Journal of Environmental Protection and Ecology 17, No 4, 1375–1384 (2016) Biology
STATE OF SOME COMMERCIALLY IMPORTANT FISH POPULATIONS IN NATURA 2000 ZONES OF BULGARIAN BLACK SEA AREA V. ST. RAYKOV*, M. YANKOVA, P. IVANOVA, A. TRAYANOVA Institute of Oceanology, 40 Parvi Mai Street, P.O. Box 152, 9000 Varna, Bulgaria E-mail:
[email protected] Abstract. Methodology for monitoring of fish fauna in Black Sea was developed. This methodology applies to all fish species monitored to the national system for monitoring biodiversity. Status assessment is carried out in three groups of parameters relevant population data, data distribution and data threats. Analysis of the resulting data is based on tracking the trends of changing the values of various parameters in different years. Species, for which no reference values for such adopt monitoring data exist in the first year, are subject to revision every ten years. Additional monitoring sites were proposed in this project in order to reach the sufficiency of data to assess at geographic (only for species that are reported under Art. 17 of the Habitats Directive) and national level. Such species in Black Sea is Pontic Shad (Alosa immaculata E. T. Bennett, 1835). Additional research on growth patterns, migration routes, spawning and feeding areas of this anadromous species with special interest under Habitat Directive is of high importance. Keywords: Black Sea, monitoring, fish, Alosa, status assessment.
AIMS AND BACKGROUND The aim of this study is to collect biological and environmental data in order to make assessment on state of the fish populations of interest in Natura 2000 zones and outside. The state1–5 of the population assessment was performed by group of parameters6, concerning population data and distribution of the species. Bulgaria is one of the EU countries with the richest biodiversity. This also determines the size of the protected areas network in Bulgaria. Protected areas under Directive 92/43/EEC in Bulgaria are 234, protected are 90 habitat types and 121 species of plants and animals, including – 24 species of fish (Multiannual National strategic plan for Aquaculture in Bulgaria, 2014–2020). The particular geological and geographical location of Bulgaria has determined the formation of a wide variety of species of aquatic organisms7–9. It has a significant number of endemic species, unique to our or the Balkan Peninsula waters. Therefore, nowadays the protection of the genetic pool and natural fish populations in the country are becoming *
For correspondence.
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increasingly important in national, regional and even global scale. Fisheries in the Natura 2000 zones – Aladzha Bank (BG0001500), Aheloi – Ravda – Nessebar (BG0000574), Galata (BG0000103), Lake Durankulak (BG0000154), Lake Shabla-Ezerets (BG0000621), Emine-Irakli (BG0001004), Emona (BG0001501), Kamchia (BG0000116) Complex Kaliakra (BG0000573), Beach Shkorpilovci (BG0000100), Beach Garden, Goldfish (BG0000146), Ropotamo (BG0001001), Otmanli (BG0001502) and Strandzha (BG0001007) (Fig. 1) of Bulgarian Black Sea area are characterised by the considerable variety of species caught, as most frequently a fishery object are the small fish species: Еuropean sprat (Sprattus sprattus sulinus), Anchovy (Engraulis encrasicholus ponticus), Mediterranean horse mackarel (Trachurus mediterraneus ponticus) and Whiting (Merlangius merlangus euxinus). Other fishes are represented with smaller quantities in the fish yield: Grey mullet (Mugil cephalus), Picked dogfish (Squalus acanthias) and Turbot (Psetta maxima). This study focuses on state of fish populations in the Natura 2000 areas, which offers critical habitat2–5 to species included in Art. 17 of the Habitats Directive, namely Pontic shad (Alosa immaculata). The species is vulnerable according to IUCN and Bulgarian Red Data Book (http://e-ecodb.bas.bg/rdb/bg/vol2/Alpontic. html; http://www.iucnredlist.org/apps/redlist/details/907/0). It is also included in Annex 2 and 4 of the Bulgarian Biodiversity Act (http://www.biodiversity.bg/fi les/ File/zak_bg_biodiv.pdf). During the summer, it is also an important spawning area for anchovy (Engraulis encrasicholus ponticus) and horse mackerel (Trachurus mediterraneus ponticus). Most of the species caught in this Natura 2000 areas are commercially important as Psetta maxima and Sprattus sprattus. The aim of the study is to assess the ecological status of five species (Psetta maxima, Sprattus sprattus, Alosa immaculata, Engraulis encrasicolus and Trachurus mediterraneus ponticus) in Natura 2000 zones of Bulgarian Black Sea area. EXPERIMENTAL Area of interest in front of Bulgarian coast. Figure 1 shows the areas specified under Habitat Directive (Council Directive 92/43/EEC) with one mile buffer (under WFD Directive 2000/60/EC) and 3 mile zone (change of Order № RD09152/09.03.2015).
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Fig. 1. Map of areas specified under Council Directive 92/43/EEC; Directive 2000/60/EC; change of Order № RD09-152/09.03.2015 in Bulgarian marine area
Gears used for sampling: Uncovered Trap nets. They are set close to the shore line in shallow waters direct in the migration tracks of the fishes. The fish enters voluntarily, but is hampered from coming out. Fishermen visit traps every day collecting only the captures and leaving the gears set in the same place for the whole season. Mid-water otter trawls (OTM) were used towing gears in order to collect the ichthyologic samples at different depths. Literature survey on distribution of four commercially important species was conducted, as the results were mapped and presented in Fig. 2. According to the survey under ‘Operational Program Environment 2007–2014’ Field studies of the distribution of species/assessment of the status of species and habitats throughout the country – Phase I – ‘Fishes’, 2 otter trawl surveys were conducted in July and September 2014. Additionally, in almost all stations replicates were done. Historical data from surveys were used for mapping the spatial and temporal distribution of turbot. The coverage of surveys was in the 12 mile zone of Bulgarian Black Sea waters. Size structure. All caught individuals are distributed in L classes, as interval is 0.5 cm. Vizualisation is done by using hystograms. ‘Unvarouble – unsatisfactory’ 1377
state is when only one maximum, placed in right or left side of histogram was observed. All the rest of cases are ‘favourable’. RESULTS AN DISCUSSION The results from literature survey2–4,6 on distribution of four commercially important marine fish species are presented in Fig. 2. The main used fishing gears were uncovered pound nets – trap nets (FPOs) and midwater trawls (OTMs).
Fig. 2. Map of literature survey on distribution of: anchovy – a; sprat – b; turbot – c, and horse mackerel – d (trap nets and trawls)
The coverage of surveys was in the 12 mile zone of Bulgarian Black Sea waters. The results of juvenile distribution are presented in Figs 3a, b. The field studies were conducted in July and September 2014.
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Fig. 3. Map of turbot juvenile distribution in Bulgarian Black Sea in July 2014 (a) and in September 2014 (b)
In July turbot immature individuals (< 45 cm TL) were predominant in the Bulgarian marine area, especially in shallow waters (Fig. 3a). The maximum length observed was 56.2 cm. Turbot individuals ranged from 22 to 40 cm in summer in the near shore area between 22 and 65.3 m depth. In September 2014 (Fig. 3b) the bulk was composed by length groups 33–40 cm, distributed in depths of 26.6 to 68.1 m, as the specimen with total length of 15–28 cm were less in terms of
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abundance in the near shore zone with depths of 21 to 58.2 m. This corresponds with the species distribution revealed in previous surveys conducted7,8,10. Juveniles and immature specimen displayed restricted habitat requirements, mainly occupation of sandy locations. Size structure. The histogram of Pontic Shad (Alosa immaculata E. T. Bennett size structure, caught in uncovered trap nets (in September, 2014) reveals bi-modal distribution on the left side of the histogram with a preponderance of size groups 13.5–14 cm. 14.5–15.0 length groups have lower numbers, as the smaller numbers have 15.5–17 cm groups (Fig. 4). There are no individuals larger than 17 cm, which indicates the presence of young, not sexually mature individuals aged 1+ years. Similar size distributions were observed in previous research2,3,10. The state according to this criteria is estimated to be ‘unfavourable unsatisfactory’. The number of caught specimen in autumn (n = 320) were lower, as clear bi-modal distribution and lack of individuals with higher than 15 cm size, reveals the state according to this criteria as ‘unfavourable unsatisfactory’.
Fig. 4. (a) A. immaculata, spring-summer, length groups (cm); (b) A. immaculata, autumn, length groups (cm); sampling gear: uncovered pound net (FPO)
The turbot (Fig. 5) size structure (July) varies within 14–53 cm. Predominant size class of 18 cm, followed by size classes of 15, 17, 20, and 22 cm (corresponding to age 1+ year) – An indicator of mass presence of undersized non-sexually mature turbot studied in investigated area. The greatest abundance was of the size class of 18 cm, which is much below the minimum allowable size6 for turbot (TL = 45 cm, FAA, 2001). The presence of similar size structure7–9 spoke of ‘unfavourable-bad’ state in terms of this parameter level monitoring Black Sea area. The data on the dynamics of the size structure of scads show a sharp dominance of separate classes (~ 10, 10.5, 11 and 11.5 cm) and relative length variation order (Fig. 6). The increased participation of these age groups contributes to lower average data dimensional structure. 1380
It is notable absence of individuals with size 15–18 cm. This is probably due to the fact that in the samples presented juveniles and young-of-the-year – 0+, 1–1 + 2–2 + 3–3 +. The increased participation of these age groups contributes to lower average data dimensional structure. This corresponds to a ‘favourable condition’ of the species in the monitoring area. Anchovy length groups varied from 9 to 13.5 cm (age: 1–3 years +). Minimum size for catch of the species identified in FAA is 8 cm (Fig. 7). The state in 2001 is estimated as ‘favourable’ as regards parameter sized structure. Such distribution corresponds with historically observed for this species10.
Fig. 5. (a) Turbot, Psetta maxima, spring-summer, length groups (cm); (b) Autumn, length groups (cm), sampling gear: midwater trawl OTM
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Fig. 6. (a) Scad, Trachurus mediterraneus, spring-summer, length groups (cm), sampling gear: uncovered pound net (FPO); (b) Scad, Trachurus mediterraneus, autumn, length groups (cm), sampling gear: midwater trawl (OTM)
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Fig. 7. Anchovy, Engraulis encrasicolus, spring-summer, length groups (cm), sampling gear: uncovered pound net (FPO) – a; anchovy, Engraulis encrasicolus, autumn, length groups (cm), sampling gear: uncovered pound net (FPO) – b
CONCLUSIONS The state of the species of commercial interest in Bulgarian marine zone and most particularly in Natura 2000 marine zones, showed highly seasonal character, especially as regards size structure. The seasonal character of different type of gears in use was also very important in analysing the state of species and populations. Acknowledgements. This article is a part of research within project ‘Field studies of distribution of species/assessment of the status of species and habitats throughout the country – I phase’ – BG161PO005/11/3.0/03/24.
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REFERENCES 1. M. GOLUMBEANU, A. OROS, M. NENCIU, M. ZAVATARELLI, A. DRAGO: Contribution of Environmental Indices in Meeting the Objectives and Principles of the Marine Strategy Framework Directive (MSFD). J Environ Prot Ecol, 15 (3), 1130 (2014). 2. P. KOLAROV: Some Features of Changes in the Age Composition of the Black Sea Shad (Alosa kessleri pontica Eichw.). Proceedings of Institute of Farming and Fishing (Varna), 5, 93 (1964). 3. P. KOLAROV: Biological Notes on Shad in Bulgarian Waters in 1981. Fisheries, (4), 17 (1982). 4. P. KOLAROV: The Stock of Shad in 1983. Fisheries, (7), 25 (1984). 5. M.-I. NENCIU (ZAHARIA), D. ROSIORU, V. COATU, A. OROS, N. ROSOIU: Characterisation of the Conditions of the Long-snouted Seahorse Habitat Environmental of the Romanian Coast. J Environ Prot Ecol, 14 4, 1695 (2013). 6. V. S. RAYKOV Fish Stock Indicators: Application of Descriptor 3 of MSFD in Black Sea. J Environ Prot Ecol, 15 (3), 1092 (2014). 7. http://e-ecodb.bas.bg/rdb/bg/vol2/Alpontic.htmlр. 8. http://www.iucnredlist.org/apps/redlist/details/907/0. 9. http://www.biodiversity.bg/fi les/File/zak_bg_biodiv.pdf. 10. M.YANKOVA: Preliminary Estimates of the Population Parameters of Four Species in the Bulgarian Black Sea Coast. International Journal of Latest Research in Sci Tech, 3 (5), 46 (2014). Received 20 October 2016 Revised 28 November 2016
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