Technical, Logistical, and Economic Considerations for the Development and Implementation of a Scottish Salmon Counter Network: Scottish Marine and Freshwater Science Vol 7 No 2

8.0 Future Research and Recommendations

8.1 Future Research

IFR noted several worthwhile areas of future research while completing this report, and emphasize the importance of considering these areas when implementing a counter network in Scotland. Access to mains power at counter sites throughout Scotland will provide an ease of operation, however mains power is prone to power fluctuations that can lead to power loss and subsequent data loss. Consequently, there is a need to investigate potential renewable power sources (e.g., wind, solar, hydropower generators) to power counters in remote areas to eliminate the dependence for mains power. Careful consideration is needed to select an optimal renewable power source for each potential counter site given variation in site characteristics (e.g., variable sun exposure due to a range in latitudes and local weather).

Further investigation into Mark 12's hardware availability and software functionality is needed. Mark 12 technology and reference material is currently not commercially available and information on the counter is extremely limited. Furthermore, its use has been limited to fish passes and small sensor units and has not been tested in free-flowing river channels. IFR only assessed Mark 12 technology in fish passes, but these counters likely have applications in other channel types.

SalmonSoft's FishTick software can potentially provide significant cost savings for video analysis. Aside from a review completed by the Environment Agency of Wales, limited information on its time savings and effectiveness exists as a video counting software. FishTick could provide significant reductions in video analysis, making video a cost-effective form of fish counting technology; however this has not been adequately assessed.

Further investigation into the accuracy of length data generated by multibeam hydroacoustic counters (operating at low resolution) is needed. Considering that these technologies have no innate fish species identification abilities, fish lengths are generally used to determine the species of individuals when analyzing hydroacoustic data. Length accuracies of high resolution hydroacoustic data have been extensively researched; however there has been no analysis of the accuracy of fish lengths collected at low resolution. Low resolution hydroacoustic fish length data will need to be validated with known fish lengths to confirm the accuracy of the counter.

Raw data that make up Aquantic's graphical trace plots need to be acquired in order to manipulate the Logie 2100C's counting algorithm. This will allow alternative algorithms to be written by the counter user, which could increase counter accuracies across a broader range of conditions and population characteristics.

Existing counter technologies can face challenges in relation to stock assessment and catchment management, particularly in rivers with several tributaries that may contain distinct populations. Integrating other remote sensing technologies (e.g., telemetry) with fish counters may aid in the enumeration of fish populations. Use of this integrative approach can lead to cost-effective solutions to challenging monitoring conditions and provide additional information relevant to the management of salmon populations.

Further development of the spatial coverage index for evaluating counter networks is needed. Various metrics could be used to determine the relative value of different counter network configurations. A spatial coverage index would provide valuable knowledge on the amount of information a counter network provides. This could be used to evaluate the trade-off between information (spatial coverage) and cost.

Finally, we emphasize the need to develop expertise throughout Scotland through training and knowledge exchanges with experienced personnel to build capacity within MSS and local fisheries biologist. Knowledge exchanges could be facilitated through visiting a range of existing counter sites, workshops and training programs for specific technologies or equipment.

8.2 Recommendations

Our findings indicate the necessity for the validation of counter data. Validation should be completed for all counter technologies, including those that are not typically considered (e.g., hydroacoustic counters). When validation data is used to generate abundance estimates, the number of fish validated is directly related to the accuracy of abundance estimates. We recommend a minimum of 500 fish be validated for most counter setups, although counter and site conditions will influence the minimum number required.

Notably, the decision and cost model herein provides real options for counter scenarios, but does not take into account the importance of site visits. We recommend a minimum of one year of monitoring at potential counter sites to collect the information needed to make an informed decision on the deployment of a suitable counter setup. Moreover, site-specific evaluations are critical for ensuring the proper application of counter technology.