|
The seminar is a follow-up of the Expert Consultation on Spatial distribution of
demersal resources in the Straits of Sicily and the influence of
environmental factors and fishery characteristics, held in Malta from 10 to
12 December 2002. The agreed work-plan includes processing of
trawl surveys data; however, in order to allow data comparison between
participating countries, it was been decided to adopt the same sampling and
processing protocol. The scope of this seminar was to present existing
sampling designs and data processing procedures adopted in on-going
monitoring trawl surveys, compare them and agree on common methodologies
based on existing ones.
Some of the
research institutions of the MedSudMed participating countries already
participate in international and/or national programs and conduct annual
trawl surveys. Important georeferenced databases have been produced on
abundance indices of several species, and biological information. In line
with the priorities of the GFCM-SAC of providing information on demersal
resources, MedSudMed Project's activities concentrate on improving the
knowledge on the spatial distribution and description of fisheries resources.
|
|
The organization is detailed in the provisional
agenda.
Each participating country (Tunisia, Malta, Libya, Italy) presented
the status and aim of its fisheries research activities, addressing
each one of the points detailed below. The protocol used for the
different steps of bottom trawl surveys were presented in plenary
session; thereafter, three working groups met in separate sessions
to examine, add and agree on specific and detailed methodologies for
each one of the issues. The working groups then presented their
documents to further discussion and approval of a common protocol in
plenary session.
| |
Planning of activities at sea and fishing gears |
Top |
|
This topic concentrated on the operations at sea
and fishing procedures. The protocol adopted by national programs for the
allocation of the hauls was presented. This regards the sampling area, the
equipment, the sampling design, and the fishing operations themselves. The
following issues were addressed:a.
study areas;
b.
sampling periods and frequency;
c.
sampling design presently used by the
participating Institutes: stratification criteria and spatial allocation
to strata;
d.
haul characteristics (number, coding, day
timing, boat speed duration, direction, validity criteria, ...);
e.
available boats and navigational devices;
f.
plan and characteristics of the gear
(setting and using the scanmar if any,rigging, mesh, net design, etc.).
|
|
Processing of the catches - biological sampling |
Top |
|
This topic dealt with the processing methods of
the catches. General information was given on the target and by-catch
species, and on the methodology used to process, measure and preserve the
samples. The following issues summarize the type of information that was
presented and discussed:
a. sub‑sampling;
b. target species;
c.
other representative species;
d.
by‑catch species;
e.
grouping level of the above species;
f.
methodology of basic measurements (total
length, carapace/mantle length, etc.);
g.
material preservation at sea and/or in
laboratory;
h. otolith
(or other hard parts such as vertebrae or scales) collection and
preservation.
|
|
Biological information on target species |
Top |
|
More specific biological sampling procedures done
on the target species were also discussed. This topic included more detailed
processing, such as organ identification and measurement, biological
sampling and analysis. The issues listed below include mainly activities
related to determination of sexual maturity:
a.
sex determination;
b.
macroscopic maturity;
c.
other morphometric measurements (e.g.
girth, pterigopod length, etc.);
d.
organ weights (gonads, liver, nidamental glands, etc.) .
|
|
Identification and discussion of further data sampling and
measurements |
Top |
|
These include:
a.
measurement of bottom water temperature;
b.
eggs and larvae collection using bongo
nets;
c.
dredging or grabbing for associated
biocenosis;
d.
analysis of discards;
e.
tagging and mark-recapture studies;
f.
diet (stomach content analysis).
|
|
Data management and processing |
Top |
|
The structure of some of the databases used in the
different research institutions were presented, including procedures used to
input and control the data in order to avoid erroneous information. In
addition, examples of data representation were given, in particular GIS
outputs. Therefore, the issues that were addressed are:
a.
structure of the data‑base;
b.
input of the data and relative control;
c.
management of data;
d.
GIS representations .
|
|
