For nearly four decades, the Colijnsplaat auction was a local authority organisation. It became independent on 1 January 1999, merging a year later with the auctions in Stellendam and Scheveningen to form United Fish Auctions.

The Colijnsplaat fish auction is a small yet dynamic auction which trades almost daily, right through the year. This is certainly the case when the fishermen come ashore with seasonal products. 

Each year, the auction sells on average 700 tons of fish and 500 tons of shrimps. The annual turnover in 2008 was 4.5 million euros.

During the summer, the fishermen supply sea bass and live Oosterschelde lobster every week to Colijnsplaat – the only place in the Netherlands. The fish market has designed its own certificates for these lobsters, stating that the lobster has come from the Oosterschelde nature reserve, and has been caught by an authorised person in season.

The Colijnsplaat site is accessible to suppliers just about 24 hours a day, regardless of tide, and has room for at least 15 euro cutters in the borough harbour. The rising price levels of the fish traded (due to the large number of mostly small traders) offers the suppliers an attractive chance to obtain maximum income.