
The sea potato or oyster thief (Colpomenia peregrina) is a brown seaweed native to the North Pacific. Non-native populations exist in Europe, the Mediterranean and Black Seas, and the Northwest Atlantic, where it was first reported in Nova Scotia in 1960. In the U.S., the species was first reported in Maine in 2010 and appears to be moving south, with reports from Rhode Island in 2017. The species can be problematic for oyster fisheries because the hollow seaweed fills with air or water and can carry oysters away. The distribution in New York is not well understood.
Description
How to identify a sea potato:
Yellow/brown
Papery texture
Up to 4 inches wide, collapses when out of water
Habitat and Distribution
The Sea potato is native to the North Pacific. The species tolerates wide ranges of environmental conditions and can be found in intertidal and subtidal habitats drifting or growing attached to substrates or other algal species. Non-native populations exist in Europe, the Mediterranean and Black Seas, and the Northwest Atlantic, where it was first reported in Nova Scotia in 1960. The species can be mistaken for the native brown algal species, the Sea Cauliflower (Leathesia marina). The distribution in New York is currently unknown.
How You Can Help
Clean, drain, and dry your watercraft and equipment thoroughly before visiting other waterbodies.
Inspect and remove debris and mud from boats, trailers, and equipment.
Dispose of all debris and bait in trash cans or at disposal stations.
Drain all water-holding compartments including live wells, bait wells, and bilge areas. If possible, visit a decontamination station and disinfect compartments with hot water (140°F) for at least 30 seconds.
Dry boats, trailers, and all equipment before use in another water body. A minimum of 5–7 days of drying time in dry, warm conditions is recommended.
Do not dump aquarium contents in any waterbodies, drainage ditches, or sewers.

Use certified bait that is non-invasive and disease free.
Learn how to identify the sea potato and report any encounters.
If you think you have found sea potato:
DO NOT RELEASE IT.
Take several photos of it from different angles and dispose of the specimen
Email the photos, noting where it was caught (coordinates preferred), to [email protected], OR
Submit a report through iMapInvasives
Additional Resources
National Estuarine and Marine Exotic Species Information System - information on marine and estuarine invertebrates and algae introduced to the United States - species profile for Sea potato.