and gear used (Grieve, Brady & Polet, 2014). In this paper, we provide an overview of the systems used around the world to classify fisheries management systems. Best practices are related to the MSC Habitats performance indicators, as well as the themes for the original project: monitoring, measuring, managing and mitigating. We conclude the report with observations and recommendations that emerged from our review, with particular reference to defining habitat for MSC purposes and the information needs for certification bodies to make better assessments, e.g. understanding seabed characteristics, estimating fishing distribution, using local knowledge particularly when data are deficient, and the challenge of scaling up results of site-specific, intensive studies to the level of a fishery

Laboratory study of the impact of repetitive electrical and mechanical stimulation on brown shrimp Crangon crangon

Pulse trawling is currently the best available alternative to beam trawling in the brown shrimp Crangon crangon and Sole Solea solea (also known as Solea vulgaris) fisheries. To evaluate the effect of repetitive exposure to electrical fields, brown shrimp were exposed to the commercial electrodes and pulse settings used to catch brown shrimp (shrimp startle pulse) or Sole (Sole cramp pulse) 20 times in 4 d and monitored for up to 14 d after the first exposure. Survival, egg loss, molting, and the degree of intranuclear bacilliform virus (IBV) infection were evaluated and compared with those in stressed but not electrically exposed (procedural control) and nonstressed, nonexposed (control) brown shrimp as well as brown shrimp exposed to mechanical stimuli. The lowest survival at 14 d (57.3%) occurred in the Sole cramp pulse treatment, and this was significantly lower than in the group with the highest survival, the procedural control (70.3%). No effect of electrical stimulation on the severity of IBV infection was found. The lowest percentage of molts occurred in the repetitive mechanical stimulation treatment (14.0%), and this was significantly lower than in the group with the highest percentage of molts, the procedural control (21.7%). Additionally, the mechanically stimulated brown shrimp that died during the experiment had a significantly larger size than the surviving individuals. Finally, no effect of the shrimp startle pulse was found. Therefore, it can be concluded that repetitive exposure to a cramp stimulus and mechanical stimulation may have negative effects on the growth and/or survival of brown shrimp. However, there is no evidence that electrical stimulation during electrotrawls would have a larger negative impact on brown shrimp stocks than mechanical stimulation during conventional beam trawling