| dc.description.abstract | Quality control of data collections is
an issue of primary importance in
conducting science and this is no
different for surveys intended to
monitor changes in fish abundance.
Essentially,
quality control is the responsibility of
the national institutes conducting the
surveys. However, if the national data
are combined in a common international
data base, as is the case with
DATRAS, the consistency of the data
submitted engages an international
dimension, because the reliability of
any comprehensive analysis of changes in
the fish community at large that
could serve as the basis for ICES advice
depends on the reliability of the
species identifications in all national
subsets. Many of the surveys that are
routinely carried out jointly under the
auspices of ICES have a
long history during which the primary
objectives have changed. Thus, the IBTS
started as a Young Herring Survey, was
then transformed in a Young Fish Survey
to obtain recruitment
estimates of commercial species, and
became only a general monitoring survey
of the entire fish community at a later
stage. Despite these changes in general
objectives, the emphasis in
data use is still largely focused on the
commercial species that are relatively
easy to identify. Although measurement
errors and punching errors for this
group may have entered the data
base, as evident from unrealistically
small or large individuals reported in
some cases, it seems generally safe to
conclude that, in view of the large
amount of detailed data collected for
these
species, these could lead only to minor
and negligible distortions in the
analyses. However, when it comes to the
less common species, studies of the IBTS
component in the past have
proven major inconsistencies in species
identification in the data set that has
been entered in DATRAS. This problem is
not restricted to a single or a few
countries, but affects all
countries, although the species involved
may differ. This suggests that it is a
direct consequence of the large number
of people involved in data collection on
board and of a generic lack of good
taxonomic knowledge among the scientific
staff at large that inhibits the
maintenance of enough quality control.
The problems identified in the past have
been the direct reason for holding this
one-off workshop to discuss the various
aspects of identifying inconsistencies
and correcting species
identifications in historic data sets
and of ensuring correct species
identification in future data
collections. Taxonomic quality control
is a complex issue, because the problems
vary by
region depending on the species that may
be encountered and therefore may require
specific approaches regionally.
Moreover, the ultimate responsibility
for introducing specific protocols
for quality control rests with the
survey working groups responsible for
data collection rather than that the
appropriate procedures can be prescribed
by others. Therefore, the aim of the
workshop has been to provide generic
guidelines for development of suitable
protocols by the survey working groups
rather than to come up with a final
answer.
It must be emphasized that so far
progress in identifying inconsistencies
in reporting of various taxa has been
restricted to the IBTS component of
DATRAS, which covers the North
Sea, Skagerak and Kattegat. For all
other surveys, similar analyses have not
yet been conducted, but there is no
reason to assume that the situation
would be any different.
Following the Terms of Reference, the
report is split in four sections that
deal with each of these respectively.
Section 3 deals with ToR a): “Identify
and correct taxonomic
mis-identifications and input
errors in DATRAS”. Obviously, this
ultimate goal was beyond reach during a
three-day workshop, and a lot more work
needs to be done. This section lists
dubious species,
inconsistent information provided
regarding taxonomic level reported,
maximum attainable size and area of
distribution, and examples of
inconsistent information reported for
some
problematic taxa. The information given
is restricted to the IBTS component of
DATRAS, but should not be interpreted as
a comprehensive analysis of all
inconsistencies that may be
2 | ICES WKTQD Report 2007 present in
this data set. Rather, it highlights
methodical aspects as to how
inconsistencies may
be elucidated. Section 4 deals with ToR
b): ”Development of protocols for
ensuring the appropriate treatment of
data reported at higher taxonomic
levels”. Historically, different
countries have
reported variously species at different
taxonomic levels (genus or families).
Also, uncertain species records may have
to be adjusted by using a higher
taxonomic level. As a consequence,
subsequent community analyses may
require that these higher taxa are split
into its constituting species based on
identifications considered reliable.
Because there are various
ways to do such computations depending
on the assumptions made, different
analyses could give different answers.
From an ICES perspective, some
consistency in the approaches used
by different working groups would seem
appropriate. This section provides the
essentials of an appropriate algorithm
based on using length frequencies, area
of distribution and year of
catch, that could serve as a first
guideline for comprehensive community
analyses as well as for trend analysis
of individual species.
Section 5 deals with ToR c): “Develop
improved protocols to ensure that
species identification in trawl surveys
is appropriate for fish community
studies, including the development of
photo-ID keys for nations participating
in surveys”. Various initiatives have
been taken by individual countries to
develop appropriate tools for species
identification, including training
courses. This section lists a number of
ways by which future data collections
may be improved or by which species
identification can be ascertained at a
later stage in the process.
Finally, section 6 deals with ToR d).
“Develop protocols for (i) improving
quality control during the submission of
data to DATRAS and (ii) the future
checking and quality assurance
of DATRAS data. This ToR relates to the
important aspect of the responsibility
of ICES for ensuring that all taxonomic
data in DATRAS are correct or, if they
are dubious but cannot be
corrected, that the information provided
to external users is properly identified
as being of a dubious nature. The
section describes a warning system that
should be developed at the
submission stage of new data so as to
inform each country that the data
submitted contain information that is
inconsistent with what is known about
the biology of the species and
therefore should be carefully checked.
It is also stressed that historic data
that cannot be corrected but remain
dubious are properly flagged internally
and potentially adjusted when made
available to external users. Proper
taxonomic quality control will remain an
issue of all monitoring programmes that
needs continuous attention and
adjustments. We can only hope that this
comprehensive description of its many
aspects helps the survey working groups
to make real progress in
achieving an urgently required revision
of the historic information provided as
well as in improving future data
submission. | en |
