Impacts on fisheries

A number of land-based waste products, notably nutrients and toxic pollutants, exert a direct effect on economically or culturally important fish-stocks. In most cases this is a negative impact, with reduced productivity, or losses of certain species, associated with declines in habitats , deoxygenation of the waters, or replacement of species with others of lower commercial value. In a few cases increases in nutrients have been reported to improve productivity: although evidence is still not clear, increased nutrient loading has been used to explain the continued high yields from the Mediterranean over the last century. The physiological impacts of some toxins on commercially important species are also a point of concern, notably the impacts of endocrine disruptors .

Fisheries closures as a result of pollution can have severe economic consequences

Pathogens, toxic waste and toxins from Harmful Aquatic Blooms (HABs) have a major impact on fisheries, not only from the impact on human health, but from the closure of fisheries in contaminated areas. The losses in areas which are permanently polluted is hard to measure, however during periods of HABs, the economic losses have been calculated for a number of locations. A red tide in Hong Kong in 1998 caused losses of US$32 million from the closure of fish farms, whilst an algal bloom in Korea in 1991-2 was estimated to cost US$133 million.

Solid waste too has an impact on fisheries, and is a regular source of complaint, notably from bottom trawlers who have to disentangle materials from their nets.