Most Þsheries literature avoids speaking about ecosystem impacts of shing, either because
impacts are not demonstrated or because a causal relationship between impacts and Þshing
cannot be formally established with the available information. However, there is mounting
evidence that Þshing has undesired e¤ects in the marine ecosystems. This overview examines the
wide ecosystem e¤ects of Þshing, describing and illustrating the potential unintended e¤ects of
the main Þsheries of the world. An operational framework for classifying the e¤ects of Þshing in
terms of the mechanisms generating the e¤ects is provided. The focus and, to a large extent, the
recourse to examples is on those Þsheries for which the impacts of Þshing have been best studied
such as those in the North Atlantic and the Northeast PaciÞc. Ecosystem e¤ects are divided into
direct and indirect: direct e¤ects include the Þshing mortality exerted on target populations
(overÞshing), the Þshing mortality sustained by non-target populations (bycatch), and the
physical impacts caused by towed gears on benthic organisms and on the seabed. Indirect
e¤ects include impacts mediated by biological interactions, the environmental e¤ects of dumping
discards and organic detritus (o¤al), and the mortality caused by lost gear (ghost Þshing).