Note 2 - Significant Accounting Policies - Revenue By Product (Details) - USD ($) $ in Thousands	3 Months Ended
Jun. 30, 2022	Jun. 30, 2021
Net sales	$ 6,716	$ 8,964
Packaged Astaxanthin [Member]
Net sales	3,524	4,040
Packaged Spirulina [Member]
Net sales	1,511	2,742
Packaged Products [Member]
Net sales	5,035	6,782
Bulk Astaxanthin [Member]
Net sales	494	405
Bulk Spirulina [Member]
Net sales	1,093	1,583
Bulk Products [Member]
Net sales	1,587	1,988
Contract Extraction [Member]
Net sales	$ 94	$ 194

Amount, excluding tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value added and excise.

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+ Details