SE16-01: Bottomfishing for samples

The primary objective of the NOAA/PIFSC Life History Program is to provide the basic biological and ecological information of subsistence, recreationally, and commercially valuable species for stock assessment and management purposes.  The more we know about a species life history (age structure, growth rates, morality rates, size- and age-at-sexual maturity), the more accurate are the estimates of stock status (i.e. number of fish in a local population) which, in turn, can lead to more appropriate management for sustainable fisheries.  Samples from Samoa Archipelago bottomfish (palu-lua, palu-malau, palu-sina and other deepwater snapper (Figure 1) are difficult to obtain for a variety of reason therefore; our knowledge of these species is lacking.  A major objective of the Samoa Archipelago Fisheries Research Cruise is to gather as many samples as possible for laboratory analysis and life history estimation at the NOAA Inouye Regional Center (home of the Life History Program).

Figure 1. Select bottomfish from Samoa captured during SE16-01 waiting to be processed.

Figure 1. Select bottomfish from Samoa captured during SE16-01 waiting to be processed.

During this cruise aboard the NOAA Ship Oscar Elton Sette, we are targeting the following deepwater snappers:

Common English Name Scientific Name Samoan Name Hawaiian Name
flame snapper Etelis coruscans palu-malau onaga
pygmy ruby snapper Etelis carbunculus palu-malau ehu
giant ruby snapper Etelis sp. palu-malau *
crimson jobfish Pristipomoides filamentosus palu-ena’ena opakapaka
goldflag jobfish Pristipomoides auricilla palu-ave yellowtail kale kale *
goldeneye jobfish Pristipomoides flavipinnis palu-pa’epa’e *
rusty jobfish Aphareus rutilans palu-gutusiliva lehi

* does not occur in Hawaii

These species are concentrated near deep-slope environments at depths ranging from 60 fathoms (360’, 110 meters) to 220 fathoms (1,320’, 402 meters).  Many of the targeted species have a strong species-specific habitat preference associated with substrate.  Yet even though these fish require certain types of high structural complexity, we see there is much overlap in the fish among the depth distributions.  The essential fish habitat of pinnacles, drop-offs and rocky substrate for bottomfish species are limited due to this area being primarily volcanic seamounts, thus, targeting these locations can be difficult.  In an effort to aid in the location of preferred bottomfish habitat, the potential fishing sites are identified using the ships instruments during nightly and early morning surveys.  Scientists then use displays on their small boat to zero in on the fish.  However, scientists need more than the knowledge of where a specific fish might be located in the ocean.

Scientists often recruit experienced fishermen to assist with the collection of specimens for their research. With the help of fishermen, scientists have collected fish using techniques similar to the commercial bottomfish fishery in the Hawaiian archipelago (Figure 2).  These fish are collected on a “rig”, which consists of a series of hooks that are arranged in varying distance from the bottom.  Each “rig” is weighted with a 4-5 pound weight to ensure that the deep depths of the preferred habitat are reached.  When a fish is hooked, they are brought to the surface using hydraulic and electric fishing reel (Figure 3).  When fish aren’t being caught scientists use video cameras in deepwater housings to determine if the fish aren’t there or are there and just aren’t biting at that time (Figure 4).

Figure 2. Scientists and fisherman collecting samples during SE16-01. Note: it’s not always sunny skies in Samoa.

Figure 2. Scientists and fisherman collecting samples during SE16-01. Note: it’s not always sunny skies in Samoa.

Figure 3. Scientist excited about a fish on the line (if you listen carefully you can almost hear her yelling “hanapa’a!”). Notice the electric fishing reel.

Figure 3. Scientist excited about a fish on the line (if you listen carefully you can almost hear her yelling “hanapa’a!”). Notice the electric fishing reel.

Figure 4. A still frame from the bottomfishing camera. A GoPro in a special housing is deployed on the fishing line and videos fish, their behavior and habitat.

Figure 4. A still frame from the bottomfishing camera. A GoPro in a special housing is deployed on the fishing line and videos fish, their behavior and habitat.

Any fish collected is a valuable asset to the research mission and kept in the most pristine condition until it can be ‘processed’ for research analysis (Figure 5).  During fish processing, scientists on board weigh, measure and determine the gender of each fish.  They then extract otoliths (fish ear “bones”) for age estimates, gonads (ovaries and testes) for reproductive status, and fin clips for genetic studies that identify stock structure.   It is important to note that some of the fish captured during the cruise are used to feed the crew or are saved for public outreach events.  However, the majority are frozen for distribution to local charities whenever we reach port.

Figure 5. Scientist processing assembly line. All fish are identified to species, weighted, measured, and sexed. Biological samples (otoliths, gonads, fin clips) are extracted for life history studies.

Figure 5. Scientist processing assembly line. All fish are identified to species, weighted, measured, and sexed. Biological samples (otoliths, gonads, fin clips) are extracted for life history studies.

The fishing has been good in American Samoa (Figure 6).  We have collected enough samples that soon after the cruise we should be able to start producing life history information for Samoan Archipelago bottomfish.  We aim to build collaborations with our Samoan colleagues from the Ministry of Agriculture and Fisheries and the Ministry of Natural Resource and Environment because they are the local knowledge.  In fact, many are participating in the final leg of SE16-01 which begins on March 30, 2016 (US) and focuses on the Independent State of Samoa waters (upcoming blog).

Figure 6. A 31 kg Etelis sp. being weighted by scientists aboard the NOAA Ship Oscar Elton Sette. This fish will provide vital information about this newly described species that was recently distinguished from its congener Etelis carbunculus.

Figure 6. A 31 kg Etelis sp. being weighed by scientists aboard the NOAA Ship Oscar Elton Sette. This fish will provide vital information about this newly described species that was recently distinguished from its congener Etelis carbunculus.

Stay tuned to the PIFSC Blog for more updates from the Samoa Archipelago Fisheries Research Cruise.  Next we’ll be showing you highlights from our coral reef life history research…

For a cruise overview, click here.

To read about the SE16-01 Blog 1 – Outreach event with American Samoa Community College Students, click here.

To read about the SE16-01 Blog 2 – Secretary of the Office of Samoan Affairs, District Governor of Manu’a, and District Governor of American Samoa East District visit the NOAA Ship Oscar Elton Sette in Pago Pago, American Samoa, click here.

To read about the SE16-01 Blog 3 – Nightlight fishing for atule in American Samoa, click here.

 

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