It is not possible to obtain reliable estimates of the
amount of plastic debris that reaches the marine environment,
but the quantities are nevertheless quite substantial.
In 1975 the world’s fishingfleet alone dumped
into the sea approximately 135,400 tons of plastic fishing
gear and 23,600 tons of synthetic packaging material
(Cawthorn, 1989; DOC, 1990). Horsman (1982) estimated
that merchant ships dump 639,000 plastic containers