Survey Results for Italy - area M4 - Part 2: Albany and SE Adriatic Sea
* LBMB, Bari, Italy.
** Ministry of Agriculture and Food, Fishery Direction, Tirana, Albania.
*** Fishery Researches Institute, Durres, Albania.
Below is a report on Medits-AL 1997 survey results, referring to south-eastern Adriatic (strata 22141-22145).
In the sampled area (8735 kmē) 40 hauls were taken by the fishing vessel "Biancamaria".
During Medits-AL 1997 the most abundant in weight ( kg/kmē) species of the reference list, over the whole area, were Merluccius merluccius (mean value 34.71 kg/kmē), Eledone cirrhosa (9.15 kg/kmē), Lophius budegassa (7.41 kg/kmē), Mullus barbatus (6.73 kg/kmē), Loligo vulgaris (5.52 kg/km; the highest numerical abundance were attributed to Parapenaeus longirostris (mean value 789 Ind/kmē), Merluccius merluccius (615 Ind/kmē), Trisopterus minutus capelanus (351 Ind/kmē), Loligo vulgaris (267 Ind/kmē), Mullus barbatus (193 Ind/kmē).
As in the 1996 survey, some of the resources are distributed in well defined bathymetric strata; Eledone cirrhosa was mainly caught between 100 m and 500 m depth, Mullus barbatus between 10 m and 200 m depth, Parapenaeus longirostris between 200 m and 500 m depth, Trisopterus minutus capelanus between 50 m and 100 m depth, Loligo vulgaris between 10 m and 50 m depth.
Merluccius merluccius is confirmed to be ubiquitous, with higher yields between 50 m and 500 m depth.
The catches referring to the above mentioned species were, generally, lower than the 1996 results; particularly, during the 1997 survey, the catches referring to the genus Trachurus and to the species Spicara flexuosa and Micromesistius poutassou were much lower than during the previous (1996) survey.
This species was caught mainly on continental shelf with abundance indexes ranged from 2.00 kg/kmē to 2.73 kg/kmē (stratum 10-50 m).
This species was caught mainly on continental shelf with very low abundance indexes.
Helicolenus dactylopterus was fished at depths greater than 100 m; abundance indexes are higher between 200 m and 500 m depth. The highest biomass and abundance values (1.74 kg/kmē, 249 Ind/kmē) was observed in 200-500 m stratum (probably an index of recruitment).
This species was caught beyond 200 m of depth with negligible yield and density; the highest biomass and abundance values (2.67 kg/kmē, 83 Ind/kmē) was observed in 200-500 m stratum.
Lophius budegassa was found across the whole depth range investigated; the highest abundance index (14.52 kg/kmē) was observed between 50 and 100 m.
This species was found sporadically; the highest abundance index (0.58 kg/kmē) was observed between 500 and 800 m.
Generally abundant in the whole area, mainly between 50 and 200 m. In this depth zone density ranged from 761/kmē to 1427/kmē. The highest abundance of 59.82 kg/kmē was observed in depth stratum 50-100 m. A dominance of juveniles was observed in the catches between 100 m and 200 m depth.
This species was found with low yield from 200 m to 800 m depth. The highest density (27 Ind/kmē) was observed in 200-500 m stratum.
This species was caught almost exclusively on the continental shelf (< 200 m). The highest abundances in weight (22.95 kg/kmē) and numbers (673 Ind/kmē) were found in the depth stratum (50-100 m).
The majority of specimens had a length between 10 cm and 20 cm.
This species was caught on the continental shelf (< 200 m) with low yield.
This species was found within 50-100 m stratum, with very low abundance.
Few specimens were fished in the deeper zone beyond 100 m.
This species was found only in the continental shelf (mainly between 10-100 m); the highest abundance index was 18.94 kg/kmē (10-50 m stratum).
It was generally found beyond 100 m of depth exhibiting the highest abundance index (2.93 kg/kmē) between 500 and 800 m. Most of the specimens fished were smaller than 20 cm.
This species was caught only once a time on shelf bottoms.
This species was found only in the continental shelf; the highest abundance index was 2.74 kg/kmē (10-50 m stratum).
This species was found down to 200 m. The highest abundance index and density were observed in the 50-100 m stratum (2.97 kg/kmē).
This species was fished on the continental shelf (<200 m) mainly between 10 m and 100 m with yields ranging from 1.42 and 5.25 kg/kmē.
This species was caught from 10 m to 500 m depth. The highest abundance indexes were obtained in 50-100 m stratum with value of 4.50 kg/kmē. Juveniles were dominant in the catches.
This species was caught between 10-200 m depth; the highest yield (10.48 kg/kmē) was found in 50-100 m depth stratum.
This species was found between 50 m and 200 m; the highest abundance value was 5.62 kg/kmē (100-200 m).
This species was only fished in the deepest water of the southern area (Vlora-Saranda). The yields were very low.
It was generally caught beyond 500 m of depth. Its yields in weight and numbers were 14.61 kg/kmē and 457 Ind/kmē respectively. The sizes of specimens mainly ranged from 25 mm to 65 mm.
This species was generally caught with valuable yields at depth greater than 200 m. The highest yield (1.55 kg/kmē) was observed between 200 and 500 m. Most carapace lengths ranged from 25 to 60 mm.
This species was abundantly caught, mainly at depths between 200 and 500 m; the highest yields were 13.97 kg/kmē and 2821 Ind/kmē in the zone of 200-500 m. The sizes of specimens mainly ranged from 12 mm to 40 mm.
It was generally fished in depths greater than 50 m and shallower then 500 m. The highest yield (23.08 kg/kmē) was observed between 100 and 200 m. Most mantle lengths ranged from 5 to 10 cm.
It was generally fished on continental shelf, between 10 m and 100 m. The highest yield (10.80 kg/kmē) was observed between 10 and 50 m.
This species was caught with higher density between 100 and 200 m depths. Its highest yield was 3.84 kg/kmē.
It was fished with remarkable yields within 100 m depth. The highest abundance index (29.57 kg/kmē) was found in the first stratum (10-50 m). The specimens mantel lengths are generally smaller than 10 cm.
This species was found as far as 100 m. The highest abundance index was 4.64 kg/kmē (50-100 m stratum). Very low values of density were observed.
Not fished at all.
In this first stratum the 5 most important species were Loligo vulgaris, Pagellus erythrinus, Merluccius merluccius, Eledone moschata, Trachurus mediterraneus.
Loligo vulgaris was found with indexes of 29.57 kg/kmē and 3218 Ind/kmē. The length frequency distribution ranged from 3 cm to 9 cm (juveniles); the modal peak is found around 5-6 cm (mantel length).
Pagellus erythrinus was caught with a mean abundance value of 18.94 kg/kmē. The mean density was 304 Ind/kmē and the length frequency distribution ranged from 12 cm to 28 cm with a modal peak around 15-16 cm.
During the Medits-AL '97 the abundance indexes of Merluccius merluccius estimated, in the first depth stratum, was 17.94 kg/kmē. The mean density was 275 Ind/kmē and the length frequency distribution ranged from 10 cm to 35 cm (higher frequencies between 16 cm and 22 cm).
Eledone moschata was found with indexes of 10.80 kg/kmē and 130 Ind/kmē.
The mean yields of Trachurus mediterraneus were 5.25 kg/kmē and 87 Ind/kmē.
The length frequency distribution ranged from 6 cm to 29 cm (higher frequencies between 14 cm and 16 cm).
The 5 most important species between 50 and 100 m in the region were Merluccius merluccius, Mullus barbatus, Lophius budegassa, Trisopterus minutus capelanus, Eledone cirrhosa.
Merluccius merluccius mean abundance index was 59.82 kg/kmē, while mean density was 761 Ind/kmē. The length frequency distribution ranged from 8 cm to 41 cm (higher frequencies between 17 cm and 20 cm).
Mullus barbatus was found with indexes of 22.95 kg/kmē and 673 Ind/kmē. The length frequency distribution ranged from 5 cm to 22 cm.
Lophius budegassa was found with yields of 14.52 kg/kmē and 35 Ind/kmē. The length frequency distribution (irregular) ranged from 12 cm to 46 cm.
The species Trisopterus minutus capelanus was found with indexes of 10.48 kg/kmē and 1057 Ind/kmē. The length frequency distribution ranged from 5 cm to 16 cm; the modal peak is found around 7-10 cm (total length).
Eledone cirrhosa was found with yields of 5.09 kg/kmē and 33 Ind/kmē. The length frequency distribution (irregular) ranged from 3 cm to 12 cm (mantle length).
The 5 most important species for this depth stratum were Merluccius merluccius, Eledone cirrhosa, Lophius budegassa, Zeus faber, Loligo vulgaris.
Merluccius merluccius mean abundance index was 45.36 kg/kmē, while mean density was 1427 Ind/kmē. The length frequency distribution ranged from 6 cm to 37 cm; the modal peak is found around 8-11 cm (recruitment).
Eledone cirrhosa was found with the yields of 23.08 kg/kmē and 129 Ind/kmē. The length frequency distribution ranged from 3 cm to 13 cm; two modal peacks are found around 3-4 cm and 10-11 cm respectively (mantle length).
The species Lophius budegassa was found with indexes of 10.45 kg/kmē and 16 Ind/kmē. The length frequency distribution (irregular) ranged from 11 cm to 56 cm.
Zeus faber was found with indexes of 5.62 kg/kmē and 9 Ind/kmē. The length frequency distribution (irregular) ranged from 3 cm to 44 cm.
Loligo vulgaris was found with the yields of 4.71 kg/kmē and 23 Ind/kmē. The length frequency distribution ranged from 10 cm to 25 cm (mantle length).
The 5 most important species for this depth range were Merluccius merluccius, Parapenaeus longirostris, Eledone cirrhosa, Loligo vulgaris, Lophius budegassa.
Merluccius merluccius mean abundance index was 26.73 kg/kmē, while mean density was 209 Ind/kmē. The length frequency distribution ranged from 10 cm to 53 cm.
The species Parapenaeus longirostris was found with indexes of 13.97 kg/kmē and 2821 Ind/kmē. The length frequency distribution (carapace length) ranged from 11 mm to 34 mm (mostly between 17 mm and 20 mm).
Eledone cirrhosa was found with the yields of 9.82 kg/kmē and 51 Ind/kmē. The length frequency distribution ranged from 3 cm to 13 cm; two modal peaks are found around 3-4 cm and 10-12 cm respectively (mantle length).
Loligo vulgaris was found with the yields of 7.30 kg/kmē and 27 Ind/kmē. The length frequency distribution (irregular) ranged from 16 cm to 30 cm (mantle length).
The species Lophius budegassa was found with indexes of 4.74 kg/kmē and 12 Ind/kmē. The length frequency distribution (irregular) ranged from 10 cm to 38 cm.
In this bathymetric stratum the 5 most important species for the region were Aristaeomorpha foliacea, Merluccius merluccius, Parapenaeus longirostris, Phycis blennoides, Nephrops norvegicus.
Aristaeomorpha foliacea was found with the yields of 14.61 kg/kmē and 457 Ind/kmē.
The length frequency distribution ranged from 26 mm to 65 mm (mainly between 34 mm and 38 mm, carapace length).
Merluccius merluccius mean abundance index was 5.85 kg/kmē, while mean density was 5 Ind/kmē. The length frequency distribution (irregular) ranged from 48 cm to 64 cm.
The species Parapenaeus longirostris was found with indexes of 5.12 kg/kmē and 314 Ind/kmē. The length frequency distribution (carapace length) ranged from 21 mm to 41 mm (mainly between 27 mm and 36 mm).
Phycis blennoides mean abundance index was 2.93 kg/kmē, while mean density was 38 Ind/kmē. The length frequency distribution ranged from 11 cm to 38 cm, with an apparent peak at 13-14 cm.
Nephrops norvegicus was found with indexes of 1.44 kg/kmē and 20 Ind/kmē. The length frequency distribution ranged from 24 mm to 63 mm (carapace length).
The data (yields in kg/kmē and Ind/kmē, length frequency distributions) collected during the Medits-AL 1997 survey are compared with those of Medits-AL 1996 one.
The length frequency distributions (per bathymetric strata) are relative to the most abundant species in the investigated area.
This species (characterized by low catches in both surveys) was during the 1997 survey with lower abundance indexes than in 1996.
This species exhibited low abundance indexes in both the surveys (0.01 kg/kmē and 1/kmē, 1997 survey; 0.05 kg/kmē and 7 Ind/kmē, 1996 survey).
This species exhibited lower biomass yields (1997 = 0.48 kg/kmē; 1996 = 0.71 kg/kmē) and higher abundance yields (1997 = 76 Ind/kmē; 1996 = 42 Ind/kmē) respect to those obtained during 1996 Medits-AL; this is probably due to a larger recruitment.
Although for negligible yields, this species exhibited comparable abundances between the two surveys.
Also for this species the yields result comparable; in fact it came out as 7.41 kg/kmē in 1997 and as 7.11 kg/kmē during 1996 cruise, while density indexes was 16 Ind/kmē in 1997 and 23 Ind/kmē in 1996.
The average yield of Lophius piscatorius obtained during the 1997 research (0.23 kg/kmē) was much lowest respect 1996 survey (5.43 kg/kmē).
Merluccius merluccius was the species fished with the highest yield during 1997 survey, but with lower biomass yield respect to previous year; in fact the average yield for the whole region was 34.71 kg/kmē during 1997 survey and 40.02 kg/kmē during 1996 while the mean density was 615 Ind/kmē and 601 Ind/kmē respectively.
For this species a decrease in abundance was yielded when 1997 survey was carried out. In fact, during this year the yield in weight and density were 0.77 kg/kmē and 7 Ind/kmē respectively whereas they were 2.81 kg/kmē and 94 Ind/kmē respectively during 1996.
For this species a light decrease in abundance was found during 1997 survey. Both yields in weight (6.73 kg/kmē) and density (193 Ind/kmē) found during the 1997 research were lower than those obtained during 1996 for which abundance index was 7.40 kg/kmē and density was 220 Ind/kmē.
This species was caught only this year, with very low abundance values; 0.13 kg/kmē and 1/kmē.
Very few specimens of this species were caught in both Medits-AL surveys.
Also this species, as the previous, was found to be rare in the investigated area during both trawl surveys of Medits-AL.
This species was found with comparable values in both the surveys; the yield found in 1997 (2.16 kg/kmē) was lower than that obtained during 1996 (2.42 kg/kmē).
This species presented, in 1997 survey, lower values than 1996 results; in fact during the last survey the yields were 0.78 kg/kmē and 19 Ind/kmē , while 2.33 kg/kmē and 118 Ind/kmē in 1996 survey .
This species was caught only this year, with very low abundance values; 0.02 kg/kmē and 1/kmē.
This species was caught with comparable yields in the surveys: the values were 1.09 kg/kmē and 0.92 kg/kmē, in 1997 and 1996 respectively.
This species were found with much lower yields during the 1997 research (0.84 kg/kmē and 23 Ind/kmē) than those found during 1996 Medits-AL (11.14 kg/kmē and 728 Ind/kmē).
Also this species exhibited a great decrease in the two surveys: 0.70 kg/kmē and 13 Ind/kmē in 1997 cruise; 8.52 kg/kmē and 154 Ind/kmē in 1996 one.
Strong decrease was detected for this species from 1996 to 1997; in fact abundance indexes came from 49.39 kg/kmē and 6673 N/ kmē in 1996, to 2.20 kg/kmē and 124 N/ kmē in 1997.
Comparable values were found for this species in the different surveys.. The abundance indexes were 3.79 kg/kmē and 351 Ind/kmē within the 1997 trawl survey and 3.47 kg/kmē and 349 Ind/kmē during 1996 Medits-AL.
This species was found with lower yields in 1997 survey; abundance indexes were 2.40 kg/kmē and 3 Ind/kmē in 1997, while they were 4.29 kg/kmē and 8 Ind/kmē in 1996.
For this species yields obtained in the 1997 research survey were higher than 1996 ones (3.19 kg/kmē and 100 Ind/kmē in 1997 survey, 2.20 kg/kmē and 87 Ind/kmē in 1996).
The yield in weight and number for this crustacean was negligible in both surveys.
The comparison of the yields for the two Medits-AL surveys showed for this species lower abundance values in present survey: 0.65 kg/kmē during 1997 and 2.03 kg/kmē within 1996.
The yields in weight and number show a strong decrease in 1997: 4.77 kg/kmē and 789 Ind/kmē in present survey, 13.46 kg/kmē and 2336 Ind/kmē in the previous one.
Also for this species a decrease in abundance was shown in the 1997. While during the 1996 research the values of abundance as 16.46 kg/kmē and 67 Ind/kmē were estimated, during 1997 Medits-AL the abundance indexes came out 9.15 kg/kmē and 51 Ind/kmē.
This species was included in the reference list for the first time this year.
This species was fished with comparable yields in both surveys: 1.34 kg/kmē in this year and 1.40 kg/kmē within 1996 Medits-AL.
This species was fished with higher yields during 1997 survey; the abundance indexes were 5.52 kg/kmē and 267 Ind/kmē , against values of 4.37 kg/kmē and 240 Ind/kmē in 1996.
A decrease in weight was observed during 1997 survey: the value of 1.50 kg/kmē was estimated within 1997 cruise and 2.92 kg/kmē in the context of 1996 one.
Not found at all during the surveys.
Apart from some numerical differences by strata between the two surveys, the structure of hake population came out overlapped. The Medits net caught, from 10 m to 500 m depth, a high percentage of 6-12 cm specimens (modal value about 10 cm).
Both surveys caught larger specimens (length > 35-40 cm) mainly below 450-500 m depth.
There werent significant differences between the sub-regions.
This species exhibited more abundant size classes between 8 cm and 15 cm during both survey; however, in some Ionian sectors this year the recruitment peak seems to be less remarkable in comparison with 1995 data.
The length frequency distribution of Mullus barbatus didnt show differences between the surveys. The length mainly ranged from 10 to 30 cm.
The catch in number was higher in 0-50 m depth stratum and in the Ionian sub-region.
The Eledone cirrhosa length frequency distribution was very similar in two surveys (size mainly ranged from 5 to 15 cm of mantle length).
The frequency distribution didnt show large bathymetric and sub-regional differences in both surveys.
Also for Nephrops norvegicus length frequency distributions were very similar in two surveys (size mainly ranged from 20 mm to 70 mm of carapace length).
Aristeus antennatus was distributed according to length in a very similar way in both Medits-IT M4 surveys. In the frequency distributions several modal lengths (in a range between 20 and 60 mm of carapace length) was evaluated. Moreover this year few specimens were caught in southern sector of Adriatic area (during 1994 and 1995 surveys the species didnt found at all in the latter area).
This species presented the same frequency polygon of sizes in both Medits-IT M4 cruise. The carapace lengths ranged mainly from 20 mm to 40 mm.
The Medits-AL '96 data represent a first homogeneous set to be utilized for a comparison with other fishing areas. The yields of the most important Medits target species seem to be higher in Albanian Adriatic waters than in South Italian Adriatic waters (mostly on continental shelf).