Clam gardens are ancient mariculture features developed by Indigenous Peoples of the Northwest Coast of North America that create shallow sloping intertidal shelves where clam productivity is enhanced. We quantify the area of clam habitat created by constructing rock-walled clam gardens terraces in northern Quadra Island, British Columbia, Canada. We combined modelling, high-resolution mapping, beach sampling, and a comprehensive survey of the shoreline to document the location and areal extent of clam habitat in clam gardens today. We divided our analysis into three classes of clam gardens, which differ in substrate and thus the amount of clam habitat created. We found that Indigenous People built clam garden walls on 35% of the shoreline and that about 112,979 m² of flat beach terrace were created by clam garden construction. Collectively, the three classes of clam gardens increased clam habitat area between 26 and 36%. About 35% of the area of clam habitat in clam gardens was constructed de novo on bedrock shelves and rocky slopes where no clam habitat existed previously. Furthermore, about 12.0% of clam gardens are smaller than 30 m², reflecting the effort put into creating enhanced food production wherever possible. Our analysis demonstrates that clam management in the form of clam gardens was extensive prior to colonization and that these features still have a significant impact on today’s intertidal ecosystems. Clam habitat expansion facilitated by clam garden construction encouraged a sustainable and abundant food source in the past and could do so again in today’s changing environmental conditions.

蛤garden花园是北美西北海岸的原住民开发的古老海水养殖特色，形成了倾斜的浅潮间潮汐架，从而提高了蛤productivity的生产力。我们通过在加拿大不列颠哥伦比亚省北部Quadra岛上建造岩壁蛤garden花园梯田来量化蛤habitat栖息地的面积。我们结合了建模，高分辨率地图绘制，海滩采样以及对海岸线的全面调查，以记录当今蛤garden花园中蛤habitat栖息地的位置和面积。我们将分析分为三类蛤garden花园，它们的基质不同，因此产生的蛤habitat栖息地数量也不同。我们发现，原住民在海岸线的35％处建有蛤garden花园墙，约有112,979 m ²平坦的海滩露台是由蛤garden花园建设创造的。总的来说，三类蛤花园使蛤habitat栖息地面积增加了26％至36％。蛤类花园中蛤类栖息地面积的大约35％是在基岩架子和以前没有蛤类栖息地的岩石斜坡上从头建造的。此外，大约12.0％的蛤lam花园小于30 m ²，反映出在可能的情况下为提高粮食产量所做的努力。我们的分析表明，在殖民化之前，以蛤garden花园形式进行蛤lam管理已经很广泛，而且这些特征仍然对当今的潮间带生态系统产生重大影响。蛤garden花园的建设促进了蛤habitat栖息地的扩展，过去鼓励了可持续和丰富的食物来源，并且在当今不断变化的环境条件下也可以这样做。