Oncorhynchus gorbuscha
The Pink Salmon
The Uninvited Guest from the Pacific
The Pink Salmon (Oncorhynchus gorbuscha) is native to the North Pacific — from Alaska to Japan. Released through Soviet stocking programmes from the 1950s to the 1990s in the White Sea and the Kola Peninsula, it has since spread explosively across all of Northern Europe.
In Finland it is called Kyttyrälohi and has been observed in increasing numbers in the rivers of Lapland since 2017. Its characteristic hump (on spawning-ready males) and massive body size make it unmistakable. The Pink Salmon has a strict 2-year life cycle: it hatches, migrates to the sea, grows for 18 months, returns, spawns and dies.
The invasion is classified as a serious threat to native Salmon and Trout. Pink Salmon compete for spawning sites, alter the nutrient balance of rivers through massive carcasses, and can introduce parasites. Finland, Norway and Sweden actively recommend the removal of every caught specimen.
Identification: Pink Salmon vs. Atlantic Salmon
Pink Salmon (invasive)
- Large, clearly visible black spots on the tail fin
- Hump on the back (males, pronounced from July)
- Small scales, very numerous
- Thin, narrow caudal peduncle
- Skin turns dark grey to black in the river
- No red spots — never spots on the lateral line
Atlantic Salmon (native)
- Few or no spots on the tail fin
- No hump, streamlined body
- Large, clearly visible scales
- Broad, strong caudal peduncle
- Silver flanks with scattered dark spots
- X-shaped spots above the lateral line
Seasonal Data
The Pink Salmon appears in rivers for just a few weeks each year — but then in enormous numbers. It no longer feeds but reacts aggressively to lures.
Invasion Chronicle in Finland
The Pink Salmon has been spreading explosively across Scandinavia since 2017. In odd years, run numbers are particularly high (2-year cycle).
First mass occurrence in northern Norway
Large schools reach Teno/Näätämöjoki (FI)
Record run: tens of thousands of Pink Salmon in Lapland
Massive invasion, first reports from southern Finland
Established population, annual 2-year cycle confirmed
Diet Spectrum
The Pink Salmon feeds only in the ocean. In the river it ceases all food intake — its digestive system degenerates. Catches rely purely on the bite reflex.
Growth by Age
The Pink Salmon has a fixed 2-year cycle. It grows exclusively in the sea and reaches its maximum weight just before the river ascent.
| Age (Years) | Length | Weight | Relative Size |
|---|
Habitat Requirements
Spawning Site Competition
Pink Salmon spawn on the same gravel bars as Atlantic Salmon and Trout. Through sheer numbers they destroy existing redds.
Nutrient Input
Tens of thousands of decomposing fish increase nitrogen and phosphorus input into oligotrophic rivers. Can trigger algae blooms.
Disease Risk
As a Pacific species, the Pink Salmon potentially introduces foreign parasites and pathogens into Atlantic waters.
Genetic Introgression
Pink Salmon cannot hybridize with Atlantic Salmon (different chromosome count). No genetic threat.
Food Web
Eagles, bears and otters benefit from the massive food supply. Long-term effects on native fish stocks are unclear.
Spread Rate
Each generation spreads further south. Now also reported in the Baltic Sea and central Finnish rivers.
How to Fish for Pink Salmon
Although the Pink Salmon no longer feeds in the river, it responds to the bite reflex: it snaps at anything that enters its territory. Bright, provocative lures in vivid colours are especially effective.
The fish run upstream in dense schools. At bottlenecks and rapids they concentrate — that's where the chances are best. The peak phase lasts only a few weeks (late July to mid-August), then it's over.
Spin Fishing
July — SeptemberLarge, bright spinners and spoons. Pink, orange and chartreuse are the colours. Aggressive retrieval style.
Fly Fishing
July — AugustLarge, colourful flies (Pink Shrimp, Egg Patterns). Presented right in front of the nose. Swinging or stripping.
Bottom Fishing
August — SeptemberAt the spawning site with a single hook and bright lure. Effective but locally restricted in some areas.
Hand Line (Pilkki)
July — AugustCommon in Norway and northern Finland: simple hand line with a jig directly into the schools.
Where Pink Salmon Appear in Finland
The invasion is concentrated in the north but is steadily spreading southward. In odd years (2025, 2027...) the run numbers are particularly high.
Teno (Tana)
70.1°N, 27.0°EEpicentre of the invasion in Finland
Over 100,000 Pink Salmon were counted at this border river to Norway in 2023 — more than Atlantic Salmon. Finnish and Norwegian authorities operate fish traps and call for active removal.
Näätämöjoki
69.7°N, 29.0°EBorder river to Norway
One of the first rivers where Pink Salmon were observed in Finland. The small Salmon population is particularly vulnerable. Sami communities operate traditional nets for removal.
Tornionjoki
66.4°N, 23.8°EAdvancing front southward
Increasing numbers of Pink Salmon have been reported at Europe's longest free-flowing river since 2021. Particular concern is the competition with the naturally reproducing Atlantic Salmon here.
Gulf of Bothnia (Coast)
64.0°N, 23.5°ENew expansion front
Since 2023, Pink Salmon have also been reported in central Finnish coastal rivers. The southward expansion is advancing with each generation. Anglers are asked to report catches.
Eating Quality: Surprisingly Good!
Report Your Catch — Help Science
Important: Pink Salmon may and should be removed. There is no closed season, no minimum size and no bag limit. Every removed fish helps to contain the invasion.
