Vesselina MihnevaAgricultural Academy - Bulgaria · Institute of Fish Resources -Varna
Vesselina Mihneva
PhD
About
47
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Publications (47)
Over the last few years, data on seasonal and interannual variations in the biological parameters of picked dogfish in the Black Sea have been limited, which hampers the understanding of the current status of this vulnerable species and management options. We studied the size and sex structure, as well as the link between the length and weight of p...
Marine biota are redistributing at a rapid pace in response to climate change and shifting seascapes. While changes in fish populations and community structure threaten the sustainability of fisheries, our capacity to adapt by tracking and projecting marine species remains a challenge due to data discontinuities in biological observations,
lack of...
During the last 20 years, a series of studies has suggested trends of increasing jellyfish (Cnidaria and Ctenophora) biomass in several major ecosystems worldwide. Some of these systems have been heavily fished, causing a decline among their historically dominant small pelagic fish stocks, or have experienced environmental shifts favouring jellyfis...
• Fisheries in the Mediterranean and Black Sea are multi-specific and multi-fleet, with small pelagic species the most important in terms of landings and small-scale fisheries (SSF) the dominant fleet. Current high rates of overfishing will affect their capacity to cope with climate change impacts.
• Surface warming, increasing heatwaves and a decr...
Large-scale transitions between alternative states in ecosystems are known as regime shifts. Once described as healthy and dominated by various marine predators, the Black Sea ecosystem by the late 20th century had experienced anthropogenic impacts such as heavy fishing, cultural eutrophication, and invasions by alien species. We studied changes re...
Understanding and Conserving Marine Biodiversity and Ecosystem
Services; MDPI Sustainability
This study was carried out thanks to the financial support of the European Commission under Regulation (EC) No199/2008 and Regulation (EU) 2017/1004 of the European Parliament and of the Council on the establishment of a Union framework for the collection, management and use of data in the fisheries sector and support for scientific advice regardin...
Catches of the commercial beam trawl fishery for Rapana venosa in Bulgarian waters were assessed during summer-autumn 2017. The fish bycatch was analysed, with a particular emphasis on the bycatch rate of turbot juveniles. Four commercial boats were chartered and catch species composition as well as weight and length of turbot bycatch were recorded...
Marine biota is redistributing at a rapid pace in response to climate change and shifting seascapes. While changes in fish populations and community structure threaten the sustainability of fisheries, our capacity to adapt by tracking and projecting marine species remains a challenge due to data discontinuities in biological observations, lack of d...
The purpose of this project is to collect data for the catches (main catches and bycatches) of marine organisms by different types of fishing activities of the Bulgarian fisheries' fleet.
The main study is carried out in 2018-2019 and the following types of fishing vessels are observed:
(1.) turbot fishery with gillnets;
(2.) pelagic and bottom sp...
Analyses of data from the biometric measurements of 2400 specimens Rapana venosa, collected during 2018 – 2019 from landings of Bulgarian fishing fleet in nine ports – Krapets, Durankulak, Kavarna, Balchik, Varna, Byala, Sozopol, Tsarevo and Rezovo are included in this study. The Rapana fishing techniques involve beam trawling and scuba diving. For...
For assessment of S. maximus abundance, the Institute of Fish Resources - Varna has conducted several demersal trawl surveys in the Western Black Sea during 2014-2016, with the frames of the National Programs for Fisheries Data Collection.
We present a general review of data about sprat diet composition and feeding indexes, collected through the National Fisheries Data Collection Program in the western part of the Black Sea. Eight pelagic trawl surveys for sprat biomass assessment were conducted during This study is based on stomach content analysis of 863 fish specimens, varying bet...
Pelagic Trawl Survey was accomplished in November-December 2018 in the Bulgarian Black Sea area. Scientific team has produced a biological analysis of the results obtained in the marine area.
The survey of pelagic trawl was carried out in November-December 2018 in the Bulgarian Black Sea area. Biological analysis is based on the biomass of the spec...
Aim
Invasive species are of increasing global concern. Nevertheless, the mechanisms driving further distribution after the initial establishment of non‐native species remain largely unresolved, especially in marine systems. Ocean currents can be a major driver governing range occupancy, but this has not been accounted for in most invasion ecology s...
This report is based on the data collected through the survey during 24-30 May 2017 , indicative of the distribution and values of the relative biomass and abundance of the reference species Scophthalmus maximus. This document contains a series of tables and figures that show the relative biomass distribution, as well as size/age and sex structure...
Identification of regional problems and seeking the solutions over a comprehensive stakeholder involvement are very important for the regional management of fisheries. The Black Sea is rather poor by means of such involvment by the riparian countries even there are many problems regarding legal, environmental, scientific and socioeconomic aspects....
Fishing season for rapana, with beam trawls, covers the period from end of April until middle of October. Rapana trawling is concentrated in the coastal zones with depths 10 - 35 m, inhabited by multiple bottom fish species. Thus, it is essential to study the effects of beam trawling on the bottom fish species, which appear components of the incide...
The goals of the present study include: (i) evaluation of the marine ecosystem status in 2015 -2016 and (ii) estimation of the spatial distribution and abundance of the main commercially exploited shellfish resources (black mussel and veined rapa whelk) along the Bulgarian coast of the Black Sea.
The results show considerable decline of the shellfi...
The European Red List of Habitats provides an overview of the risk
of collapse (degree of endangerment) of marine, terrestrial and
freshwater habitats in the European Union (EU28) and adjacent
regions (EU28+), based on a consistent set of categories and
criteria, and detailed data and expert knowledge from involved
countries1. A total of 257 benthi...
Pelagic Trawl Survey was accomplished in August – September and December 2016 in the Bulgarian Black Sea area. Scientific team has produced a biological analysis of the results obtained in the marine area.
The analysis is based on the reference species biomass (Sprattus sprattus) at the scale of the whole survey. Furthermore, an analysis of the dis...
By the late 20th century, a series of events or ‘natural experiments’, e.g. the depletion of apex predators, extreme eutrophication and blooms of invasive species, had suggested that the Black Sea could be considered as a large ecosystem ‘laboratory’. The events resulted in regime shifts cascading through all trophic levels, disturbing ecosystem fu...
The European Red List of Habitats provides an overview of the risk of collapse (degree of endangerment) of marine, terrestrial and freshwater habitats in the European Union (EU28) and adjacent regions (EU28+), based on a consistent set of categories and criteria, and detailed data and expert knowledge from involved countries. A total of 257 benthic...
This study is focused on the identification of the main components of the sprat diet in early summer and feeding pattern variations in the western Black Sea. Four trawl surveys were performed during 2007 - 2010 (~35 trawls included in one survey); 15 - 25 sprat specimens per each trawl catch were randomly selected and preserved in 10% formaldehyde...
A new cyclopoid copepod species, Oithona davisae was discovered during regular monitoring along the western coast of the Black Sea in 2009–2012. In the short period since its discovery off the Bulgarian Coast, O. davisae populations have increased to become one of the dominant zooplankters, contributing up to 63.5–70.5 % of total mesozooplankton nu...
Preliminary study of hyperbenthos composition in Varna Bay (the Western Black Sea) was carried out in June, August and October 2007, and in June and October 2008. A total of 37 hyperbenthos and zooplankton taxa were established. The hyperbenthos consisted mainly of decapod's larvae (6), fish eggs and larvae (10) and 4 crustacean's groups, belonging...
In 2008-2010, pronounced offshore gradients and decrease of mesozooplankton abundance and biomass from the Beloslav/Varna Lakes system and Varna Bay towards the open sea have been established. In the lake system, a few zooplankton species dominated in huge quantities. Low species diversity associated with high biomass is characteristic of highly eu...
In the present study, time series (1965 - 2009) about the gelatinous plankton quantity in the Black Sea are assessed for their importance as an ecosystem regime shift indicator. Two dominant species appear to define the most substantial inter-annual variability of the jelly-plankton biomass - Аurelia аurita and Mnemiopsis leidyi, the first one - an...
The ctenophore Bolinopsis vitrea is first reported from the Turkish and Bulgarian regions of the Black Sea. In Turkish waters, a considerable aggregation was found in Sile on the Asian side and at Kilyos on the European side in 2007. This appears to be the first record of this species in the Black Sea, which is known in the Mediterranean Sea includ...
It is well known that human activities, such as harvesting, have had major direct effects on marine ecosystems. However, it is far less acknowledged that human activities in the surroundings might have important effects on marine systems. There is growing evidence suggesting that major reorganization (i.e., a regime shift) is a common feature in th...
A specific marine biological data management tool, the Black Sea Mnemiopsis leidyi database system was created within the European Commission 6th framework Black Sea SCENE project for the Black Sea region and is now being supported by the Permanent Secretariat of the Black Sea Commission. The core team of scientists studying M. leidyi in the Black...
In this study, the stomach contents of 153 sprat specimens were examined to identify key components of sprat diet during the early summer. Based on calculations of sprat stomach fullness indices and indices of relative importance of different prey zooplankton species, we aimed to establish sprat feeding patterns and their spatial changes along the...
Scientific information about the Black Sea ecosystem with respect to jelly plankton – fisheries interactions is reviewed. Long time-series of the main components of pelagic community: fishes, invertebrates, discussed trends, and relationships between them are analysed. The amount of information and results from the analyses will be used to formulat...
The Bay of Bourgas is the largest Bulgarian bay on the western coast of the Black Sea, situated to the south of Cape Emine. The system has a semi-enclosed water circulation (preliminary cyclonic) and relatively small river inflow into it (average flow about 0.2 x 109 m3 per year) through two large limans - Bourgas and Mandra Lakes. The Lakes and th...
Diurnal investigations of the distribution and migration of different organisms (zooplankton, jelly plankton and fish) were performed in the Bulgarian Black Sea waters in August 2003, during a seasonal cruise of the R/V “Prof. Valkanov” within the framework of "EUROGEL" EVK3-CT-2002-00074. The acoustical investigations of the water column were acco...
Human-induced factors such as eutrophication, heavy fishing, and the introduction of exotic species have been evoked to explain the Black Sea ecosystem changes in recent decades (Caddy and Griffiths, 1990b; Zaitsev, 1993; Prodanov et al., 1997). However, having recognized that natural factors are responsible for the basic physical, chemical and bio...
Projects
Projects (6)
The main tasks of the demersal trawl surveys include: (i) Qualitative and quantitative analysis of the catches and biometric measurements; (ii) Estimation of demographic structure, sex ratio and growth of turbot; (iii) Analysis of stomach content; (iv) Assessment of catch per unit effort ,catch per unit area, total biomass/abundance of turbot, and analysis of the of the opportunities of stock exploitation.
1. Determining the "hotspots" of white mussels accumulations off the Bulgarian coast by assessment of the stocks and biological characteristics of the species of the group of white mussels (Chamelea gallina, Donax, Anadara iaequivalvis, etc) and comparison with previous studies.
2. Enrichment of information on descriptors D 1 (Biodiversity) and D 3 (Sustainable stocks of species subject to industrial fishing) to the Marine Strategy Framework Directive (MSFD, 2008/56/EC) concerning the studied habitats - infra- and sublittoral biocenoses, with dominant white mussel species.
3. Proposals for regulatory measures - reduction of fishing effort, measures related to maritime spatial planning and marine protected areas and studies on good practices for conservation and recovery of white mussel stocks in different regions of the World Ocean.
The project aims at data collection for the bycatch of marine organisms by different types of fishing activities of the Bulgarian fisheries' fleet. During 2018 - 2020 the following types of fishing vessels were observed:
(1.) turbot fishing with gillnets;
(2.) pelagic and bottom species fishing with pelagic trawl;
(3.) Rapana fishing with beam trawl;
(4.) pelagic and bottom species fishing with polyvalent active and passive gears.
The collected data include total catch of the target species, composition and quantities of the bycatches of marine organisms. The dynamics of the main catches and bycatches quantities by months and seasons were estimated, as well as bycatch species composition, bycatch rate, size, sex and age structure.
