As early as 1976 a short-term, relatively small, dead zone off the coasts of New York and New Jersey cost commercial and recreational fisheries over $500 million. In 1998 a HAB in Hong Kong killed over $10 million in high-value fish.
In 2009, the economic impact for the state of Washington's coastal counties dependent on its fishing industry was estimated to be $22 million. In 2016, the U.S. seafood industry expected future lost revenue could amount to $900 million annually.
NOAA has provided a few cost estimates for various blooms over the past few years: $10.3 million in 2011 due to a HAB at Texas oyster landings; $2.4 million lost income by tribal commerce from 2015 fishery closures in the pacific northwest; $40 million from Washington state's loss of tourism from the same fishery closure.
Along with damage to businesses, the toll from human sickness results in lost wages and damaged health. The costs of medical treatment, investigation by health agencies through water sampling and testing, and the posting of warning signs at effected locations is also costly.
The closures applied to areas where this algae bloom occurs has a big negative impact of the fishing industries, add to that the high fish mortality that follows, the increase in price due to the shortage of fish available and decrease in the demand for seafood due to the fear of contamination by toxins. This causes a big economic loss for the industry.
Economic costs are estimated to rise. In June 2015, for instance, the largest known toxic HAB forced the shutdown of the west coast shellfish industry, the first time that has ever happened. One Seattle NOAA expert commented, "This is unprecedented in terms of the extent and magnitude of this harmful algal bloom and the warm water conditions we're seeing offshore...." The bloom covered a range from Santa Barbara, California northward to Alaska.
The negative impact on fish can be even more severe when they are confined to pens, as they are in fish farms. In 2007 a fish farm in British Columbia lost 260 tons of salmon as a result of blooms, and in 2016 a farm in Chile lost 23 million salmon after an algal bloom.