Turkish Journal of Zoology Turk J Zool (2013) 37: 773-781 http://journals.tubitak.gov.tr/zoology/ © TÜBİTAK Research Article doi:10.3906/zoo-1212-31 Abundance and distribution of eggs and larvae of anchovy (Engraulis encrasicolus, Linnaeus, 1758) and horse mackerel (Trachurus mediterraneus, Steindachner, 1868) on the coasts of the eastern Black Sea 1, 2 Cemalettin ŞAHİN *, Necati HACIMURTAZAOĞLU 1 Faculty of Fisheries, Recep Tayyip Erdoğan University, Rize, Turkey 2 Republic of Turkey Ministry of Food, Agriculture, and Livestock, Trabzon, Turkey Received: 27.12.2012 Accepted: 08.07.2013 Published Online: 04.10.2013 Printed: 04.11.2013 Abstract: Sampling for this survey was performed in 5 stations located in the bays of Sürmene and Rize in the eastern Black Sea between April and October 2006. During the sampling, the quantities and distributions of eggs and larvae of anchovies (Engraulis encrasicolus) and horse mackerel (Trachurus mediterraneus) were determined. For horizontal towing carried out from the surface (0–5 m), a plankton net of 50 cm in diameter and 500 µm mesh. The eggs of anchovy and horse mackerel sampled in plankton tows were found to be 438.33 ind./100 m3 and 5.71 ind./100 m3 for horizontal tows. During horizontal tows, the larvae of anchovy and horse mackerel were found to be 8.00 ind./100 m3 and 0.68 ind./100 m3, respectively. During the surveys, a total of 14,535 anchovy eggs, 147 horse mackerel eggs, 256 anchovy larvae, and 7 horse mackerel larvae were sampled. Mortality rates were calculated as 81.18% for anchovy and 37.41% for horse mackerel. According to our results, the ranges of spawning periods for anchovy and horse mackerel were determined as May–September and June–August, respectively. Key words: Abundance, anchovy, eastern Black Sea, egg, horse mackerel, ichthyoplankton, larva 1. Introduction abundance of pelagic eggs and larvae of teleost fish in the In Turkey’s seafood products industry, anchovy and horse northern Marmara Sea (Yüksek, 1993); distribution of mackerel are ranked in the top 2 positions within the anchovy eggs and larvae in the Black Sea (Niermann et species obtained by fishing from natural resources. These al., 1994); seasonal distribution of certain teleost fishes in 2 small pelagic species of fish are the major species in the the Bay of Sürmene (Başar, 1996); distribution of fish eggs Black Sea and constitute approximately 59% of the seafood and larvae off the coast of Trabzon (Ak, 2009); the effect of production in Turkey. Anchovy and horse mackerel that are environmental conditions in the distribution of the eggs landed in the eastern Black Sea constitute 27.4% (184,417 t) and larvae of anchovies in the Black Sea (Kideys et al., and 4.1% (17,755 t) of the total marine fish catch of Turkey 1999); and ichthyoplankton of Feodosiya Bay (Klimova, (TÜİK, 2012). These species, possessing such significance 2009). in Turkey’s fishing industry, must be observed in all phases An egg survey is required in order to determine the of their life cycle in order to ensure the sustainability of spawning periods and spawning areas of the fish and the their stocks. The most important of these phases are the periodic changes taking place in these environments, ichthyoplankton phases (eggs and larvae). Slastenenko the losses in the egg and larvae phases, the ratio of entry (1956) provided significant information concerning into the adult stocks, and the number of spawning adult the spawning characteristics, egg types, and egg sizes of individuals in the stocks and their relationship with the the fish in the Black Sea for the first time. The following environment. Although there are a significant number have also been investigated: morphologies and ecologies of studies in the Black Sea in this context, egg survey of certain bony fish (teleosts) in the Marmara Sea and investigations are scant in the eastern Black Sea region. Black Sea (Arım, 1957); pelagic eggs and larvae of teleosts Along with the seasonal abundance of eggs and larvae, in Turkish waters (Demir, 1974); distribution of fish the determination of their horizontal distribution was eggs and larvae at the Black Sea entrance of the İstanbul performed in this research in order to be able to make straits (Mater and Cihangir, 1990, 1997); distribution and proper decisions about the future of the anchovy and horse * Correspondence: [email protected] 773 ŞAHİN and HACIMURTAZAOĞLU / Turk J Zool mackerel stocks, which have an economic significance for and Çoker (2002), and Çoker (2003) were utilized as the region. references. Abundances and distributions of eggs and larvae according to stations were calculated utilizing the 2. Materials and methods individual per m3 B = C / V relationship in horizontal The survey was carried out in the eastern Black Sea on tows, where B is abundance (ind./m3), C is total number of the Trabzon Sürmene, İyidere, and Rize coasts between samples in horizontal sampling, and V is volume of water April 2006 and October 2006. Samplings were performed filtered (m3). The water volume V was obtained by V = A horizontally at 5 stations (A1, A2, B1, C1, C2) using the × r × c, where A = area of net mouth (m2), r = flowmeter research vessel “R/V DENAR–1” belonging to Karadeniz rotation number, and c = flowmeter calibration rate (m / Technical University. The distances between the coastal rotation). The determination was done with a Hydro-Bios stations are 13 NM (A1–B1) and 10 NM (B1–C1), 438 115 model flowmeter (Smith and Richardson, 1977). respectively. For the offshore stations (A2–C2), the Flowmeter calibration rate was 0.3. distance is 5 NM from the coast. The depths of stations Dead eggs were determined according to Iseki were determined as 18 m, 415 m, 14 m, 15 m, and 310 m, and Kiyomoto (1997) and Yüksek and Gücü (1994) respectively (Figure 1). as abnormally developed eggs, such as those with For horizontal samplings, a 50-cm-diameter and decomposition process of the embryo, and physically 500-µm-mesh plankton net was used. Samplings were decayed eggs without categorized embryo stage and with carried out during the day at depth intervals of 0–5 m decomposition of the perivitelline layer of the eggs. by towing the net for 10–15 min at a vessel speed of 2.5 A normality test (Shapiro–Wilk) was applied to miles h–1. Temperature and salinity measurements were larvae and egg number distributions between stations conducted at stations A2 and C2 throughout the survey. and months. ANOVA for parametric and Kruskal–Wallis The temperature and salinity values were determined by analysis for nonparametric data were conducted using using equipment by Aanderaa Instruments, the RCM9 the software packages PAST (version 1.8) (Hammer et al., model CTD and YSI 85 model probe, during the uptake 2001) and Sigma Plot (version 11.0). Statistical analyses of the material. The collected material was preserved in were considerate significantly different at the level of α = 4% formaldehyde solution with a borax buffer (Smith 0.05. and Richardson, 1977). Samples of ichthyoplankton were sorted from the zooplankton material and species 3. Results identification was performed. For the determination of 3.1. Physicochemical properties of water column egg and larvae species, the works of Arım (1957), Dekhnik The maximum surface water temperature of station A2 was (1973), Russell (1976), Yüksek and Gücü (1994), Mater found to be 23.90 °C in July and the minimum was 13.80 N 41O 30' Hopa BLACK SEA C2 C1 41O B1 RİZE A2 40˚ A1 İyidere Turkey TRABZON Sürmene 40O 40O 30' 41O 41O 30' Figure 1. Sampling area. 774 ŞAHİN and HACIMURTAZAOĞLU / Turk J Zool °C in April; the maximum at station C2 was found to be 3.2.1. Horizontal distribution, abundance, and mortality 25.5 °C in August and the minimum was found to be 12.34 rates of anchovy (Engraulis encrasicolus) eggs °C in April. Throughout the sampling, the average surface During horizontal samplings, 438.33 ind./100 m3 eggs (a water temperature at stations A2 and C2 was calculated total of 14,535 eggs) and 8.00 ind./100 m3 larvae (a total to be 20.12 ± 4.43 °C and 20.68 ± 0.84 °C, respectively of 256) were collected between May and September. In (Figure 2). The minimum surface water salinity of station June, the maximum numbers of eggs (8430 total) were A2 was 17.24‰ in April and the maximum was 18.39‰ in encountered. In the horizontal distribution, the largest September; the minimum at station C2 was 17.11‰ in June number of eggs was found in June at station A2 (2401.43 and the maximum was 17.68‰ in September. The average ind./100 m3). Anchovy eggs were found only in stations surface water salinity at stations A2 and C2 was measured B1 and C1 in May. During June and July, anchovy eggs to be 17.81 ± 0.36‰ and 17.50 ± 0.32‰, respectively were encountered at all stations. During September, 2.06 (Figure 3). The average temperatures measured to a depth ind./100 m3 and 229.82 ind./100 m3 eggs were calculated of 50 m were respectively 15.12 ± 5.866 °C and 16.46 ± at stations A2 and C2, respectively. The most larvae in the 6.227 °C, while average salinities were 18.49 ± 1.216‰ horizontal samplings were found during August at station and 18.56 ± 1.131‰. Temperature of the surface water was B1 (37.84 ind./100 m3) (Table 1). found to be 21.18 °C in June and 23.90 °C in July. Salinity The eggs were obtained at all stations in June and was determined to be 17.68‰ in June and 17.90‰ in July.