Raising marine animals for sale was a record- breaking business in Hawaii last year, according to a new federal report, though the major driver of the growth in local aquaculture farming is murky.

The U.S. Department of Agriculture reported that statewide aquaculture sales soared to $78.2 million last year. That represented a 40 percent spike over the $55.7 million in sales reported in 2012; there was no comparable measurement of revenue in 2013.

Hawaii’s aquaculture industry has generated robust revenue gains consistently since 2011 after four choppy years that followed nearly two decades of pretty modest growth.

The dominant product in the industry is algae, which is produced largely for nutritional supplements and last year represented $33.1 million of sales. Algae sales in 2012 totaled $28.4 million.

Still, most of the sales surge last year came from products other than algae. What that other seafood is, however, remains a mystery because disclosure could put the producer or producers at a competitive disadvantage by divulging private business revenue of individual companies.

It could be tilapia or kampachi or shrimp — all of which are farmed in Hawaii for commercial sale. The U.S. Department of Agriculture, with assistance from the state Department of Agriculture, surveys aquaculture farmers for sales figures, but does not disclose product-specific sales data if the information would enable the public, including competitors, to discern the revenue of individual companies.

“The challenge in the aquaculture industry in Hawaii is we have some major producers that produce just one type of commodity,” said Kathy King, statistician for the Hawaii field office of the USDA’s National Agricultural Statistics Service.

As a result, sales in a category dubbed “other” totaled $45.2 million last year, up from $27.3 million the year before. This category includes “finfish” such as moi and Asian catfish, shellfish such as clams and oysters, and ornamental fish such as koi and angelfish. It also includes sales of baby fish by hatcheries.

One contributor to higher sales in 2014 was Kualoa Ranch, which started selling endemic Pacific saltwater oysters raised in an ancient Oahu fishpond last year after about four years of preparation. The tourist attraction sells its oysters for $15 per dozen, and had about 28,000 oysters valued at $35,000 ready for the market early last year.

Maria Haws, director of the Pacific Aquaculture and Coastal Resources Center at the University of Hawaii at Hilo, conservatively estimated last year that shellfish produced in Hawaii could generate more than $20 million in annual revenue in the next five to 10 years. The last time the USDA disclosed the value of Hawaii shellfish sales was in 2011, when it represented $413,000.

Ron Weidenbach, president of the Hawaii Aquaculture and Aquaponic Association, said it’s great to see aquaculture farming taking off after decades of groundwork that included research, grants and regulatory approvals.

“The aquaculture industry (in Hawaii) is still in its infancy or childhood relative to where it must and will go in the decades ahead,” he said. “The industry’s growth trajectory over the past five-10 years is much more indicative of our growth trajectory going forward than the necessary baby steps of the early aquaculture development years. This is a success story that all whom have been involved with our state aquaculture industry over the past 40 years can be proud of, with the best still yet to come.”