1. Oyster shells and other debris used as a base for oyster larvae to attach and grow in oyster beds.
Usage: nautical; regional (U.S. East Coast)
2. Rubbish, junk, or worthless material.
Usage: informal; dialectal

Examples

• Oyster farmers spread culch across the beds to encourage spat settlement.
• The harbor bottom was covered with culch from old shells and broken pottery.
• They cleared away the culch before laying new foundation stones.
• The boat's hold was filled with culch and other maritime waste.
• Culch serves as an essential substrate in commercial oyster hatcheries.