by Maria González and Luis Gil de Sola
A total
of 117 hauls were carried out in May 1999 with the R/V ŦCornide de Saavedraŧ.
All were valid. A total of 370 species were identified: 156 fishes, 88
crustaceans, and 66 molluscs, of which 32 cephalopods, 32 echinoderms, and 28
other invertebrates. Fishes represented 80.0% of the total weight, crustaceans
4.9%, cephalopods 8.1%, other molluscs 0.2%, echinoderms 2.5% and other
invertebrates 4.3%. In number, fishes represented 64.5% of the total catch,
crustaceans 28.7%, cephalopods 5.2%, other molluscs 0.2%, echinoderms 0.5% and
other invertebrates 0.9%.
The most
frequent species in the total of hauls (in terms of presence/absence) were (in decreasing
order) Merluccius merluccius (it
appeared in 60% of the hauls), Illex
coindetii, Phycis blennoides, Alloteuthis media, Trachurus trachurus, Liocarcinus
depurator, Eledone cirrhosa, Helicolenus dactylopterus, Mullus barbatus,
Capros aper and Conger conger,
which were present in more than 40% of the hauls.
In the
Alboran Sea, the species of the reference list which presented a high biomass
index (more than 10 kg/kmē) were (in decreasing order) Galeus melastomus, Helicolenus
dactylopterus, Phycis blennoides, Pagellus
acarne, and Illex coindetii. The
species with the highest densities (more than 200 individuals/kmē) were Galeus melastomus, Phycis blennoides, Helicolenus dactylopterus, and Merluccius merluccius. The reference
list species Eutrigla gurnardus,
Lepidorhombus boscii, Raja clavata,
Aristaeomorpha foliacea and Sepia
officinalis were not caught.
In the
Alicante region, the highest mean biomass values were observed for Micromesistius poutassou, Octopus
vulgaris, Galeus melastomus, Pagellus acarne, and Merluccius merluccius. Species with the highest densities were Micromesistius poutassou, Merluccius
merluccius, Trachurus trachurus, Phycis blennoides, Spicara smaris, Trachurus
mediterraneus and Spicara smaris.
In this region, Eutrigla gurnardus and
Lophius piscatorius were not caught.
In the
Catalan Sea, Micromesistius poutassou,
Merluccius merluccius, Trachurus
trachurus, Phycis blennoides, Eledone
cirrhosa and Mullus barbatus were
the most abundant species and Micromesistius
poutassou, Merluccius merluccius, Trisopterus
minutus capelanus, Trachurus
trachurus, Phycis blennoides, Mullus
barbatus and Spicara flexuosa had
the largest index of density (more than 200 N/kmē). Aristaeomorpha foliacea and
Loligo vulgaris were not caught in the Catalan Sea.
Solea vulgaris was not caught in the whole area.
Aspitrigla cuculus
Benthic
species of the continental shelf. It generally showed low biomass indices with
exception in the stratum 100-200 m. In the Catalan Sea, it was found in
higher abundance (BI = 8.04). The sizes ranged between 10 and 40 cm.
Boops boops
Boops boops was caught on the continental shelf, up to
200 m depth. The highest biomass and density indices were observed in the
coastal stratum in Alicante area: BI = 76.24, DI = 1860 between 10-50 m;
BI = 22.47 and DI = 659 between 50-100 m. The modal class was
12 cm, and sizes ranged between 6 and 26 cm.
Capros aper
This
non-commercial species was abundant between 50 and 200 m of depth. In the
Alboran Sea it was more abundant in the stratum 50-100 m (64.45 kg/kmē).
Its maximum biomass index appeared in the Alicante area, between 100-200 m
(BI = 115.80). Length distribution ranged from 2 to 12 cm. Modal class was
6 cm.
Galeus melastomus
Distributed
on the upper slope. Very high abundances between 500 and 800 m depth: BI =
349.32 in the Alboran Sea, BI = 62.70 in the zone of Alicante and BI = 45.50 in
the Catalan Sea. The sizes increased with depth. Size range of the caught
specimens was 10-68 cm. Modal class was 42 cm.
Helicolenus dactylopterus
Found in
depths greater than 200 m in all regions. This species was more abundant
in the Alboran Sea. Sizes bigger in the deepest strata: the modal class of the
individuals caught between 200 and 500 m was 4 cm, and the modal
class of the specimens caught between 500-800 m is located in 23 cm.
In the other sectors the abundance indices were higher between 100 and
200 m.
Lepidorhombus boscii
Found at
depths greater than 100 m in the Alicante area and the Catalan Sea; but it
was not caught in the Alboran Sea. Its abundance increased from south to north.
The maximum value of the biomass index was 5.08 kg/kmē in the Catalan Sea
between 200 and 500 m. Most of the individuals caught had a small size.
Lophius budegassa
Found in
all depths of the three sectors sampled. Few individuals were caught, with
sizes between 5 and 55 cm of total length.
Merluccius merluccius
Fished
in depths from 10 to 500 m in all sectors. A strong presence of young
specimens was observed in the shallowest strata (up to 200 m): 96.43% below
17 cm of total length. The size range oscillated between 2 and 61 cm.
The highest abundances were obtained for depths between 100 and 200 m in
the Catalan Sea (BI= 40.37; DI= 4107) and between 50 and 100 m in the same
area (BI= 31.15; DI= 2683). Catches were also important in the stratum 100-200
in the Alboran Sea and in the zone of Alicante.
Micromesistius poutassou
Micromesistius poutassou was observed at depths below
100 m in all sectors. The highest biomass and density indices were
reported between 100 and 200 m in the Catalan Sea (BI= 1432.90 kg/ kmē;
DI= 96540 ind/ kmē). Its abundance was also important in the area of Alicante:
BI= 174.34 between 100-200 m and BI= 162.46 between 200- 500 m.
Catches presented a high variability due to its mesopelagic condition.
Actually, this species constitutes important shoals and makes daily migrations.
Most of the captured individuals (99.82%) presented sizes below 18 cm, and
a clear modal class was present at 13-14 cm. Another large modal size
class was found at 26 cm.
Mullus barbatus
Usually
caught on the continental shelf, generally scarce at depths below 200 m.
More abundant in Catalonia and Alicante: BI= 19.77 in the shallowest stratum of
the Alicante area; BI= 20.85 between 100 and 200 m in the Catalan Sea.
Length of the specimens caught ranged between 9 and 25 cm. Modal class was
13 cm.
Mullus surmuletus
M. surmuletus is also a species mainly distributed on the
continental shelf. In general it presented lower abundances than M. barbatus, except in the area of
Alicante, where its BI was 28.71 kg/kmē in the most superficial stratum. The
sizes were included between 10 and 32 cm, and the modal class was located
at 17 cm.
Pagellus acarne
This
species presented high catches in the three shallowest strata in the Alboran
Sea and up to 100 m in the other two sectors. Pagellus acarne showed biomass and density indices lower than the
previous year in the Alboran Sea:
83.69 kg/kmē between 100 and 200 m. In the Alicante zone and the Catalan
Sea the biomass index was lower than 40 kg/kmē in all strata. Modal class was
found at 18 cm.
Pagellus bogaraveo
It was
caught occasionally at very diverse depths. Most of the specimens captured were
small-sized. The highest biomass index was observed in the zone of Alicante
between 50-100 m (6.46).
Pagellus erythrinus
It is
the most coastal Pagellus, normally
captured down to 100 m depth. Its abundance increased from the Alboran Sea
toward the Catalan Sea. In this region it presented the highest biomass index
in the shallowest stratum: 28.31 kg/kmē, and 11.24 kg/kmē between
50-100 m. Sizes were between 8 and 38 cm.
Phycis blennoides
Phycis blennoides was mainly distributed on the upper slope. The population showed two cohorts:
juveniles with a modal class at 10 cm and another at 24 cm. As for
the majority of species on the slope, catch of Phycis blennoides was greatest in the Alboran Sea: 26.39 kg/kmē
between 500 and 800 m. Length distribution was between 5 and 47 cm.
Scyliorhinus canicula
It
showed a wide bathymetric distribution, but was more abundant in the Catalan
Sea. The highest biomass index
(23.02) was found in this region between 200 and 500 m.
Spicara flexuosa
This
species was found in shallow waters (10-100 m) in all sectors. Biomass
index was particularly high in the Alboran Sea, especially in the stratum
10-50 m with values of 62.0 kg/kmē. The sizes ranged from 9 to 22 cm.
The modal class was 12 cm.
Spicara smaris
S. smaris, as S.
flexuosa, lives in shallow waters. It has been caught down to 100 m.
High BI were found in the most coastal stratum of the zone of Alicante (111.94)
and between 50-100 m in the Alboran Sea (41.54).
Trachurus mediterraneus
This
coastal species had a very low abundance in the Alboran Sea. The most important
catches were made between 30 and 50 m depth in the Alicante area (35.8
kg/kmē) and in the Catalan Sea (19.22 kg/kmē). 93.4% of the individuals caught
were juveniles (smaller than 23 cm) and the modal class was 6 cm
(very small). The size ranged between 5 and 32 cm. Several adult
individuals were caught near the coast.
Trachurus trachurus
The
bathymetric distribution of Trachurus
trachurus was wider than that of
Trachurus mediterraneus. Some individuals were found in the upper slope.
The highest biomass index was 36.44 kg/kmē in the Catalonian sector and 15.14
kg/kmē in the Alboran Sea between 50-100 and 30-50 m depth, respectively.
97.5% of the individuals caught were juveniles
(size lower than 20 cm). Two modal classes were apparent: 8 cm
and 18 cm. Sizes ranged between 3 and 35 cm.
Trigloporus lastoviza
This
species was observed down to 200 m depth in the three sectors. Catches
were generally low, except in the most coastal stratum in the zone of Alicante
(BI= 26.80) and between 50 and 100 m in the Alboran Sea (BI= 10.29).
Trisopterus minutus capelanus
This
species presented two cohorts, the first one with a modal class at 6 cm
length (juveniles) and the second one with a modal class at 15 cm
(adults). Juveniles were more abundant and they appeared in the same strata as
adults. Biomass and density indices of Trisopterus
minutus capelanus increased from the Alboran Sea to the Catalan Sea. In
this last region the highest values were 18.05 kg/kmē and 5890 N/kmē between
100 and 200 m depth.
Aristeus antennatus
Found at
depths greater than 500 m except in the Alboran Sea. In this region, some
individuals were caught in the 200-500 m stratum. Its abundance was
highest in the Alicante area (BI= 7.38), and the greatest proportion of large
specimens was found in the Alboran Sea. Wide range of sizes, especially in the
Alboran Sea.
Nephrops norvegicus
Highest
abundances were found in the upper slope, between 200 and 500 m. Abundance
increased from south to north: the highest densities were found in the Catalan
Sea (BI= 9.77, DI= 635 between 200 and 500 m). Sizes were comprised
between 15 and 65 mm of caparace length (CL). The size distribution was
polymodal: 24 and 32 mm of CL were the main modal size classes.
Parapenaeus longirostris
Its
bathymetric distribution was comprised between 100 and 500 m, with highest
abundances in the Alboran Sea (DI= 276 in the stratum 100-200 m, and DI=
436 in the stratum 200-500 m), and in the Alicante area (DI= 240 in the
stratum 200-500 m). Size increased with depth: the modal class in the
stratum 100-200 was 20 mm CL, and 26 mm in the stratum 200-500. The
range of sizes varied between 6 and 37 mm CL.
Alloteuthis media
This
small cephalopod was caught down to 200 m, but it presented its maximum
density values between 10 and 100 m. Alloteuthis
media is a mesopelagic species that forms shoals near the bottom. The
highest density index were obtained in the Alboran Sea: 12936 ind/ kmē in the
first stratum (10-50 m) and 6753 ind/ kmē in the second (50-100 m).
Eledone cirrhosa
This
species was caught between 50 and 500 m depth, and was more abundant in
the Alboran Sea between 50 and 100 m (BI= 18.22), and in the Catalan Sea
(BI= 15.90, 17.01, and 19.16 in the second, third and fourth stratum
respectively). The range of sizes varied between 2 and 14 cm. The modal
size class was 9 cm mantle length (ML).
Illex coindetii
The
highest abundances were located between 50 and 200 m depth in the Alboran
Sea (BI= 44.73 in the stratum 100-200 m), and in the Catalan Sea (BI= 17.63
at 100-200 m). The number of juveniles captured in the present survey was
less than in the previous years. The range of sizes was comprised between 2 and
27 cm.
Octopus vulgaris
Octopus vulgaris was only found at depths shallower than
200 m in all sectors, and its greatest abundances occurred shallower than
100 m in the Alicante area: BI= 135.28 between 30 and 50 m and BI=
88.33 in the stratum 50-100 m. Sizes ranged from 5 to 21 cm (Dorsal
Mantle Length). Modal class was 11 cm.
In this
stratum 22 species of the reference list were caught: 17 fishes and 5
cephalopods. Crustaceans were not caught. Three types of catches were evident:
Species
with coastal distribution patterns: Octopus
vulgaris, Spicara flexuosa, Spicara smaris, and Boops boops.
Species
that live in deeper waters but a more coastal distribution of juveniles: Pagellus acarne, Merluccius merluccius.
Pelagic
species that constitute shoals near the bottom during the day: Alloteuthis media.
Generally,
the abundance indices of the most coastal species decreased from the Alboran
Sea to the Catalan Sea, with the exception of pelagic species, more abundant in
the Catalan Sea.
|
|
Alboran |
Alicante |
Catalan |
|||
|
|
kg/kmē |
N/kmē |
kg/kmē |
N/kmē |
kg/kmē |
N/kmē |
|
Alloteuthis media |
32.64 |
12936 |
4.16 |
1493 |
10.28 |
3796 |
|
Boops boops |
2.37 |
32 |
76.24 |
1860 |
16.06 |
831 |
|
Octopus vulgaris |
10.22 |
21 |
135.28 |
190 |
51.62 |
59 |
|
Pagellus acarne |
30.45 |
441 |
32.50 |
490 |
13.03 |
154 |
|
Merluccius merluccius |
9.89 |
210 |
5.54 |
155 |
14.57 |
915 |
|
Spicara flexuosa |
62.00 |
1198 |
25.33 |
923 |
24.86 |
1182 |
|
Trachurus mediterraneus |
2.94 |
32 |
35.80 |
2721 |
19.22 |
373 |
|
|
Alboran |
Alicante |
Catalan |
|||
|
|
kg/kmē |
N/kmē |
kg/kmē |
N/kmē |
kg/kmē |
N/kmē |
|
Alloteuthis media |
16.38 |
6753 |
10.53 |
4664 |
5.60 |
4065 |
|
Boops boops |
8.35 |
70 |
22.47 |
659 |
9.56 |
208 |
|
Eledone cirrhosa |
18.22 |
54 |
1.32 |
3 |
15.90 |
41 |
|
Merluccius merluccius |
6.72 |
297 |
12.66 |
967 |
31.15 |
2683 |
|
Octopus vulgaris |
46.26 |
50 |
88.33 |
66 |
3.69 |
5 |
|
Pagellus acarne |
10.03 |
111 |
40.61 |
472 |
6.14 |
54 |
|
Trachurus trachurus |
4.54 |
52 |
9.99 |
1773 |
36.44 |
1915 |
A total
of 28 different target species were fished in this stratum: 21 fishes, 2
crustaceans and 5 cephalopods.
The
distribution of the most abundant species coincided with that of the most
abundant species in the first stratum: Pagellus
acarne, Octopus vulgaris, Merluccius merluccius, Boops boops, and Alloteuthis media. Abundance of juveniles of Trachurus trachurus and Trachurus
mediterraneus was also important.
26 of
the 36 target species were caught in this depth range: 22 fishes, 2 crustaceans
and 4 cephalopods.
In this
stratum the most abundant species was Micromesistius
poutassou: 1432.9 kg and 96540 N/kmē in the Catalan Sea. In density, Capros aper (28299 N/kmē in the Alboran
Sea, and 49135 N/kmē in the Alicante zone) and Merluccius merluccius (4818 N/kmē in the Alicante zone and 4107
N/kmē in the Catalan Sea) were the most important species. In biomass, they
were Capros aper (115.80 kg/kmē in
the Alicante area), Lepidopus caudatus (105.97
kg/kmē in the Alicante area), and Pagellus
acarne (83.69 kg/kmē in the Alboran Sea). As in other years, the survey
coincided with the main period of hake recruitment.
|
|
Alboran |
Alicante |
Catalan |
|||
|
|
kg/kmē |
N/kmē |
kg/kmē |
N/kmē |
kg/kmē |
N/kmē |
|
Capros aper |
52.48 |
28299 |
115.80 |
49135 |
6.56 |
1912 |
|
Eledone cirrhosa |
4.97 |
24 |
6.10 |
20 |
17.01 |
86 |
|
Illex coindetii |
44.73 |
336 |
8.80 |
56 |
17.63 |
182 |
|
Lepidopus caudatus |
8.37 |
458 |
105.97 |
3669 |
4.10 |
129 |
|
Merluccius merluccius |
29.30 |
1714 |
29.51 |
4818 |
40.37 |
4107 |
|
Micromesistius poutassou |
0.00 |
0 |
174.34 |
9889 |
1432.90 |
96540 |
|
Mullus barbatus |
1.56 |
20 |
8.42 |
157 |
20.85 |
499 |
|
Pagellus acarne |
83.69 |
405 |
0.26 |
3 |
0.92 |
4 |
21
species of the reference list were found: 15 fishes, 3 crustaceans and 3
cephalopods. The most abundant species in biomass were Micromesistius poutassou (162.47 kg/kmē in Alicante area, 64.27
kg/kmē in the Catalan sector), and Lepidopus
caudatus (104.76 kg/kmē in the Alboran Sea, 61.72 kg/kmē in the Alicante
zone). In density, the most abundant species were Micromesistius poutassou (7040 N/kmē in Alicante area), Phycis blennoides (1486 N/kmē in the
Catalan Sea), and Lepidopus caudatus
(690 N/kmē in Alboran area). In general, catches in this stratum were lower
than in the shallower strata.
|
|
Alboran |
Alicante |
Catalan |
|||
|
|
kg/kmē |
N/kmē |
kg/kmē |
N/kmē |
kg/kmē |
N/kmē |
|
Eledone cirrhosa |
2.80 |
20 |
2.84 |
12 |
19.17 |
40 |
|
Lepidopus
caudatus |
104.76 |
690 |
61.72 |
90 |
0.22 |
2 |
|
Micromesistius
poutassou |
2.17 |
18 |
162.47 |
7040 |
64.27 |
1840 |
|
Parapenaeus
longirostris |
4.33 |
436 |
1.33 |
112 |
0.61 |
57 |
|
Phycis
blennoides |
17.45 |
1038 |
17.11 |
444 |
19.60 |
1486 |
|
Scyliorhinus canicula |
0.97 |
10 |
2.15 |
9 |
23.03 |
218 |
16
species of the reference list were caught: 12 fishes, 3 crustaceans and 1
cephalopod.
The most
important species in biomass was Galeus
melastomus: 349.32 kg/kmē in the Alboran Sea, 62.70 kg/kmē in the Alicante
zone, and 45.50 in the Catalan Sea. In number, they were Galeus melastomus (1761 N/kmē in Alboran) and Phycis blennoides (530 N/kmē in Alboran). In general, the
importance of deeper species was greater in the Alboran Sea.
|
|
Alboran |
Alicante |
Catalan |
|||
|
|
kg/kmē |
N/kmē |
kg/kmē |
N/kmē |
kg/kmē |
N/kmē |
|
Alepocephalus rostratus |
17.23 |
124 |
48.82 |
210 |
0.00 |
0 |
|
Aristeus antennatus |
4.52 |
283 |
7.38 |
589 |
6.68 |
612 |
|
Galeus melastomus |
349.32 |
1761 |
62.70 |
278 |
45.50 |
173 |
|
Phycis blennoides |
26.39 |
530 |
13.38 |
407 |
19.31 |
968 |