Survey Results for Italy - area M5 – Italia, Slovenia, and international waters

by C. Piccinetti

Introduction

The report considers the results obtained in the Italian, Slovenian and international waters of northern and central Adriatic Sea. In 1999 the general situation of fisheries in the Adriatic Sea is very particular due to the presence on the sea bottom of a number of bombs discharged at sea during the war in the Balkan area. The time necessary to remove the bombs at sea and the prohibition of the fisheries for three months has obliged to postpone the survey in the area. The Medits '99 survey was carried out from August 4^th to October 14^th.

Global comments for Fish, Crustaceans and Cephalopods, Survey 1999

The most abundant species is Mullus barbatus with 51.2 kg/km² and 2961 N/km². In decreasing order we find Merluccius merluccius (32.25 kg/km²), Illex coindetii (21.97 kg/km²), Eledone moschata (18.84 kg/km²), Loligo vulgaris (15.32 kg/km²), Trisopterus minutus capelanus (12.93 kg/km²), Trachurus trachurus (12.09 kg/km²), Micromesistius poutassou (11.48 kg/km²), Sepia officinalis (3.97 kg/km²), Lophius budegassa (2.83 kg/km²), Nephrops norvegicus (2.66 kg/km²), Pagellus erythrinus (2.5 kg/km²), Raja clavata (2.2 kg/km²).

All other reference species show indices lower than 2 kg/km².

Fish

Aspitrigla cuculus

The biomass index is 1.78 kg/km². This species is abundant at depths greater than 200 m (9.48 kg/km² and 215 N/km²).

Citharus linguatula

The species is not abundant. Nevertheless, it is found on the whole shelf. Abundance indices are 0.17 kg/km² and 6 N/km².

Eutrigla gurnardus

This species is not abundant and abundance indices are 1.06 kg/km² and 65 N/km². It is found on the whole shelf.

Galeus melastomus

Caught with very low abundance at depth over 200 m. Abundance indices are 0.19 kg/km² and 1 N/km².

Helicolenus dactylopterus

This species is distributed mostly at depths over 200 m. Abundance indices in the stratum between 200 and 800 m are 17.84 kg/km² and 220 N/km².

Lepidorhombus boscii

This species is distributed at depths over 200 m. Abundance indices are 0.68 kg/km² and 9 N/km².

Lophius budegassa

It is caught in the whole area at depth from 50 to 800 m with abundance indices of 2.83 kg/km² and 40 N/km². The range of the frequency distribution is 10 – 48 cm.

Lophius piscatorius

This species is not abundant. Abundance indices are 1.08 kg/km² and 2 N/km².

Merluccius merluccius

Species very abundant, distributed in the whole area with abundance indices of 32.25 kg/km² and 603 N/km². Small M. merluccius are caught mostly in the “Pomo Pit”, the larger specimens (30 – 60 cm) are found in 200-800 m depth stratum.

Micromesistius poutassou

It is generally present in strata deeper than 200 m. Average biomass and density indices are respectively 11.48 kg/km² and 470 N/km².

Mullus barbatus

This is the most abundant species caught in 1999. Red mullet is caught in the Adriatic area with high abundance (51.2 kg/km², 2961 N/km²). The highest biomass (55.65) and density indices (3220) are observed in stratum 50-100 m.

Mullus surmuletus

As red mullet, this species was distributed over the whole investigated area, but with very low abundance (1.94 kg/km², 68 N/km²).

Pagellus acarne

Caught only on the shelf with very low density indices (0.25 kg/km², 11 N/km²).

Pagellus bogaraveo

The species is found in low quantities (0.12 kg/km², 5 N/km²).

Pagellus erythrinus

This species is caught in the stratum 10 – 200 m (2.5 kg/km², 121 N/km²).

Sparus pagrus

Absent in the catches.

Phycis blennoides

This species is caught especially at depths over 200 m. Abundance indices are 0.65 kg/km ² and 10 N/km².

Raja clavata

Abundance indices of this species are 2.2 kg/km² and 1 N/km².

Solea vulgaris

This benthic species is present at depths between 50 and 100 m. Abundance indices are 0.68 kg/km ² and 5 N/km².

Spicara flexuosa

This species is caught, especially on the shelf, with abundance indices of 1.83 kg/km² and 230 N/km². Not caught over 200 m.

Spicara smaris

The species is caught with very low abundance: abundance indices are 0.48 kg/km ² and 15 N/km².

Trachurus mediterraneus

Caught at depths between 10-200 m (1.4 kg/km ² and 29 N/km²).

Trachurus trachurus

This species is distributed in all areas with Abundance indices of 12.09 kg/km ² and 721 N/km². The highest values are found at depth from 10 to 200 m.

Trigloporus lastoviza

This species is caught at low depths (10-100 m). Abundance indices are 0.57 kg/km² and 18 N/km².

Trisopterus minutus capelanus

Abundance indices are 12.93 kg/km² and 894 N/km². The highest abundance is in shallow waters at depth between 50 and 100 m.

Zeus faber

Abundance indices are 1.23 kg/km² and 6 N/km².

1.1 Crustaceans

Aristeus antennatus

This species is not found in the North and Central Adriatic Sea.

Aristaeomorpha foliacea

Also this species is not found in the North and Central Adriatic Sea.

Nephrops norvegicus

Abundance indices are 2.66 kg/km² and 116 N/km². This species is present at depth over 50 m. Small individuals dominated in “Pomo Pit” at depth between 100 and 200 m.

Parapenaeus longirostris

Abundance indices are 0.22 kg/km² and 29 N/km². This species is more abundant at depth over 200 m.

1.2 Cephalopods

Eledone cirrhosa

This species is not abundant. Abundance indices are 1.43 kg/km² and 33 N/km².

Eledone moschata

This species is abundant especially in the shallowest water (10-200 m). Abundance indices are 18.84 kg/km² and 125 N/km².

Illex coindetii

This species is abundant in all area with higher abundance at depth over 200 m. Abundance indices are 21.97 kg/km² and 860 N/km².

Loligo vulgaris

This species is more abundant in the strata between 10 and 200 m. Abundance indices are 15.32 kg/km² and 789 N/km².

Octopus vulgaris

This species is not abundant and is caught in coastal water. Abundance indices are 1.34 kg/km² and 2 N/km².

Sepia officinalis

Abundance indices are 3.79 kg/km² and 87 N/km². This species is distributed in coastal waters at depth between 10 and 50 m.

Comments by stratum, survey 1999

In the Adriatic Sea, depths decrease very slowly and the limits between strata are very inconsistent. For this reason we will consider only two big strata (10-200 and 200-800 m) below.

1.3 Stratum 10-200 m

The most abundant species in this stratum is Mullus barbatus with 55.65 kg/km². Recruits make a very important part of the total catch of red mullet, in particular off the Italian coastal area. The high abundance of this species this year, compared to the ones recorded during the previous Medits surveys, is probably due to the trawling ban of three months in 1999.

The second species in biomass is Merluccius merluccius with 32.64 kg/km², an index lower than the one recorded for the previous survey.

Other important species in the catch are three cephalopods: Eledone moschata (20.48 kg/km²), Illex coindetii (20.15 kg/km²) and Loligo vulgaris (16.66 kg/km²). All of these three species show an evident increase of the biomass from 1998 to 1999. Trisopterus minutus capelanus with 13.82 kg/km² in this survey presents a strong decrease from 1998.

1.4 Stratum 200-800 m

In this stratum the most abundant species is Micromesistius poutassou (59.61 kg/km²) with a strong increase in abundance with regard to the previous year. The second species is Illex coindetii (42.77 kg/km²) also with a strong increase compared with 1998.

Abundance of Merluccius merluccius in this stratum (27.87 kg/km²) is similar as the one for 1998.

For other species, catch increased in this stratum: Helicolenus dactylopterus (17.84 kg/km²), Aspitrigla cuculus (9.48 kg/km²), Lepidorhombus boscii (7.42 kg/km²), Lophius budegassa (5.56 kg/km²) and Phycis blennoides (4.21 kg/km²).

A very strong decrease is evident for Eledone cirrhosa and Nephrops norvegicus (1.33 kg/km²).

Discussion and remarks

The particular situation encountered for the survey in 1999, with a shifting of the period and after a three-month fishing ban, makes difficult comparison with the previous surveys in this area.

So, for few species (Mullus barbatus, Loligo vulgaris), size composition of the catch shows a high level of recruitment. This abundance of yearly young fish may be explained by the interdiction of trawling during three months. For other species, the high variability in the catch with high C.V. explains the variations of abundance in the year.

Restriction of the cruise in Slovenian, Italian and International waters, and excluding Croatian territorial waters limits our considerations to only a part of the Adriatic Sea.