Justification
Merluccius merluccius is found throughout the Mediterranean Sea, and is common. This species is a commercial fish and has been exploited since historical times. FAO statistics indicate that there has been an estimated 10-40% decline in landings over the past 10 years (40% decline between 1996 and 2005; 10% decline between 1997 and 2005). The General Fisheries Commission for the Mediterranean has also concluded that stocks are declining and it has been stated that the stocks are over-exploited in some regions. Although landings statistics do not take fishing effort into consideration, it is assumed that effort over this time has not decreased. This species is therefore listed as Vulnerable, especially as exploitation of the species is ongoing and effort does not appear to have decreased.
Geographic Range Information
This species is distributed in the east Atlantic from Norway and Iceland, south to Mauritania.
In the Mediterranean Sea, this species occurs from Gulf of Alicante (Garcia-Rodriguez et al. 2006), Catalan Sea (Martin et al. 1999, Olivar et al. 2003, Morales-Nin and Moranta 2004, Sardà et al. 2004, Bozzano et al. 2005, Sardà et al. 2005, Bahamon et al. 2006, Coll et al. 2006, Maynon et al. 2006, FAO-GFCM 2007), Balearic Islands (Alemany and Alvarez 2003), Gulf of Lion (Morales-Nin and Aldebert 1997, Gaertner et al. 1998, Letourneur et al. 2001), Ligurian Sea (Abella et al. 1999, Dremiere et al. 1999, Martin et al. 1999, Pietrapiana et al. 2002, Tunesi et al. 2002, Molinari and Tunesi 2003, Tunesi et al. 2005), Tyrrhenian Sea (Abella et al. 1999; Badalamenti et al. 2002; IREPA 2003; Colloca et al. 2003, 2004; Abella et al. 2005; Carpentieri et al. 2005; Belcari et al. 2006; FAO-GFCM 2007; Sbrana et al. 2007), Strait of Sicily (Fiorentino et al. 2003, Gristina et al. 2006), Maltese waters (FAO-GFCM 2007), Adriatic Sea (Dremiere et al. 1999, Fiorentini et al. 1999, Perugini et al. 2007), Ionian Sea (Madurell et al. 2004, Mytilineou et al. 2005, Maravelias and Papaconstantinou 2006), Cretan sea (Tsimenides et al. 1991, Kallianiotis et al. 2000), Sea of Marmara (Deval et al. 2007), Aegean Sea (Moutopoulos and Stergiou 2002, Karpouzi and Stergiou 2003, Kallianiotis et al. 2004, Machias et al. 2004, Celik and Oehlenschlager 2005, Labropoulou and Papaconstantinou 2005, Karakulak et al. 2006, Kontas 2006, Maravelias and Papaconstantinou 2006, Maravelias et al. 2006, Gokce and Metin 2007, Ozaydin et al. 2007). It is also present along the south coast of the Black Sea.
Population Information
This species is very common in the Mediterranean Sea. This species is commercially exploited in the region. Muus and Nielsen (1999) reported that the stocks of this species appeared to be over-fished. The General Fisheries Commission for the Mediterranean has also concluded that stocks are declining and it has been stated that the stocks are over-exploited in some regions.
The Food and Agriculture Organization (FAO) landings statistics for the Mediterranean indicate that there have been declines in landings of 10-40% between 1996 and 2005 (40% decline between 1996 and 2005; 10% decline between 1997 and 2005). Although landings statistics do not take into consideration fishing effort and cannot always be directly translated into population declines, it is likely that fishing effort for this species has remained the same if not increased over this time period.
Annual landings (in tons) in the Mediterranean Sea (1996–2005), obtained from the FAO FISHSTAT Fisheries Statistical Database (2007): 43,816 (1996), 29,956 (1997), 26,545 (1998), 24,144 (1999), 22,558 (2000), 23,322 (2001), 21,680 (2002), 21,305 (2003), 21,872 (2004), 27,430 (2005).
Other records for this species in the Mediterranean include:
According to Belcari et al. (2006), 32,767 specimens, with length from 4.0 to 84.5cm TL were collected by trawling in the north Tyrrhenian sea, in February, April, July and September 2001.
Gristina et al. (2006) mentioned that this species was sampled during two trawl surveys (Autumn 1997, Autumn 1998) carried out in the strait of Sicily using an otter trawl with a 28mm codend mesh opening. Mean density values from 247 to 300 specimens from 62 hauls (trawls), with mean abundance varied from 225 to 994 specimens per km2.
According to Carpentieri et al. (2005), this species was sampled during four seasonal 24h surveys conducted in July 2001 (286 ind./24h), November 2001 (282 ind./24h), March 2002 (92 ind./24h) and May 2002 (2,508 ind./24h) in the shelf break off the central Tyrrhenian sea. In each survey 8 hauls of 30 minutes each were performed every 3 hours throughout the 24h period with an otter trawl mounted into a 40 mm head rope, a 40 mm ground chain and 30-40 mm stretched mesh in the wing and cod-end respectively.
Bozzano et al. (2005) mentioned that 494 specimens were collected during two consecutive 24h pelagic trawl cycles and diurnal bottom trawls conducted for 3 days in September 1999 on the Catalan Sea shelf at a depth of 100-200m. The opening of the pelagic net was 9x6m and a lifter of 12mm stretch mesh covered the codend, while the benthic net had a 12x1.8m opening.
Morales-Nin and Aldebert (1997) mentioned that 17,190 specimens, with lengths ranging from 8.0 to 30.9 cm were collected at the Sete auction market in the period of January 1990 to March 1991.
According to Ozaydin et al. (2007), 2,711 specimens were collected from Izmir Bay (central Aegean Sea) between February and December 2005 using bottom trawls (mesh size 24 mm at stretched cod-end), with TL ranging from 2.7 to 48.8 cm.
Karakulak et al. (2006) mentioned that 22 specimens (19.7 to 41.1cm TL) were collected from a survey conducted from selectivity by gill and trammel nets (inner mesh sizes 16, 18, 20, 22, 26, 28, 30 and 32mm bar length) in the coastal waters of Turkey from March 2004 to February 2005.
According to Mytilineou et al. (2005), this species was collected in the north-east Ionian Sea during four experimental survey (Sept. 1999, Apr. 2000, Jul. 2000, Sept. 2000), by means of trawls of 40mm stretched mesh size in the cod-end, with density of 35.3 individuals per hauls in the depth range of 300-500m (44 hauls), and 2.8 individuals per hauls in the depth range of 500-700m (52 hauls).
Moutopoulos and Stegiou (2002) mentioned that 168 specimens were collected during experimental fishing trials conducted with gill nets and long lines during 1997-98 in the Aegean Sea (Cyclades).
According to Karpouzi and Stergiou (2003), 90 specimens (16.3 to 41.7 cm TL) were collected from October 1997 to September 2000, with a small fishing vessel, in the waters off Naxos Island (Cyclades, Aegean Sea, east Mediterranean Sea) with: (a) gillnets of mesh-sizes 22, 24, 26 and 28 mm (bar length) and longlines of hook sizes no. 11, 12, 13 and 15 (Mustad brand), during October 1997 to October 1998, (b) trammel nets of inner mesh-sizes 20, 24 and 28 mm (bar length), during October 1999 to September 2000. Fishing took place at depths ranging from 4 to 90 m.
According to Gokce and Metin (2007), 7 specimens were collected using three artisanal fishing boats (6.7 and 10 m long) comprising 39 fishing operations. The trials took place between May and October 2003 in Izmir Bay, Turkey. The fishing gear was combined trammel net to trammel net with one lower and one upper part. Each part is formed of three layers: the inner layer with a small mesh size (40 mm stretched mesh), the outer layers with a larger mesh size (220 mm stretched mesh). These nets, each 100 m long and 1.30 m deep, are hung to a common float line and lead line.
Badalamenti et al. (2002) mentioned that a study carried out in the Gulf of Castellammare (southern Tyrrhenian sea), where most trawling was banned from 1989 onwards was conducted in order to compare data from spring trawl surveys in terms of abundance data, before (1987 and 1989) and after (1994 and 1998) the trawling ban. Mean abundance data (number of specimens per hauls - number of hauls = 10) was 4.3 in 1984, 6.4 in 1988, 40.4 in 1994 and 70.2 in 1998.
According to Sardà et al. (2004), 30,494 specimens (7 to 30 cm TL) were collected at depth between 50 and 300 m in the fishing ground off the port of Vilanova and Glentru (Catalan Sea), in June 2002, from 25 hauls with trawls.
Morales-Nin and Moranta (2004) mentioned that 3,815 specimens (3 to 49 cm TL), were collected by trawling at depths between 50 and 350 m off the Catalan Sea. The trawling net used had a cod-end mesh size of 40 mm and a cod-end linear mesh size of 6 mm.
Habitat and Ecology Information
This is a demersal species, that is found usually between 70 and 370 m depth. In the Mediterranean Sea, it has been found from 30 to 1,000 m. In the Ligurian Sea the species was caught starting from 18 m depth (Relini et al. 1986). It lives close to the bottom during day-time, but moves off-bottom at night. Adults feed mainly on fish (small hakes, anchovies, pilchard, herrings, cod fishes, sardines and gadoid species) and squids. The young feed on crustaceans (especially euphausiids and amphipods).
Size at maturity is between 26 and 27 cm for the males and 26 and 40 cm for the females (Golani et al. 2006). In the Tyrrhenian sea, size at maturity is 35 cm for the females (Sbrana et al. 2007). Bouaziz (2002) found the size at maturity to be females = 30.6 cm, males = 21.3 cm. Generation length is estimated at around 3 to 3.5 years, depending on the area (Bouaziz et al. 1992).
Threats Information
This is a species with high commercial importance in the Mediterranean. There is evidence to support that this species is over-exploited and that over-fishing is a major threat to the populations.
The main fishing methods used catch this fish are trawls, fixed nets and seines. Bottom longline and set-net fisheries are targeting adults of this species in some areas (not in Turkish waters at present). Details of this fishing effort are only rarely available.
Use and Trade Information
This is a species with high commercial importance in the Mediterranean.
It is used fresh, dried or salted and frozen (Frimodt 1995).
Conservation Actions Information
Merluccius merluccius is a priority species for the General Fisheries Commission for the Mediterranean (GFCM). It is regulated through fishing effort controls, selectivity, fishing closures, minimum landing size, etc. in the GSAs. There are also some national regulations regarding minimum landing size (e.g., in Turkey, minimum landing size is 25 cm, in Morocco minimum size is 20 cm) and an EC regulation for minimum landing size of 20 cm. It occurs in some marine protected areas.
Recommendations for this species are: implementation of GFCM recommendations (fishing effort controls, selectivity, fishing closures, minimum landing size, etc.) and improved enforcement of fishing controls in the Mediterranean Sea.
