18.2.2 MEDITS Survey
The data from the MEDITS Survey (Bertrand et al. 2002) are obtained from a total of
25 bottom trawl surveys carried out during the spring of 1994 to 2018. The covered
area was between 30 and 800 m depth (in GSA 02, between 150 and 800 m). The
randomized stratified sampling design defined five bathymetric strata: 30–50 m,
51–100 m, 101–200 m, 201–500 m, and 501–800 m. Haul duration varied according
to depth: 30 min at depths above 200 m and 60 min below 200 m. All the surveys
were carried out with the same otter bottom trawler (GOC-73) using a net with a cod
mesh size of 20 mm. The mean towing speed of the vessels was 3.0 knots. The
values of the vertical and horizontal opening of the gear were monitored by a
SCANMAR trawl sensor device. For each sampling station, all specimens were
sorted, identified, counted, and weighed on board. In this chapter, the mean abundance (num.individuals/km2) and biomass (kg/km2) of the main target species of
bottom trawl fishery were calculated per year. Also, length data for these species
(mean valuesÆstandard error, mode, and size range) were calculated throughout the
25 trawl surveys. Distribution maps of the species comprise data from the last year of
the MEDITS survey (from 2012 to 2018).
18.3 Fishing Fleet and Main Ports
The total fishing fleet in GSA01 and GSA02 accounts for a total of 645 vessels. The
fleet is composed mainly of artisanal vessels between 6 and 12 m of overall length
and trawlers and purse seiners between 18 and 24 m of overall length (Table 18.1).
The number of vessels in this area has been continuously decreasing in the last
decades, from more than 1045 vessels in 2004 to 645 in 2017. The biggest reductions have taken place in the set longliners, purse seiners, and bottom trawlers
(Fig. 18.3).
The fleet is distributed in 14 ports along the coast. As concerns the number of
vessels, the main harbors in GSA 01 are Almeria, Vélez-Malaga, Algeciras, and
Estepona. In general terms, the small-scale fleet seems to decrease from the west to
the east (Table 18.2).
On the other hand, bottom otter trawl is the second fleet in the number of vessels
with respect to the other fishing modalities developed in the area (Table 18.2), being
the biggest in tonnage and power (Table 18.1). Also it is the second fleet in landings
(the first one of the demersal fisheries) and the first fleet in economic value of the
landings (Fig. 18.4).
This chapter focuses on the bottom otter trawl fishery both for its importance in
demersal fisheries (Sánchez et al. 2004) and for the existence of other chapters
dedicated to artisanal, purse seine, and longline fisheries.
18 Demersal Resources
593
The data from the MEDITS Survey (Bertrand et al. 2002) are obtained from a total of
25 bottom trawl surveys carried out during the spring of 1994 to 2018. The covered
area was between 30 and 800 m depth (in GSA 02, between 150 and 800 m). The
randomized stratified sampling design defined five bathymetric strata: 30–50 m,
51–100 m, 101–200 m, 201–500 m, and 501–800 m. Haul duration varied according
to depth: 30 min at depths above 200 m and 60 min below 200 m. All the surveys
were carried out with the same otter bottom trawler (GOC-73) using a net with a cod
mesh size of 20 mm. The mean towing speed of the vessels was 3.0 knots. The
values of the vertical and horizontal opening of the gear were monitored by a
SCANMAR trawl sensor device. For each sampling station, all specimens were
sorted, identified, counted, and weighed on board. In this chapter, the mean abundance (num.individuals/km2) and biomass (kg/km2) of the main target species of
bottom trawl fishery were calculated per year. Also, length data for these species
(mean valuesÆstandard error, mode, and size range) were calculated throughout the
25 trawl surveys. Distribution maps of the species comprise data from the last year of
the MEDITS survey (from 2012 to 2018).
18.3 Fishing Fleet and Main Ports
The total fishing fleet in GSA01 and GSA02 accounts for a total of 645 vessels. The
fleet is composed mainly of artisanal vessels between 6 and 12 m of overall length
and trawlers and purse seiners between 18 and 24 m of overall length (Table 18.1).
The number of vessels in this area has been continuously decreasing in the last
decades, from more than 1045 vessels in 2004 to 645 in 2017. The biggest reductions have taken place in the set longliners, purse seiners, and bottom trawlers
(Fig. 18.3).
The fleet is distributed in 14 ports along the coast. As concerns the number of
vessels, the main harbors in GSA 01 are Almeria, Vélez-Malaga, Algeciras, and
Estepona. In general terms, the small-scale fleet seems to decrease from the west to
the east (Table 18.2).
On the other hand, bottom otter trawl is the second fleet in the number of vessels
with respect to the other fishing modalities developed in the area (Table 18.2), being
the biggest in tonnage and power (Table 18.1). Also it is the second fleet in landings
(the first one of the demersal fisheries) and the first fleet in economic value of the
landings (Fig. 18.4).
This chapter focuses on the bottom otter trawl fishery both for its importance in
demersal fisheries (Sánchez et al. 2004) and for the existence of other chapters
dedicated to artisanal, purse seine, and longline fisheries.
18 Demersal Resources
593