Impacts from HABs affect freshwater and marine aquaculture industries. In the ocean, large numbers of salmon and other farmed fish can be killed in just a few hours, succumbing either to toxic algae or to species that kill in other ways. For example, in 1987, phytoplankton blooms of the non-toxic diatom Chaetoceros convolutus were linked to the mortality of 250,000 Atlantic salmon valued at over $500,000. The diatoms lodged in the gill tissues, causing excessive mucus production, suffocation, and death. Blooms of the toxic raphidophyte Heterosigma akashiwo have caused even more extensive farmed-fish mortalities in Washington state. The NOAA Center for Sponsored Coastal Research provided funds for limited field work and compilation of a summary of past H. akashiwo blooms, the causes and distribution as summarized in the report, "Fish kills from the harmful alga Heterosigma akashiwo in Puget Sound: Recent blooms and review. Freshwater aquaculture operations are also subject to risks from cyanobacteria and other HAB-producing toxins that kill the fish or accumulate in tissues.Prymnesium parvum Blooms Kill Fish in Brackish Water Systems
An emerging problem in the U.S. is the impact from golden-algal blooms caused by Prymnesium parvum, a species that thrives in brackish water typical of rivers and reservoirs in parts of Texas, Oklahoma, and Wyoming. Fish kills attributed to P. parvum were first documented in the U.S. in 1985 in Texas. Since that time, 41 different fish kills have been linked to P. parvum in Texas, killing over 18 million fish worth an estimated $7 million. The majority of major kills have occurred since 2000 as this toxic alga has been found in an increasing number of river basins in the state. Local communities have experienced huge financial losses as tourists stay away and fishing guides lose their customers. P. parvum poses a threat to cultured as well as native fish in rivers and lakes. In the 1940's P. parvum caused significant fish mortality in Israeli aquaculture ponds and in 2001, it killed the entire year's production of striped bass at Texas' Dundee State Fish Hatchery with over 5 million fish lost.
Last updated: February 25, 2016