Effects of changing nutrient inputs on the ratio of small pelagic fish stock and phytoplankton biomass in the Black Sea

2017 ◽  
Vol 197 ◽  
pp. 173-184
Author(s):  
Oleg A. Yunev ◽  
Violeta Velikova ◽  
Jacob Carstensen
Keyword(s):  
Black Sea ◽  
Phytoplankton Biomass ◽  
Pelagic Fish ◽  
The Black Sea ◽  
Fish Stock ◽  
Nutrient Inputs ◽  
Small Pelagic Fish

Condition of the Pelagic Fish Spawn in Coastal Waters of the Black Sea near Sevastopol

2004 ◽  
Vol 40 (3) ◽  
pp. 42-54 ◽  
Author(s):  
A. D. Gordina ◽  
V. G. Tsytsugina ◽  
Ye. I. Ovsyaniy ◽  
A. S. Romanov ◽  
R.B. Kemp
Keyword(s):  
Black Sea ◽  
Coastal Waters ◽  
Pelagic Fish ◽  
The Black Sea ◽  
Fish Spawn

scholarly journals The Results of Zmiinyi Island (Black Sea) Coastal Waters Ichtiofauna Monitoring in 2016-2017

2020 ◽  
Keyword(s):  
Black Sea ◽  
Coming Out ◽  
Coastal Waters ◽  
Structural Characteristics ◽  
The Black Sea ◽  
Fish Stock ◽  
Biomass Estimation ◽  
Ecological Groups ◽  
Biodiversity Indicators ◽  
Island Area

Purpose. To study the state of ichthyofauna in the Zmiinyi Island coastal waters in 2016-2017. Methods. Standard methods of ichthyofauna sampling, determination, abundance and biomass estimation. Results. During the period of studies, 68 species of marine, brackish-water and freshwater fish were found in the Zmiinyi Island area belonging to 18 orders, 41 families and 55 genera. The biggest number of taxa belongs to Perciformes order. The representatives of this order make one-half of all the species found near the island. Indicators of ichthyofauna species diversity in the Zmiinyi Island area were gradually decreasing in the period from 2003 to 2009. In 2015-2016 all those indicators grew significantly. Biodiversity level (Shannon index values calculated coming out of number) in 2016 varied from 0.86 to 3.06 making in the average 2.06; in 2017 – from 2.40 to 2.54 making in the average 2.47. Minimal values of biodiversity indicators were registered in the end of autumn and in winter, maximal – in May-June. In the Zmiinyi Island coastal waters 30.9% of all the fishes registered in the Black Sea were found. The fishes caught near the island belonged to 5 ecological groups. The basis of ichthyofauna in the area was formed by marine fish species – 52 species (76.5 % of the total number of species). Most of species (54 species or 89.4%) were bottom-dwelling or near-bottom. Pelagophylic and protecting species prevailed and their numbers were almost equal (24 species or 35.3% and 23 species or 33.8% respectively). On the type of feeding, predatory (37%) and benthos-eating (33%) species prevailed. Out of 68 species found in the island area, 16 species are included into the Red Book of Ukraine, 22 species – into the Black Sea Red Data Book, 7 species – into the IUCN Red List. More than one-half of the species registered in the area (36 species or 52% of all the species) have a protected status. Сonclusions. Results of analysis of biodiversity, structural characteristics and taxonomic composition of ichthyofauna in the Zmiinyi Island coastal waters have been presented. Seasonal dynamics of its number and biomass has been studied. The results of the analysis of some aspects of ecology and biology of the main mass species of fish are presented. Recommendations are given to improve monitoring of the ichthyofauna of coastal waters. Quality of bottom communities monitoring in the Zmiinyi Island coastal waters can be increased significantly by development and implementation of non-contact low-budget video-monitoring methods to solve the problem of fish stock and biodiversity studying in inaccessible areas. It is anticipated that the method developed will help high precision assess of fish stock in inaccessible shelf areas where application of other methods is connected with technical difficulties, high cost and can lead to unreliable results. Elaboration of the method aimed at development of video materials received computer processing algorithms will significantly simplify the analysis of the data collected.

Fish Stock Indicators as Measure for Sustainability

2015 ◽  
pp. 118-182 ◽  
Author(s):  
Violin S. Raykov ◽  
Ivelina Zlateva
Keyword(s):  
Black Sea ◽  
Fishery Management ◽  
Management Strategies ◽  
Age Determination ◽  
Reproductive Potential ◽  
Local Environment ◽  
Point Of View ◽  
The Black Sea ◽  
Fish Stock ◽  
Mortality Estimation

Particular species may be good indicators of specific environmental factors in their local environment. It was found that one of the main objectives for effective and sustainable management of the fish stocks is to make regular annual assessment of the parental stock biomass, length and weight growth, age determination, mortality estimation and reproductive potential estimation. The Black Sea sprat (Sprattus sprattus L.) is a key species in the Black Sea ecosystem. Small pelagic forage fish and especially local one with shared stocks are very important from ecological (key trophic level) and commercial (intensively exploited) point of view. Fishery management strategies must ensure that fishing mortality will not exceed that which corresponds to MSY, and that the biomass will not fall below a predefined threshold. The goal of the chapter is to define the main objectives and measures for sustainable sprat exploitation in order to be in favour of decision makers and fishery managers.

Effect of phytoplankton adaptation on the distribution of its biomass and chlorophyll a concentration in the surface layer of the Black Sea

2019 ◽  
Vol 48 (4) ◽  
pp. 404-414 ◽  
Author(s):  
Liudmila Stelmakh ◽  
Tatiana Gorbunova
Keyword(s):  
Surface Layer ◽  
Spatial Variability ◽  
Black Sea ◽  
Phytoplankton Biomass ◽  
Abiotic Factors ◽  
Nitrogen Concentration ◽  
The Black Sea ◽  
Total Phytoplankton ◽  
Upper Mixed Layer ◽  
Effect Of Light

Abstract Using the field data collected in the Black Sea in September 2005–May 2013, the authors studied the spatial variability of the ratio of organic carbon to chlorophyll a (C:Chl a) in the sea surface layer (0–1 m). The C:Chl a ratio is an important parameter that reflects the phytoplankton adaptation to abiotic factors. Its maximum variations occurred in September–October 2005 and October 2010 when the highest spatial variability of average light intensity and nitrogen concentration was observed in the upper mixed layer. As a result, the maps of phytoplankton biomass differed from chlorophyll maps. In August 2011, no effect of light or nitrogen on the spatial variability of the C:Chl a ratio was found. Changes in the contribution of dinoflagellates to the total phytoplankton biomass affected the C:Chl a ratio variability, which was two times lower compared to September–October 2005 and October 2010. Also, the spatial distribution of phytoplankton biomass differed from the distribution of chlorophyll a concentration only in some areas of the sea. In May 2013, environmental factors slightly varied across the study area and the spatial variability of the C:Chl a ratio was insignificant. Therefore, the map of phytoplankton biomass indicated similarities with the chlorophyll map.

Changes in chemical parameters in the Bulgarian Black Sea coastal area as an indication of the ecological state of the environment

1999 ◽  
Vol 39 (8) ◽  
pp. 37-45 ◽  
Author(s):  
G. Shtereva ◽  
S. Moncheva ◽  
V. Doncheva ◽  
O. Christova ◽  
I. Shterev
Keyword(s):  
Black Sea ◽  
Coastal Area ◽  
Phytoplankton Biomass ◽  
Positive Sign ◽  
The Black Sea ◽  
Ecological State ◽  
Chemical Parameters ◽  
Phytoplankton Communities ◽  
High Level ◽  
State Of The Environment

In the present paper the main trends in the principal chemical parameters and the phytoplankton communities in the close coastal area are discussed, aimed at evaluating the present ecological state of the environment and water quality in comparison with historical data. The results reveal a decrease in the content of PO4 and Si, while there is no apparent trend in the N-NO3 variability. In seasonal terms a change in the minima and maxima of some parameters is evident, and a seasonal dynamic closer to the natural annual cycle in the Black Sea. A decrease in the average annual phytoplankton biomass is established, especially pronounced during the summer period. The results suggest a positive sign of evolution of the environmental characteristics of the coastal zone, which should be treated rather tentatively due to the still high level of nutrients and the capacity of the ecosystem to produce and maintain high phytoplankton biomass.

scholarly journals EXPLOITATION AND CPUE TREND OF THE SMALL PELAGIC FISHERIES IN THE SULAWESI SEA, INDONESIA

2012 ◽  
Vol 18 (2) ◽  
pp. 63
Author(s):  
Lilis Sadiyah ◽  
Purwanto Purwanto ◽  
Andhika P. Prasetyo
Keyword(s):  
General Pattern ◽  
Pelagic Fish ◽  
Fish Stock ◽  
Yield Model ◽  
Small Pelagic Fish ◽  
Fish Stocks ◽  
Increasing Trend ◽  
The Status ◽  
Expected Benefits ◽  
Pelagic Fisheries

One of the expected benefits of the Sulu-Celebes Sea Project during its implementation is to have increased fish stocks at demonstration sites, as indicated by the Catch per Unit of Effort (CPUE). Analysis of catch and effort data of the small pelagic fisheries by using the surplus yield model was done to obtain information on the likely trend of CPUE for the last ten years. By using the pajeko as the standardized fishing gear the trend of CPUE has been calculated. Between 2000-2005, the trend of production (catch), effort and CPUE followed the general pattern of the exploited fisheries that already fully exploited, where the increasing trend of effort was not followed by the increasing catch. On the other hand, the trend of CPUE is decreased. In the following years, the trend of both catch and CPUE do not follow the general pattern of the exploited fisheries. The trend of catch, effort and CPUE has likely been stable, indicating that the fishery in this period has been leveled-off. The status of exploitation of the small pelagic fish resources in the Indonesian Sulawesi Sea is demermined by the MSY level that has likely been surpassed during the period 2003-2004. Therefore with the increasing effort in the following year the trend of catch was relatively stable. It is likely that the small pelagic fish stock in the Indonesian Sulawesi Sea might be ‘fully exploited’.

scholarly journals KAPASITAS PENANGKAPAN PUKAT CINCIN MINI DI PEMALANG

2017 ◽  
Vol 15 (2) ◽  
pp. 171
Author(s):  
Erfind Nurdin ◽  
Tri Wahyu Budiarti
Keyword(s):  
Data Envelopment Analysis ◽  
Capacity Utilization ◽  
Pelagic Fish ◽  
Fish Stock ◽  
Data Envelopment ◽  
Small Pelagic Fish ◽  
Fishing Capacity ◽  
Java Sea ◽  
Fishery Status ◽  
Dea Method

Sumber daya ikan pelagis kecil di Laut Jawa merupakan komoditi perikanan yang penting dan bersifat strategis. Sejalan dengan perkembangan pemanfaatannya, tekanan penangkapan yang tinggi dialami oleh hampir seluruh kawasan, terlebih di wilayah tradisionil. Kapasitas penangkapan akhir-akhir ini menjadi isu penting dalam perikanan global, mengingat di berbagai kawasan terjadi kapasitas berlebih dan penurunan stok ikan. Salah satu cara untuk mengetahui status perikanan terkini dilakukan dengan mengukur kapasitas perikanan. Penelitian ini dilakukan pada bulan Mei dan Juli tahun 2007 dengan metode Data Envelopment Analysis. Nilai rata-rata pemanfaatan variabel input (VIU) untuk daya lampu dan bahan bakar menunjukkan nilai di atas 1 (optimum = 1) yang mengindikasikan adanya kelebihan penggunaan variabel sehingga dipandang perlu untuk melakukan pengurangan variabel input. Nilai pemanfaatan kapasitas (CU) lebih besar dari 0,5 hampir mencapai 60% dari 106 kapal contoh. Hal ini menunjukkan bahwa nilai CU kurang dari 1 mendominansi distribusi perolehan nilai CU yang dapat diartikan telah terjadi kelebihan kapasitas pemanfaatan untuk penangkapan pukat cincin mini dengan basis di Pemalang, sehingga perlu upaya pengurangan kapasitas. Small pelagic fish resource in Java sea is an important fishery commodity. Nowadays high fishing pressure is experienced by mostly fishing areas, particularly in traditional zone. Fishing capacity recently becomes important issue in global fishery, because over capacity and fish stock decreasing is occured in various areas. One method to know the fishery status is by measuring fishery capacity, which is categorized as over capacity, under capacity or optimal condition. This study was carried out on May and July 2007. The method applied in this measurement of fishing capacity was DEA method (Data Envelopment Analysis). The average of variable input utilization for light intensity and fuel showed value of more than 1 (optimum = 1), indicating the usage of excess variable that need to reduce the input variable. The value of higher than 0.5 of capacity utilization showed 60% from 106 ships sample. This indicates that the CU value of less than 1 dominated the distribution of capacity utilization value. For mini purse seine based in Pemalang showed over capacity. This means, it needs to reduce the effort of fishing capacity.

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