Deposition of egg capsule and larval development of Rapana venosa (Gastropoda: Muricidae) from the south-eastern Black Sea

2007 ◽  
Vol 87 (4) ◽  
pp. 953-957 ◽  
Author(s):  
H. Saglam ◽  
E. Duzgunes
Keyword(s):  
Black Sea ◽  
Egg Laying ◽  
Reproductive Pattern ◽  
The South ◽  
Rapana Venosa ◽  
Egg Capsules ◽  
South Eastern ◽  
Larval Production ◽  
The Mean ◽  
Veliger Larvae

Egg capsules and intracapsular embryos of Rapana venosa were studied to determine the reproductive pattern of this invader species in the south-eastern Black Sea. Egg deposition of R. venosa in the laboratory at 25°C was described. Egg laying began in mid-June, reached a peak in July and ended in late August in 1996. The total number of the egg capsules per whelk ranged between 197 and 999 (mean 575 ±41). The mean length of the egg capsules was 13.26 mm. Each capsule contained between 124 and 1090 embryos with a mean of 555 ±10. Mean larval production per rapa whelk was about 392,931 ±42,731. The mean size of eggs produced was 213.8 μm. Five different stages of intracapsular development were observed. Embryos developed without nurse eggs. Veliger larvae completed their intracapsular development and hatched in 22 days at 25°C.

scholarly journals A new grid-net design to eliminate by-catch for the veined rapa whelk beam trawl fisheries in the south-eastern Black Sea

2018 ◽  
Author(s):  
AHMET RAIF ERYAŞAR
Keyword(s):  
Black Sea ◽  
The Black Sea ◽  
Beam Trawl ◽  
The South ◽  
South Eastern ◽  
Sea Beam ◽  
The Mean ◽  
By Catch ◽  
Trawl Fisheries ◽  
Rapa Whelk

            The beam trawl fisheries in the Black Sea only target the veined rapa whelk (Rapana venosa) individuals, and other species like fishes and crabs are thrown back into the sea dead or alive. Furthermore, small bivalves and crabs are packed with the target species without any elimination. In this study, a grid-net design (GND) with two different bar spacing was tested to reduce the by-catch. In total 30 hauls (15 hauls for each bar spacing) were carried out in the south-eastern Black Sea between 17 and 26 August 2017. A commercial diamond mesh and one of the grid-net beam trawls were towed simultaneously onboard a commercial vessel to compare the by-catch compositions. Results showed that there were statistically significant (p<0.01) 78% and 83% decreases in the mean weight of the by-catch for 20 and 30 mm grid-nets, respectively. When compared to the conventional gear, a commercial loss of 14% in the 20 mm GND, and 39% in the 30 mm GND in landing values were estimated. In conclusion, use of grid-nets in south-eastern Black Sea beam trawl fisheries can significantly reduce the by-catch of most benthic species. However, it also causes some commercial loss which might be compensated by providing some compensation to fishers such as extension of the fishing season.

scholarly journals Phytoplankton community composition in the south-eastern Black Sea determined with pigments measured by HPLC-CHEMTAX analyses and microscopy cell counts

2014 ◽  
Vol 95 (1) ◽  
pp. 35-52 ◽  
Author(s):  
Ertugrul Agirbas ◽  
Ali Muzaffer Feyzioglu ◽  
Ulgen Kopuz ◽  
Carole A. Llewellyn
Keyword(s):  
Black Sea ◽  
High Performance ◽  
Phytoplankton Community ◽  
Phytoplankton Community Structure ◽  
The South ◽  
Coastal Station ◽  
Chl A ◽  
South Eastern ◽  
Cell Counts ◽  
Offshore Station

The phytoplankton community structure and abundance in the south-eastern Black Sea was measured from February to December 2009 using and comparing high performance liquid chromatography pigment and microscopy analyses. The phytoplankton community was characterized by diatoms, dinoflagellates and coccolithophores, as revealed by both techniques. Fucoxanthin, diadinoxanthin, peridinin and 19′-hexanoyloxyfucoxanthin were the main accessory pigments showing significant correlation with diatom-C r2 = 0.56–0.71, P < 0.05), diatom-C (r2 = 0.85–0.91, P < 0.001), dinoflagellate-C (r2 = 0.39–0.88, P < 0.05) and coccolithophore-C (r2 = 0.80–0.71, P < 0.05), respectively. Microscopy counts indicated a total of 89 species, 71% of which were dinoflagellates, 23% were diatoms and 6% other species (mainly coccolithophores). Pigment-CHEMTAX analysis also indicated the presence of pico- and nanoplankton. Phytoplankton carbon (phyto-C) concentrations were highest in the upper water column, whereas chlorophyll-a (Chl-a) showed a deep maximum. Average phyto-C was higher at the coastal station (291 ± 66 µg l−1) than at the offshore station (258 ± 35 µg l−1), not statistically different (P > 0.05). The coastal station also had higher Chl-a concentrations (0.52–3.83 µg l−1) compared to the offshore station (0.63–2.55 µg l−1), not significant (P > 0.05). Our results are consistent with other studies and indicate that the southern Black Sea is shifting towards mesotrophy with the increasing prevalence of dinoflagellates compared to diatoms.

scholarly journals Reproductive biology of Sympterygia bonapartii (Chondrichthyes: Rajiformes: Arhynchobatidae) in San Matías Gulf, Patagonia, Argentina

2017 ◽  
Vol 15 (1) ◽  
Author(s):  
María L. Estalles ◽  
María R. Perier ◽  
Edgardo E. Di Giácomo
Keyword(s):  
Sexual Dimorphism ◽  
Reproductive Biology ◽  
Early Spring ◽  
Egg Laying ◽  
Reproductive Pattern ◽  
Reproductive Parameters ◽  
Egg Capsules ◽  
Northern Patagonia ◽  
Total Length

ABSTRACT This study estimates and analyses the reproductive parameters and cycle of Sympterygia bonapartii in San Matías Gulf, northern Patagonia, Argentina. A total of 827 males and 1,299 females were analysed. Males ranged from 185 to 687 mm of total length (TL) and females from 180 to 742 mm TL. Sexual dimorphism was detected; females were larger, heavier, exhibited heavier livers, wider discs and matured at lager sizes than males. Immature females ranged from 180 to 625 mm TL, maturing females from 408 to 720 mm TL, mature ones from 514 to 742 mm TL and females with egg capsules from 580 to 730 mm TL. Immature males ranged from 185 to 545 mm TL, maturing ones from 410 to 620 mm TL and mature males from 505 to 687 mm TL. Size at which 50% of the skates reached maturity was estimated to be 545 mm TL for males and 594 mm TL for females. According to the reproductive indexes analysed, S. bonapartii exhibited a seasonal reproductive pattern. Mating may occur during winter-early spring and the egg-laying season, during spring and summer.

scholarly journals Population parameters of the pontic shad, Alosa immaculata Bennett, 1835 in the Fatsa coast of the south-eastern Black Sea

2019 ◽  
Vol 36 (4) ◽  
pp. 319-324
Author(s):  
İsmet Balık
Keyword(s):  
Black Sea ◽  
Maximum Yield ◽  
Total Mortality ◽  
Reference Points ◽  
Growth Equation ◽  
Fishing Mortality ◽  
Population Parameters ◽  
The South ◽  
South Eastern ◽  
Exploitation Rate

The aim of this study is to estimate population parameters of pontic shad, Alosa immaculata Bennett, 1835 in the Fatsa coast of the south-eastern Black Sea. A total of 314 pontic shad specimens were collected from study area using artisanal fishing gears from March 2013 to February 2014. In the study, parameters of the von Bertalanffy growth equation were found as L∞=43.05 cm; k=0.430 per year and t0=-0.451 year. The growth performance index (Φ') was estimated as 2.90. The total mortality (Z), natural mortality (M), fishing mortality rates (F) were calculated as 1.33 year-1, 0.75 year-1 and 0.58 year-1, respectively. The annual instantaneous fishing mortality rate was greater than both the target (Fopt=0.375 year-1) and limit (Flimit=0.50 year-1) biological reference points. Similarly, the present level of exploitation rate (E=0.43) was higher than the exploitation ratio for maximum yield per recruit (Emax=0.375) suggesting that overexploitation occurred. These results showed that this species has been over-exploited in the Fatsa coast of the south-eastern Black Sea. Measures should be taken to reduce the current exploitation rate for sustainable fishing of pontic shad in the Fatsa coast of the south-eastern Black Sea.

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