with a treaty with Japan and Canada regarding salmon fishing in the North Pacific. Other uses Drift nets also are used in ecological studies in studying the downstream drift of invertebrates and Ichthyoplankton. The nets are strung across a stream and allowed to sit overnight, collecting samples. These nets are crucial in the understanding of how watersheds function. Quantitative estimates derived from drift nets used in this way in rivers need careful consideration given the clogging of the nets and decay in performance that can occur as a result. See also Earthtrust References External links "Fishy Business": documentary film about the illegal driftnet fishery in the Mediterranean National Geographic's An Incidental Kill Fishing industry Environmental impact of fishing Fishing techniques and methods Fishing nets