Hawaiʻi Deep 7 Bottomfish Research in the Maui Nui Region to Develop a Fishery-Independent Survey for MHI Bottomfish Stocks

October 15, 2015
The NOAA Ship Hiʻialakai departing Pearl Harbor.
The NOAA Ship Hiʻialakai departing Pearl Harbor.

On October 15, 2015, the NOAA Ship Hiʻialakai departed her homeport of Pearl Harbor, Oʻahu, to continue exploring the use of deep water camera systems to study Hawaiian bottomfish in the waters between the islands of Maui, Lānaʻi, and Kahoʻolawe. Seven species of deepwater snapper – Onaga, Ehu, Kalekale, ʻŌpakapaka, Gindai, Lehi – and one species of grouper (Hapuʻupuʻu) are commonly known as the "Hawaiʻi Deep 7" and are among the most important of our commercial and recreational fisheries. These brilliant red fish are commonly a mealtime centerpiece at family gatherings around the holidays.

The Hawaii Deep 7 species: 
        a) onaga (Etelis coruscans); 
        b) ehu (E. carbunculus); 
        c) kalekale (Pristipomoides sieboldii); 
        d) ʻōpakapaka (P. filamentosus); 
        e) gindai (P. zonatus); 
        f) hāpuʻupuʻu (Epinephelus quernus); and 
        g) lehi (Aphareus rutilans).
The Hawaiʻi Deep 7 species: a) onaga (Etelis coruscans); b) ehu (E. carbunculus); c) kalekale (Pristipomoides sieboldii); d) ʻōpakapaka (P. filamentosus); e) gindai (P. zonatus); f) hāpuʻupuʻu (Epinephelus quernus); and g) lehi (Aphareus rutilans).

The NOAA Pacific Islands Fisheries Science Center (PIFSC) leads this 11 day expedition as part of a broader collaboration with the Pacific Islands Fisheries Group (PIFG), a team of scientists from the University of Miami Rosenstiel School for Marine and Atmospheric Science, NOAA and the University of Hawaiʻi Joint Institute for Marine and Atmospheric Research to operationalize a fisheries-independent survey.

The work aboard the Hiʻialakai focuses on the continued research and development of a new digital video camera system to collect video of Deep 7 bottomfish. Video cameras allow researchers to collect information on fish abundance without catching or harming them and also within protected areas where fishing is not allowed. This is called a fisheries-independent survey, or a survey in which no fish are captured and removed from the system.

Our video camera, the modular optical underwater survey system (MOUSS) unit showing frame, harness, video recorder (DVR) bottle (top 
        center), battery bottle (bottom center), power cables, and two cameras.
Our video camera, the modular optical underwater survey system (MOUSS) unit showing frame, harness, video recorder (DVR) bottle (top center), battery bottle (bottom center), power cables, and two cameras.

The video systems being tested are stereo-camera systems. These use binocular vision similar to human eyes, which allows researchers to accurately both count and measure the fish captured in the video. In these field trials we are testing, the "MOUSS" or Modular Optical Underwater Survey System, which is a new smaller, lighter, and more versatile version of the larger "BotCam" underwater camera system that has been used in Hawaiʻi for many years. During this most recent mission, the small survey vessels (the Rubber Duck and the Steel Toe) launched the MOUSS 176 times. The Hiʻialakai also conducted 31 deployments of a combined BotCam and MOUSS system; this means that both camera systems were recording the same field of view.

BotCam video of ʻōpakapaka (video contains no audio).

Back at the lab, researchers will use special software to scan through the video collected by each camera, find that period of time with the most fish and analyze the frames identifying, counting, and measuring the Deep 7 species within them. They then compare the data between the camera systems. Were the measurements the same? Different? Why? What was the error range? This combined camera work is necessary to ensure that the data we collect using the MOUSS is comparable to that collected with the older dependable BotCam system. Eventually only the newer smaller and lighter system will be deployed in our fisheries independent survey.

Ultimately this fisheries-independent survey will give us an estimate of how many individual fish there are of each species and how big they are without having to rely only on catch information. We can use both the estimates of numbers of fish, as well as the length information, to get at how many and how old the fish are, which is important for stock assessments because it gives us an idea of how many are likely to be reproducing and how many fish may be available in the future.

One of the PIFSC 19' SafeBoats on its way back to the NOAA Ship Hiʻialakai.
One of the PIFSC 19' SafeBoats on its way back to the NOAA Ship Hiʻialakai.
A screen grab example from the SeaGIS EventMeasure™ desktop software package showing measurement (red line) of 
        individual fishes.
A screen grab example from the SeaGIS EventMeasure™ desktop software package showing measurement (red line) of individual fishes.