Test of ROV-based harvesting methods for sea urchins and scallops. Part one: Report on Sea Urchin (Kråkebolle) collection trial

Summary

One of the major bottlenecks to the development of a sea urchin industry in Norway is a reliable and economically viable method of collecting urchins. The current trial aimed to test the economic feasibility of fishing commercial quantities of sea urchin during winter conditions in northern Norway using a modified ROV. The results of the trial showed that in 4.5 days of fishing (excluding Day 1 and morning of Day 2) a total catch of 1.88 t was recorded with 34.9 % of the total catch (659,5 kg) consisting of export quality sea urchins (> 45 mm test diameter). The authors suggest that the amount of sea urchins from the total catch that could be sold could have been increased to 52.1 % of the total catch (807 kg) by lowering the minimum size of the urchins that were landed to the industry recommended size of 40 mm test diameter and processing any damaged sea urchins to utilize the roe in these animals. The average daily catches for the ROV this was substantially higher (146 kg/day) than for previous dive operations in Båtsfjord (average 90.9 kg/day). The results of the current trial clearly show that the SeabedHarvester ROV provides an effective method of collecting sea urchins in winter conditions in northern Norway and this method is likely to be more effective than using divers in summer as well as in winter. The density of sea urchins present at any given site and the type of bottom terrain play an important role in determining the catch efficiency of the ROV and so it will be important to undertake preliminary mapping of an area prior to committing time and capital resources into ROV fishing.