* LBMB, Bari, Italy.
**
Fishery Researches Institute, Durres, Albania.
Below is
a report on Medits-AL 1999 survey
results, referring to Southeastern Adriatic Sea (strata 22141-22145).
The
fishing vessel "Pasquale e Cristina" took 40 hauls in the sampled
area (8735 km²).
During Medits-AL 1999 the most abundant in
weight species of the reference list, over the whole area, were Loligo vulgaris (biomass index mean
value = 28.2 kg/km²), Spicara flexuosa
(value = 18.8), Illex coindetii
(value = 14.7), Merluccius merluccius (value
= 14.7), and Galeus melastomus (value
= 13.2). The highest densities (N/km²) were attributed to Loligo vulgaris (mean value = 1764), Spicara flexuosa (value
= 1249), Parapenaeus longirostris
(value = 474), Spicara smaris (value
= 433), and Illex coindetii (value = 299).
Some of
the most abundant resources are distributed in well defined bathymetric strata.
Loligo vulgaris was mainly caught between 10 m and 100 m, Spicara flexuosa and Spicara smaris between 10 m and
200 m depth, Illex coindetii
between 50 m and 500 m depth, and Galeus
melastomus between 500 m and 800 m depth (blackmouth catshark was
included in the main species list this year). Parapenaeus longirostris was homogeneously distributed in the
different depth strata, and Merluccius
merluccius is confirmed to be ubiquitarian.
Quite
large variations in the abundance indices were found between 1999 and 1998
surveys with regard to some species or categories. Generally speaking a biomass
decrease of some benthic species such as Merluccius
merluccius and Eledone cirrhosa
was recorded, while nectobenthic species as the fish genus Spicara and mostly the cephalopods Loligo vulgaris and Illex
coindetii increased. The decrease of the hake and horned octopus was also
observed in the last surveys and it should be monitored in the next years to
better explain the situation.
The
length frequency distribution of some of the most important species (Loligo vulgaris, Illex coindetii, Merluccius merluccius) shown differences
between 1999 and 1998 surveys; cephalopods species mean length increase (mostly
broadtail squid), while hake mean length decrease (it was also due to the
highest density of juveniles in the present survey).
Aspitrigla cuculus
The
species was caught mostly on lower border of continental shelf; highest
abundance index (23.9) was found in the stratum 100-200 m, where density
index was 699.
Citharus linguatula
The
species was caught on continental shelf, mainly in the stratum 10-50 m;
highest abundance index was 4.2 while density was 170.
Eutrigla gurnardus
This
species was rarely found with negligible yields.
Galeus melastomus
The
species was caught on bathyal bottoms only; highest abundance index (59.9) was
found in the stratum 500-800 m, where density index was 723.
Helicolenus dactylopterus
Helicolenus dactylopterus was fished at depths greater than
200 m; abundance indices are higher between 500 m and 800 m
depth. The highest biomass and density values (abundance index = 2.5) was found
at 500-800 m, while highest density (density index = 34 ) was
observed in 200-500 m depth stratum.
Lepidorhombus boscii
This
species was mostly caught beyond 200 m of depth with abundance and density
indices of 3.0 and 22 respectively (500-800 m depth stratum).
Lophius budegassa
Lophius budegassa was found across the whole depth range
investigated; the highest biomass index (14.7 ) was observed between
50 and 100 m depth. Density was higher in the depth stratum 100-200 m
(25 individuals).
Lophius piscatorius
Not
found at all.
Merluccius merluccius
The
species was distributed in the whole area. Density index ranged from 17
(500-800 m depths) to 719 (10-50 m depths). The highest biomass index
of 19.1 was observed
in depth stratum 50-100 m.
The Medits net caught a high percentage of
11-13 cm (total length) specimens in the 50-200 m depth strata, while
it caught larger specimens, with length > 35-40 cm, mainly below
450-500 m depth.
Micromesistius poutassou
The
species was found with low abundance from 200 m to 800 m depth
(indices ranging from 3.2 to 7.1). The highest density index (168) was observed
in 200-500 m stratum.
Mullus barbatus
The
species was caught almost exclusively on the continental shelf (depth < 200 m). The highest
biomass index (11.6) was found in the depth stratum 50-100 m, with a
density of 638.
Most of
specimens had a length between 10 cm and 14 cm.
Mullus surmuletus
The
species was caught on the continental shelf
(depth < 200 m) with low yield.
Pagellus acarne
This
species was mostly found within 10-200 m strata, with very low abundance.
Pagellus bogaraveo
Few specimens
were fished in the whole area.
Pagellus erythrinus
The
species was found only in the continental shelf (mainly between 10-100 m);
the highest biomass index was 71.5 (10-50 m stratum) and the
density was 1886.
Phycis blennoides
It was
generally found beyond 100 m of depth exhibiting the highest biomass index
(29.6) between 500 and 800 m. Most of the fished specimens were smaller
than 20 cm.
Raja clavata
Not
found at all.
Scyliorhinus canicula
This
species was caught within the whole investigated area, mainly in 50-500 m
depths. Highest abundance was 7.0 (200-500 m), with a density of 109.
Solea vulgaris
The
species was found only in the continental shelf (50-100 m); biomass index
was very low (0.3).
Spicara flexuosa
It was
found between 10 and 200 m depths, mainly in the 50-100 m stratum.
Abundance and density were 61.8 and 4180, respectively.
Spicara smaris
This
species was found between 10 and 200 m depths, mainly in the 50-100 m
stratum. Abundance and density were 21.6 and 1588, respectively.
Trachurus mediterraneus
The
species was fished in the 200-500 m stratum with negligible yields.
Trachurus trachurus
The
species was caught from 10 m to 500 m depth. The highest biomass
index was obtained in 50-100 m stratum with value of 12.6. Small specimens
were dominant in the catches. Modal peak was found at 7-9 cm.
Trigloporus lastoviza
Not
found at all.
Trisopterus minutus capelanus
The
species was caught between 50-200 m depth; the highest biomass index (1.5)
was found in 50-100 m depth stratum.
Zeus faber
The
species was found within the whole investigated area; the highest abundance was
6.6 (100-200 m), while highest density (62 specimens) was found between 10
and 50 m.
Aristaeomorpha foliacea
It was
caught beyond 500 m of depth. Its biomass index was 11.2, while the
density was 649. The sizes of specimens (carapace length) mainly ranged from
28 mm to 34 mm.
Aristeus antennatus
The
species wasn’t caught during 1999 survey.
Nephrops norvegicus
The
species was generally caught with valuable abundance at depth greater than
200 m. The highest biomass index (3.0) was observed between 500 and
800 m. Most carapace lengths ranged from 20 to 40 mm.
Parapenaeus longirostris
The
species was frequently caught in the whole area, mainly at depths between 200
and 800 m; the highest biomass index was 8.6 (500-800 m depths),
while the maximum density value was 908 (200-500 m depth). The sizes of
specimens mainly ranged from 10 mm to 35 mm. Moreover, in
200-500 m depth stratum, modal carapace lengths were found at
20-22 mm.
Eledone cirrhosa
It was
generally fished in depths greater than 50 m and shallower than
500 m. The highest biomass index (2.2) was observed between 200 and
500 m. Density values were negligible.
Eledone moschata
It was
generally fished on continental shelf, between 10 m and 100 m. The
highest biomass index (45.7) was observed between 10 and 50 m, where
density was 624. Most mantle lengths ranged from 50 to 100 mm.
Illex coindetii
The
species was caught with higher abundance between 100 m and 500 m
depth. Its highest abundance and density indices (29.7 and 649, respectively)
were found in 100-200 m depth stratum.
Loligo vulgaris
It was
fished with remarkable abundance within 100 m depth. The highest biomass
index (137.1) was found in the
first stratum (10-50 m). The specimens mantel lengths were generally
smaller than 10 cm, but some specimens with size larger than 15 cm
were found between 200 and 500 m depths.
Octopus vulgaris
The
species was generally found on continental shelf. The highest biomass index was
2.2 (100-200 m
stratum).
Sepia officinalis
Common
cuttlefish was caught on continental shelf with low yields; remarkable indices
(abundance = 9.1; density = 263) were only found in the first depth stratum
(10-50 m).
In this
first stratum the five most important species were Loligo vulgaris, Pagellus erythrinus, Eledone moschata, Merluccius
merluccius, and Trachurus trachurus.
Loligo vulgaris was found with very high abundance and density
indices (137.1 and 11401, respectively). The length frequency distribution
ranged from 2 cm to 12 cm; modal peak was found at 5-7 cm
(mantel length).
Pagellus erythrinus was caught with a mean biomass index
of 71.5. The mean density index was 1886 and the length frequency
distribution ranged from 11 cm to 20 cm (higher frequencies at
13-15 cm total length).
Eledone moschata was found with biomass index of 45.7 and
density index of 642. The length frequency distribution ranged from 4 cm
to 10 cm (modal peaks at 5 and 7 cm mantle length).
The mean
values for Merluccius merluccius were
16.4 (biomass index) and 719 (density index). The length frequency distribution
ranged from 7 cm to 29 cm (higher frequencies between 12 cm and
14 cm).
The five
most important species between 50 and 100 m in the region were Spicara flexuosa, Loligo vulgaris, Spicara smaris, Merluccius merluccius, and Pagellus erythrinus.
Spicara flexuosa mean biomass index was 61.8, while mean
density was 4180. The length frequency distribution ranged from 8 cm to
18 cm (two modal peaks were
found at 10 and 13 cm total length).
Loligo vulgaris was found with biomass index of 52.3 and
density index of 3508. The length frequency distribution ranged from 3 cm
to 16 cm mantel length (higher frequencies between 5 and 7 cm).
Spicara smaris mean biomass index was 21.6 while density index
was 1588. The length frequency distribution ranged from 8 cm to 16 cm
(modal peak at 10 cm total length).
Merluccius merluccius was found with biomass index of 19.1
and density index of 373. The length frequency distribution ranged from
9 cm to 34 cm; no modal peak could be found in such a distribution.
Pagellus erythrinus was found with abundance of 16.4
(biomass index) and 376 (density index). The length frequency
distribution ranged from 11 cm to 24 cm, with modal peak at
13 cm.
The five
most important species for this depth stratum were Illex coindetii, Aspitrigla cuculus, Merluccius merluccius, Lophius budegassa, and Mullus barbatus.
Illex coindetii mean biomass index was 29.7, while mean density
was 649. The length frequency distribution ranged from 1 cm to 21 cm
(mantle length), with a modal peak around 11-12 cm.
Aspitrigla cuculus was found with indices of 23.9 (biomass index)
and 699 (density index). The length frequency distribution ranged
from 4 cm to 22 cm (total length); two modal peaks were found at 13
and 16 cm.
Merluccius merluccius was found with abundance of 11.5
(biomass index) and 372 (density index). The length frequency distribution
ranged from 5 cm to 30 cm (higher frequencies were found between 11
and 13 cm total length).
Lophius budegassa was found with indices of 11.4 (biomass) and 25 (density). The length
frequency distribution (irregular) ranged from 29 cm to 54 cm.
Mullus barbatus was found with biomass index of 10.6 and
density index of 279. The length frequency distribution ranged from
10 cm to 20 cm; mostly of specimens had 11-13 cm total length.
The five
most important species for this depth range were Illex coindetii, Loligo vulgaris, Merluccius merluccius, Lophius budegassa, and Parapenaeus longirostris.
The
species Illex coindetii was found
with indices of 27.3 (biomass) and 523 (density). The
length frequency distribution (mantle length) ranged from 5 cm to
18 cm (higher frequencies between 11 cm and 13 cm).
Loligo vulgaris was found with biomass index of 16.2 and
density index of 66. The length frequency distribution ranged from 7 cm to
27 cm (mostly between 17 and 21 cm mantle length).
Merluccius merluccius mean biomass index was 9.2, while
mean density was 205. The length frequency distribution ranged from 9 cm
to 75 cm total length, with a modal peak at 11-12 cm.
The
species Lophius budegassa was found
with indices of 7.1 (biomass) and
14 (density). The length frequency distribution (irregular) ranged from
11 cm to 69 cm.
Parapenaeus
longirostris was found with biomass index
of 7.0 and density index of 908. The length frequency
distribution (carapace length) ranged from 9 mm to 35 mm (mostly
between 20 mm and 22 mm).
In this
bathymetric stratum the five most important species for the region were Galeus melastomus, Phycis blennoides, Merluccius merluccius, Aristaeomorpha foliacea, and Parapenaeus longirostris.
Galeus melastomus was found with abundance indices of 59.9
(biomass) and 723 (density). The length frequency
distribution (total length) ranged from 14 cm to 56 cm (mostly
between 18 cm and 20 cm).
Phycis blennoides was found with biomass index of 29.6 and
density index of 540.
The
length frequency distribution ranged from 9 cm to 52 cm; modal peak
was found at 12 cm total length.
Merluccius merluccius mean biomass index was 17.9, while
mean density was 17. The length frequency distribution (irregular) ranged from
27 cm to 66 cm.
Aristaeomorpha foliacea mean biomass index was 11.2, while
mean density was 649. The length frequency distribution ranged from 17 mm
to 54 mm (carapace length); mostly of specimens were caught at
29-31 mm carapace length.
Parapenaeus longirostris was found with abundance of 8.6 and
density of 718. Length frequency distribution ranged from 21 mm to
39 mm carapace length (mostly between 25 and 28 mm).
Global
analysis of Medits-AL 1999 data
provided additional information about the bathymetric, geographic distribution
and relative abundance of fishery resources in the investigated area.
Some
remarks could be pointed out with regard to the abundance of the most important
fishery species for the area (as reported to the Project General Co-ordinator);
with respect to 1998 survey, a yield decrease of Eledone cirrhosa (very strong),
Parapenaeus longirostris (quite strong) and Merluccius merluccius (slight) was observed, while Phycis blennoides and Aristaeomorpha foliacea increased the biomass
index value. Other species (i.e. Mullus
barbatus, Helicolenus dactylopterus, Lepidorhombus boscii and Nephrops norvegicus) showed abundance
close to 1998 results. The decrease of the hake and horned octopus was observed
in the last surveys also.
Moreover
some nectobenthic coastal species such as the cephalopods Loligo vulgaris, Illex coindetii and the fish Spicara spp. strongly increase the yields (mostly due to the high
recruitment rate); it could be probably explained by the different survey
period (this year during August) or the “war ban” in the Adriatic Sea (in the
previous months).
Length
frequency distributions of the most important species in the 1999 survey appear
to be close to 1998 results, with the exception for hake. Merluccius merluccius in the 1999 survey pointed out a largest
percentage of juveniles with respect to 1998 data.
* LBMB, Bari, Italy.
**
Fishery Researches Institute, Durres, Albania.
Below is
a report on Medits-AL 1999 survey
results, referring to Southeastern Adriatic Sea (strata 22141-22145).
The
fishing vessel "Pasquale e Cristina" took 40 hauls in the sampled
area (8735 km²).
During Medits-AL 1999 the most abundant in
weight species of the reference list, over the whole area, were Loligo vulgaris (biomass index mean
value = 28.2 kg/km²), Spicara flexuosa
(value = 18.8), Illex coindetii
(value = 14.7), Merluccius merluccius (value
= 14.7), and Galeus melastomus (value
= 13.2). The highest densities (N/km²) were attributed to Loligo vulgaris (mean value = 1764), Spicara flexuosa (value
= 1249), Parapenaeus longirostris
(value = 474), Spicara smaris (value
= 433), and Illex coindetii (value = 299).
Some of
the most abundant resources are distributed in well defined bathymetric strata.
Loligo vulgaris was mainly caught between 10 m and 100 m, Spicara flexuosa and Spicara smaris between 10 m and
200 m depth, Illex coindetii
between 50 m and 500 m depth, and Galeus
melastomus between 500 m and 800 m depth (blackmouth catshark was
included in the main species list this year). Parapenaeus longirostris was homogeneously distributed in the
different depth strata, and Merluccius
merluccius is confirmed to be ubiquitarian.
Quite
large variations in the abundance indices were found between 1999 and 1998
surveys with regard to some species or categories. Generally speaking a biomass
decrease of some benthic species such as Merluccius
merluccius and Eledone cirrhosa
was recorded, while nectobenthic species as the fish genus Spicara and mostly the cephalopods Loligo vulgaris and Illex
coindetii increased. The decrease of the hake and horned octopus was also
observed in the last surveys and it should be monitored in the next years to
better explain the situation.
The
length frequency distribution of some of the most important species (Loligo vulgaris, Illex coindetii, Merluccius merluccius) shown differences
between 1999 and 1998 surveys; cephalopods species mean length increase (mostly
broadtail squid), while hake mean length decrease (it was also due to the
highest density of juveniles in the present survey).
Aspitrigla cuculus
The
species was caught mostly on lower border of continental shelf; highest
abundance index (23.9) was found in the stratum 100-200 m, where density
index was 699.
Citharus linguatula
The
species was caught on continental shelf, mainly in the stratum 10-50 m;
highest abundance index was 4.2 while density was 170.
Eutrigla gurnardus
This
species was rarely found with negligible yields.
Galeus melastomus
The
species was caught on bathyal bottoms only; highest abundance index (59.9) was
found in the stratum 500-800 m, where density index was 723.
Helicolenus dactylopterus
Helicolenus dactylopterus was fished at depths greater than
200 m; abundance indices are higher between 500 m and 800 m
depth. The highest biomass and density values (abundance index = 2.5) was found
at 500-800 m, while highest density (density index = 34 ) was
observed in 200-500 m depth stratum.
Lepidorhombus boscii
This
species was mostly caught beyond 200 m of depth with abundance and density
indices of 3.0 and 22 respectively (500-800 m depth stratum).
Lophius budegassa
Lophius budegassa was found across the whole depth range
investigated; the highest biomass index (14.7 ) was observed between
50 and 100 m depth. Density was higher in the depth stratum 100-200 m
(25 individuals).
Lophius piscatorius
Not
found at all.
Merluccius merluccius
The
species was distributed in the whole area. Density index ranged from 17
(500-800 m depths) to 719 (10-50 m depths). The highest biomass index
of 19.1 was observed
in depth stratum 50-100 m.
The Medits net caught a high percentage of
11-13 cm (total length) specimens in the 50-200 m depth strata, while
it caught larger specimens, with length > 35-40 cm, mainly below
450-500 m depth.
Micromesistius poutassou
The
species was found with low abundance from 200 m to 800 m depth
(indices ranging from 3.2 to 7.1). The highest density index (168) was observed
in 200-500 m stratum.
Mullus barbatus
The
species was caught almost exclusively on the continental shelf (depth < 200 m). The highest
biomass index (11.6) was found in the depth stratum 50-100 m, with a
density of 638.
Most of
specimens had a length between 10 cm and 14 cm.
Mullus surmuletus
The
species was caught on the continental shelf
(depth < 200 m) with low yield.
Pagellus acarne
This
species was mostly found within 10-200 m strata, with very low abundance.
Pagellus bogaraveo
Few specimens
were fished in the whole area.
Pagellus erythrinus
The
species was found only in the continental shelf (mainly between 10-100 m);
the highest biomass index was 71.5 (10-50 m stratum) and the
density was 1886.
Phycis blennoides
It was
generally found beyond 100 m of depth exhibiting the highest biomass index
(29.6) between 500 and 800 m. Most of the fished specimens were smaller
than 20 cm.
Raja clavata
Not
found at all.
Scyliorhinus canicula
This
species was caught within the whole investigated area, mainly in 50-500 m
depths. Highest abundance was 7.0 (200-500 m), with a density of 109.
Solea vulgaris
The
species was found only in the continental shelf (50-100 m); biomass index
was very low (0.3).
Spicara flexuosa
It was
found between 10 and 200 m depths, mainly in the 50-100 m stratum.
Abundance and density were 61.8 and 4180, respectively.
Spicara smaris
This
species was found between 10 and 200 m depths, mainly in the 50-100 m
stratum. Abundance and density were 21.6 and 1588, respectively.
Trachurus mediterraneus
The
species was fished in the 200-500 m stratum with negligible yields.
Trachurus trachurus
The
species was caught from 10 m to 500 m depth. The highest biomass
index was obtained in 50-100 m stratum with value of 12.6. Small specimens
were dominant in the catches. Modal peak was found at 7-9 cm.
Trigloporus lastoviza
Not
found at all.
Trisopterus minutus capelanus
The
species was caught between 50-200 m depth; the highest biomass index (1.5)
was found in 50-100 m depth stratum.
Zeus faber
The
species was found within the whole investigated area; the highest abundance was
6.6 (100-200 m), while highest density (62 specimens) was found between 10
and 50 m.
Aristaeomorpha foliacea
It was
caught beyond 500 m of depth. Its biomass index was 11.2, while the
density was 649. The sizes of specimens (carapace length) mainly ranged from
28 mm to 34 mm.
Aristeus antennatus
The
species wasn’t caught during 1999 survey.
Nephrops norvegicus
The
species was generally caught with valuable abundance at depth greater than
200 m. The highest biomass index (3.0) was observed between 500 and
800 m. Most carapace lengths ranged from 20 to 40 mm.
Parapenaeus longirostris
The
species was frequently caught in the whole area, mainly at depths between 200
and 800 m; the highest biomass index was 8.6 (500-800 m depths),
while the maximum density value was 908 (200-500 m depth). The sizes of
specimens mainly ranged from 10 mm to 35 mm. Moreover, in
200-500 m depth stratum, modal carapace lengths were found at
20-22 mm.
Eledone cirrhosa
It was
generally fished in depths greater than 50 m and shallower than
500 m. The highest biomass index (2.2) was observed between 200 and
500 m. Density values were negligible.
Eledone moschata
It was
generally fished on continental shelf, between 10 m and 100 m. The
highest biomass index (45.7) was observed between 10 and 50 m, where
density was 624. Most mantle lengths ranged from 50 to 100 mm.
Illex coindetii
The
species was caught with higher abundance between 100 m and 500 m
depth. Its highest abundance and density indices (29.7 and 649, respectively)
were found in 100-200 m depth stratum.
Loligo vulgaris
It was
fished with remarkable abundance within 100 m depth. The highest biomass
index (137.1) was found in the
first stratum (10-50 m). The specimens mantel lengths were generally
smaller than 10 cm, but some specimens with size larger than 15 cm
were found between 200 and 500 m depths.
Octopus vulgaris
The
species was generally found on continental shelf. The highest biomass index was
2.2 (100-200 m
stratum).
Sepia officinalis
Common
cuttlefish was caught on continental shelf with low yields; remarkable indices
(abundance = 9.1; density = 263) were only found in the first depth stratum
(10-50 m).
In this
first stratum the five most important species were Loligo vulgaris, Pagellus erythrinus, Eledone moschata, Merluccius
merluccius, and Trachurus trachurus.
Loligo vulgaris was found with very high abundance and density
indices (137.1 and 11401, respectively). The length frequency distribution
ranged from 2 cm to 12 cm; modal peak was found at 5-7 cm
(mantel length).
Pagellus erythrinus was caught with a mean biomass index
of 71.5. The mean density index was 1886 and the length frequency
distribution ranged from 11 cm to 20 cm (higher frequencies at
13-15 cm total length).
Eledone moschata was found with biomass index of 45.7 and
density index of 642. The length frequency distribution ranged from 4 cm
to 10 cm (modal peaks at 5 and 7 cm mantle length).
The mean
values for Merluccius merluccius were
16.4 (biomass index) and 719 (density index). The length frequency distribution
ranged from 7 cm to 29 cm (higher frequencies between 12 cm and
14 cm).
The five
most important species between 50 and 100 m in the region were Spicara flexuosa, Loligo vulgaris, Spicara smaris, Merluccius merluccius, and Pagellus erythrinus.
Spicara flexuosa mean biomass index was 61.8, while mean
density was 4180. The length frequency distribution ranged from 8 cm to
18 cm (two modal peaks were
found at 10 and 13 cm total length).
Loligo vulgaris was found with biomass index of 52.3 and
density index of 3508. The length frequency distribution ranged from 3 cm
to 16 cm mantel length (higher frequencies between 5 and 7 cm).
Spicara smaris mean biomass index was 21.6 while density index
was 1588. The length frequency distribution ranged from 8 cm to 16 cm
(modal peak at 10 cm total length).
Merluccius merluccius was found with biomass index of 19.1
and density index of 373. The length frequency distribution ranged from
9 cm to 34 cm; no modal peak could be found in such a distribution.
Pagellus erythrinus was found with abundance of 16.4
(biomass index) and 376 (density index). The length frequency
distribution ranged from 11 cm to 24 cm, with modal peak at
13 cm.
The five
most important species for this depth stratum were Illex coindetii, Aspitrigla cuculus, Merluccius merluccius, Lophius budegassa, and Mullus barbatus.
Illex coindetii mean biomass index was 29.7, while mean density
was 649. The length frequency distribution ranged from 1 cm to 21 cm
(mantle length), with a modal peak around 11-12 cm.
Aspitrigla cuculus was found with indices of 23.9 (biomass index)
and 699 (density index). The length frequency distribution ranged
from 4 cm to 22 cm (total length); two modal peaks were found at 13
and 16 cm.
Merluccius merluccius was found with abundance of 11.5
(biomass index) and 372 (density index). The length frequency distribution
ranged from 5 cm to 30 cm (higher frequencies were found between 11
and 13 cm total length).
Lophius budegassa was found with indices of 11.4 (biomass) and 25 (density). The length
frequency distribution (irregular) ranged from 29 cm to 54 cm.
Mullus barbatus was found with biomass index of 10.6 and
density index of 279. The length frequency distribution ranged from
10 cm to 20 cm; mostly of specimens had 11-13 cm total length.
The five
most important species for this depth range were Illex coindetii, Loligo vulgaris, Merluccius merluccius, Lophius budegassa, and Parapenaeus longirostris.
The
species Illex coindetii was found
with indices of 27.3 (biomass) and 523 (density). The
length frequency distribution (mantle length) ranged from 5 cm to
18 cm (higher frequencies between 11 cm and 13 cm).
Loligo vulgaris was found with biomass index of 16.2 and
density index of 66. The length frequency distribution ranged from 7 cm to
27 cm (mostly between 17 and 21 cm mantle length).
Merluccius merluccius mean biomass index was 9.2, while
mean density was 205. The length frequency distribution ranged from 9 cm
to 75 cm total length, with a modal peak at 11-12 cm.
The
species Lophius budegassa was found
with indices of 7.1 (biomass) and
14 (density). The length frequency distribution (irregular) ranged from
11 cm to 69 cm.
Parapenaeus
longirostris was found with biomass index
of 7.0 and density index of 908. The length frequency
distribution (carapace length) ranged from 9 mm to 35 mm (mostly
between 20 mm and 22 mm).
In this
bathymetric stratum the five most important species for the region were Galeus melastomus, Phycis blennoides, Merluccius merluccius, Aristaeomorpha foliacea, and Parapenaeus longirostris.
Galeus melastomus was found with abundance indices of 59.9
(biomass) and 723 (density). The length frequency
distribution (total length) ranged from 14 cm to 56 cm (mostly
between 18 cm and 20 cm).
Phycis blennoides was found with biomass index of 29.6 and
density index of 540.
The
length frequency distribution ranged from 9 cm to 52 cm; modal peak
was found at 12 cm total length.
Merluccius merluccius mean biomass index was 17.9, while
mean density was 17. The length frequency distribution (irregular) ranged from
27 cm to 66 cm.
Aristaeomorpha foliacea mean biomass index was 11.2, while
mean density was 649. The length frequency distribution ranged from 17 mm
to 54 mm (carapace length); mostly of specimens were caught at
29-31 mm carapace length.
Parapenaeus longirostris was found with abundance of 8.6 and
density of 718. Length frequency distribution ranged from 21 mm to
39 mm carapace length (mostly between 25 and 28 mm).
Global
analysis of Medits-AL 1999 data
provided additional information about the bathymetric, geographic distribution
and relative abundance of fishery resources in the investigated area.
Some
remarks could be pointed out with regard to the abundance of the most important
fishery species for the area (as reported to the Project General Co-ordinator);
with respect to 1998 survey, a yield decrease of Eledone cirrhosa (very strong),
Parapenaeus longirostris (quite strong) and Merluccius merluccius (slight) was observed, while Phycis blennoides and Aristaeomorpha foliacea increased the biomass
index value. Other species (i.e. Mullus
barbatus, Helicolenus dactylopterus, Lepidorhombus boscii and Nephrops norvegicus) showed abundance
close to 1998 results. The decrease of the hake and horned octopus was observed
in the last surveys also.
Moreover
some nectobenthic coastal species such as the cephalopods Loligo vulgaris, Illex coindetii and the fish Spicara spp. strongly increase the yields (mostly due to the high
recruitment rate); it could be probably explained by the different survey
period (this year during August) or the “war ban” in the Adriatic Sea (in the
previous months).
Length
frequency distributions of the most important species in the 1999 survey appear
to be close to 1998 results, with the exception for hake. Merluccius merluccius in the 1999 survey pointed out a largest
percentage of juveniles with respect to 1998 data.