Survey Results for Italy - area M1 - Ligurian and Tyrrhenian Seas

by G.D. Ardizzone and A. Belluscio

Introduction

Below is a report on the abundance indices and size distribution data obtained during the Medits '99 - M1 Region - trawl survey. It deals with the Ligurian Sea (strata 13201 -13205), the northern Tyrrhenian Sea (strata 13206 - 13210), the northern part of central Tyrrhenian Sea (strata 13211 - 13215) and the southern part of central Tyrrhenian Sea (strata 13216 - 13220).

In the M1 region the 1999 Medits survey was carried out from May 17 to July 10 using, as the previous year, the professional trawler "Francesco Padre". A total of 153 valid hauls were carried out. Water temperature close to the bottom ranged from 13.8°C (slope hauls) to 17.2°C (shelf hauls).

A total of 221 animal species were identified, 146 of fishes, 31 of Cephalopods and 44 of Crustaceans, and a lot of non-commercial species.

Global comments for Fish, Crustaceans and Cephalopods, Survey 1999

The species which were most abundant during the Medits '99 trawl survey in the M1 zone were, in order of density, Merluccius merluccius (mean value 4,482 N/km², CV 17.7 over the whole zone), Trachurus trachurus (mean value 2,160, CV 36.2), Micromesistius poutassou (mean value 1,766 N/km², 48.8 C.V.), Trisopterus minutus (mean value 636, CV 16.5), Phycis blennoides (mean value 576 N/km², 12.3 C.V.), Spicara flexuosa (mean value 523, CV 64.8), Mullus barbatus (mean value 466, CV 29.4).

From the point of view of biomass, the most significant species in the M1 area is M. merluccius (mean value 59.48 kg/km², CV 17.7, over the whole area), followed by Trachurus trachurus (mean value 22.5, CV 26.7), Galeus melastomus (mean value 22.0 kg/km², 14.6 C.V.), Mullus barbatus (mean value 20.82, CV 31.9), Micromesistius poutassou (mean value 19.7 kg/km², 42.9 C.V.), Trachurus mediterraneus (mean value 13.20, CV 28.6) and Eledone cirrhosa (mean value 12.17, CV 9.4).

Species as Citharus linguatula, Eutrigla gurnardus, Trigloporus lastoviza, Sepia officinalis exhibit very low abundance indices in the area.

The areas with the most abundant biomass indices inside the M1 region were the northern Tyrrhenian Sea and the northern part of Tyrrhenian Sea in the upper strata (10-200 m) while in the deeper strata (200 - 800 m) abundant biomass values were also in the Ligurian Sea and southern part of central Tyrrhenian Sea.

Important nurseries areas has been identified in the Ligurian Sea (for Lophius piscatorius, Spicara smaris, Trachurus trachurus, Aristeus antennatus), in the Northern Tyrrhenian Sea (for Micromesistius poutassou, Pagellus bogaraveo, Trachurus mediterraneus, T. trachurus, Trisopterus capelanus), in the northern part of Central Tyrrhenian Sea (for M. merluccius, S. flexuosa) and in the southern part of central Tyrrhenian Sea (for M. merluccius, Aristaeomorpha foliacea).

The coastal species Engraulis encrasicolus (44.95 kg/km²), Sardina pilchardus (24.2 kg/km²), Lepidopus caudatus (19.0 kg/km²) Glossanodon leioglossus (15.8 kg/km²), Diplodus annularis (14.3 kg/km²⁾ and the deeper water species Todaropsis eblanae (4.6 kg/km²), Chlorotocus agassizi (4.44 kg/km²) and Gadiculus argenteus (4.11 kg/km²) were the more common species between those not present in the reference list.

Sardina pilchardus showed higher biomass in the northern part of central Tyrrhenian Sea (168.3 kg/km²) between 10 and 50 m and in the Ligurian Sea (73.4) between 50 and 100 m. Engraulis encrasicolus was very abundant in the Ligurian Sea between 50 and 100 m (395.7 kg/km²) and in the southern part of central Tyrrhenian Sea between 100 and 200 m (98.9 kg/km²).

Fish

A total of 43 of the 44 reference list species of the Medits protocol were collected. The most abundant species in biomass was Merluccius merluccius in all the strata.

In the 10 - 200 m stratum were also abundant a non-target species (Engraulis encrasicolus) and Trachurus trachurus.

In the 200 - 500 m stratum were abundant Galeus melastomus, Lepidopus caudatus, Gadiculus argenteus and Micromesistius poutassou.

As far as density is concerned, M. merluccius was the most important species mainly due to the large number of small specimens. In the 10 - 200 m stratum important catches were for T. trachurus and M. poutassou with important number of recruits, and for not target species such as Glossanodon leioglossus, E. encrasicolus S. pilchardus, Macroramphosus scolopax. In the 200-500 m stratum important number of M. merluccius, M. poutassou, G. argenteus, Chlorophtalmus agassizi and Phycis blennoides (juveniles) were caught.

In the Ligurian Sea the most abundant species of reference list were Spicara smaris, Trachurus trachurus, Mullus barbatus, Merluccius merluccius, Galeus melastomus, Lophius piscatorius.

In the Northern Tyrrhenian Sea the most abundant species of reference list were Micromesistius poutassou, Mullus barbatus, Trachurus mediterraneus, Trachurus trachurus, Merluccius merluccius.

In the northern part of central Tyrrhenian Sea the highest biomass were recorded for Merluccius merluccius, Mullus barbatus, Galeus melastomus, Spicara flexuosa, Trachurus trachurus.

In the southern part of central Tyrrhenian Sea the highest abundances were recorder for Merluccius merluccius, Trachurus trachurus, Galeus melastomus, Phycis blennoides, Trachurus mediterraneus.

It must be pointed out that the catches of these species were made up largely of small specimens.

Below is a report on the data obtained for the reference list species.

Aspitrigla cuculus

Aspitrigla cuculus showed low mean biomass values for the M1 region (2.8 kg/km²). A. cuculus occurred relatively commonly in the northern Tyrrhenian Sea between 50 and 100 m (9.2 kg/km²) and 100 and 200 m (28.6 kg/km²).

The lengths ranged from 3 to 26 cm with 2 o 3 distinct cohorts.

Citharus linguatula

Citharus linguatula showed abundance less than 1 kg/km² in every zone and occurred relatively commonly in the northern Tyrrhenian Sea between 50 and 100 m (0.78 kg/km²) and in the southern part of central Tyrrhenian Sea between 100 and 200 m (0.34 kg/km²). Mean biomass values for the M1 region were very low (0.17 kg/km²).

The lengths ranged from 6 to 24 cm.

Eutrigla gurnardus

This specie was caught mainly in the 100-200 m stratum. Biomass values in the region were low (0.12⁾ and 1.37 in the northern Tyrrhenian Sea was the highest value. Practically absent from the Ligurian Sea and the southern part of central Tyrrhenian Sea.

The lengths ranged from 13 to 34 cm.

Galeus melastomus

G. melastomus was present from 200 to 800 m and more abundant between 500 - 800 m in all sub-areas. The species shown high biomass in the northern part of central Tyrrhenian Sea (117.2 kg/km²) and Ligurian Sea (80.6).

A wide range of size was recorded. The lengths ranged from 10 to 64 cm.

Helicolenus dactylopterus

Helicolenus dactylopterus was present from 100 to 800 m and more abundant between 500 - 800 m. H. dactylopterus shown high biomass in the northern Tyrrhenian Sea (9.95 kg/km²) and Ligurian Sea (10.7).

The lengths ranged from 3 to 30 cm with 2 o 3 distinct cohorts. A higher percentage of small individuals (< 10 cm TL) were found.

Lepidorhombus boscii

More abundant in the strata 200 - 500 m in the Ligurian Sea (3.3 kg/km², CV 25) and the northern Tyrrhenian (3.1 kg/km²). It was found also abundant in the 500-800 m stratum in the northern Tyrrhenian Sea (1.44 kg/km²).

The lengths ranged from 4 to 32 cm with 2 o 3 distinct cohorts.

Lophius budegassa

Lophius budegassa was relatively abundant between 100 and 500 m particularly in the Ligurian Sea (15 kg/km² in the 10-50 stratum) and northern Tyrrhenian Sea (23.6 kg/km²) in the 100-200 stratum.

The lengths ranged from 7 to 64 cm.

Lophius piscatorius

Almost absent in the southern part of central Tyrrhenian Sea, L. piscatorius was caught in all the strata. The species shown high biomass in the Ligurian Sea between 50 and 100 m (15.6, CV 36) and between 100 and 200 m (69.6, CV 36.1).

The lengths ranged from 9 to 85 cm.

Merluccius merluccius

M. merluccius was caught in larger numbers in the southern part of central Tyrrhenian Sea between 100 and 200 m (12,832 N/km², CV 34.7) and in the northern part of central Tyrrhenian Sea between 100 and 200 m (12,553, CV 23.2) and between 200 and 500 m (15,109, CV 44.4). From the point of view of biomass, Hake was more abundant in the southern part of central Tyrrhenian Sea between 100 and 200 m (130.7 kg/km², CV 29.6) and between 200 and 500 m (231.3, CV 63), but high values were found for all the area. Mean biomass values for the M1 region of 59.5 (CV 17.7) was given by this specie.

M. merluccius had a length frequency distribution which was homogeneous over the whole region. The greatest proportion (between 40 and 90%) of the specimens present in the haul ranges between 5 and 22-24 cm in length over the whole area. Specimens exceeding 30 cm in length were usually present below 200 m. The biggest individual measured was of 65 cm.

Micromesistius poutassou

M. poutassou was abundant in the northern Tyrrhenian Sea between 100 and 200 m (10,873 N/km²) and 200-500 m (15,854 N/km²). M. poutassou shown high biomass values in the northern Tyrrhenian Sea (150.8 between 200 and 500 m, CV 68.5).

Mean biomass values for the M1 region of 19.71 kg/km² (CV 42.9) was given by this specie.

The length frequency of this specie was distributed according to the depth, with smaller individuals found between 100 and 200 m and adults found below 200 m. The lengths ranged from 8 to 38 cm. Small specimens were caught mainly in the northern and central Tyrrhenian Sea.

Mullus barbatus

Mullus barbatus was particularly abundant between 10 and 50 m in the Ligurian Sea (88.82 kg/km², CV 31.5) and northern part of central Tyrrhenian Sea (266.85 kg/km², CV 37.9) and between 50 and 100 m in the northern Tyrrhenian Sea (60.7 kg/km², CV 34.9). Mean biomass values for the M1 region of 20.8 kg/km² (CV 31.9) was given by this specie.

At the time of the survey there were no young specimens of M. barbatus in the M1 region. The normal sizes for fish of this species in the caught were between 6 and 26 cm with almost 2 distinct cohorts.

Mullus surmuletus

M. surmuletus was caught with a relatively high abundance in the northern part of the central Tyrrhenian Sea at depth of 10 - 50 m (18.49 kg/km², CV 83.8) and in the northern part of the central Tyrrhenian Sea at depth 100 - 200 m (4.10 kg/km², CV 42.3).

Pagellus acarne

Was very abundant in some hauls between 10 and 50 m in the southern part of central Tyrrhenian Sea (175 N/km² and 6.7 kg/km²). In the other areas showed high biomass between 100 and 200 m (2.75 kg/km² in the northern part of central Tyrrhenian Sea).

Mean biomass values for the M1 region of 1.14 (CV 24.5) was given by this specie. The smallest individuals (6-14 cm) were located between 10 and 50 m mainly in the central Tyrrhenian Sea.

Pagellus erythrinus

There were significant numbers of small specimens of P. erythrinus at depths between 10 and 50 m in the northern Tyrrhenian Sea (602 N/km²). The specie was caught from depth of 10 m to 200 m. Biomass values of 6.4 were found in the area.

Total Lengths seams to increase in according to depth.

Pagellus bogaraveo

Was common in the northern Tyrrhenian Sea at depths between 200 and 500 m (10.7 kg/km², CV 62.8) where large specimens (35 - 48 cm TL) were caught.

Phycis blennoides

Phycis blennoides shown high biomass between 200 and 500 m in the Ligurian Sea (34.98) and in the northern Tyrrhenian Sea (14.11 kg/km²) and between 500 and 800 m in the Ligurian Sea (28.17 kg/km²). Mean biomass values for the M1 region of 10.46 (CV 8.9) was given by this specie.

Juveniles were caught mainly in the Ligurian Sea and southern part of Central Tyrrhenian Sea. P. blennoides was found in 3 and more distinct cohorts, which were distributed according to depth in the entire zone. The lengths ranged from 6 to 53 cm.

Raja clavata

Raja clavata was significantly present only in the northern Tyrrhenian Sea between 50 and 200 m (up to 14.2 kg/km², CV 53.1). Mean biomass values for the M1 region of 2.77 (CV 33.5) (3 N/km²) were found. Practically absent in the hauls made in the southern part of central Tyrrhenian Sea.

The lengths ranged from 13 to 91 cm.

Scyliorhinus canicula

Occurred between 100 and 500 m, more commonly in the northern part of central Tyrrhenian Sea. Mean biomass values for the M1 region of 1.7 (CV 25.3) (17 N/km²) were found.

The lengths ranged from 10 to 49 cm. Juveniles were mainly found in the 200-500 stratum in the northern Tyrrhenian Sea.

Solea vulgaris

Solea vulgaris was found mainly in the northern part of central Tyrrhenian Sea between 10 and 50 m (2.6 kg/km²) and in the Ligurian Sea between 50 and 100 m (5.3 kg/km²). Mean biomass value for the M1 region of 0.44 (CV 31.7) was found.

Spicara flexuosa

Occurred between 10 and 200 m, more commonly in the northern part of central Tyrrhenian Sea and the Ligurian Sea (between 10 and 50 m), less so in other Tyrrhenian areas. Mean biomass values for the M1 region of 5.54 (CV 39.9) (523 N/km²) were found.

The lengths ranged from 7 to 19 cm. Small specimens were caught mainly in the northern part of central Tyrrhenian Sea.

Spicara smaris

Occurred between 10 and 200 m, more commonly in the Ligurian Sea between 50 and 100 m (129.1 kg/km², CV 35.6, 3,536 N/km², CV 35.5) less so in other Tyrrhenian areas. Mean biomass values for the M1 region of 3.91 (CV 61) (114 N/km²) was found.

The lengths ranged from 3 to 23 cm. Small specimens were caught mainly in the Ligurian Sea and northern Tyrrhenian Sea.

Trachurus mediterraneus

Was common in the northern Tyrrhenian Sea (180.4 kg/km², CV 25.9) and northern part of central Tyrrhenian Sea (56.1 kg/km², CV 14.7) between 10 and 50 m but also between 50 and 100 m. Mean biomass value for the M1 region of 13.20 (CV 28.57) (470 N/km²) was found.

The lengths ranged from 6 to 36 cm. Several distinct cohorts (with an important cohort of recruits) were found in the northern Tyrrhenian Sea.

Trachurus trachurus

T. trachurus gave high biomass values between 10 and 50 m (up to 122.2 kg/km², - 17,392 N/km², in the northern Tyrrhenian Sea) and in the 100-200 stratum in the northern part of central Tyrrhenian Sea (76.2 kg/km²,). Mean biomass value for the M1 region of 22.5 kg/km², CV 26.7 (2,160 N/km²) was found.

The small specimens were dominant in the catches of the shallowest strata in the entire zone. High numbers of small specimens were caught mainly in the northern Tyrrhenian Sea between 10 and 50 m.

Trigloporus lastoviza

Nearly absent in the southern part of central Tyrrhenian Sea, this specie was found in the Ligurian Sea between 10 and 50 m (6.15 kg/km², CV 28.8).

The lengths ranged from 7 to 26 cm.

Trisopterus minutus capelanus

Nearly absent in the Ligurian Sea, this specie was found in the northern Tyrrhenian Sea between 50 and 100 m (32.2 kg/km², CV 44.3) and between 100 and 200 m (16.14 kg/km², CV 17.8). From the point of view of density T. minutus was more abundant between 100 and 200 m in the northern Tyrrhenian Sea (2,703).

T. minutus was found in at least 2 distinct cohorts (the first one between 2 and 10 cm TL). Small specimens were found in the northern and central Tyrrhenian Sea between 200 and 500 m.

Zeus faber

Occurred mainly between 100 and 200 m in the northern Tyrrhenian Sea (23.78 kg/km², CV 34.1) and in the Ligurian Sea (28.6 kg/km²). The lengths ranged from 11 to 52 cm.

Crustaceans

All the 6 target species of crustaceans were collected. The highest biomass were observed for Nephrops norvegicus (mean value 4.6, CV 12.6), Parapenaeus longirostris (mean value 4.42, CV 19.7), Aristaeomorpha foliacea (mean value 2.3, CV 40.2) and Aristeus antennatus (mean value 0.7, CV 42.9).

In terms of density, the most abundant species were P. longirostris and A. foliacea.

There were also relevant catches of species which were not being targeted by the reference list, such as Plesionika martia and P. edwardsii.

Below is a report on the data obtained for the reference list species.

Aristeus antennatus

A. antennatus was slightly less common than Aristaeomorpha foliacea.

This red shrimp shown high biomass in depths more than 500 m only in the Ligurian Sea (12.56, CV 46.9) and in the northern part of central Tyrrhenian Sea (1.05, CV 74.3). Mean biomass value for the M1 region of 0.7 (CV 42.9) (density of 31) was found.

The lengths ranged from 20 to 59 mm CL. The catches are mainly made of adult female, but several small specimens were caught in the Ligurian Sea.

Aristaeomorpha foliacea

Was more abundant in the whole central Tyrrhenian Sea (22.3 kg/km², CV 51.4 for the southern part, 6.29 kg/km², CV 45.6, for the northern part). Mean biomass value for the M1 region of 2.3 kg/km² (CV 40.3) (density of 145) was found.

The lengths ranged from 15 to 62 mm CL. Also for this specie, the catches are mainly made of adult female, but recruits were caught in the southern part of central Tyrrhenian Sea.

Nephrops norvegicus

As far as crustaceans are concerned, N. norvegicus (4.6 kg/km², CV 12.6 over the whole area) showed the highest biomass, This species was caught mainly in the northern Tyrrhenian Sea (22.7 kg/km², CV 25.2) and in the Ligurian Sea (16.2 kg/km², CV 24.4). The lengths ranged from 15 to 60 mm CL.

Parapenaeus longirostris

For the M1 region, a mean biomass value of 4.42, CV 9.7, (density of 408) was found. P. longirostris was fished in depths between 100 and 500 m. The specimens were mainly caught in the southern (density of 15.5) and northern (density of 23.0) part of central Tyrrhenian Sea.

The lengths ranged from 9 to 40 mm CL.

Cephalopods

All the cephalopod species of the Medits reference list were caught.

The mean biomass values were highest for Eledone cirrhosa (mean value 12.2 kg/km², CV 9.4) followed by Octopus vulgaris (mean value 6.2, CV 19.9), Illex coindetii (mean value 2.2, CV 13.0), Sepia officinalis (mean value 0.23, CV 36.2), Loligo vulgaris (mean value 0.4, CV 30.6), Eledone moschata (mean value 0.48, CV 37.4).

Among the species which were not being targeted by the trawl survey but which were present: Loligo forbesi, Pteroctopus tetracirrhus and Octopus salutii.

Below is a report on the data obtained for the reference list species.

Eledone cirrhosa

The species of cephalopod which occurred in the highest biomass was E. cirrhosa. It was particularly common in depths up to 500 m in the northern Tyrrhenian Sea (48.57 between 50 and 100 m, 43.39 between 100 and 200 m) and in the southern part of central Tyrrhenian Sea (19.74 between 200 and 500 m). A mean biomass value for the M1 region of 12.2, CV 9.4) was found.

The population of E. cirrhosa was made up of two cohorts (1-5 cm and 6-13 cm ML).

Eledone moschata

Absent from the Ligurian Sea, a very low mean biomass value for the region M1 of 0.48 was found. Was mostly caught in the northern Tyrrhenian Sea in depths between 10 and 100 m. Length ranged from 2 to 13 cm ML

Illex coindetii

A mean biomass value for the region M1 of 2.21 (CV 12.9) was found. Caught in depths between 50 and 200 m, was abundant mainly in the central part of Tyrrhenian Sea and in the northern Tyrrhenian Sea.

Length ranged from 3 to 23 cm ML with almost 2 distinct cohorts. Small specimens (< 10 cm DML) were found in all sub-areas.

Loligo vulgaris

It was found in relatively high biomass in the northern part of central Tyrrhenian Sea between 10 - 50 m (3.3, CV 42.3).

Small specimens less than 10 cm ML were found mainly in the northern part of central Tyrrhenian Sea.

Octopus vulgaris

O. vulgaris (abundance of 6.18, CV 19.9 in the whole M1 region) was found at depths up to 200 m. It was more common in the Ligurian Sea (biomass of 52.44, CV 15.2) and in the northern part of central Tyrrhenian Sea (biomass of 45.9, CV 20.6) between 10 and 50 m.

Lengths ranged from 2 - 17 cm ML.

Sepia officinalis

Biomass of Sepia officinalis was low and relatively more common in the northern Tyrrhenian Sea and Ligurian Sea in depths less than 50 m (biomass up to 3.2 kg/km², CV 31.4) but was absent from the waters of the southern part of central Tyrrhenian Sea. The mean biomass value for the region M1 of 0.23, CV 36.2, was found.

Comments by stratum, survey 1999

In the 10-200 m stratum the species with highest biomass indices were Merluccius merluccius, Engraulis encrasicolus, Sardina pilchardus, Trachurus trachurus, Mullus barbatus, (fishes), Eledone cirrhosa and Octopus vulgaris (cephalopods) and Parapenaeus longirostris (crustaceans).

In the 200-800 m stratum, the species with the highest biomass indices were Merluccius merluccius, Galeus melanostomus, Lepidopus caudatus, Chlorophtalmus agassizi, Gadiculus argenteus, Micromesistius poutassou Phycis blennoides (fishes), Eledone cirrhosa and Todaropsis eblanae (cephalopods) and Nephrops norvegicus, Parapenaeus longirostris and Aristaeomorpha foliacea (crustaceans).

Stratum 10-50 m

In this stratum the captures regarded a significant quantities of recruits of 5 - 6 species, some of them with low economic value.

The most abundant species in biomass in this stratum were Mullus barbatus, Trachurus mediterraneus, Octopus vulgaris, Pagellus erythrinus, and Merluccius merluccius.

M. barbatus, O. vulgaris, M. merluccius and P. erythrinus had highest biomass in the Ligurian Sea, T. mediterraneus in the northern Tyrrhenian Sea. The most important species in density were Mullus barbatus, Spicara flexuosa (mainly in the northern part of central Tyrrhenian Sea), Trachurus trachurus and Trachurus mediterraneus (mainly in the northern Tyrrhenian Sea), and Loligo vulgaris.

^10 - 50 m	^Ligurian S.		^North T. S		^n.p. Central T. S		^s.p. South T. S
^Species	^kg/km²	^N/km²	^kg/km²	^N/km²	^kg/km²	^N/km²	^kg/km²	^N/km²
Mullus barbatus	88.8	2568	58.8	1851	266.8	5475	12.8	315
Trachurus mediterraneus	47.3	1841	180.4	7443	56.1	1692	31.4	584
Trachurus trachurus	68.5	6196	122.3	17392	23.6	3645	43.1	3119
Spicara flexuosa	58.9	2964	3.7	216	109.3	16903	17.6	870
Octopus vulgaris	52.4	54	6.0	3	45.9	118	19.4	47

Stratum 50-100 m

In this stratum the most abundant species were Merluccius merluccius and Trachurus trachurus (abundant in the northern part of central Tyrrhenian Sea), Spicara smaris (abundant in the Ligurian Sea), Mullus barbatus, Eledone cirrhosa and Trisopterus minutus (abundant in the northern Tyrrhenian Sea).

Large quantities in number were of Merluccius merluccius and Trachurus trachurus (mainly in the northern part of central Tyrrhenian Sea), Mullus barbatus (abundant in the northern Tyrrhenian Sea), Spicara smaris (abundant in the Ligurian Sea). Also in this case the large numbers of specimens in the Ligurian Sea and in the central Tyrrhenian Sea were recruits.

^50 – 100 m	^Ligurian S.			^North T. S		^n.p. Central T. S		^s.p. South T. S
^Species	^kg/km²		^N/km²	^kg/km²	^N/km²	^kg/km²	^N/km²	^kg/km²	^N/km²
Merluccius merluccius	19.6	770		31.0	487	59.6	1928	37.7	1459
Spicara smaris	129.2	3536		3.3	146	2.6	139	0.6	24
Trachurus trachurus	6.4	592		33.1	1216	47.5	5842	32.5	2427
Mullus barbatus	19.9	720		60.7	1734	0.7	12	0.12	3
Eledone cirrhosa	5.2	143		48.6	239	8.9	30	2.7	39

Stratum 100-200 m

In this stratum the most abundant species in biomass were Merluccius merluccius (abundant in the northern part of central Tyrrhenian Sea), Trachurus trachurus, Micromesistius poutassou, Mullus barbatus, and Eledone cirrhosa (mainly in the northern Tyrrhenian Sea

The most important species in density were Merluccius merluccius (mainly in the southern part of the central Tyrrhenian Sea), Trachurus trachurus (Ligurian Sea), Micromesistius poutassou, Trisopterus capelanus minutus and Mullus barbatus (northern Tyrrhenian Sea).

^100 - 200 m	^Ligurian S.			^North T. S		^n.p. Central T. S		^s.p. South T. S
^Species	^kg/km²	^N/km²		^kg/km²	^N/km²	^kg/km²	^N/km²	^kg/km²	^N/km²
Merluccius merluccius	52.8		2453	76.4	5245	130.7	12553	97.6	12832
Trachurus trachurus	76.2		10097	15.9	512	18.1	2218	32.2	2278
M. poutassou	1.1		5	111.5	10873	0.9	58	0.0	0
Mullus barbatus	16.8		295	75.0	1200	6.8	112	8.9	170
Trisopterus capelanus	4.8		1495	16.8	2703	13.0	1502	14.2	2112

Stratum 200-500 m

The most abundant species in biomass in this stratum were Merluccius merluccius (abundant in the northern part of central Tyrrhenian Sea) and Micromesistius poutassou (abundant in the northern Tyrrhenian Sea). Then we had Phycis blennoides (mainly in the Ligurian Sea), Nephrops norvegicus (abundant in the northern Tyrrhenian Sea) and Eledone cirrhosa (abundant in the southern part of central Tyrrhenian Sea). Large quantities in number were of M. merluccius, Micromesistius poutassou, Phycis blennoides, Parapenaeus longirostris, and Nephrops norvegicus.

^200 - 500 m	^Ligurian S.		^North T. S		^n.p. Central T. S		^s.p. South T. S
^Species	^kg/km²	^N/km²	^kg/km²	^N/km²	^kg/km²	^N/km²	^kg/km²	^N/km²
Merluccius merluccius	14.5	83	54.7	2280	231.3	15109	75.7	6552
M. poutassou	32.5	290	150.8	15854	8.4	192	5.5	56
Phycis blennoides	35.0	1702	14.1	633	16.4	1512	29.5	2265
Nephrops norvegicus	16.2	390	22.7	642	12.4	369	7.5	197
Eledone cirrhosa	14.0	72	13.5	78	7.7	38	19.7	63

Stratum 500-800 m

In the deeper stratum the most abundant species in biomass were Galeus melastomus (mainly in the northern part of central Tyrrhenian Sea), Phycis blennoides (in the Ligurian Sea) and Aristaeomorpha foliacea (mainly in the southern part of central Tyrrhenian Sea). Then we had Helicolenus dactylopterus (in the Ligurian Sea), and Nephrops norvegicus (mainly in the northern part of central Tyrrhenian Sea).

Large quantities in number were of A. foliacea, G. melastomus, P. blennoides, N. norvegicus, and A. antennatus.

^500 - 800 m	^Ligurian S.		^North T. S		^Central T. S.		^South T. S
^Species	^kg/km²	^N/km²	^kg/km²	^N/km²	^kg/km²	^N/km²	^kg/km²	^N/km²
Galeus melastomus	80.6	390	38.8	161	117.7	916	78.4	367
Phycis blennoides	28.2	368	12.4	181	19.4	860	17.5	703
Aristaeomorpha foliacea	0.9	45	0.8	65	3.5	287	2.0	1466
H. dactylopterus	11.1	145	0.1	91	16.3	46	22.3	7
Nephrops norvegicus	3.4	105	3.7	97	8.4	255	3.8	94

Discussion and remarks

The results of the Medits-IT M1 1999 survey confirm previous observations on the geographic and bathymetric distribution of the fishery resources in the Ligurian Sea, northern and central Tyrrhenian Sea. Data point out the importance of some species in the M1 area: Mullus barbatus in coastal waters, crustacean species in the upper slope and Merluccius merluccius on a wide depth range. The results confirm that recruitment represents the remarkable fraction of the catch for most of the species.

Merluccius merluccius is confirmed to be widespread and abundant in the whole M1 area, and an increasing of its yield (from 20.7 in 1994 to 59.5 kg/km² in 1999) has been shown in the last surveys

A marked increase of Micromesistius poutassou catch (42.9 kg/km²) respect to 1994 survey (10.9 kg/km²) and the previous three years (1996 = 4.5 kg/km²; 1997 = 17.2 kg/km²; 1998 = 21.1 kg/km²) has been observed.

The highest abundance indices for Phycis blennoides related to the whole M1 area have been recorded in this last survey 10.5 kg/km²). Although its highest biomass was generally found in the southern part of central Tyrrhenian Sea, its density was sometime higher in the Ligurian Sea, as shown in this last survey.

The yield of Mullus barbatus related to the whole M1 area in this last survey (20.8 kg/km²) is higher respect the previous years (1996 = 12.7 kg/km²; 1997 = 11.9 kg/km²; 1998 = 15.3 kg/km²) and greater respect the first surveys (1994 = 6.4 kg/km²; 1995 = 7.2 kg/km²). The highest abundances of this fish have generally been found in the northern part of central Tyrrhenian.

Concerning the crustacean species, Aristeus antennatus was found with very low yields throughout the Medits surveys while Aristaeomorpha foliacea was caught with fluctuating abundance indices, between 0.89 kg/km² (1994) and 2.3 kg/km² (1999). This shrimp is a typical resource of the Ligurian Sea even though significant areas of abundance may be found in the central part of Tyrrhenian Sea.

Also Parapenaeus longirostris was collected with changing yields (between 0.5 kg/km² in 1996, 2.8 kg/km² in 1998 and 4.4 kg/km² in 1999).

The catches of Nephrops norvegicus in M1 area were rather comparable among the 6 Medits surveys and comprised between 4.36 kg/km² (1997) and 5.97 kg/km² (1998). This species is typically more abundant in the northern Tyrrhenian Sea.

With regard to the cephalopod species, a decrease of the yield has been shown in Eledone cirrhosa (20.0 kg/km² in 1994, 14.1 kg/km² in 1996 and 12.2 kg/km² in 1999).