The KOSDSFB runs and maintains a Smolt trap within the Shin river catchment.
 Smolt trap |
History - the trap has been in place since the late 1960's. When the Hydro Electric scheme was built in the 1950’s the smolt trap stream was diverted to the power station. The trap is required to allow the fish to be caught and transported to the main river avoiding the generating turbine and then out to sea. The trap had a complete refit two years ago, it is of the “Wolf” type.
Operation - salmon spend their early years in fresh water. As fry they tend to be quite sedentary, not moving far from where they hatched. On becoming one year old they are named parr. At this stage of their lives they will migrate large distances within river systems to find suitable habitat and food supply. Normally at >10cm in length the fish may start their migration to sea, typical smolts in our system are between 12 and 15 cm in length. At “smolting” the fish take on a different appearance, becoming silver in colour, their shape changes, becoming sleeker and more “adult like. They also gain the ability to cope with the differences between salt water and fresh water. Typically smolts are between 1 and 3 years old when they start their journey to sea.
The trap is normally operational at the end of March, it closes in June once the smolt run has ceased. The peak of the run is at the end of April and into the first half of May. Numbers of fish migrating can be effected by water height, moon phase and temperature amongst other factors.
Data Collection - the trap is checked twice daily by KOSDSFB staff and emptied of its contents. The fish are counted, placed in buckets and taken to the river Shin where they are released. From here they find their own way to sea. Approximately 4000 smolts are collected from this facility every year.
 Smolt trap stream, mid winter |
Use of Data - the area above the trap is inaccessible
to wild adult salmon, therefore we plant the stream with un-fed
fry from
our hatchery. Normally between 200 and 220 thousand fry are stocked
into this area. This number has been derived by calculating the wetted
area (meters squared) of the stream and multiplying by our stocking
density. Typical in the KOS we try to stock between 3 and 5 ova or
fry per square meter. Also we can calculate the survival from fry
to smolt using this data. Values in the east coast region of Scotland
are normally between 1.4% and 2%. The KOSDSFB figure is typically
within this bracket. The data derived is very important for the management
of the fishery as a whole. It allows us to annually monitor smolt
survival. We can also apply the data
to other system within the KOS region. The Shin gains 4000 smolts
that it would
not
have
without KOSDSFB time and effort.