The Shetland Islands Regulated Fishery (Scotland) Order (also known as a Regulating Order) came into force in 1999. The Shetland Shellfish Management Organisation (SSMO) was set up in 2000 and was granted the legal right to manage the Regulating Order. There have since been another two Regulating Orders with the current one being conferred on SSMO until 2028.

SSMO, therefore, manages the commercial shellfish fisheries between tide line and the 6 mile limit around the coast of Shetland. These fisheries are for lobsters, crabs, scallops, queens, whelks, clams, razorshells, cockles, mussels and oysters. Amongst other things, the Regulating Order give the SSMO the power to impose restrictions and regulations, to issue licences and the right to set tolls.

The SSMO is a partnership of organisations with an interest in the future of Shetland's shellfish fisheries. The organisation is legally constituted as a company limited by guarantee and is run by a board of directors half of whom are active fishermen. The SSMO Board membership has been restructured over the years and currently comprises 8 directors as follows:

1 member from the Association of Shetland Community Councils (nominated by the association) - currently Mr Ian Walterson who is also the Chairperson

1 shellfish processor (nominated by Seafood Shetland) - currently Mr Robert Williamson

2 Shetland Island Council (SIC) elected members (nominated by the SIC) - currently Mr David Sandison and Ms Amanda Westlake

2 Shetland Fishermen's Association (SFA) members (nominated by the SFA Small Boat Committee) - currently Mr Garry Leask and Mr Leslie Tait who is also Vice-Chairperson

2 SSMO licencees (nominated and voted for by SSMO members) - currently Mr Sean Williamson and Mr Alan Pottinger

The SSMO Board meet 9 times a year and there is also a SSMO Advisory Group who meet on a regular basis and which advises the SSMO Board.

In 2012, SSMO gained Marine Stewardship Council (MSC) Accreditation , a sustainability standard, for three fisheries - Velvet Crab, Brown Crab and King Scallops. Shetland continues to have the only certification for Brown Crab world-wide and the King Scallop dredge fishery is the only one in Europe to be certified (outside of Europe only the Faroe Islands have a similar certification). The SSMO is, therefore, considered nationally to be a leader in Inshore Fisheries Management.