Bluefin tuna are the most prized fish in the lucrative Japanese sashimi market. The local Japanese species, pacific bluefin tuna (Thunnus orientalis) and atlantic bluefin tuna (Thunnus thynnus), are rarely reported in Australian waters. However thanks to strong international management, the sister species, southern bluefin tuna (Thunnus maccoyii), are becoming more abundant off the coast of Australia each year.

When caught in an Australian commercial fishery, every southern bluefin tuna (SBT) must be tagged with an official, individually numbered tag. The tags are made from a high impact plastic that is able to withstand freezing to -60 degrees Celsius and once applied cannot be easily removed. Any SBT without tags cannot be legally sold, either in Australia or Japan. Fish without tags will not be allowed into Japan and compliance is stringent.

The length and the weight of each tagged fish are recorded and submitted to the Commission for the Conservation of Southern Bluefin Tuna (CCSBT). Previously, all of this data had been handwritten onto paper forms. As you can imagine, for 600t or approximately 12,000 fish this can be a time consuming process and recording long, ten-digit alpha numeric codes can lead to errors.

This year, for the first time, all tags used by Australian commercial longliners have bar codes. Not only does this improve the efficiency of entering the length and weight data into electronic databases, it allows fish to be more easily tracked from the moment they are caught to when they are sold in a market in Sydney or Tokyo.

Systems tracking food ‘from the paddock to the plate’ are often referred to as traceability systems and are becoming more common in all areas of food production, but are increasingly  being used in fisheries to ensure illegally caught fish don’t enter the market.

The traceability system used for SBT is set up by CCSBT and is called the Catch Documentation Scheme or CDS. It requires all SBT caught by commercial boats, whether they are Australian, Japanese or any other member, to tag, weigh and measure each and every fish once it is caught.

Commercial caught couthern bluefin tuna can only be caught by an authorised vessel and can only be landed to an authorised fish receiver, who is registered with CCSBT. They must complete detailed paper work for each consignment of fish and independently verify the weight of every fish landed. Each export consignment also needs to be authorised by an authorised government delegate.

Most internationally traded SBT end up in Japan. Japanese officials are able to check that all fish being imported into Japan are tagged and are accompanied by the authorised paperwork. It is not uncommon for Japanese officials to scrutinise the paper work for even the smallest discrepancies and shipments have been known to be delayed or impounded in cases where paperwork was not one hundred percent correct.  

The introduction of the CDS is one of the key reasons that scientifically set catch limits are now adhered to, which has led to the rebuilding of the SBT population.

During the 1960s, 70s and 80s, SBT were overfished by commercial boats. The CCSBT was formed in 1994 but was largely unsuccessful in rebuilding SBT throughout the late 1990s and early 2000s. Dramatically improved compliance and strong science based international catch limits implemented over the last 12 years have seen the population of SBT rebuild from historic low levels of the early 2000s. This rebuilding has seen improved numbers of SBT off south-eastern Australia and led to increased catches from both recreational and commercial fishers, but there is still some way to go before the stock will be fully recovered.

Despite the recent increase in numbers, the population remains quite low compared to pre-fished levels, with the breeding population still less than 20 per cent of what it was in 1950. The good news is that continued sound management by the CCSBT, the Australian Fisheries Management Authority (AFMA) and state fisheries authorities, should continue to rebuild the stock. To make sure that this happens, Australia has the responsibility to ensure its entire catch is within the limits set by CCSBT.

Last year, commercial longliners off NSW and Tasmania caught over 600t of SBT, the highest catch in nearly 30 years. All of the commercial catch is required to be covered by quota issued by AFMA and the catch is closely monitored to ensure catches remain within sustainable levels.

All commercial boats in Commonwealth waters are required to have a satellite based monitoring system so that AFMA knows where they are at all times. Tuna longliners are also required to have an electronic monitoring system (known as e-monitoring) installed on their boats. These systems involve four cameras, that record all fishing activity. E-monitoring is used to ensure all SBT catches are recorded on official logbooks and that no dead fish are discarded. Small tuna are allowed to be released only if they are alive and vigorous.

The rebuilding of the SBT stock is a demonstration of what good fisheries management can achieve, with science and consultation with industry contributing to the determination of rules and catch limits. What it has shown is that if global catches can be kept within scientifically set limits, tuna populations can increase. The Australian commercial SBT Fishery is managed to ensure that every fish is counted against quota. As a group with a strong track record of fisheries stewardship, it will be crucial for recreational fishers to also play a strong role in managing total catches of SBT within sustainable limits. 

View the article printed in issue 133 of Bluewater Magazine.