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Contracting Party or fishing entity. Data provided by scientists during the SCRS meetings are also included. The
stock assessment methodology is mostly based on the VPA with a lot of exploratory hypothesis or comparison
with other methodologies when necessary. The SCRS and the ICCAT Secretariat have high-level experts able to
run these sophisticated models, which are considered the best available on the scientific market. This situation,
which appears as one of the best among the various RFMOs, is not able to overcome a series of problems which
are knows since many years.

It is well known that VPA is a model widely used in many fisheries and for a broad range of species, but it is not
adequate to describe the enormous complexity of species having a huge geographic distribution and very
complex movements (even massive), either vertical and horizontal. It relays mostly on total catch by gear, size
frequencies distribution by gear, area and time strata, recruitment and standardised CPUE series by gear (other
inputs exists and others are also possible). It provides a range of predictive hypothesis, which could be huge
according to various choices, taking into account the uncertainties inputted by the scientists. This is the best
available tool at the moment and this is the reason why it is adopted by SCRS and ICCAT, but everybody knows
that it is not a magic tool and its limits in describing large pelagic fish populations are very well known by the
specialists. Anyway, this is what we have and we have to deal with it.

There is a very well-known sentence about the mathematic models: “garbage in, garbage out”. It is often recalled
during the SCRS discussion to underline the bad quality of several data sets, particularly those on bluefin tuna
and even more so after the adoption of the quota system in 1996. In the past situation, catch data were sometimes
incomplete or missing for some Contracting Parties (the statistical services were very different in each CP), but
they were “honest” in their quality. Size frequencies, biological data and CPUE were usually provided by
scientists and, even if they were often very localised, their quality was always considered sufficiently reliable.

When ICCAT decided to adopt and enforce the quota system for the bluefin tuna (was the first TAC never
adopted in the Mediterranean Sea and it is still the only one), then the “gold rush” started and this was the cause
of the incredible deterioration of the data submitted to ICCAT, as SCRS reports stated for many years.

The data that were submitted by scientists at the end of the 1990s were used by some CPs to raise issues about
compliance with the ICCAT rules, even if this is not possible in theory. This fact created an enormous problem
in the system, because scientists coming to SCRS meetings, and particularly those working under contracts with
national governments (the large majority), started to pay a lot of attention to their data, avoiding to present data
that were in contrast with the official data provided by the governments. This doesn’t mean that the scientists
manipulated their data: it simply means that some data sets were not presented anymore. This fact is very evident
when examining the size frequencies and their distribution. Small tunas became rare in the reports, because the
undersize catches were not reported by many of the CPs.

This is a very relevant point, because it raises a few important and basic problems: the use of scientific data for
compliance issues and the direct detrimental effects on the assessment model.

The first is a procedural problem, because scientific data must always be used only for scientific purposes, to
better understand the situation concerning a species and for suggesting the necessary strategies to better manage
that species according to the best scientific evidence. If those data are used against individual Contracting
Parties, it is logical that national scientists cannot take this individual responsibility on their shoulders. This is an
old discussion, going on in various fora: as a general principle, data from scientists should be used only for
scientific purposes, while data from inspectors can be used for compliance purposes. The risk in also using the
scientific data for compliance purposes is to face the situation SCRS is facing since years.

The second is a perverted effect, because if Contracting Parties are not reporting the catch of undersized fish,
then it is very difficult to understand how recruitment occurs every year, particularly when fishery-independent
research is not available. The fishery of juvenile bluefin tuna is quite common in the Mediterranean since
historical times. It is reported by ancient writers, but it was considered a great problem also in the 18th and 19th
centuries: Avolio (1805) underlined the need to protect the juvenile bluefin tunas and reported royal decrees
imposing the protection of juveniles and the prohibition to catch, retain and sell them from September to
December in 1795, extended to March in 1796. ICCAT had established various measures to protect juvenile
bluefin tunas, but some of them were contradictory, allowing derogations for some fisheries, due to political
negotiations carried out at the Commission level. But the real problem was not only the catch of juveniles by
large vessels in some areas: it is the huge amount of small boats and vessels catching juvenile bluefin tuna when
these fish approach the coast to get the best food chain. As was written in several reports (Di Natale et al., 1986,

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