Open Closed or Catch and Release - How our rivers are categorised for salmon exploitation.
Open Closed or Catch and Release
Recreational anglers and indeed commercial nets men ask the question each season as to why their river is open,closed or catch and release.
The simple explanation is if there is an identifiable surplus above a scientifically derived number of salmon which are required to spawn in a particular catchment then that catchment is open for exploitation. If there is no surplus available then exploitation is not allowed.
The number of salmon required (CL) in any river to produce the optimum number of juveniles to ensure future generations is derived by examining the habitat and physical characteristics of the catchment.
After examining the data the number of salmon required to produce enough juveniles to provide a healthy and self sustaining population is arrived at. The number of salmon is called the rivers conservation limit (CL).
Exploitation and Scientific Data
The decision to open a river for exploitation is arrived at using a broad range of parameters including juvenile survey results, rod catch, commercial catch and fish counting facilities. The decisions are based on a five year rolling average of the above factors.
In regards to rod catch, each river has an exploitation rate decided upon by the Standing Scientific Committee (SSC) which is then used to equate numbers of salmon remaining to spawn. The rivers that are open for exploitation must have an identifiable surplus of fish thus allowing a limited exploitation.
Some rivers are closed due to the very poor data available with rivers with an annual salmon catch of below 10 fish deemed to be data poor and thus closed.
Other rivers are deemed to be suitable for catch and release where the SSC and Technical Advisory Group on Salmon deems that they have a "high probability of achieving 50% of their conservation limit (CL) or exceeding a qualifying fry threshold of ≥ 15 fry (0+) per 5 minute electro-fishing (multiple site catchment average)".
The following data resources may be of interest and include rod and commercial fisheries statistics, fish counter reports, juvenile salmonid reports and scientific advice given by the Standing Scientific Committee.