06 | Fisheries, Game Management and Beekeeping

PRELIMINARY COMMUNICATION

The first registration of oilfish Ruvettus pretiosus (Cocco, 1833) in the waters of the Albanian coast of the Adriatic Sea; morphometry

Dritan Arapi1, Rigerta Sadikaj2,Vladimir Spaho3 1Flora and Fauna Research Center, University of Tirana, Tirana, Albania ([email protected]) 2Faculty of Natural Sciences, University of Tirana, Tirana, Albania 3Agricultural University, Tirana, Albania

Abstract In February 2017, it was recorded for the first time the presence of the fish “oilfish” (Ruvettus pretiosus Cocco,1833) in the waters of the Albanian coast of the Adriatic Sea, near Karaburun peninsula. This alien fish was caught as by-catch during fishing with hooks (longline fishing) which is carried out for large pelagics. Its overall live weight was W=26.1 kg while the values for some morphometric indicators were TL=173.5 cm; FL=155 cm, SL=146cm and cf=40.2 cm. The caught specimen was donated to the Museum of Natural Sciences at the University of Tirana. Key words: oilfish, morphometry, Adriatic Sea, Albania, alien species

Introduction Alien invasive species (IAS) are considered as a major threat to global diversity (Bax et al. 2003.). In the recent years, in the scientific literature have apparently increased the reports on the involvement of alien species, originating from temperate and tropical climate, in the ictic fauna of the Mediterranean basin. Alien or non-native fish have been introduced in the Mediterranean and Black Sea Basins through the Suez Canal, the Gibraltar Strait and the ballast water. The opening of Suez Canal, climate changes and the intensification of international shipping activities are factors that have favored an increase in the number of alien species. The number of alien species in the Mediterranean area has increased to 68.42% in the period 2002-2010. Out of these, 67 species have entered from the Atlantic Ocean through Gibraltar Strait, 86 species have entered from the Red Sea through the Suez Canal and four species originate from the Pacific Ocean (Oral, 2010.). Lipej et al. (2009.) have reported that not long ago 13 rare or unknown or non-native fish species were identified on the Slovenian coast. According to their opinion, biotic globalization (meridionalization and bioinvasion) is among the main factors promoting the expansion of non-native species. Meridianization is a factor that only relates to temperature and causes changes in the distribution of icticidal species. They have been recorded displacements in some types of warm waters from the southern regions towards the northern regions. Bioinvasion is a process that is related to the intervention of several factors, among which the most important may be temperature, hydrological factors and the presence of unsaturated ecological niches. Some displacements of fish, that are known as “Lessespian migrations”, are mainly caused by the increase of water temperature in the Mediterranean basin. Global warming is considered as a major factor that favors the expansion of the diffusion areas especially for the tropical species (Pećarević et al., 2013.). The intensification of the tropical inflammation through Gibraltar Strait and Suez Canal has resulted as a result of the so-called “tropicalization” of the Mediterranean Sea. Scenarios proposed by the Intergovernmental Panel on Climate Change, which define a further heating, make the

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Mediterranean tropicalization of the Mediterranean basin inevitable (Raitsos et al., 2010.). These authors point out that biodiversity changes in the Mediterranean Sea are developing at exceptional rates, characterized by the introduction of a kind for every week and a half. In the last ten years, several studies have been carried out on the icticidal alien species that have been recorded on the eastern coast of the Adriatic Sea and the Ionian and Aegean seas. Corsini-Foka and Economidis, (2007.) have published a list containing 41 alloctone marine fish species, six of which were introduced by man for aquaculture purposes. Most of the species (79.4%) originated by Indo-Pacific Oceanic and Red Sea regions and had entered the Mediterranean through Suez Canal. The list published by Lipej et al. (2009.) consisted of 13 species of alloctone fish that were found on the Slovenian coast of the Adriatic Sea. Pećarević et.al (2013.) had found 22 species of alloctone fish in the Croatian coast of Adriatic. These authors have noted that the largest number of new species of fish has been found in the recent decades and that the abundance of species that were once rare in the Adriatic Sea has increased. This phenomenon has been particularly remarkable for thermophilous species, which originally appeared in the southern Adriatic and are now increasingly encountered in the northernmost regions of this sea. There have been several publications reporting on the presence of alien species Rufettus pretiosus Cocco, 1829 (Perciformes: Gempylidae) in the waters of the Adriatic and Aegean seas (Kampouriset al. 2013.; Dulčić et al., 2014.). For the first time, the presence of this species on the Albanian shores of the Adriatic Sea was recorded in the second half of February 2017 near Vlora Bay (5-6 miles to the West of the Cape of Gjuze). In this paper we will present the results of the evaluation of some morphometric and meristic features, based on the data obtained from the analysis of sample of this species fished with hooks (long lines) from the motorboat “Pavaresia”. This specimen was donated to the Museum of Science at the University of Tirana.

Material and methods The data was obtained from the analysis of specimen that was involved as by-catch during longline fishing carried out by the fishermen of the Albanian coast area for the catching of large pelagics. The fishing zone was located outside the Bay of Vlora, in the western direction, at a distance of 5-6 miles from the Cape of Gjuhe, which is the terminal part of Karaburun Peninsula. The analyzes were carried out on the refrigerated individual, 10-12 hours after the catching of the “oilfish”. To determine the species, they were used the keys of determination as well as the respective catalogs (Jones and Silas, 1961.; Nakamura and Parin, 1993.; Smith, 1997.). The evaluation of morphometric indicators was performed using the main measurements shown in the type schemes for fishes under the Scombroidei suborder (Hajjejet al., 2013.; Tanoue et al., 2014.). The values resulting from the morphometric measurements were used to calculate the value of the ratio between each morphometric indicator (x) and the length up to bifurcation (F), ie x/FL, as well as the relative morphometric indices values, in % towards the total length (x*100/TL). These values are used in the case of comparisons with the results of the other morphometric studies carried out with the species R.pretiosus.

Results and discussion Morphological features: R.pretiosus is known as a batipelagic with a big body (Figure 1). The body is semifused, pressed by the sides (the cross cut is almost oval). Based on our measurements, the length of the head was 25.9% of the length up to the fork length, whereas the greatest depth of the body was 20% of the length up to the bifurcation. The lower jaw

346 53. hrvatski i 13. međunarodni simpozij agronoma | 18. do 23. veljače 2018., Vodice, Hrvatska 06 | Fisheries, Game Management and Beekeeping emerged slightly above the upper jaw (Figure 2), as long as the length of the first was about 1.0 cm (or 4.65%) larger rather than of the second one.

Figure 1. The “oilfish” fish caught in the Albanian Adriatic coast (coastal region of Vlora)

Figure 2 The head of R.pretiosus. The difference in the length of two jaws and the shape of the teeth is distinguished

The tips of both jaws were without dermal processes. The dorsal fin (D) consisted of two lobes. The frontal lobe was lower than the back one (Figure 3). The formula of the slits on the dorsal fin was D XIV, 16. There were two finlets behind the second lobe of the dorsal fin. For the other fins (pelvic, pectoral and anal) the formulas of the rays were: P 15; V I, 5 and A 16. It was distinguished the presence of two fins behind the anal fin

Figure 3. The shape of dorsal fins (D), anal fins (A) and caudal fin (C) as well as the presence of the finlets behind the dorsal and anal fins

Morphometric features: In Table 1 we have set the results for the determination of values for 13 morphometric characters and a main gravimetric feature, as it is the total live weight (Wkg) of the analyzed individual of R.pretiosus.

53rd Croatian & 13th International Symposium on Agriculture | February 18 - 23, 2018, Vodice, Croatia 347 06 | Ribarstvo, lovstvo i pčelarstvo

Table 1. Morphometric data for of oilfish (Ruvettus pretiosus) cought in Adriatic sea waters of Albania Morphometric data Empirical value Total length (TL) 173.5 cm Standard length (SL) 146 cm Fork Length (FL) 155 cm Head length (Cf) 40.2 cm Greatest depth of body (H) 31 cm Least depth of caudal peduncle (h) 7.2 cm Orbit diameter (Or) 5.9 cm Mandibulary length (Man) 21.5 cm Maxillary length (Max) 20.5 cm Length of pectoral fin (P) 18 cm Length of pelvic fin (V) 11.9 cm Height of anal fin (A) 13.7 cm Anterior height of second part of dorsal fin (D) 15.7 cm Total live weight (W) 26.1 kg

Initially, we would like to point out that this paper is primarily intended to inform you about the first record of the alien ictic species Ruvettus pretiosus on the Albanian shores of the Adriatic Sea.The limitation of the analysis with only one specimen did not give us the chance to make allometric evaluations. On the other hand, this situation has made it impossible to apply biometry to compare our results with the results of the works of other authors involved in this direction of the study. As we have pointed out, due to the only one analyzed individual, we cannot make biometric analysis to determine the significance of the changes for the same estimated attributes in individuals that were caught in different regions where this species was encountered. From a simple comparison it turns out that our figures that resulted from the morphometric calculation of indices are more alike with those that are published by Ben Amor et al. (2010.) for R. pretiosus caught on the Tunisian coast of the Mediterranean Sea as well as from Sureshkumar et al. (2013.) for individuals of this type populating the Indian shores of Indian Ocean. Meanwhile the figures published by Elbaarasi et al. (2007.) for individuals of R. pretiosus that were caught on the Mediterranean coast of Libya are all higher compared to the figures we have calculated. Regarding a meristemic diagnostic feature, such as the number of strong and soft rays on the fin, the results of the four evaluations contain several variations that differ in particular the anal fin (A). There is a possibility that the source of these differences is the unequal interpretation of the criteria for distinguishing the two types of rays present in the swimming fins. Thus, in the publication performed by Elbaarasi et al. (2007.), for the individual fished in the Mediterranean coast of Libya, it is not specified the presence of fins behind the dorsal and anal fins, whereas Ben Amor et al. (2010.) not mentioned the presence of the finlets behind the anal fin for the individual caught at the Mediterranean coast of Tunisia.

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