How do we Monitor Fish?

There are two common methods for monitoring the number of fish in and outside of reserves. Scientists monitor fish so that they are able to calculate how many fish there are. The two common methods are Baited Underwater Video and Scuba Diving.

What is a Baited Underwater Video?

A Baited Underwater Video (BUV) is a triangular metal frame with a camera pointing downwards to a bait box. BUV is used by DOC to to compare the abundance (how many individuals of species that are present) of fish inside and outside marine reserves.

How do BUV work to capture footage in Marine Reserves?

The frame is lowered off the side of the boat, where it settles onto the rocky reef or seabed. Small underwater floats keep the frame upright, and a rope attached to a surface buoy which ensures the frame and camera can be retrieved. After the camera has been filming for thirty minutes, it is pulled back up to the surface and deployed again in a different location to capture more footage in another spot.

buv frame diagram.png

What is Scuba Diving?

Scuba diving is where divers wear a self contained underwater breathing apparatus to help them stay underwater for long periods of time. A scuba diver can complete fish monitoring by having an underwater camera and manually take footage of the fish.

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BUV vs Scuba Diving to capture footage:

  • Scuba Divers can scare and attract different fish which can affect numbers captured
  • BUV can collect footage a lot deeper than a diver can
  • BUV is not affected by visibility as much as a Scuba Diver as long as the BUV reaches the seabed. On a murky day Divers have limited vision and this will affect the number counted

sevengill shark clear water CON28_2012_Parininihi.jpg

A sevengill shark (Notorynchus cepedianus) swimming over a BUV size marker and bait box (Spyfish Aotearoa).

Keywords

  • Baited Underwater Video (BUV)
  • Scuba Diving
  • Fish Abundance