This report includes information on the infestation of the Steel Mariner barge by D. vexillum; images of the species; location maps; a report by P. Mather (Kott) on the identification of the didemnid; a survey of the didemnid on the barge and its spread to the seabed beneath it; and the potential risks posed by the spread of the species.
Coutts, A.D.M., 2002, A biosecurity investigation of a barge in the Marlborough Sounds (New Zealand): Cawthron Institute Report 744, 68 p. (PDF format)
This report includes information on: the infestation of the Holyhead Marina by D. vexillum; results of a survey of the marina, the wider harbour, and other sites along the coast of Wales; images of the species, including brooding unhatched larvae; and location maps.
Holt, R., Ramsay, K., Mowat, S., Kent, F., and Griffith, K., 2009, Survey of non-native ascidian (sea squirt) Didemnum vexillum in Holyhead Harbour: Countryside Council for Wales Marine Monitoring Report No. 67, 24 p. (PDF format)