Chemical Composition of Spiny Dogfish (Squalus suckleyi) Harvested in Alaska

Spiny dogfish is an underutilized yet abundant species harvested as bycatch in Alaska. The research goal was to determine the nutritional composition of dogfish by-products and compare results with headed and gutted (H&G) dogfish. Large differences existed in lipid content between the heads (1.8% w/w), H&G (9.2% w/w) and livers (65.4% w/w). The overall omega-3 fatty acid content ranged from 75.7 to 162 mg/g lipids in all tissues. Cholesterol content was significantly higher in livers (602 mg/100 g tissue) than in heads or H&G. Values for three potentially limiting amino acids ranged in the tissues from 2.6 to 2.8% w/w for methionine, 4.2 to 5.2% w/w for threonine and 6.9 to 8.8% w/w for lysine. Dogfish livers are a good source of fish oil, while heads and H&G are rich in protein and low in ash, which make these two products ideal raw materials for production of fish hydrolysates. Practical Applications This research is part of an ongoing effort to increase utilization and value of underutilized Alaska fish species and their respective by-products. Spiny dogfish caught from Alaska waters has some economic value as human food; however, an obstacle in processing and marketing shark fillets is the fact that its muscle tends to deteriorate quickly under refrigerated storage. Understanding the chemical composition and nutritional value of dogfish and its by-products is the first step to promote development of value-added products from these raw materials.