Shellfish Stock Assessment Programme



The Shellfish Stock Assessment Programme is coordinated by Dr Beth Leslie and provides fisheries data, information and advice to the Shetland Shellfish Management Organisation (SSMO). The SSMO is responsible for managing the Shetland Islands Regulated Fishery (Scotland) Order and the organisation relies on outputs from the shellfish programme to facilitate their decisions. Commercial shellfish managed by the SSMO include Lobster (Homarus gammarus), Edible crab (Cancer pagurus), Velvet swimming crab (Necora puber), Green Crab (Carcinus maena), King scallop (Pecten maximus), Queen scallop (Aequipecten opercularis) and the Common whelk (Buccinum undatum).


The main rationale of the shellfish programme is to assess the state of all the shellfish stocks around Shetland and to do this a comprehensive monitoring and evaluation programme is carried out. Routine fisheries data, such as estimates of population size distributions and size at age data are collected throughout the year from onboard commercial vessels, at piers, vivier operators and local processing factories.

The first preliminary stock assessments for all shellfish species were carried out in 2005 after obtaining 5 years worth of continuous data and these results can be found in the NAFC fisheries report "Shetlands Shellfish Stock Assessments, 2005".

Subsequent stock assessment reports have been produced:

  • Mouat, B., Laurenson, C., Riley, D., Marrs, S.and Henderson, S. (2006). Shetland Shellfish Stock Assessments 2006.  NAFC Marine Centre Report 68pp.
  • Leslie, B., Laurenson, C., Shelmerdine, R. & Riley, D. (2007).  Shetland Shellfish Stock Assessments 2007. NAFC Marine Centre Report 93pp.
  • Leslie, B., Laurenson, C., Shelmerdine, R., Riley, D. & Simmons, S. (2008).  Shetland Shellfish Stock Assessments 2008.  NAFC Marine Centre Report 94pp.
  • Leslie, B., Laurenson, C.H., Shelmerdine, R.L., Gear, D.J.R & Winter, K.A. (2009).  Shetland Shellfish Stock Assessments 2009.  NAFC Marine Centre Report, 100pp.

Please Contact NAFC for copies of these reports.

The shellfish programme also endeavours to implement research projects to address current issues, when funding and resources allow. Examples of projects to date include:

  • Lobster Conservation
  • Shellfish tagging studies
  • Size at sexual maturity of the common whelk
  • Spatial and temporal differences in the moulting period of velvet crabs
  • Effects of a landslide on water quality and shellfish stocks