How do we monitor fish?

There are two common methods for monitoring the number of fish in and outside of reserves. Scientists monitor fish to calculate how many 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. Scientists use BUV to compare the abundance (how many individuals of species are present) of fish inside and outside marine reserves.

How does BUV capture footage in Marine Reserves?

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

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 record photos of fish with an underwater camera or use an underwater pen and paper to write down how many fish has seen.

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

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