Tracking back from plate to net

88 % of species fished in Europe cannot be optimally replenished because they are overexploited. © Shutterstock
88 % of species fished in Europe cannot be optimally replenished because they are overexploited.
© Shutterstock

Combating illegal fishing is critical for achieving sustainable management of the seas. But the very vastness of the big blue makes it extremely difficult to outwit fraudsters. Researchers are right now developing new tools to trace a fish’s origin and determine whether it was caught legally or not.

‘Sea fishing is free because it is impossible to exhaust the wealth of the sea,’ wrote legal expert Hugo Grotius in his book Mare Liberum back in 1609. Since then, things have changed dramatically. 28 % of fished species are now overexploited, depleted or in the process of rehabilitation, and 52 % of stocks have reached a point of maximum exploitation(1). In Europe, 88 % of species are unable to renew optimally because exploited beyond the limits of maximum sustainable yield. For the 30 % that are outside safe biological limits(2), it may already be too late.

With restrictions on the size and number of vessels and the amount of time at sea or imposition of fishing quotas by species, the fishing industry labours under such a weight of regulations that some choose simply to disregard them. This is now a major problem that is threatening the proper management of fish stocks. Experts refer to this problem with the words ‘illegal’, ‘unreported’ and ‘unregulated fishing’ – IUU (« Illegal, unreported and unregulated fishing: reference points »).

Elusive illegal fishing?

‘In Europe, illegal and unreported fishing rose sharply in the mid-’90s in the wake of a cut in fishing quotas which were introduced without real consultation with fishermen, who often perceive these measures as unjust,’ says David Agnew, a researcher in marine biology from Imperial College London (UK), a specialist in issues relating to IUU fishing. ‘Over the past two to three years, the situation has improved. New national and European measures have been introduced that better reflect the difficulties that fishermen encounter. There has also been a strong response from the processing industry to limit the trade in fraudulent catches.’

But illegal fishing continues. According to a recent study led by David Agnew, between 11 and 26 million tonnes of fish are caught each year illegally and without being reported, equivalent to between 12 % to 31 % of the total global sea catch(3). To arrive at these figures, David Agnew and his team had no other choice than to carefully pick through existing national-level reports and case studies. ‘The problem is right there,’ he explains. ‘These documents are based on a wide variety of techniques. There is no standardised methodology, which makes any general assessment approximate.’

For Gary Carver, professor of molecular ecology at Bangor University (UK), countering illegal fishing is a question of resources. ‘IUU fishing continues mainly because there is no technology to determine the origin of fish. If a ship is spotted in an area that is closed to fishing, inspectors have no tools to prove that the catches aboard the vessel actually come from that part of the sea.’

Anti-fraud genetics

Since February 2008, Gary Carvalho has been coordinating FishPopTrace, a European project that has set out specifically to develop a set of tools to track down the geographic origin of a catch and in this way determine whether the fish was caught illegally or not. ‘The main objective is to design an analysis protocol that is easy to use by inspectors and accurate enough for the results to serve as evidence in court against those responsible for IUU fishing,’ he explains. ‘Our research focuses on four of Europe’s most caught species: cod, hake, herring and sole. But the technique can in principle be used for all European stocks’.

The protocol the FishPopTrace researchers have developed breaks down into three steps. The first step is to determine the species of the tissue being analysed. Here, researchers are focusing on genetic features that act as ‘barcodes’. The principle is to examine a genetic marker and compare it with information collected in a database. From this one can determine the species of the sample in question (see « Genetic barcodes»).

Once the species is known, it remains to locate the origin of the specimen. For this, researchers are focusing on the single nucleotide polymorphisms (SNPs), that is minuscule variations of the nitrogenous bases of DNA. These mutants are specific to each individual fish, even within the same species. ‘We are hoping to identify 1 200 SNPs for each species studied by FishPopTrace,’ says Gary Carvalho. ‘These SNPs are all specific to the populations of a given area. By setting up databases, we will end up with a set of collective signatures and be able to trace the origin of the products tested.’

Between control and listening

The latest analysis technique that Fish- PopTrace has developed can further refine the previous results. This time, the method relies, not on the DNA but on the otoliths, the bones of the inner ears of the fish. ‘Just like tree rings, the shape and biochemical composition of the otoliths vary depending on the environment surrounding the specimen. Analysis of otoliths allows us not only to define the age of the fish, but also the composition of the seawater in which it has evolved,’ says Gary Carvalho.

We can thus refine the geographic location established using SNPs while determining if the fish has been caught prematurely, because there are also regulations that seek to secure the renewal of populations by prohibiting the capture of undersized fish.

Launched in 2008, the FishPopTrace project is still in its infancy, but Gary Carvalho is confident. ‘We’ve already identified many SNPs for each species studied. It remains to determine which are most relevant for locating the original environment of the fish. We have also launched a huge sampling campaign to create the database with which to compare the results of the different analyses. This is a timeconsuming process, but we are already well on the way and the project is not planned to end until February 2011.’

There is no doubt that this sort of research can pave the way towards more effective control of fishing fraud. ‘With the development of new deterrent tools we should, however, not forget the need to involve fishermen as much as possible in any decision-making on the sustainable management of stocks,’ David Agnew insists.

Julie Van Rossom

  1. «The state of world fisheries and aquaculture 2008», FAO, Rome, 2009 –
  2. Green Paper: «Réforme de la politique commune de la pêche», Commission européenne, 2009 –
  3. David J. Agnew & Co, «Estimating the Worldwide Extent of Illegal Fishing», 2009 – NB: This study does not take into account unregulated fishing, which, in the author’s opinion, is extremely widespread.

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Genetic barcodes

To identify the species of a particular piece of tissue, researchers examine, not the nuclear DNA, but the mitochondrial genomes. These intracellular structures (organelles) are abundant in the cells and their DNA is easier to isolate, even when the tissue has been cooked or industrially processed. And as part of their genetic sequence has a specific structure for each species, we can use this sequence as a sort of bar code for identifying them.

‘This is a formidable weapon for protecting consumers,’ says Gary Carver, professor of molecular ecology at Bangor University (UK). ‘Already several years ago, an analysis of the genetic barcodes of the content of tins marked as containing red snapper showed that 77 % was in fact of another type of fish!’

Illegal, unreported and unregulated fishing: reference points

Illegal fishing: applies to vessels that violate the rules, for example by fishing in prohibited areas.

Unreported fishing: refers to boats failing to report all or part of their catches to the competent authorities.

Unregulated fishing: takes place in highseas areas not falling under the jurisdiction of any regional fishing regulatory authority.


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