A10. Underwater viewing room

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1. Objectives[edit]

The objectives are similar to the ‘normal’ video-counting system but additionally can:

  • Reduce the cost of installing a video-counting system
  • Keep any computer equipment safe if the area is known for vandalism
  • Make a fish observatory for people to practice citizen science

2. Method summary[edit]

The method involves counting fish inside a purpose built channel, which consists of an underwater room with a glass panel that allows fish to be viewed as they exit the fishway. The camera is set in front of the glass while an illuminated panel is installed on the opposite side of the channel to illuminate the fishway. Within the video image data fish appear in profile, enabling individuals to be counted, measured and assigned to their species. Careful consideration of the design of the underground chamber needs to be had before its installation to ensure it is properly integrated within the fishway.

3. Advantages[edit]

  • Large quantity of information can be acquired.
  • Suitable for long term and very-long term studies.
  • The use of software to automatically distinguish videos sequences containing fish from those that contain objects that are not (e.g. branches, leaves etc.) increases the time efficiency of the method.
  • None labour intensive for the surveyor(s).
  • The camera systems can be set up to record data automatically and if an internet connection is available data can be streamed off-site.
  • Possibility for cheaper video counting system, e.g. one that is not weatherproof.
  • Visual data is simple to interpret thus suitable for citizen science and educational purposes.
  • Device protected from vandalism.

4. Disadvantages[edit]

  • Difficult to disassemble structure post-study.
  • Requires routine maintenance (e.g. cleaning parts of the device that is underwater, computer maintenance, removal of detritus in fishway etc.).
  • Does not function well during flood events or high turbidity.
  • The channel makes a good predation spot, increasing vulnerability of certain fish species.
  • If the water flow is too slow, fish can stay in the channel in front of the camera.
  • Difficult to assess fish health based on video image data.

5. Recommendation for method application[edit]

  • The installation of the device needs to be considered during the design/planning stage of the structure (i.e. weir or dam) into which it will be integrated. Meet with the device contractor as soon as possible.
  • Consider the need to install an internet connection for accessing device remotely. This allows for desktop checks on functionality and remote data transfer.
  • Design should consider maintenance needs, i.e. must be safe for the cleaning team.
  • Routine checks and maintenance of the device may need to be scheduled depending on local conditions, e.g. rate of algae and macroinvertebrate growth etc.
  • Underground viewing rooms can provide an excellent opportunity for outreach events, e.g. site visits and media events etc., but must be managed to ensure the capacity of the space is not exceeded.

6. Costs[edit]

Expensive, but construction costs included in the building of the fishway.

7. Data analysis[edit]

From devices that only have cameras (without any measuring apparatus):

  • Species richness and abundance.
  • Populations phenology.
  • Fish behaviour analysis facing the device.
  • Passability of a fishway depending on flow condition.
  • Observe behaviour of predatory fish.

From devices allowing fish measurement:

  • As above, plus assessment of cohort and population characteristics.