Note 13 - Product Line and Geographic Information - Net Sales by Product Line (Details) - USD ($) $ in Thousands	3 Months Ended																12 Months Ended
	Mar. 31, 2018	[1]	Dec. 31, 2017	[1]	Sep. 30, 2017	[1]	Jun. 30, 2017	[1]	Mar. 31, 2017	[1]	Dec. 31, 2016	[1]	Sep. 30, 2016	[1]	Jun. 30, 2016	[1]	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2016
Net sales:
Net sales	$ 8,101		$ 9,150		$ 8,055		$ 8,809		$ 7,253		$ 7,605		$ 9,862		$ 7,322		$ 34,115	$ 32,042	$ 31,840
Natural Astaxanthin Products Bio Astin [Member]
Net sales:
Net sales																	21,650	19,357	19,829
Spirulina Products [Member]
Net sales:
Net sales																	$ 12,465	$ 12,685	$ 12,011

[1] The first, second, third and fourth quarters of 2018 include abnormal production costs of $9,000, $75,000, $4,000 and $720,000, respectively. The first, second, third and fourth quarters of 2017 include abnormal production costs of $28,000, $73,000, $148,000 and $5,000, respectively.