A.S. Revill

The fishing capacity of gillnets lost on wrecks and on open ground in UK coastal waters

This study investigated the changes in fishing capacity of gillnets deployed and abandoned over wrecks and on open ground in UK coastal waters. Divers surveyed 11 wrecks and found the remains of 27 separate gillnets (lost from the fishery) distributed among 7 of the wrecks. No animals (alive or dead) were found entrapped in any of these gillnet remains, whose fishing capacities were estimated to be negligible. Two gillnets were deployed and deliberately abandoned, one over a wreck and another on open ground. They were subsequently monitored for 2 years by divers. Both demonstrated a loss in fishing capacity of more than 50% during the first few weeks of immersion. The open ground net was washed ashore after 58 days, while the wreck net remained in situ and continued to fish, albeit with decreasing capacity, over 2 years. The study supports the general view that lost/abandoned gillnets in UK coastal waters are an insignificant source of unaccounted fishing mortality and do not present an ecological hazard whether deployed over wrecks or on open fishing ground.

The selective properties of some sieve nets

By-catch and discarding of juvenile fish species in the brown shrimp (Crangon crangon) fishery is a well-recognised problem. Sieve nets have recently been introduced as a mandatory technical measure to reduce this by-catch under EC Council regulations. Four different designs of sieve nets were developed and tested in UK waters and compared for their selective properties. The question of efficiency in capture and loss of the target species was also assessed. Three species of fish were measured in the standard gear and the experimental gear to determine selectivity ogives. Only few fish were observed in the majority of the hauls and it was therefore not possible to use standard analysis techniques to obtain release-curves by individual hauls. The paper demonstrates the selective properties of the sieve nets as determined by the use of bootstrapping techniques in combination with the SELECT model. The potential for a reduction in benthic impact resulting from sieve net usage is also discussed.

The effects of temporary exclusion of activity due to wind farm construction on a lobster (Homarus gammarus) fishery suggests a potential management approach

Offshore wind farms form an important part of many countries strategy for responding to the threat of climate change but their development can conflict with other offshore activities. Static gear fisheries targeting sedentary benthic species are particularly affected by spatial management that involves exclusion of fishers. Here we investigate the ecological effect of a short-term closure of a European lobster (Homarus gammarus (L.)) fishing ground, facilitated by the development of the Westermost Rough offshore wind farm located on the north-east coast of the United Kingdom. We also investigate the effects on the population when the site is reopened on completion of the construction. We find that temporary closure offers some respite for adult animals and leads to increases in abundance and size of the target species in that area. Reopening of the site to fishing exploitation saw a decrease in catch rates and size structure, this did not reach levels below that of the surrounding area. Opening the site to exploitation also allows the fishery to recuperate some of the economic loss during the closure. We suggest that our results may indicate that temporary closures of selected areas may be beneficial and offer a management option for lobster fisheries.