Assessing trawling impact in regional seas (Black Sea Case Study) (original) (raw)
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Report on assessing trawling impact in regional seas
2014
Baltic Sea Benthic ecosystem impacts from demersal fishery in the western Baltic is assumed to come mainly from Nephrops trawling in the central and southern Kattegat, mussel dredging in the Belt Sea, and mixed cod trawling in the western Baltic Sea.These fisheries both impact the seabed, as well as produce substantial amounts of discards. The western Baltic Sea offer a unique opportunity to analyse the benthic effects of fishingthanks to the closure of Oresund to towed gears since the 1920s, and the introduction of the Kattegat MPA in2009 (including cod closure) and the western Baltic Sea Natura-2000 areas. Furthermore an extensive benthic nationalmonitoring and data collection effort has taken place in the area over a number of years, which can be usedto investigate spatial and temporal differences in the development of benthic communities in (chronically) towed and non-towed areas. To evaluate benthic impacts of towed gears in the Baltic Sea a number of gear technological innovat...
The impact assessment of cage aquaculture on benthic communities along the south eastern Black Sea
Iranian Journal of Fisheries Sciences, 2014
The present study was conducted to examine the impact of cage aquaculture on benthic communities in coastal areas (depth 25 to 50 m) from fish farming operations located along the southeastern Black Sea (Ordu-Persembe, Trabzon-Yomra and Rize central). Sampling was conducted seasonally from April 2007 to 2009. Sediment samples were taken using Ekman Grab (box core- 0.04 m 2 ). Temperature, salinity, and water velocity were periodically measured to determine influencing sedimentary organic matter in the sediment, oxygenation, and anoxic conditions. In addition, grain size of sediment, organic carbon content, and distribution of benthic communities were investigated. In order to determine benthic impact of fish farms on the region, Shannon – Wiener diversity index (H’), AMBI (AZTI Marine Biotic Index) and M-AMBI (Multivariate- Marine Biotic Index) indices were used. Results of current study showed that benthic zone ecological quality of stations with number 01, 02, 03, and 04 at Ordu-P...
Catch Composition of Bottom Trawl Fisheries in Düzce Coast, southwestern Black Sea
Natural and Engineering Sciences, 2017
This study was performed to identify the catch composition of Düzce coast (southwestern Black Sea) at depths of 30-110 meters by bottom trawl between September 2014 and August 2015. In the catch compositions of the Düzce coast, the abundance of the first, second and third species were Merlangius merlangus with 73.12% (1290.29 kg / km 2), Gobius spp. with 9.30% (164.04 kg/km 2) and Mullus barbatus with 9.05% (159.61 kg / km2), respectively. The other 33 species make up 8.53% of total fish biomass. When seasonal distribution was examined, the total catch of fish were 1038.54, 2552.37, 1068.72, 5132.96 kg/km 2 , of which economic (target) fish species (Merlangius merlangus) constitute 745.72, 1726.14, 724.58, 4910.15 kg/km 2 in autumn, winter, spring and summer respectively. In this study, fishing a very high rate of discard whiting in little sizes draws the attention. Whiting constitutes 56% of discard. Single or sporadic captures were also recorded for Acipenser stellatus, Trachurus trachurus, Spicara smaris, Lophius piscatorius, Serranus hepatus and Hippocampus hippocampus. Moreover, in this study, red list status for 36 fish species belonging to 27 family in Düzce coasts were considered with the Red List published by the International Union for conservation of Nature and Natural Resources (IUCN). As a result of this comparison, it was determined that 2 species Critically Endangered (CR), 5 species Vulnerable (VU), 22 species Least Concern (LC), 4 species Not Evaluated (NE), 2 species Data Deficient (DD).
Discards in bottom-trawl fishery in the western Black Sea (Turkey)
Journal of Applied Ichthyology, 2017
The aim of this study was to estimate the discards of target and non-target species from bottom trawlers (rhombic and 40 mm cod end mesh size nets) in the Black Sea. On-board sampling was conducted on the southwestern coasts of the Black Sea in the fishing ports of Rumelifeneri and Igneada for a total of 66 hauls on two commercial bottom trawlers from October 2012 to April 2013 and from October 2013 to April 2014. A total of 32 species were captured, including 25 species of fish, three crustacea, two echinodermata and two mollusca. Mullus barbatus and Merlangius merlangus euxinus were the target species, whereas 24 species were always discarded. Scophthalmus maximus and Pomatomus saltatrix were always retained. The two regions were similar in terms of catch and discard compositions, CPUE, DPUE and discard ratio. Discarding is important in the Black Sea commercial bottom trawl fishery and accounts for as much as 31.4% of the total bottom trawl catch. The results showed that the discard rates varied among species, depths (p = .04) and seasons (p = .0001). Finally, it was concluded that in the western Black Sea, when the impacts of depth and season are considered, that the discard quantity can be reduced.
Biodiversity Data Journal, 2021
Habitat mapping is nеcessary for the efficient conservation and protection of marine ecosystems. In addition, it is a requirement for EU Member States as stated in the European Union (EU) Habitats Directive (92/43/EEC), as well as necessary for the achievement and maintenance of 'good environmental status (GES)' of benthic marine habitats in the framework of the EU Marine Strategy Framework Directive (2008/56/EC). This study provides baseline information on the marine benthic habitats of Sozopol Bay (Black Sea) and Karpathos and Saria Islands (Mediterranean Sea). These two Natura 2000 sites were selected as study sites of the RECONNECT project, which aimed at creating a transnational cooperative network to confront the environmental threats of ecosystems with a high natural and cultural interest, by the establishment of common practices and a joint regional strategy. The specific objective was to map the marine habitats using a defined a priori classification (EUNIS), with t...
Bottom trawl fishery discards in the Black Sea coast of Turkey
Mediterranean Marine Science, 2013
The purpose of this study is to determine the amount of bycatch and discardfish caught by bottom trawlers used in the Black Sea coasts of Turkey anddiscard changes depending on the depth. The study was conducted during theSeptember 2009 – April 2010 fishing season. Twenty-one bottom trawleroperations were sampled and the catch composition was determined. A total of 26species were caught, which included 22 species of fish, 2 species of arthropods,1 species of gastropods and 1 species of bivalves. Two of these were targetspecies (Mullusbarbatus, Merlangius merlangus), while 25 species werediscarded including trash fish and specimens below the legal size. A total of2142.76 kg of biomass was caught during the operations, of which 53.99 % bycatch.The weighted discard rate was determined as 42.06% and two different groupswere identified in discards (T1: 10-57 m, T2: 72-118 m) based on the depth. Significantdifferences were identified between these depth groups (p<0.05). It was determin...
Marine Ecology, 1998
An extensive survey of the benthic fauna was carried out at two neighbouring regions of the Aegean Sea, one normally trawled and the other closed to trawlers. Benthic samples were collected from seven areas located away from land-based sources. The faunistic analysis showed that species diversity and abundance was higher in the trawled area compared with the untrawled area, a fact which was attributed to the difference in sediment characteristics between the two areas. A degree of disturbance detected in the trawled area was evidenced by an increase in the number of polychaetes at the expense of other benthic groups and an abundance of some opportunistic species. This could possibly be related to trawling activities. as no other causes of disturbance were found in either area. Problem In the framework of the research project 'Trawling Impact on Benthic Ecosystems' financed by the European Commission, two neighbouring areas of South Evvoikos Gulf were chosen for an experimental trawling and environmental assessment study. The areas were chosen as most appropriate for this kind of study because they offer the advantage of comparing a sufficiently extensive undisturbed fishing area, neighbouring a normally trawled one. Evvoikos Gulf holds an important position in the Aegean Sea due to its special hydrographic conditions. Its southern part is divided into two main regions: the innermost part, South Evvoikos proper, is an elongated area which communicates with the North Evvoikos Gulf by the Euripus Channel and presents sedimentological properties of semi-enclosed areas. The southern part, called Petalioi
Spatial pattern and characteristics of the benthic marine litter in the southern Black Sea shelf
The abundance and characteristics of benthic marine litter in the southern Black Sea shelf were demonstrated. During the surveys, 671 litter items weighing 83.93 kg were collected from the stations. The average density by number and weight were 460.70 ± 99.71 n/km 2 and 80.68 ± 48.06 kg/km 2. The litter density was significantly higher at 10-20 m (646.09 ± 165.63 n/km 2) compared to 20-30 m (165.53 ± 81.02 n/km 2) and >30 m (413.87 ± 146.59 n/km 2) depth classes. Plastic (69.03%) was the most abundant material by number, followed by textile (20.94%) and metal (5.68%). The litter composition differed between the no-trawl zone and trawl ground. Our results indicate that more detailed research is needed to understand the interaction of various factors influencing transportation and accumulation of marine litter in the Black Sea.
Scientia Marina, 2014
This short-term study on commercial discards was carried out in fishing grounds around Gökçeada Island in the northeastern Aegean Sea, a geographic area where fisheries information is rather limited. A total of 28 bottom trawls were performed between 70 and 410 m depth from December 2009 to February 2010. All the samples were collected on board a commercial trawler under commercial fishing conditions. A total of 3143 kg of biomass was caught in 28 valid hauls. Landings accounted for about 67% of the total catch while the remaining 33% was discarded. Fish species comprised 85% of the total catch and their composition could be divided into four main groups related to depth: shallow shelf (70 to 88 m), deep shelf (155 to 180 m), shelf break (196 to 276 m), and upper slope (307 to 410 m). Fish dominated the abundance and biomass of both landings and discards in all bathymetric strata. Echinoderms also accounted for a large proportion of the discards. Mean total catches varied between 78.4 kg/h on the shallow shelf and 38.1 kg/h on the shelf break with no differences in the landing biomass between groups, but with slightly higher discards over the shallow shelf. Taking into account the preliminary nature of the findings, based on a short-term analysis, the minimum mesh size and minimum landing size currently applied in the Turkish bottom trawl fishery are not sufficient to reduce discards and to protect juveniles of commercially important species in the northeastern Aegean Sea.
The General Assessment of Black Sea Ecological Problems and Recommendations of Eliminate Them
American Scientific Research Journal for Engineering, Technology, and Sciences, 2018
In the article is presented the result of the 2008-2017 research, particularly, the general assessment of Black Sea ecological problems, quality of sea and inflow water, also depth distribution level of hydrogen sulfide. It has been evaluated abrasion processes of the Black Sea coastal zone and the possibility of its stabilization by regulation of solid sediment transported by rivers. It is estimated that the number of solid sediment scales that will stop or significantly reduce the seaside capture and wash away. It has been made general assessments of the Black Sea ecological problems and recommendations for their elimination.