2020 tuna research at sea conducted, but cut back to follow COVID-19 rules

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Two important tuna research trips have gone ahead in the Western and Central Pacific Ocean (WCPO) this year, although the research programs and the routes had to be curtailed dramatically.

Both programs, which are run by the Pacific Community (SPC), were cut back to comply with regional practices put in place to prevent the transmission of COVID-19.

For the Pacific Tuna Tagging Programme, scientists continued routine tagging of tuna and tested new sampling methods that will help scientists analyse the structure and behaviour of tuna populations. 

The research was conducted in the high seas and the exclusive economic zone (EEZ) of the Kiribati groups of Line Islands and Phoenix Islands. 

This year’s cruise was originally to have focused on understanding more about the habit of tuna to gather around drifting fish-aggregating devices (FADs). It was to have been conducted in waters around Tuvalu, which have one of the highest densities of drifting FADs in the WCPO.

Three men on deck of research vessel Gutsy Lady 4 being prepared at Kewalo Basin, Honolulu, for the tuna tagging cruise in the central Pacific. Photo SPC.
Research vessel Gutsy Lady 4 being prepared at Kewalo Basin, Honolulu, for the tuna tagging cruise in the central Pacific. Photo: SPC.

SPC research scientists Bruno Leroy and Valérie Allain reported on this year’s tuna tagging cruise in issue 162 of SPC’s Fisheries Newsletter.

The tagging cruise left from Honolulu, Hawaii, in mid-August, and returned to the same port in early October, staying clear of any other ports. Mr Leroy and Dr Allain said that protocols to protect Pacific Islands people from COVID-19 meant that, before the research vessels could depart, the crew and scientists had to stay isolated for 14 days and return negative test results to the disease.

Mr Leroy said that, since the Pacific Tuna Tagging Programme began in 2006, about 455,000 tuna had been tagged. If SPC tagging campaigns carried out since the end of the 1970s were included, the number was more than 800,000. On the 2019 cruise, researchers tagged nearly 17,000 tuna.

Second study to develop better ways to sample small marine animals 

Bruno Leroy and Valérie Allain also reported on a second SPC research cruise, which was also curtailed to comply with COVID-19 rules. 

The SPC’s scientific team conducted a four-day trial to develop a new sampling method to collect micronekton from the surface of the ocean to a depth of 600 m. (Micronekton are marine animals such as fish, crustaceans, jellies and squids that measure 2–20 cm in length. They are the main source of food for seabirds, tuna and marine mammals.)

As the research vessel Alis is based in New Caledonia, the trial was conducted inside the country’s EEZ.

The original cruise planned for this year in the waters of New Caledonia, Solomon Islands and Federated States of Micronesia has been postponed until 2021. It is part of a long-term program to study the ecosystem of the open oceans in the Western and Central Pacific. 

Crew on the research vessel Alis haul in a net full of micronekton during the 2020 research cruise in New Caledonian waters. Photo: Valérie Allain, SPC.
Crew on the research vessel Alis haul in a net full of micronekton during the 2020 research cruise in New Caledonian waters. Photo: Valérie Allain, SPC.

Western and Central Pacific banks on SPC specimen collection

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One of the most important tools in understanding the biology and environment of tuna in the Western and Central Pacific Ocean is a bank.

This particular institution, the Pacific Marine Specimen Bank (PMSB), has been slowly building its revenue of research currency – muscle, organ and bone samples, stomach contents, photographs, and radiographic images – since 2000.

It also collects samples from other large, oceanic species such as marlin and swordfish that are also economically valuable.The PMSB is managed by scientists in the Oceanic Fisheries Programme of the Pacific Community (SPC). The datasets held in the bank help the scientists understand the world of tuna. Their knowledge forms part of SPC’s annual assessments of the state of health of tuna populations. In turn, the assessments are used to manage tuna fishing in the region.

Analysis of the specimens held in the bank also helps scientists understand how the climate crisis is influencing changes in the location of tuna and changes in their diet.

Specimen banks are important because they throw light on our understanding of current situations – and because scientists in the future can use the same samples to find answers to new questions or to ask the same questions using new techniques or research tools.

Four of the scientists involved in PMSB explained the difficulties of managing the specimen bank in the latest Fisheries Newsletter published by SPC.

One of the challenges the staff of PMSB face is ensuring that samples, which are collected all over the Western and Central Pacific Ocean, are kept in prime condition until they get to a permanent storage facility. Part of the scientists’ work is to prepare some samples to make it easier to transport them to analysis laboratories outside New Caledonia.

Two tuna lie in a cradle on a fishing vessel at sea. They are being tagged for scientific research by two men. Photo Pacific Community.
Tagging tuna on a pole-and-line vessel during a research voyage in the WCPO. Data collection during tagging is stored in the specimen bank. Photo: SPC.

Much care goes into getting, storing, and transporting samples so they can be used for immediate research and analysis, and also in many years’ time.

This usually means that they have to be kept cold enough. Many samples can be kept at –20°C; however, those used in genetic analysis must be kept at –80°C. Freezers of the second kind are difficult to come by, and expensive to run.

Other tissue must be preserved in formalin and then transferred into ethanol.

The nine cubic metres of freezer space at the laboratory at SPC in Noumea is now too small to contain the growing collection. Although there are plans to enlarge it, research partners are also helping to house pieces of the collection in other parts of the region.

And SPC has funded the purchase of freezers in the main fishing ports in the region to that samples can be stored safely until they are transferred to their final destination.

In April, the PMSB contained nearly 120,000 samples collected from 34,000 specimens. Some national observer programs have participated in collecting samples for the bank since 2002.

Note: post updated 6 July 2020 to correct a spelling error.

Survey shows focus on tuna stocks

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A survey of people interested in Pacific fisheries shows that 92% were most interested to find out more about tuna stocks in the Pacific.

97 people completed a survey about a new website being developed by the Oceanic Fisheries Management project.

The next topic of interest was finding out about fishing catch statistics.

Catching tuna in the Pacific (Photo: SPC)
Catching tuna in the Pacific (Photo: SPC)