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The Marine Fisheries in Bulgaria’s Exclusive Economic Zone, 1950–2013

Authors:
  • Mersea Marine Consulting
  • Institute of Oceanology - Bulgarian Academy of Sciences

Abstract and Figures

This study presents a reconstruction of the total catch of Bulgarian marine fisheries in the Bulgarian Exclusive Economic Zone for the time period 1950–2013, including previously unreported landings, discards, recreational and subsistence catches. The landings data officially reported by Bulgaria to the Food and Agriculture Organization of the United Nations for the Mediterranean and Black Seas (FAO Area 37) were revised in line with all available information. The reconstructed total catch for 1950–2013 was 1.7 times the (adjusted) baseline data reported by Bulgaria to FAO and 1.5 times the unadjusted data as reported by FAO. This study revealed major deficiencies in the officially reported Bulgarian catch data, foremost the large amount of unreported industrial catches, especially for the last two decades. The exclusion of some fisheries sectors, notably the absence of data on the subsistence and recreational fisheries in reported data are also noteworthy
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ORIGINAL RESEARCH
published: 02 March 2017
doi: 10.3389/fmars.2017.00053
Frontiers in Marine Science | www.frontiersin.org 1March 2017 | Volume 4 | Article 53
Edited by:
Lyne Morissette,
M - Expertise Marine, Canada
Reviewed by:
Dimitrios K. Moutopoulos,
Technological Educational Institute of
Messolonghi, Greece
Valeria Mamouridis,
Institut de Ciències del Mar (CSIC),
Spain
*Correspondence:
Çetin Keskin
seahorse@istanbul.edu.tr
Specialty section:
This article was submitted to
Marine Fisheries, Aquaculture and
Living Resources,
a section of the journal
Frontiers in Marine Science
Received: 15 December 2016
Accepted: 15 February 2017
Published: 02 March 2017
Citation:
Keskin Ç, Ulman A, Zylich K,
Raykov V, Daskalov GM, Pauly D and
Zeller D (2017) The Marine Fisheries in
Bulgaria’s Exclusive Economic Zone,
1950–2013. Front. Mar. Sci. 4:53.
doi: 10.3389/fmars.2017.00053
The Marine Fisheries in Bulgaria’s
Exclusive Economic Zone, 1950–2013
Çetin Keskin 1*, Aylin Ulman 2, 3, Kyrstn Zylich 2, Violin Raykov 4, Georgi M. Daskalov 5,
Daniel Pauly 2and Dirk Zeller 2
1Fisheries Faculty, University of Istanbul, Istanbul, Turkey, 2Sea Around Us, Global Fisheries Cluster, University of British
Columbia, Vancouver, BC, Canada, 3Department of Earth and Environmental Sciences, University of Pavia, Pavia, Italy,
4Institute of Oceanology of Bulgarian Academy of Science, Varna, Bulgaria, 5Laboratory of Marine Ecology, Institute of
Biodiversity and Ecosystem Research, Bulgarian Academy of Sciences, Sofia, Bulgaria
This study presents a reconstruction of the total catch of Bulgarian marine fisheries in the
Bulgarian Exclusive Economic Zone for the time period 1950–2013, including previously
unreported landings, discards, recreational and subsistence catches. The landings data
officially reported by Bulgaria to the Food and Agriculture Organization of the United
Nations for the Mediterranean and Black Seas (FAO Area 37) were revised in line with
all available information. The reconstructed total catch for 1950–2013 was 1.7 times
the (adjusted) baseline data reported by Bulgaria to FAO and 1.5 times the unadjusted
data as reported by FAO. This study revealed major deficiencies in the officially reported
Bulgarian catch data, foremost the large amount of unreported industrial catches,
especially for the last two decades. The exclusion of some fisheries sectors, notably
the absence of data on the subsistence and recreational fisheries in reported data are
also noteworthy.
Keywords: Black Sea, invasive species, landing, overfishing, small pelagics, unreported catches
INTRODUCTION
Global fisheries catches have been decreasing in recent decades (Pauly and Zeller, 2016), which
has not only impacted the populations of target species (i.e., population size, demographic and
genetic characteristics), but has also changed community structure (biodiversity) and the function
of the other components of ecosystems (i.e., trophic levels, Pauly et al., 1998, 2002; Daskalov, 2002;
Tsikliras et al., 2015).
The impact fishing has on marine ecosystems can be demonstrated at the broadest scale by
initially examining the data documenting extractions of the marine resources. Based on this
concept, reconstructing the national fisheries catch data set can provide insights into the historical
catch time-series and create a more detailed, comprehensive regional dataset (Pauly and Zeller,
2016 and references therein). The aim of this study is to assemble the total reconstructed catch
of Bulgaria in the Black Sea, and to provide a comprehensive dataset which includes all marine
fisheries removals, such as landings and unreported catches (discards, subsistence and recreational
catches) from the Bulgarian component of the Black Sea ecosystem as a baseline for future studies.
Study Area
The Black Sea has a surface area of 422,100 km2(excluding the Sea of Azov), and a mean and
maximum depths of approximately 1,300 and 2,210 m, respectively. The Black Sea is connected
to the Aegean and hence Mediterranean Sea through the Bosphorus and the Dardanelles, which
themselves are connected by the Sea of Marmara.
Keskin et al. Marine Fisheries of Bulgaria
The upper layer of the Black Sea has low salinity (averaging
around 17–18 psu) and warmer average summer temperatures
(up to 30C), both of which inhibit the surface layer from mixing
with the deeper layer, which has a salinity averaging 22–24 psu
and temperatures of approximately 8.5C. The majority of the
Black Sea water column (about 90%), is deeper than 150–200 m
and is anoxic and devoid of multicellular life (Oguz et al.,
1998). The contrast between the river runoff (mainly from the
Danube, Dniester and Dnieper rivers), and high-salinity waters
(from the Mediterranean Sea, entering the Black Sea via the
Bosphorus Strait) enhance the stratification, and prevent any
mixing between surface and deeper layers. Although the lower
90% of the Black Sea basin is devoid of oxygen and contaminated
with hydrogen sulfide, the upper layer is productive and provides
suitable habitats for numerous epipelagic and neritic species
(Zaitsev, 2008).
The Black Sea ecosystem has suffered from several
anthropogenic disturbances, such as eutrophication, the
introduction of alien species (Mnemiopsis leidyi) and the
overexploitation of large pelagic predators in the mid- to late
twentieth century (Prodanov et al., 1997; Zaitsev and Mamaev,
1997; Caddy, 2008). Eutrophication has dramatically altered the
base of the marine food web; additionally, the overexploitation
and decline of some fish populations, such as large pelagic fishes,
contributed to providing the necessary conditions for successful
alien species invasions (Daskalov, 2002).
In 1946, a large sea snail, the invasive rapa whelk (Rapana
venosa), was first seen in the Black Sea. The rapa whelk was
successful in its new environment and became widespread
(except in very low salinity areas). It is a notorious predator which
feeds on oysters, mussels and other bivalves, and thus exerts
a major influence on local populations of malacofauna. In the
1980s, in response to an international demand for sea snails, a
massive fishery for the rapa whelk emerged in Turkish waters.
Along the Bulgarian coast, a rapa whelk fishery commenced in
1994 (Daskalov and Rätz, 2010), which helped reduce the rapa
whelk’s impact on its prey species. This may possibly be the only
example of a human-induced decline in an introduced species in
the Black Sea.
Despite the entire Black Sea ecosystem being affected by these
and similar issues, they are all treated as “national” issues, as there
is no ecosystem-wide management authority or agreement.
Fishing History
The Bulgarian Exclusive Economic Zone (EEZ) is around
35,000 km2(Figure 1, http://www.seaaroundus.org), which
corresponds to just under 7% of the total Black Sea area (Popescu,
2011). The Black Sea corresponds to Major Fishing Area 37 of the
General Fisheries Commission for the Mediterranean (GFCM),
Sub-area 37.4; Division 37.4.2, and Bulgaria’s fisheries occur
within Geographical Sub-area 29.
Bulgarias continental shelf (to 100 m depth) along the
Bulgarian coast is about 40 km wide; the relatively shallow
fishing grounds (down to depth of 100–120 m) range from Cape
Kartalburun (near the Romanian border) to the Rezevo River
(near the Turkish border). The exploitation of fisheries resources
is limited to the upper shelf, since depths below 100–150 m are
anoxic.
Bulgarian marine fish catches have exhibited trends similar to
other Black Sea countries. In the mid-1960s, Atlantic mackerel
(Scomber scombrus), Atlantic bonito (Sarda sarda) and bluefish
(Pomatomus saltatrix) were the commercially most important
species (Ivanov and Beverton, 1985). In the late 1960s and early
1970s, Atlantic mackerel, Atlantic bonito and bluefish catches
dramatically decreased in the Bulgarian Black Sea fisheries.
Among demersal species, turbot (Scophthalmus maximus) was
one of the most important commercial species, and catches
averaged around 330 t·year1in the 1960s, but dropped to 12
t·year1by the 1980s (Zaitsev and Mamaev, 1997). In the 1970s,
the over-exploitation of larger pelagic predators, combined with
the increased eutrophication of the north-western Black Sea led
to a dramatic increase in the catches of small pelagics such as
sprat (Sprattus sprattus), anchovy (Engraulis encrasicolus) and
Mediterranean horse mackerel (Trachurus mediterraneus). The
sprat population saw a massive increase in biomass from the mid-
1970s and 1980s, and its maximum catch was recorded in 1989,
after which the stock collapsed, but later rebounded (Radu et al.,
2010). In the late 1980s, an alien invasive ctenophore, the warty
comb jelly (Mnemiopsis leidyi) reached its maximum abundance
in the Black Sea, and thus became a powerful food competitor of
adult planktivorous fish, and a significant predator of their eggs
and larvae. As a consequence of this and other changes in this
Large Marine Ecosystem (LME, Pauly et al., 2008), the rapa whelk
has become, since 1995, the most commercially important taxon,
followed by sprat.
Modernization of the Bulgarian fishing fleet began just before
the 1950s. Industrial or large-scale purse seine and trawl vessels
developed in the 1950s. In the 1960s, however, Bulgaria began to
buy high-seas fishing and support vessels from the Soviet Union,
Poland and East Germany, and began to build infrastructure
for fish processing. From 1965 to 1990, Bulgaria owned a
large high-seas distant-water fleet (consisting of 30 high-capacity
trawlers and 6 transport vessels) that was actively engaged in
the Atlantic and in the south-eastern Pacific. This fleet was
liquidated in the early 1990s after the collapse of the former
USSR, and the Bulgarian fishing fleet refocused their efforts
on the Black Sea coastal zone (Popescu, 2011). In the 1970s,
approximately 80% of marine catches came from the industrial
fisheries, and the remainder came from the artisanal sector, which
used mainly passive gears (Kumantsov and Raykov, 2012). In
2008, the Bulgarian fleet consisted of 2,547 vessels with a total
gross tonnage (GT) of 8,378 and total kilowatts (kW) of 63,860
(Table 1). The small-scale sector represented 96% of the fishing
fleet in term of vessel numbers, i.e., 2,440 vessels under 12 m in
length, and was responsible for landing around 57% of the Black
Sea catch (Radu et al., 2010). Throughout this study, we use the
term “industrial” to refer to the large-scale commercial sector,
and “artisanal” to refer to the small-scale commercial sector.
Bulgarian fisheries policy is shaped by several international
fisheries agreements (i.e., UNCLOS, UNCLOS, CITES) and the
European Union Common Fisheries Policy (since its entry
into the European Union in 2007). The country is also a
member of General Fisheries Commission for the Mediterranean
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Keskin et al. Marine Fisheries of Bulgaria
FIGURE 1 | Exclusive Economic Zone (EEZ) and continental shelf (to
100 m depth) of Bulgaria in the Black Sea.
(GFCM) and the FAO. The National Agency for Fisheries and
Aquaculture within the Ministry of Aquaculture and Food is
the executive body responsible for national policy on fisheries
and aquaculture and implements the Fisheries Legislation in
Bulgaria. In this context, Total Allowable Catches (TACs) for
sprat and turbot were set in the mid-late 2000s. Some other
management implementations include a licensing system for
fishers, effort control via limiting fishing gear, engine power and
vessels; seasonal closures are imposed to protect some stocks
during their reproductive periods; and closed areas and bans of
bottom trawling and dredging are imposed. Since 2012, beam
trawling is allowed only in selected areas. No permit or licenses
are required to participate in the marine recreational fishery.
“Industrial” (Large-Scale) Fishery
In 2008, the industrial fleet consisted of 108 vessels >12 m
in length. Sprat is to this day targeted mainly by large-scale
pelagic trawlers seasonally from February to November. Whiting
(Merlangius merlangus), turbot, anchovy, shad (Alosa spp.),
Mediterranean horse mackerel and red mullet (Mullus barbatus)
are incidentally caught as by-catch (Radu et al., 2010), but
sold commercially. The bottom trawl fishery began to develop
for turbot in the 1950s, but was banned in 1994 to protect
declining turbot stocks and beds of Mediterranean mussel,
Mytilus galloprovincialis (Konsulova et al., 2001).
Dredges and beam trawlers were used in the rapa whelk
fishery, but were also banned in 2001 to protect vulnerable
benthic biotic communities such as mussel beds. Note that
dredge and beam trawl fisheries may be classified as small-
scale fisheries in Bulgaria, as domestic classification is based
on vessel size only. However, for the purposes of the Sea
TABLE 1 | Composition of the Bulgarian fishing fleet in 2008 (Radu et al.,
2010).
Length (m)
<6 m 6–12 12–18 18–24 24–40
Registered vessels 842 1598 68 27 12
Active vessels 213 434 45 13 11
Active gear Pelagic trawlers 0 3 8 2 11
Other gear 22 115 17 4 0
Passive gear Hook and line 14 23 2 0 0
Drift/fixed netters 166 224 8 1 0
Pots/traps 3 33 1 0 0
Other passive gear 2 11 0 0 0
Variable gear Active and passive gear 6 25 9 6 0
Around Us (www.seaaroundus.org), any fishing gears that are
actively dragged across the sea-floor or through the water column
using engine power are considered “industrial” (i.e., large-scale),
following Martín (2012).
“Artisanal” (Small-scale Commercial)
Fishery
The coastal fishery has traditionally been carried out by small
vessels (<12 m) which use mainly passive fishing gear, such
as trap nets (uncovered pound nets), and beach seines in the
inshore area. Here, these vessels/gears are considered “artisanal.”
Pound nets are deployed in 9 to 12 m depth in coastal inshore
waters (Radu et al., 2010) from March to November, and target
species vary according to season: sprat is targeted during spring
and the beginning of summer, and anchovy and Mediterranean
horse mackerel are targeted in summer and autumn. Whiting,
turbot, red mullet and other demersal species are incidentally
caught as by-catch, but retained for commercial sale (Radu et al.,
2010). The set gillnet fishery operates in the coastal and offshore
waters of Bulgaria and targets primarily turbot, while dogfish
(Squalus acanthias), thornback ray (Raja clavata), common
stingray (Dasyatis pastinaca) and sturgeons (Acipenseridae) are
often incidentally caught as by-catch (Radu et al., 2010). The
number of vessels operating by LOA (length overall) in 2008 is
given in Table 1.
METHODS
Reported Catch Data
The baseline data used for the work presented here are
the catch statistics submitted annually by Bulgaria to
FAO which are incorporated into the global database
(FishStat; www.fao.org/fishery/statistics/software/fishstatj/en),
complemented by national Bulgarian data published by
Prodanov et al. (1997); Mikhailov and Prodanov (2003), and
Panayotova et al. (2012). Tunas and other large, highly migratory
pelagic fishes (e.g., swordfish), which were originally abundant
in the Black Sea, are not considered here.
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Keskin et al. Marine Fisheries of Bulgaria
According to the data reported by FAO on behalf of Bulgaria
in the Mediterranean and Black Seas (FAO Area 37, release date
March 2015), total catches appeared very high for the years
between 1964 and 1969 (driven by high values for “marine
fishes nei,” i.e., “marine fish not elsewhere identified”). On closer
inspection of Bulgarian FAO data for areas other than 37, it
was found that duplicate “marine fishes nei” (or Miscellaneous
Marine Fishes, MMF) values had been reported for Bulgaria
fishing in three other areas (the central-eastern Atlantic, south-
eastern Atlantic and north-western Atlantic), i.e., the exact same
values were present in all three areas. By comparing FAO data
with Northwest Atlantic Fisheries Organization (NAFO) data,
it was found that these MMF values were indeed incorrect.
It was therefore assumed that the reported catch for FAO
Area 37 (Mediterranean and Black Seas) also had these values
mistakenly added on to the real reported MMF catch. We
therefore subtracted the duplicated MMF tonnage reported in
the other areas from the MMF in FAO Area 37 for the years
1964–1969. This resulted in an adjusted FAO baseline, which
was used for the rest of the reconstruction as reported baseline
data. We suggest Bulgaria formally request a retrospective data
correction of FAO data.
Since all taxa were reported as “marine fishes nei” from
1950 to 1963, we disaggregated this category taxonomically by
using reports of national data to assign most of the tonnage to
specific species or families (Prodanov et al., 1997; Mikhailov and
Prodanov, 2003; Panayotova et al., 2012). Any remaining tonnage
was kept as “marine fishes nei.” These national reports were also
used to improve the catch data from 1964 to 1969, as much of
these data still remained as MMF and many species/families had
rounded, estimated values listed.
Unreported Catches
Unreported catches as defined here include unreported
commercial, subsistence and recreational catches, as well as
discarded catch.
Commercial Catches
Sprat has been the main catch for Bulgaria since 1970. However,
published reports on Bulgarian fisheries have clearly documented
that some commercial sprat catches have gone unreported
(Mikhailov and Prodanov, 2003; Daskalov and Rätz, 2010). On
average, Daskalov and Rätz (2010) estimated of actual catches for
1992 and 1993 were 55% higher than the reported sprat catches
in 1990 and 1991. From 1994 to 1999 sprat catches were assumed
to have been under-reported by the same ratio and averaged 1.79
times higher than reported data (Daskalov and Rätz, 2010), and
were used to estimated unreported sprat component for 2000
and 2001. The ratio was not applied to the years 2002–2003,
as the reported data exhibited a spike in these years and it was
assumed that reporting coverage was more complete in this time
period. Therefore, in order to remain conservative, we linearly
interpolated the unreported tonnage from 2001 to 2004. There
was also an expert assessment in 2007 which estimated catches to
be 2,985 t as opposed to 2,559 t (EU, 2008), with FAO using the
former value. Thus, we assume that catches were fully reported
in 2007 and use the ratio (unreported =0.17reported) between
the two 2007 estimates in Daskalov and Rätz (2010) to obtain a
conservative estimate of unreported catches in 2008–2013. We
also assumed there to be a much lower likelihood of under-
reporting from 1950 to 1989 (during communist rule), and
therefore added a conservative 10% of landings to account for
under-reporting of sprat during that period.
In Bulgaria, marine bivalve catches include the striped Venus
clam (Chamelea gallina), bean clam (Donax spp.) and mussel.
According to information available at the FAO (http://www.
fao.org/fi/oldsite/FCP/en/bgr/body.htm), the 2000 FAO reported
data for rapa whelk equated to 90% of the total shellfish catch.
We considered the remaining 10% to be comprised equally
of C. gallina,Donax spp. and miscellaneous marine molluscs
(“marine molluscs nei”) for the 1994 to 2013 period.
Some sturgeons are anadromous or potamodromous, as in
the case of the sterlet sturgeon (Acipenser ruthenus) (Mikhailov
and Prodanov, 2003); thus, A. ruthenus was excluded from
consideration in the present study. While the fringebarbel
sturgeon (Acipenser nudiventris) is commercially extinct, the
beluga sturgeon (Huso huso) and the Russian sturgeon (Acipenser
guldenstaedti) are still commercially important in the Bulgarian
fishery. Wild caviar export data were used to estimate unreported
sturgeon catches from 1998 to 2006 (Kecse-Nagy, 2011;Table 2).
We converted caviar weight to fresh fish weight for H. huso,
A. gueldenstaedti and Acipenser stellatus, using gonado-somatic
coefficients from Jivkov et al. (2003), and then estimated catches
by using the sex ratio of the same three species (Tables 2, 3).
Bulgaria became a member of the European Union (EU)
in 2007, and intra-EU trade no longer appears in the CITES
(Convention on International Trade in Endangered Species of
Wild Fauna and Flora) data for caviar exports. It is likely
that caviar export to other EU countries have continued after
2007 without being recorded in CITES data, and the estimated
unreported catch in 2006 was thus used as estimate for the years
2007 to 2013.
TABLE 2 | Wild origin caviar exports used to estimate sturgeon catches (wet weight) in Bulgaria (from the CITES Trade Database; Kecse-Nagy, 2011).
1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010
Exported caviar (kg) 2,392 2,025 2,788 992 2,337 1,563 920 1,421 667
Estimated female (t) 13 11 15 6 13 9 5 8 4
Estimated male (t) 40 34 46 17 39 26 15 24 11
Estimated total (t) 53 45 62 22 52 35 20 32 15 –
Unreported catch (t) 39 33 59 22 45 31 16 30 15 15 15 15 15
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Keskin et al. Marine Fisheries of Bulgaria
Rapa whelk has become a commercially valuable resource with
high demand on the international market. In Bulgaria, this fishery
commenced in 1994 and rapa whelk were originally caught by
scuba divers. However, shortly thereafter, there was illegal rapa
whelk fishing by bottom trawlers, beam trawlers and dredgers
(Daskalov and Rätz, 2010). For the period from 2000 to 2010, the
bulk of rapa whelk catches were illegally taken by dredges and
beam trawls (V. Raykov, pers. obs.). We estimated an unreported
catch component for rapa whelk based on export data for the
period from 2002 to 2010 (Table 4). The same percentage rates
for the select processing types of rapa whelk in 2009 (Daskalov
and Rätz, 2010) were used and applied to the 2002–2010 period to
disaggregate the unreported catch component. Since rapa whelk
is exported without its shell, the exported amounts first had to
be converted to equivalent weights with shell on, to account for
total fishery removals. A rate of 85.8% of total weight was added
to both the frozen meat and sweetbread rapa whelk exported
amounts to account for this (Düzgüne¸s et al., 1988). Unreported
rapa whelk catches were interpolated from zero in 1993 to the
estimate of 12,313 t in 2002 that came from the export data.
Finally, the ratio of reported to unreported rapa whelk catches
in 2010 was applied to the 2011–2013 reported data.
An unreported catch of turbot (Scophthalmus maximus) taken
by Bulgaria was estimated from sources stating that Bulgarian
fishers also have under-reported their own turbot catches from
the Bulgarian EEZ in recent years (total estimated at 300 t·year1;
EU, 2009). The total turbot catch was accepted as 250 t·year1
to avoid over-estimation, and this was used as an anchor point
in 2007 (last year of data in the EU, 2009 report). To remain
conservative, the unreported catch was then interpolated from
zero in 1994 (year before turbot catches started again) to 183
t in 2007 (difference between 250 t and the reported amount).
The ratio of reported to unreported data in 2007 was then
applied to the reported data from 2008 to 2013. We also assumed
some turbot catches to have been unreported throughout the
TABLE 3 | Gonado-somatic coefficients (G) and sex ratio (female: male) for
sturgeons in Bulgaria (adapted from Jivkov et al., 2003).
Species G (%) Sex ratio Species contribution (%)
Huso huso 18 3:1 83
Acipenser gueldenstaedti 16 1:1 10
Acipenser stellatus 16 2:1 7
1950–1989 period, but to a much lesser extent. Thus, from
1950 to 1989, an additional 10% of the reported turbot catch
amount was estimated to have been unreported, and added to the
reported component.
Lastly, there were also data in the national reports used
above (Prodanov et al., 1997) from an expert assessment of
whiting (Merlangius merlangus) that we incorporated, and which
indicated that catches were severely under-reported from 1975
to 1993.
Discards
To estimate discards, published reported discard rates by select
fisheries from the Black Sea and eastern Mediterranean were
sought, which included both industrial (mid-water trawl, bottom
trawl, purse seine, dredge) and artisanal fisheries (gill and
trammel nets, hand line, long line, fish pound net, beach seine
net). These discard rates were then applied to the reported
data for each of the target species for each fishery with the
help of expert advice (Table 5). Given that discard rates were
only applied to reported catches (and thus represent minimum
estimates of discards), the discards of the rapa whelk fishery
are likely considerably underestimated as there was a substantial
unreported landings component to that fishery.
Whiting contribute greatly to the trawl catches in the Black
Sea, but are not a targeted fishery and are mostly discarded
by Bulgarian fishers (Raykov et al., 2008). In neighboring
TABLE 5 | Discard rates applied to select fisheries in Bulgaria.
Ecosystem Fishing gear Discards (%)
Marmara SeaaBottom trawl 16.2
Black SeabSea snail dredge 11.5
GlobalbBottom long line 8.2
GlobalbBeam trawl 7.5
Black SeabMid-water trawler 5.1
GlobalbBeach seine 4.4
GlobalbHand line 1.8
Black SeacPurse seine 1.0
GlobalbGill net and trammel net 0.5
GlobalbPound nets, weirs 0.5
aZengin and Akyol (2009).
bKelleher (2005).
c¸Sahin et al. (2008).
TABLE 4 | Exported rapa whelk tonnages (NAFA, Bulgaria for the purposes of National report of Focal point of Bulgaria to AG FOMLR, BCS).
Type of Rapa whelk 2002 2003 2004 2005 2006 2007 2008 2009 (%) 2010
Frozen 284 343 302 269 351 436 324 146 (13) 167
Frozen sweetbread 656 792 698 620 811 1,005 747 326 (30) 386
Frozen meat 1,136 1,373 1,209 1,075 1,405 1,743 1,295 572 (52) 668
Frozen meat with shell 109 132 116 103 135 168 125 59 (5) 64
Exported 2,185 2,641 2,325 2,067 2,702 3,351 2,491 1,104 (–) 1,285
In 2009, the processed category percentage is given in brackets (adapted from Daskalov and Rätz, 2010, Table 4.7.3.1).
Frontiers in Marine Science | www.frontiersin.org 5March 2017 | Volume 4 | Article 53
Keskin et al. Marine Fisheries of Bulgaria
Romania, the whiting portion of reported demersal catches
was 42% from 2000 to 2006 (Maximov and Staicu, 2008). To
account for discarded whiting in Bulgaria, an additional 20% was
conservatively assumed to account for this component and was
applied to the reported catches of demersal taxa by industrial
bottom trawls from 1950 to 1994 (as bottom trawling was banned
after 1994).
Recreational and Subsistence Catches
Recreational fishing is understood here to mean fishing primarily
for leisure or enjoyment, while subsistence fishing is understood
to mean fishing for the primary purpose of providing protein
for self- or family-consumption (recreational and subsistence
fisheries are here assumed not to generate discards) While the
two sectors are difficult to separate, it is generally understood that
subsistence fishing over time evolved into recreational fishing,
as incomes increased and food security was no longer a primary
concern.
In Bulgaria, recreational fishing is most popular from April
to June, and from September to November. It occurs in inshore
waters and targets gobies (Gobiidae), grey mullets (Mugilidae),
horse mackerel, bluefish, Atlantic bonito, turbot, Mediterranean
horse mackerel and garfish (Belone belone). However, no data
on the number of recreational fishers and/or their catch rates or
amounts have been collected in Bulgaria.
There has been both recreational and subsistence fishing
in Bulgaria for the 1950 to 2010 period. Since no data on
this topic exists, estimated catch rates from the Black Sea
coast of Turkey were used as a starting point (Ulman et al.,
2013) to estimate recreational and subsistence catches, i.e., 0.258
t·fisher1·year1in 1950 and 0.129 t·fisher1·year1in 2010.
To derive the number of recreational/subsistence fishers for
Bulgaria, we assumed that in 1950, 2% of the coastal population
fished either recreationally and/or for subsistence purposes, and
this rate was linearly decreased to 0.95% of the coastal population
by 2013 due to the declining availability of larger fish. To derive
the coastal population, we started with total population data
from Populstat (1950–1959; http://www.populstat.info) and The
World Bank (1960–2013; www.data.worldbank.org) and then
assumed that only people living within 20 km from the coast
were involved in these fisheries. The coastal population data,
however, was only available for 100 km from the coastline
(CIESIN, 2012); therefore, we conservatively assumed 25% of
the population within 100 km of the coast were actually living
within 20 km of the coast. The coastal population data was also
only available for the years 1990, 2000, and 2010. Therefore, we
used the proportion of total population living 100 km from the
coastline in 1990 and applied this from 1950 to 1989 and the
proportion for 2010 was applied to 2011–2013. We then also
interpolated the proportion between the 1990 and 2000 anchor
point, as well as the 2000 and 2010 anchor point and applied this
to the total population. We then reduced the catch rates used for
Bulgaria by 50% from that used for Turkey in 1950, i.e., 0.129
t·fisher1·year1, and 20% in 2010, i.e., 0.103 t fisher1·year1,
since recreational fishing appeared to be less intensive than in
Turkey (V. Raykov, pers. obs.); the interpolation was carried
forward to 2013. We also made an adjustment to the catch
in the early 1990s, as all fisheries were affected by a massive
invasion of ctenophore in the Black Sea, which was deemed a
“fisheries crisis” and resulted in a temporarily collapse of the
pelagic fisheries (Daskalov, 2002). In light of this crisis, from 1989
to 1991, we decreased the recreational/subsistence catch rates by
a further 75%. The newly adjusted 1991 value and the 1993 catch
amount were then interpolated as there was a quick recovery
period for small pelagics. In order to assign the estimated
recreational/subsistence catches to the two sectors, we assumed
that in 1950, 70% of these catches were taken for subsistence
purposes, which was linearly decreased to 30% by 2010 (with
decline carried forward to 2013), and the remaining catches
were assigned to the recreational fishery (i.e., increasing from 30
to 70%). Sturgeon, Atlantic bonito, Atlantic mackerel, bluefish,
turbot, Mediterranean horse mackerel, grey mullet and gobies
were the main recreational/subsistence taxa for the 1950–2013
period (Table 6). We assumed that the overwhelming majority
recreational/subsistence fishers operate from shore.
RESULTS
The reconstructed total catch for the marine fisheries of Bulgaria
for 1950–2013 was estimated to be 1.7 times the (adjusted)
data reported by FAO for the Black Sea fisheries of Bulgaria
(Figure 2A). Total catches were only slightly higher than those
reported by the FAO (after adjustment for likely over-reporting)
on behalf of Bulgaria up until 1993 (just before the rapa whelk
fishery commenced). Total catches increased from an annual
average of around 5,800 t·year1in the 1950s (only slightly
TABLE 6 | Catch composition (%) for recreational and subsistence catches in Bulgaria from 1950 to 2013 (based on V. Raykov unpublished data).
Taxon 1950–1959 1960–1969 1970–1979 1980–1989 1990–1999 2000–2013
Atlantic bonito 35 30 5 1 1 2
Atlantic mackerel 25 22 5 2 − −
Bluefish 15 20 10 2 1 2
Horse mackerel 3 3 50 60 50 35
Grey mullet 5 5 15 20 23 30
Goby 2 2 13 15 25 30
Turbot 10 15 1 − − 1
Sturgeon 5 3 1 − − −
Frontiers in Marine Science | www.frontiersin.org 6March 2017 | Volume 4 | Article 53
Keskin et al. Marine Fisheries of Bulgaria
FIGURE 2 | Reconstructed total catches for Bulgaria in the Black Sea,
1959–2013. (A) Landings by fisheries sector +discards; officially reported
data as reported by FAO (adjusted for duplicate reporting between 1964 and
1969) on behalf of Bulgaria are overlaid as line graph. Subsistence and
recreational catches are included, but too small to be visible; (B) by major
taxa. The category “others” consists of 38 additional, minor taxa. The
significant reduction in fishing around 1990 resulted from the privatization of
the fishing fleet from a state-owned industry.
higher than the 5,100 t·year1reported by the FAO on behalf
of Bulgaria) to a peak of 25,500 t in 1981 (of which 19,800 t
were reported; Figure 2A). Catches declined to a low in the early
1990s with an estimated 4,700 t·year1and then increased to a
second peak of 32,000 t in 2003, before declining to an average of
13,600 t·year1at the end of the time period (2010–2013). Total
reconstructed catch was on average only 1.2 times the adjusted
reported data from 1950 to 1989, and increased to 1.9 times
in the 1990s (Figure 2A), and were then, on average, 3.1 times
for the rest of the time period (Figure 2A; Appendix Table 1 in
Supplementary Material). The reconstructed total catch consisted
of reported industrial landings (54%), unreported industrial
landings (34%), industrial discards (3.3%), reported artisanal
landings (6.1%), unreported artisanal landings (0.6%), artisanal
discards (0.1%), subsistence catches (0.9%), and recreational
catches (0.8%).
Total industrial catches increased from 4,100 t·year1in the
1950s, to a peak of 24,600 t in 1981. Catches then declined
to a low of 3,900 t in 1992. Catches increased in 1994, due
to the opening of the rapa whelk fishery, to a second peak
of 31,000 t in 2003, before declining to an average of 12,600
t·year1at the end of the time period (2010–2013, Figure 2A).
Industrial unreported catches were 41% of the reconstructed total
industrial catch (37.5% unreported landings and 3.6% discards).
Unreported industrial landings increased throughout the time
period, from 3% of the industrial catch in the 1950s to an average
of 20% and 17% in the 1970s and 1980s, respectively. Unreported
industrial landings increased rapidly in the mid-1990s due to the
rapa whelk fishery and averaged 58% in the 2000s.
The discards from the industrial and artisanal fisheries
amounted to 3.3 and 0.1%, respectively, of the reconstructed
total catches (Figure 2A). Discards increased from 210 t·year1
in the 1950s to 780 t·year1from the late 1970s to late 1980s.
Discards then decreased to 130 t·year1in the early 1990s but
increased again to an average of 570 t·year1for the rest of the
time period. The main discarded species were sprat (55%), rapa
whelk (26%), whiting (8%), turbot (4%) and Mediterranean horse
mackerel (1%).
Reconstructed total catches were mostly composed of sprat
(47%), rapa whelk (28%), Mediterranean horse mackerel (4%),
whiting (4%), Atlantic bonito (3%) and turbot (2%; Figure 2B,
Appendix Table 2 in Supplementary Material).
DISCUSSION
The prospects for the marine fisheries in the Bulgarian EEZ are
limited by the specific characteristics and production potential
of the Black Sea ecosystem, especially by its limited shelf area.
Another constraint is the limited biodiversity, which is under
constant threat. There are only 134 fish species recorded in
the Bulgarian section of the Black Sea (Stefanov, 2007). During
1960–1970, 26 of these fish species were commercially targeted,
which decreased to 5 major target species by the 1980s (Zaitsev
and Mamaev, 1997). Our results show three separate periods
revealing distinctive catch compositions for the Bulgarian coastal
waters: (1) from 1950 to 1969, the major species caught were
sprat and Atlantic bonito; (2) from 1970 to the mid-1990s,
catches were dominated by sprat; and (3) and from the mid-1990s
onwards, catches were dominated by rapa whelk, still with a large
contribution of sprat (Figure 2B).
The contribution of Bulgarian fisheries catches to total Black
Sea catches is low, only slightly over 2% of Turkey’s reconstructed
total catch from 1950 to 2010 (Ulman et al., 2013). On the other
hand, the reconstructed total catch for 1950 to 2013 was 67%
higher than the data submitted by Bulgaria to the FAO. Most
of the unreported catches were deemed to have occurred after
1990, since reporting and control measures were much stricter
in the planned economy of the earlier period, as was the case
for neighboring Ukraine (Ulman et al., 2015). Total commercial
catches in the Black Sea significantly decreased after the collapse
of the Black Sea pelagic fisheries at the end of the 1980s due
to overfishing, a trophic cascade and the ctenophore invasion
(Daskalov, 2002; Daskalov et al., 2007). The catch dynamics
of the most important species in the Bulgarian Black Sea shelf
zone illustrate a prominent decreasing trend beginning in the
1990s.
Frontiers in Marine Science | www.frontiersin.org 7March 2017 | Volume 4 | Article 53
Keskin et al. Marine Fisheries of Bulgaria
On a sectoral basis, the reconstructed total catch of Bulgaria
was similar to that of the Turkish Black Sea (Ulman et al., 2013),
both having a small artisanal catch component (7–15%) and a
much higher industrial component (75–90%), although, as stated
above, the catches of Turkey slightly under of Bulgaria. Bulgaria’s
reconstructed total catches differed from that of Romania, in
terms of its much lower artisanal catch contribution (7% for
Bulgaria compared with 66% for Romania) due to the highly
popular traditional Romanian fishing method “crawling” (a
stationary inshore net deployed in shallow waters) which was the
main fishing technique used in Romania until the 1980s (Ulman
et al., 2015). The reconstruction for Ukraine demonstrated that
the national catch statistics included only commercial large-
scale landings and failed to include small-scale, recreational or
artisanal catches (Ulman et al., 2015), and at present are just over
6 times that of Bulgaria’s marine fisheries.
The three distinct periods of catch, characterized by three
distinct ecological shifts, can be distinguished in the catch
composition of Bulgarian fisheries: during the first and second
periods, the catch composition was similar to that of other
Black Sea countries in terms of dominance by pelagic fishes,
i.e., larger pelagics in the first period and small pelagics in the
second. The third period differed from the trends in other Black
Sea countries owing to a high rate of rapa whelk catches in
Bulgaria. During this third period, targeted species were small
pelagic fish (i.e., sprat, Mediterranean horse mackerel, anchovy)
and demersal fishes (turbot, gobies, dogfish and most recently
red mullet), while the rapa whelk gained the prominent role
in the commercial fisheries. Although the introduction of the
rapa whelk contributed to the fisheries economy after 1993, high
disturbance to the benthic ecosystem from destructive fishing
practices (dredging and beam trawling) resulted in negative
ecological effects on benthic communities, especially on the
Mediterranean mussel beds (Konsulova et al., 2001; Daskalov
and Rätz, 2010), as also noticed in neighboring Ukrainian waters
where macrobenthos biomass was reduced 20-fold due to intense
trawling (Ulman et al., 2015). Taking into consideration the
amount of illegal unreported rapa whelk taken from Bulgarian,
Ukrainian (Ulman et al., 2015) and Turkish waters (Ulman et al.,
2013), habitats and biodiversity are likely much more under
threat from illegal mobile bottom-fishing gear than previously
assumed.
Russia, Ukraine, Bulgaria, Romania, Turkey and Georgia all
share the stocks of migratory Black Sea species. Cold-water
small pelagics complete their entire life cycle in the Black Sea,
seasonally migrate to reach wintering areas in the south and
return to feeding and spawning areas in the following spring in
the north (Ivanov and Beverton, 1985). In contrast, larger warm-
water pelagics, such as bluefish, Atlantic mackerel and Atlantic
bonito are highly migratory, i.e., move from the Sea of Marmara
or to the Eastern Aegean Sea through the Bosphorus, then swim
westwards and northward along the Bulgarian and Romanian
coasts to reach their summer feeding grounds in the western and
northwestern Black Sea (Demir, 1957; Türgan, 1959).
The northwest and western region of the Black Sea, with its
large shallow continental shelf areas and high nutrient inputs by
rivers provide highly productive waters, which are suitable for
spawning and feeding. Sprat, a cold-water species, prefers the
coldest habitable portions of the Black Sea, as the shoals move
toward coastal waters in the northwest in winter and offshore
in autumn (Ivanov and Beverton, 1985). Mediterranean horse
mackerel are a warm-water migratory species which pass from
south to north to spawn along the Bulgarian coast in spring, and
from north to south for feeding in autumn. These two species also
provide seasonal catches in the Bulgarian EEZ.
Turbot is the main commercial demersal fish species and
is mainly found in the western and northwestern shelf of the
Black Sea along the coasts of Bulgaria, Romania and Ukraine.
Its migration along the shelf links shallow waters (in spring,
for spawning) and deeper waters (in winter, for feeding). The
previously discussed illegal turbot catch (by Turkish fishers) from
Bulgarian and Romanian waters (Ulman et al., 2013; Banaru et al.,
2015), points to a need of a common policy between member
countries (Bulgaria and Romania), and cooperation with the
remaining four non-EU bordering countries to recover turbot
stocks to a previous larger-size and population levels.
In the Black Sea, the status of turbot and anchovy stocks
were reported as “overexploited” and “in overexploitation,
respectively, the Mediterranean horse mackerel stock was
reported as “overexploited” and the dogfish population was
considered “depleted” at the Black Sea scale. In contrast, Black
Sea sprat stocks were deemed as sustainably exploited (GFCM,
2014).
This study illustrates some major deficiencies in the nationally
(and hence internationally) reported fisheries data, such as the
exclusion of some fisheries sectors, notably the absence of any
catches stemming from subsistence and recreational fisheries.
We feel that our estimates of total marine fisheries catch for
Bulgaria provide a more accurate and comprehensive baseline,
which should be further improved through targeted studies of the
previously omitted sectors.
The European Union’s Marine Strategy Framework Directive,
2008/56/EC (MSFD), the first legislative instrument dedicated
to protecting biodiversity for all of Europe’s regional seas by
2020, seeks to achieve a Good Environmental Status (GES) in
European Seas by protecting the resource base. Although the
MSFD seeks to foster the ecosystem approach, environmental
protection and sustainable use, if all resource users are not made
to fish sustainably, it is highly unlikely that the directive will
work. In the Mediterranean and Black Sea basins, the regions
in most peril from overexploitation are the Black Sea and the
Eastern Mediterranean (Tsikliras et al., 2015). The main driver
for the high rate of exploitation is likely the overcapacity of the
Turkish large-scale commercial fishery. As long as rebuilding
stocks to some optimal former level is not prioritized by all
shared users of the Black Sea (Ulman, 2014), it will remain at
its current degraded state yielding mainly low value species such
as sprat and anchovy, and the future of the fisheries will remain
questionable.
This reconstruction of marine fisheries catches for Bulgaria
provides an improved baseline for its marine fisheries, to help
understand the impact fisheries have had, and to help the
implementation of management rules of the MSFD. Because
of the many assumptions that were made, some parts of this
Frontiers in Marine Science | www.frontiersin.org 8March 2017 | Volume 4 | Article 53
Keskin et al. Marine Fisheries of Bulgaria
reconstruction will be very uncertain, however. Thus, readers
are welcome to send suggestions for corrections, updates and/or
other improvements via www.seaaroundus.org, from which
the detailed data underlying this reconstruction can also be
downloaded.
AUTHOR CONTRIBUTIONS
The original methodology was decided upon by DZ. VR and
GD provided some of the background data. ÇK, AU, KZ, and
DZ helped calculate the methodology. ÇK, AU, KZ, VR, GD,
DP, and DZ contributed to both the writing and editing of the
paper.
ACKNOWLEDGMENTS
ÇK wishes to thank The Scientific and Technological Research
Council of Turkey (TÜB˙
ITAK) (2219 International Post-
Doctoral Research Fellowship Programme); AU, KZ, DP, and
DZ acknowledge support from the Sea Around Us, a scientific
initiative funded by The Paul G. Allen Family Foundation.
SUPPLEMENTARY MATERIAL
The Supplementary Material for this article can be found
online at: http://journal.frontiersin.org/article/10.3389/fmars.
2017.00053/full#supplementary-material
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Conflict of Interest Statement: The authors declare that the research was
conducted in the absence of any commercial or financial relationships that could
be construed as a potential conflict of interest.
Copyright © 2017 Keskin, Ulman, Zylich, Raykov, Daskalov, Pauly and Zeller. This
is an open-access article distributed under the terms of the Creative Commons
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is permitted, provided the original author(s) or licensor are credited and that the
original publication in this journal is cited, in accordance with accepted academic
practice. No use, distribution or reproduction is permitted which does not comply
with these terms.
Frontiers in Marine Science | www.frontiersin.org 10 March 2017 | Volume 4 | Article 53
... Although an attempt to characterise fisheries within the Mediterranean and Black Seas has been made as part of the 'SeasAroundUs' project (http://www.seaaroundus.org/) [53][54][55][56][57][58], the landings provided were an average for 2010-2013 and were not split by country. In addition, the MRF catch estimates attained at a country level were reconstructed for almost all species [53][54][55][56][57][58] meaning further reconstructions would have introduced a large amount of uncertainty, so were unlikely to be representative of the true catch. ...
... [53][54][55][56][57][58], the landings provided were an average for 2010-2013 and were not split by country. In addition, the MRF catch estimates attained at a country level were reconstructed for almost all species [53][54][55][56][57][58] meaning further reconstructions would have introduced a large amount of uncertainty, so were unlikely to be representative of the true catch. Indeed, Venturini et al. [59] also quantified MRF catches in an Italian marine protected area, however, the study area was considered too small to reconstruct data from. ...
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... The Black Sea has been identified as one of the most vulnerable ecosystems on the globe, affected by discharges from land-based sources on the territories of the central and eastern European countries along the river Danube ( Zaitsev, 2008 ). Under anthropogenic and natural affects, the Black Sea ecosystem experienced dramatic structural and functional changes in the '80s ( Daskalov, 2002 ;Ivanov and Beverton, 1985 ;Keskin et al., 2017 ;Pauly et al., 1998Pauly et al., , 2002. Excessive overfishing, eutrophication, and the introduction of invasive species ( Caddy, 2008 ;Prodanov, et al., 1997 ;Zaitsev and Mamaev, 1997 ) were reported as key factors in the disruption of the ecosystem structure and the significant loss of biodiversity. ...
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