Swan Egg

Swan Egg

　　The swan egg, scientifically known as the purple stone ark clam, is a type of marine bivalve and one of the prized seafood products along the coast of Yantai. It typically lives in areas with good water flow and coarse sandy or gravel seabeds. It is found in a narrow stretch of water between the "Little Elephant Island" behind Yangma Island in Muping and Yangma Island itself, covering an area of about 100 acres. As a cold-water bivalve, it has strong cold resistance. The clams are relatively large, with some measuring over 115 millimeters in length and weighing more than half a kilogram. They have plump meat, an exceptionally delicious taste, and high nutritional value.

　　 This clam prefers to inhabit clear-water, well-circulated gravelly or sandy-mud seabeds. It often buries itself 10–25 centimeters deep in the sand and mud, leaving only its siphons

　　slightly exposed on the seabed surface for water exchange and feeding. It is distributed in the 4–15 meter shallow coastal waters from Changdao to Rongcheng, particularly abundant around Kongtong Island in Zhifu District, Yantai City,

　　Nanzhusha Island in Huancui District, Weihai City, and the waters near Yangma Island in Muping County. The total resource distribution area in the province is about 1,500 acres, with an estimated current stock of about 300 tons,

　　including 700 acres and 40 tons in Zhifu District. It is considered an economically valuable bivalve with relatively limited resources.

　　 Muping County began developing and utilizing this clam relatively early, starting in the 1960s. Due to its scarcity and the difficulty of harvesting, the annual catch is only about 3–5 tons.

　　Since 1981, the Provincial Aquatic Products School, the Yantai Aquatic Research Institute, and the Muping County Marine Specialty Experimental Farm have collaborated on artificial breeding trials of the purple stone ark clam

　　and have achieved preliminary success. It has now been listed as a key project for aquaculture development.