What is the meaning of Culch?

The rocks, crushed shells, and other sea detritus that create an oyster bed, where oyster spawn can attach themselves; a collection of such detritus, accumulated on land, to drop in the sea to build up oyster beds.

An accumulation of small items of little current value -- materials, broken items, miscellaneous fasteners -- for possible future use.

Junk or debris.

Location where potentially useful junk items are collected: culch corner, culch drawer, culch pile.

To prepare an oyster bed with such (culch) attachments; to sort shellfish or fish catch by size -- most often oysters -- so as to throw back the smallest to grow bigger and breed.

Source: wiktionary.org