Population monitoring for Government Regulation and for fishing efficiency in Iceland

A dredge survey was conducted by Thorisholmi and Marine Research Institute in September 13-18, 2015. The aim was to provide the first assessment of green sea urchin resources in southern Breidifjördur by a dredge and an underwater camera. The ski-dredge used is the same as the one that is used for commercial fishing, a modified scallop dredge of 250 cm width and a bag of 150 cm length.  The mesh size of the bag is 100mm. The whole area investigated was 9.7 km2 and was divided into seven separate fishing areas of different sizes, depths (8-60m) bottom types and quality. Sea urchins of good quality (roe filling >10%) were observed in 45% of the whole area investigated. The maximum densities observed in an area were 0.12 kg/m2 or 1.5 indiv/m2. Information on population structure and roe yield was also investigated and these differed between areas. The size range was 17-85mm but over 50% of the urchins were in the size class 55-65mm. The relationship between size (diameter) and wet weight was good, especially at the stations where a few small individuals were sampled. The efficiency and selectivity of the dredge is unknown but will be assessed when results from the bottom photographs become available.


The dredge used in the Icelandic fishery


The catch coming onboard


Unsorted catch


Sorted catch