Sustainable Seaweed Farming and Bull Kelp Harvesting Industry Bull kelp (Nereocystis luetkeana) is a nutritional powerhouse of the North Pacific. Its unique anatomy—a long, whip-like stipe ending in a gas-filled pneumatocyst (the "bulb")—allows it to stay afloat and reach sunlight. While you may have eaten it in specialty seaweed salads, its derivatives are even more common; kelp extracts like alginates are used as thickening agents in everything from ice cream and salad dressings to toothpaste