Cessation of the Norwegian drift net fishery: changes observed in Norwegian and Russian populations of Atlantic salmon

Published source details Jensen A.J., Zubchenko A.V., Heggberget T.G., Hvidsten N.A., Johnsen B.O., Kuzmin O., Loesnko A.A., Lund R.A., Martynov V.G., Nꬱsje T.F., Sharov A.F. & Økland F. (1999) Cessation of the Norwegian drift net fishery: changes observed in Norwegian and Russian populations of Atlantic salmon. ICES Journal of Marine Science, 56, 84-95.
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This study is summarised as evidence for the following.

	Action	Category
	Establish long-term fishery closures Action Link
	Cease or prohibit mobile midwater (pelagic) fishing gears Action Link

Establish long-term fishery closures

A replicated, before-and-after study in 1980–1994 of four Norwegian rivers draining to the Norwegian Sea (Jensen et al. 1999) found that in the five years following a long-term ban on a coastal drift net fishery for Atlantic salmon Salmo salar, there were increases in the catch abundance and weights of young (one-sea winter) salmon returning to rivers, but fewer changes for multi-sea-winter salmon. In three of four rivers, overall numbers of grilse (young salmon returning from the sea to fresh water for the first time) were higher in the five years after the ban (after: 500–4,000 fish, before: 80–1,200 fish) and numbers of older, multi-sea-winter salmon were similar (after: 50–3,200 fish, before: 50–3,200 fish). Average weight of grilse increased in all four rivers (after: 1,714–2,340 g, before: 1,558–1,996 g), whereas two-sea-winter salmon weights decreased in two (after: 5,769–6,211 g, before: 6,500–6,988 g) and there were no changes for three-sea-winter salmon (after: 9,075–10,764 g, before: 8,938–10,752 g). In addition, effects of the ban on salmon populations returning to four Russian rivers (outside of the ban area) were found for three rivers draining to the Barents Sea, but not for one draining to the White Sea (see paper for data). A total ban on sea fishing for salmon using drift nets was introduced in Norway in 1989, while other methods such as bag and bend nets continued. Data on catches of salmon (mainly rod and line) for four Norwegian rivers (Repparfjord, Alta, Namsen, Stryn) from 1980–1994 were taken from Norwegian Official Statistics.

(Summarised by: Khatija Alliji)
Cease or prohibit mobile midwater (pelagic) fishing gears

A replicated, before-and-after study in 1980–1994 of four Norwegian rivers draining to the Norwegian Sea (Jensen et al. 1999) found that in the five years following a ban on drift netting in a coastal fishery, there were increases in the catch abundance and weights of young (one-sea winter) Atlantic salmon Salmo salar returning to rivers, but fewer changes for multi-sea-winter salmon. In three of four rivers, overall numbers of grilse (young salmon returning from the sea to fresh water for the first time) were higher in the five years after the ban (after: 500–4,000, before: 80–1,200) and numbers of older, multi-sea-winter salmon were similar (after: 50–3,200 before: 50–3,200). Average weight of grilse increased in all four rivers (after: 1,714–2,340g, before: 1,558–1,996 g), whereas two-sea-winter salmon weights decreased in two (after: 5,769–6,211 g, before: 6,500–6,988) and there were no changes for three-sea-winter salmon (after: 9,075–10,764 g, before: 8,938–10,752 g). In addition, effects of the ban on salmon populations returning to four Russian rivers (outside of the ban area) were found for three rivers draining to the Barents Sea, but not for one draining to the White Sea (see paper for data). A total ban on sea fishing for salmon using drift nets was introduced in Norway in 1989, while other methods such as bag and bend nets continued. Data on catches of salmon (mainly rod and line) for four Norwegian rivers (Repparfjord, Alta, Namsen, Stryn) from 1980–1994 was taken from Norwegian Official Statistics.

(Summarised by: Khatija Alliji)