Pink Salmon in the Clyde. Hopefully not!

Background 

In recent weeks, anglers in Scotland (Rivers Ness, Dee and Helmsdale) have reported several captures of fresh
run non-native Pink Salmon (Oncorhynchus gorbuscha). Some captures have also been reported in some
salmon net fisheries in Scotland and both rod and net fisheries in England and Ireland. These fish are not
native to Scotland and are likely to have ‘strayed’ from some of the rivers in northern Norway or Russia.
These fish were originally introduced to some Russian rivers in the 1960s, have slowly spread westwards and
have now colonised some northern Norwegian rivers. These fish spawn at a different time from Atlantic
salmon, have a 2-year lifecycle and generally spawn in summer (and often in main river channels, in the lower
reaches of rivers, and sometimes in upstream tributaries). Due to their 2 – year lifecycle, the progeny will be
derived from distinct ‘odd’ or ‘even’ years, with the Russian/Norwegian fish being odd-year stocks. It is
therefore possible, and likely, that they will occur again in 2019. Whilst it is theoretically possible that these
non-native species could establish themselves in Scottish rivers, the higher water temperatures make this
unlikely. Whilst the risks are not known, in terms of their interaction with Atlantic salmon and other native
Scottish fish, they are unlikely to have a positive impact.

See more information on pink salmon.

Identification
Pacific pink salmon, when fresh from the sea, are steel blue to blue-green on their backs, silver on the flanks
and white on their bellies. There are large black spots on the backs, upper flanks, adipose fins and tail – some
of the spots on the tail can be as large as the fish’s eyes. They are very uniform in size, reaching only 40 to
60cms in length.

‘Fresh run’ pink salmon
Breeding males are immediately identifiable because of their humps and they will almost certainly be running
milt at this time of year. Their black tongues and heavily spotted tails are also very obvious. Females will show
heavily spotted tails and be pinkish-brown on the flanks.

What should you do if you capture a Pacific salmon?
As above, Pacific pink salmon are usually clearly identifiable from their Atlantic counterparts –
particularly when mature and in spawning condition. If you are confident that you have captured a
pacific pink salmon, it should be humanely despatched and retained. It would be helpful if captures
are reported to the relevant district salmon fishery board and fishery trust. If it is practical to do so,
please pass the fish to the relevant personnel at the DSFB or trust for further inspection and analysis.

ICES WGNAS REPORT 2013 | 37
In Russia, pink salmon were introduced to the White Sea basin in the 1950s with annual egg transfers
from the Far East of Russia into hatcheries of Murmansk and Archangelsk regions (Gordeeva and
Salmenkova, 2011). Despite over 20 years of introductions no consistent natural reproduction occurred
and they disappeared when the introduction stopped in 1979. This failure was attributed to use of
populations from the southern part of the native range. As time of spawning migration and spawning
time are strictly fixed in salmonids, the introduced ‘‘southern’’ pink salmon began to spawn too late
and eggs were lost as water temperatures in Autumn were colder than in their native habitat especially
in even-year generations (Dyagilev and Markevich, 1979). Therefore successful natural reproduction
took place only during some years of the North Atlantic warming (Karpevich et al. 1991).
The introduction of odd-year pink salmon to the White Sea basin was undertaken in 1985, when a new
broodstock population was selected from the northern part of the species range (Okhotsk Sea basin,
Loenko et al. 2000). This single pink salmon egg transfer from an odd-year population resulted in the
establishment of local self-reproducing populations in the White sea rivers of Murmansk and
Archangelsk regions of Russia with the adult returns fluctuating between 60 000 to 700 000 fish during
the period 1989 through 2009 (Zubchenko et al. 2004; Gordeeva et al. 2005). Pink salmon introduced to
Russia since 1930s have resulted in catches in Norwegian waters (up to 20 t in some years). The species
has also now established in eleven rivers in N. Norway (Finnmark); Hesthagen and Sandlund (2007).
The commercial fishery for Pink Salmon takes place in the coastal areas of the White Sea and with the
same gears and in the same season as Atlantic salmon fisheries. The total declared pink salmon catch
in 2009 was 139 t, twice as much as a declared Atlantic salmon catch (ICES, 2010).
At the same time, transfers of even-year-broodlines from the same river of the Okhotsk Sea basin were
unsuccessful despite the large number of eggs that were transferred and the favourable rearing
conditions at hatcheries. The last egg transfer of 1998 resulted in comparatively large return in the first
generation, but the abundance of pink salmon declined subsequent generations and after that they
appeared only in small numbers in even years. No commercial fishery for pink salmon is conducted in
the White Sea in even years
Pink salmon have the shortest life cycle among species of the genus Oncorhynchus, as they mature and
reproduce after only two years. Therefore, there are two reproductively isolated populations spawning
in alternate even and odd years (Heard, 1991).
Pink salmon migrate a shorter distance up rivers to spawn than most other salmonids (Heard 1991); in
addition, spawning in pink salmon seems to be terminated before the spawning of Atlantic salmon
starts. As such, there does not appear to be any evidence of interactions with Atlantic salmon at the
spawning grounds, such as competition for spawning sites or destruction of redds.
Pink salmon fry migrate to sea in early summer, shortly after emerging from the gravel. Due to their
rapid exodus from streams at emergence, pink salmon fry feed less in fresh-water than other Pacific
salmon. Hence, any competition for food between pink salmon and Atlantic salmon may take place
during a short period in early summer, only.

 

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