Project “Capacity building in the exploration and management of marine non-fishery resources in the Black Sea (ECRAMON BLACK SEA, 2015 - 2017)”, under Programme BG 02 “Integrated marine and inland water management, FM of the EEA.

The main goal of the project is to analyze the distribution, biological parameters and stocks of the commercially exploited non-fish marine resources - black mussel (Mytilus galloprovicialis) and rapana (Rapana venosa) and supply measures for their management. As an additional task, the current ecological state of the marine environment is to be studied with the primary focus to identify the main processes and drivers that have the most significant impact on the dynamics and faith of both species.

The main tasks of the project are:

1) Increase the capacity to assess and forecast the stocks of commercially exploited shellfish species – rapana and black mussel

2) Improve the cooperation and data exchange between the relevant stakeholders in the field of fishery and aquacultures

The main activities within task 1 are: (i) field measurements, laboratory analysis, statistical analysis, (ii) ecological status assessment, (iii) ecological numerical modelling and preparation of measures for sustainable use of the non-fish resources. The main results are aimed at achieving a better understanding of the current ecological status of the marine environment, the stock and the dynamics of the population parameters of commercially exploited mollusc species and the environmental factors that affect their distribution and abundance.

The main activities within task 2 are: (i) administrative and financial management, interaction with the monitoring and control institutions, (ii) conduction of procedures according to the PPL and contracts awarding, (iii) public awareness – organization of two round tables and final conference, publish conference paperwork, organization of information day, creation of multimedia – video, and (iv) elaboration of socio-economic analysis. The final results are related to the smooth running of the administrative, scientific and financial services of the project and successful transfer of knowledge to a wide range of stakeholders - fisheries organizations, processing industry, national agencies and ministries, Black Sea Basin Directorate, scientific community and NGOs.

The main scientific tasks include:

  • Field work – hydro-biological  and hydro-chemical monitoring; currents measurements; bottom trawls to identify the state and distribution of the rapana and black mussel;
  • Laboratory analysis of different hydro-chemical and hydro-biological parameters – nitrite and nitrate nitrogen, phosphate phosphorus, permanganate oxidizability, radioecological sediment analysis; phytoplankton, zooplankton, zoobenthos, linear-weight structure analysis;
  • Statistical analysis – derive the linear-weight ratios, elaboration of histograms of linear and weight classes, cumulative distribution analysis, spatial dynamics, use of linear models and multivariable analysis to assess the role of the main drivers and proceses affecting the abundance of the shellfish species;
  • Stock assessment of the target species;
  • Use of software package MIKE 21 FM & Ecolab to model the ecological processes;
  • Preparation of the final report for the assessment of the marine environment;
  • Preparation of the final report with particular measures for sustainable management of the target non-fish resources..

Scientific problem and results:

Overfishing in the world's oceans, including the Black Sea, is leading to a reduction in commercial fish stocks and the fisheries sector is increasingly turning to shellfish. The use of non-fish resources in the Black Sea includes two types of shellfish - rapana and black mussel, the second type forming by-catch in rapana.

The black mussel fields play an important role in the Black Sea ecosystem. Black mussels are characterized by high filtration capacity, accumulate heavy metals and other chemicals and help purify the sea water, create specific biotopes that support biodiversity and food base for many demersal and pelagic fish. The predatory snail R. venosa is an invasive species for the Black Sea. Carried by waters with ocean salinity, the species adapts to the conditions in the Black Sea and causes significant damage to local bivalve molluscs. The most affected species of rapana predation is the black mussel, as it forms a significant part of the rapana diet. In the 90s of the XX century, R. venosa became a topical object for the maritime economy, and the catch of rapana was practiced by all Black Sea countries. In front of the Bulgarian coast, the species ranks first in the importance of catches, along with the sprat.

The data collected during the scientific study show a decrease in the stocks of the two molluscs species in the area up to the 35-meter isobath, as a consequence mainly of the intensive bottom trawling. A well-defined differentiation of the spatial habitats between the two species was established. Black mussel develops in areas with a depth of 35 - 45 m, with quantities reaching a maximum of 913 kg/hae in the region of Balchik / Kranevo - Golden Sands, where a well-represented mussel field is formed. At the same time, the rapana is almost completely absent in the catches at depths > 32 m, and in the more shallow parts the quantity of the species is greatly reduced compared to previous years. For comparison, it can be pointed out that the highest catches of rapana in 2015-2016 decreased about 11 ÷ 12 times compared to 2013.

The ecological modeling (MIKE 21 & Ecolab) shows that the recovery of the black mussel population can be achieved by introducing designated areas where bottom trawling is prohibited for a period of 3 years, with the possibility to control and move the area after this period in order to seek optimal use of resources. It is proposed to form a new, prohibited for rapanoul zone, with an area of ​​13,500 hectares, located in the area between Kamchia and Emona (25-35 m isobaths), where significant seizures of molluscs are currently registered, and in the past part of the mussel was concentrated field in front of cape Emine. The simulation and results from the ecological modelling show the possibility of sustainable development of the black mussel in uch protected areas.

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