Chamber and committees

Marine Scotland science assesses velvet crab stocks using official landings data, size composition data collected as part of its market sampling programme and other biological parameters. Using these data it is possible to estimate stock status in terms of fishing mortality relative to a proxy for Fmsy – Fmsy being the fishing mortality which maximises the average long-term yield from a stock under prevailing environmental conditions. When a stock is fished above Fmsy, it is often advised that measures be introduced to reduce fishing mortality to achieve a higher average yield and biomass in the long term. Marine Scotland science has sufficient data to provide assessments in six of the 12 assessment areas (Table 1 below). These six areas account for around 90% of total Scottish landings of velvet crabs. Stock assessments are conducted for males and females separately. Stock status may differ between sexes and assessment areas. For the Shetland assessment area the fishery is currently fished below Fmsy for both males and females. In the Hebrides and South Minch one of the sexes is assessed as being fished above Fmsy. For the remaining three assessment areas both species are assessed as being fished above Fmsy.

Table 1 – Tonnage of velvet crabs landed into Scotland 2010 – 2014. Landings data for 2014 are provisional. It is worth of note that from May 2015 a larger minimum landings size for velvet crabs has been introduced for the Outer Hebrides. A consultation has also recently closed on introducing an increased minimum landing size for the Orkney Isles. Increasing the minimum landing size of shellfish should allow animals more time to breed before becoming legally harvestable.