Kona-based health-product maker Cyanotech Corp. reported a 15 percent gain in fourth-quarter net sales, to $6,897,000, from $5,986,000 in the fourth quarter of 2012.

The company produces Spirulina and makes Astaxanthin products and reports its Nutrex Hawaii business was up 14 percent, that its mainland business was up 73 percent, its online sales were up 90 percent and its international business was up 203 percent, all in the fourth quarter.

Net sales for the year were up 12 percent over 2012, at  $27,581,000 from $24,631,000, with gross profit at $10,958,000, representing gross profit margin of 40 percent, the same as a year ago.

Cyanotech trades on the Nasdaq under the CYAN symbol.