Tag: tuna management

Tuna carry evidence of the human causes of global heating

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A group of 22 scientists has discovered that tuna carry inside them clues to how climate heating caused by humans is changing ocean water and types and quantities of plankton – and therefore the tuna we eat.

At the core of their research is one of the elements at the heart of a heating planet: carbon.

By tracing two of the most abundant forms of carbon, the isotopes carbon-12 and carbon-13, they were able to show that a significant amount of global heating is caused by human activities rather than natural processes.

They also found that several other factors also influence the amount of different carbon isotopes in tuna. 

Scientists find evidence of changes in the food chain

One of the most important happens at the start of the food chain, with a group of plankton known as phytoplankton, which use sunlight and carbon to make the energy they need. 

The scientists showed that the abundance of different kinds of phytoplankton has changed in the past 15 years, directly as a result of the burning of fossil fuels. They also showed that the proportion of carbon-12 and carbon-13 available changes the kinds and abundance of phytoplankton. These changes don’t stop here, but alter the kinds and abundance of animals, including tuna, all the way up the food chain.

Numbers of some phytoplankton are shrinking, and this too is affecting the abundance and location of tuna. 

The change in the balance of phytoplankton is made worse by another effect of climate change: ocean stratification. Surface and deep waters of oceans now mix less, and that fewer nutrients are stirred up and made available for plankton to consume. 

The research also showed changes in how quickly phytoplankton grow. 

An example of phytoplankton. Photo US National Oceanic and Atmospheric Administration MESA Project.
Phytoplankton, the foundation of the oceanic food chain. Photo NOAA MESA Project.

The scientists traced two forms of carbon

The research involved scientists from several fields. Among them was Valérie Allain of the Pacific Community (SPC). 

The scientists took 4,500 samples of muscle from albacore, bigeye and yellowfin tuna over 15 years, from 2000 to 2016, from the Pacific, Indian and Atlantic Oceans. They found that changes were most pronounced in the Pacific Ocean.

They traced two forms of carbon, carbon-12 and carbon-13. This is possible because each isotope each has a different weight and also behaves slightly differently. 

Carbon is found naturally in living things, and in the air, land and water. It is also present in coal and oil, and when these burn, carbon-12 is released into the atmosphere. 

More than 90% of atmospheric carbon is absorbed by the oceans. From there, it enters the food chain, being taken up by plankton and passed on to each predator up the chain, until it ends up in tuna, along with other forms of carbon such as carbon-13.

Reporting on their findings in the most recent issue of SPC’s Fisheries Newsletter, Valérie Allain and another researcher, Anne Lorrain, said that the data will be “of inestimable value” in projecting the effects of climate change on the health and quantity of seafood, and in validating modelling. This is because they collected so much data over such a long time and a very large geographical area.

Their research makes much more certain that humans do affect the environments and inhabitants of the open oceans.

Nearly 17,000 tuna tagged in latest research cruise

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More than 16,600 tuna were tagged in a recent scientific tagging expedition in ocean generally north of Papua New Guinea.

The voyage targeted skipjack tuna, which makes up 70% of the volume of tuna caught in the Western and Central Pacific Ocean (WCPO).

Tuna tagging helps the Western and Central Pacific Fisheries Commission (WCPFC) and national fisheries managers assess numbers of tuna. The assessments are used to set catch limits.

This voyage was conducted largely in the exclusive economic zones (EEZs) of Papua New Guinea, Solomon Islands, Palau, and Federated States of Micronesia, with a little time spent also in two pockets of high seas.

In its most recent fisheries newsletter, SPC reported that fisheries authorities in PNG, Palau and FSM provided research permits and gave support to the research being done in their EEZs.

An average of almost 450 tuna were tagged and released each fishing day. Most – 93% – were skipjack, the rest being yellowfin (6%) and bigeye (1%). Most came from free-swimming schools (i.e. the tuna were not caught near fish-aggregating devices, or FADs).

Some fish were implanted with what is known as an archival tag, a physical device which must be inserted using small surgery and a very fast turnaround – no more than 30 seconds – so that the tuna doesn’t become too stressed and lacking in oxygen.

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 an earlier research voyage in the WCPO. Photo Pacific Community (SPC).

SPC reported that it expected some of the tuna tagged in this way would be recovered and would provide good data on the behaviour and movement of the fish.

The agency also reported that some tuna were injected with strontium chloride, a slightly radioactive salt that becomes incorporated into a part of the tuna’s skeleton known as the otolith (or ‘ear stone’). As the fish grows, scientists can use the mark left by the strontium chloride in the otolith to estimate how old the fish is. (Otoliths help fish to balance and to understand how fast they are swimming.)

To conduct the tagging cruise, SPC chartered a pole-and-line vessel from Noro, in Solomon Islands. 

This was the fifth western Pacific tagging cruise, and it lasted from July to September 2019.

Tuna tagging has been carried out regularly since the Pacific Tuna Tagging Programme ran its first voyage in 2006.

This trip came under a new tagging experiment introduced by the Pacific Community (SPC) to implement a recommendation of the 12th meeting of the Scientific Committee of the Western and Central Pacific Fisheries Commission (WCPFC). 

Report indicates key tuna stocks in Western and Central Pacific are healthy

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Republished from SeafoodSource, 12 December 2019

Bigeye, yellowfin, South Pacific albacore, and skipjack tuna are all reported to be in healthy condition, according to a 2018 stock assessment announced this week during the 16th Western and Central Pacific Fisheries Commission (WCPFC) meeting in Port Moresby, Papua New Guinea.

The stock-assessment report of the Pacific Community (SPC) stated that the estimate of the total tuna catch in the WCPFC Convention Area for 2018 is 2,790,859 metric tons (MT), which represents 81% of the total Pacific Ocean catch of 3,443,174 MT, and 54% of the global tuna catch, which was 5,172,543 MT.

According to SPC’s overview of the tuna fisheries paper, the total estimated value of the tuna catch in the convention area increased by 1% to US$6.01 billion (€5.47 billion) in 2018.

The value of the purse-seine catch is US$3.26 billion (€2.9 billion), accounting for 54% of the total value of the tuna catch. The value of the longline fishery increased 16% to US$1.72 billion (€1.5 billion), accounting for 29% of the total value of the tuna catch.

WCPFC Executive Director Feleti Teo said, in his opening statement at the meeting on 5 December, that the region has high levels of tuna production. He said the region’s key commercial tuna stocks of bigeye, skipjack, albacore, and yellowfin were “assessed to have been managed and maintained above agreed sustainable levels”.

Teo added that, compared to other ocean regions, the tuna stocks in the region are not overfished.

Graham Pilling, director of the Oceanic Fisheries Program at the Pacific Community, added in a media release that conservation measures have contributed to the sustainability of the Pacific tuna stock.

“The healthy status of WCPO tuna stocks is attributed to the management of the fishery through the WCPFC process and its members, including the key roles played by the Pacific island member-countries and subregional fisheries agencies including the Fisheries Forum Agency [FFA] and the Parties to the Nauru Agreement [PNA],” Pilling said.

Despite the positive assessment, Teo said that the tuna commission should continue with its collective conservation efforts and not “to be complacent and to be less vigilant”.

But the Pacific Community also pointed out that there are still challenges such as the state of certain Western Central Pacific Ocean billfish and shark stocks that need to be addressed by the Commission. It said they are in need of urgent attention. 

Economic impacts resulting from the recent decline in the price of skipjack tuna also poses a challenge in the region. Skipjack prices have fallen below US$1,000 (€900) per MT for the first time in a number of years. 

But the WCPFC is developing and implementing harvest strategies for key tuna stocks to address the challenges, WCPFC Chair Jung-re Riley Kim said.

“I am very grateful to SPC for their significant contribution to providing science and data inputs into the important harvest strategy work of the commission, and their innovative efforts and initiatives to engage with cooperating members, cooperating non-members and participating territories, and contribute to building their capacity in terms of harvest strategy,” Kim said in a release.  

2019 tuna report card gives thumbs up for four tuna species in WCPO

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School of tuna. Photo FabienForget, ISSF.

The 2019 ‘report card’ on the state of health of tuna fisheries in the Western and Central Pacific Ocean is out.

It said all four species that are economically important in the region – skipjack, South Pacific albacore, yellowfin and bigeye – are being fished sustainably.

In the parlance of the report, “none is being overfished, and overfishing is not occurring”, although there was “no room for complacency” in how fish stocks are managed because all four species continue to decline overall.

The abundance of a species is estimated against a benchmark, called a target reference point (TRP), which is a desirable level of stock needed to maintain the healthy functioning of the species, the environment it lives in, and the sustainability of fishing.

The report card said that numbers of skipjack tuna are above the target reference point (TRP) for that species. TRPs are being developed for the other three species.

The report noted that the value of tuna fishing to the region is increasing, and had passed the target for 2020. 

Local employment in the tuna industry was also increasing, and was on target to meet the 2023 target.

Tuna stocks are not assessed every year, although a report card is issued every year, and uses data from the most recent assessment of each species of tuna. The report cards are published to help fisheries managers meet the goals of the Regional Roadmap for Sustainable Pacific Fisheries.

The report card was published by the Pacific Islands Forum Fisheries Agency (FFA) and the Pacific Community (SPC).

Marshalls fisheries department updating tuna plan with New Zealand aid

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Purse seine fishing vessels have crowded Majuro’s lagoon since late May as low world market prices and over-stocks of tuna at Bangkok canneries have slowed the transshipment process. Majuro has been the world’s busiest tuna transshipment port for the past several years.
Photo: Marianas Variety/Garry Venus,Francisco Blaha

Republished from Marianas Variety, 17 June 2019

by Giff Johnson

MAJURO — The Marshall Islands Marine Resources Authority or MIMRA is engaged in updating its strategic and tuna management plans, said Director Glen Joseph Thursday.

“Tuna is the number one driver of the economy here,” said Joseph. “We’ve had tuna management plans over the years. We’re revising it now so it caters to our regional and international obligations and development of the vessel day scheme.”

Majuro has developed into the world’s busiest tuna transshipment port, with 400-500 purse seine vessel transshipments annually. In 2017, 423 purse seiners transshipped nearly 300,000 tons of tuna in Majuro that were delivered to off-shore canneries by tuna carrier vessels, according to MIMRA.

In addition, revenue generated from the tuna fishery has skyrocketed since 2010 under the management of the Parties to the Nauru Agreement’s vessel day scheme. Marshall Islands is one of nine islands that implements PNA’s VDS to manage purse seine fishing in the region. Tuna revenue hovered around $3 million annually in the early 2000s. In 2017, a new record was set in Marshall Islands with over $33 million generated from the commercial tuna industry.

During the past month, over 30 purse seiners and carrier vessels have been anchored in Majuro’s lagoon awaiting transshipment as low world market prices and a glut of tuna in Bangkok have slowed the transshipment process.

MIMRA’s Oceanic Division is engaged in developing the new management plan with the assistant of two Fisheries New Zealand representatives. Dr. Aimee Komugabe-Dixson, a Pacific Fisheries Advisor, and Hilary Ayrton, a Fisheries Analyst with the Highly Migratory Species Team, have been working since last week with MIMRA’s team at the fisheries department’s Majuro headquarters.

They’ve been meeting daily with Oceanic Division staff since June 3 to put the new plan together.

Komugabe-Dixson made it clear that, “We don’t write plans.” The tuna management plan now in preparation is being developed by MIMRA staff with advice and support of the Fisheries New Zealand team. “We provide structure and guidance,” she said, adding the aim is to “develop a plan that is useable.”

Fisheries New Zealand comes under the Ministry of Primary Industries and the two visiting fisheries advisors are part of a program that is called “Te Pātuitanga Ahumoana a Kiwa” (Partnerships in Pacific Fisheries). It works with government organizations that administer fisheries in Pacific island countries and territories.

Komugabe-Dixson said their program works to build capacity in the Pacific region by developing partnerships and relationships with fisheries staff in each island. MIMRA staff are driving the process for developing the new plan, she said.

Offshore Fisheries Advisor Francisco Blaha, who is based in Majuro and focuses his work with MIMRA staff in tuna transshipment and other tuna-related work, said Fisheries New Zealand takes a long-term view toward developing partnerships in the region that lead to improvements in management of the fishery.