LESS KNOWN ASPECTS OF PENAEUS KERATHURUS (FORSKAL, 1775) (DECAPODA, PENAEIDAE) OBTAINED FROM THE FISHERMEN IN THE SEA OF MARMARA: AGE, GROWTH, AND MORTALITY RATES

Penaeus kerathurus is an important species for the fishery, thanks to its high nutritional and economic value. Therefore, this study attempts to determine the length distribution, length-weight relationship, age composition, growth parameters, and mortality rates of a population of P. kerathurus. The material was monthly collected from commercial fishermen in and around Karabiga and the Gulf of Erdek in the Sea of Marmara, between May 2018 and April 2019. The carapace length-weight relationships were calculated as W = 0.0023 x CL2.57, W = 0.0036 x CL2.46, and W = 0.0026 x CL2.56 for the females, males and both sexes combined, respectively. The population studied was distinguished into four age groups, and the t(max) (= maximum theoretical age) was found to be reached at 11.9 year. The growth parameters were observed to be L-infinity = 60.9 mm; K = 0.24 year(-1), and t(0) = -0.58 year. The rates of total mortality (Z), natural mortality (M), fisheries mortality (F), and exploitation (E) were calculated to be 1.32, 0.43, 0.89, and 0.67, respectively. The results showed that P. kerathurus suffers from a heavy fishing pressure in the sampled area.Office of Scientific Research Coordination at Canakkale OnsekizMart University [FBA-2018-2473]This work was financially supported by the Office of Scientific Research Coordination at Canakkale OnsekizMart University (project number: FBA-2018-2473)

Age, growth and reproductive biology of the saddled seabream (Oblada melanura) in the North Aegean Sea, Eastern Mediterranean

This study determines the length distribution, length– weight relationship, age, growth parameters, mortality rate, sex ratios, length at first maturity and reproduction of saddled seabream (Oblada melanura) collected monthly by fishermen around the Northern Aegean Sea between November 2017 and October 2018. The length–weight relationship was calculated as W = 0.0091 × L3.11 (R² = 0.95) and positive allometric growth was found. The condition factor and GSI varied between 0.81–1.58 and 0.01–9.61, respectively. The spawning season extended from May to July and peaked in June. Total lengths at 50% maturity were 18.97 cm for males and 18.83 cm for females. Parameters of the von Bertalanffy growth equation were: L∞  =  29.91 cm, K  =  0.27 per year, t 0   =  −0.82 year and age varied between 1 and 8. The instantaneous rates of total mortality (Z) and natural mortality (M) were 1.36 and 0.58 per year, respectively. Rates for fishing mortality F and exploitation E were 0.78 and 0.57 per year, respectively. The mean absolute fecundity (F) was 117 075 ± 23 243 oocytes, ranging from 19 130 to 470 132.This study determines the length distribution, length– weight relationship, age, growth parameters, mortality rate, sex ratios, length at first maturity and reproduction of saddled seabream (Oblada melanura) collected monthly by fishermen around the Northern Aegean Sea between November 2017 and October 2018. The length–weight relationship was calculated as W = 0.0091 × L3.11 (R² = 0.95) and positive allometric growth was found. The condition factor and GSI varied between 0.81–1.58 and 0.01–9.61, respectively. The spawning season extended from May to July and peaked in June. Total lengths at 50% maturity were 18.97 cm for males and 18.83 cm for females. Parameters of the von Bertalanffy growth equation were: L∞  =  29.91 cm, K  =  0.27 per year, t 0   =  −0.82 year and age varied between 1 and 8. The instantaneous rates of total mortality (Z) and natural mortality (M) were 1.36 and 0.58 per year, respectively. Rates for fishing mortality F and exploitation E were 0.78 and 0.57 per year, respectively. The mean absolute fecundity (F) was 117 075 ± 23 243 oocytes, ranging from 19 130 to 470 132

Biological traits and population dynamic of Parapenaeus longirostris (Lucas, 1846) in the Marmara Sea, Turkey

Parapenaeus longirostris is a valuable resource for the crustacean fisheries in the Marmara Sea, therefore, in this study length-weight relationships, growth, mortality, reproduction, recruitment patterns, the probabilities of capture and per recruit analyses were determined. Total 36288 samples were collected by beam trawl between September 2011 and July 2014 in 229 sampling stations. The total length (TL), body weight (g) and carapace length (CL) values ranged between 34 -175 mm, 0.2 - 28.9 g and 8 - 41 mm, respectively. CL-weight relationship equations were calculated for females, males and combined sexes, respectively, W=0.0023xCL(2.)5, W=0.0029xCL(2.43), W=0.0022xCL(2.52). The growth parameters were determined as L-infinity=199.5 mm, k=0.47, t(0)=-0.5 in TL, L-infinity=36.8 mm, k=0.37, t(0)=-0.69 in CL. L-25, L-50, and L-75 values were found to be 15.15 mm, 16.29 mm, 17.44 mm for males and 16.62 mm, 18.07 mm, 19.52 mm for females. The sexual maturity length for females was found 27.3 mm CL and the exploitation rate was found at 0.62 for the whole population.TAGEM project [TAGEM/HAYSUD/2011/09/02/04]This study is a part of the Ph.D. thesis as `Spatial-Temporal Variations in Population Structure, Abundance and Catch Rates of Parapenaeus longirostris (Lucas, 1846) in The Sea of Marmara' and financially supported by TAGEM project no: TAGEM/HAYSUD/2011/09/02/04. And the authors would like to thanks the staff who helped in the laboratory and the fieldwork

Reproductive biology of Penaeus kerathurus (Forskål, 1775) (Decapoda: Penaeidae) in the Sea of Marmara, Turkey

One of the economically important species is Penaeus kerathurus (Forskål, 1755), which is widespread in the Mediterranean ecosystem. This paper presents results of research on reproductive biology of Penaeus kerathurus in the Sea of Marmara. A total of 1404 specimens were dissected to determine the maturity stages, reproduction time, and length at first reproduction. The female-to-male ratio was 1:0.9. A high percentage of mature females was determined in April, May and July. Moreover, the value of the gonadosomatic index (GSI) decreased after July. The spawning period was observed between April and July, and its intensity increased in July. The carapace length at first sexual maturity was determined to be 39 mm

Marmara ve Ege Deniz’lerindeki İzmarit balığı’nın (Spicara maena Linnaeus, 1758) yaş ve büyüme özellikleri

Bu çalışmanın amacı Marmara Denizi ve Ege Denizi'nde Spicara maena'nın bazı populasyon parametrelerini belirlemekti. S. maena örnekleri Şubat-Ekim 2013 tarihleri arasında ticari balıkçılık, fanyalı ağlar ve olta balıkçılığı ile Kuzey Ege Denizi (Dikili, Altınoluk ve Küçükkuyu) ve Marmara Denizinden (Karabiga, Bandırma ve Tekirdağ) elde edilmiştir. Çalışmada elde edilen toplam 323 adet S. maena bireyine ait total boy değerinin 8.4-18.4 cm arasında olduğu belirlenmiştir. Boy-ağırlık ilişki parametreleri Marmara Denizi için a=0,003, b=3,532 ve Kuzey Ege Denizi için a=0,010, b=3,063 olarak hesaplamıştır. Buna göre S. maena'nın Kuzey Ege Denizinde izometrik ve Marmara Denizinde ise pozitif allometrik büyüme özelliği sergilediği görülmüştür. Marmara Denizindeki bireylerin 1-4 yaş arasında ve Kuzey Ege Denizindeki bireylerin ise 2-6 yaş arasında dağılım gösterdiği belirlenmiştir. Her iki cinsiyet dahil olmak üzere von Bertalanfy büyüme parametresi değerleri Marmara Denizinde L?=17,17 cm, k=0,52 yıl, t0=-1,04 yıl-1 ve Kuzey Ege Denizinde L?=18,71 cm, k=0,35 yıl, t0=-1,98 yıl-1 olarak hesaplanmıştır. Otolit boyu-total boy ilişkisi Marmara Denizi için OL=0,301×TL+1,049 ve Kuzey Ege Denizi için OL= 0,249×TL+1,885 olarak tahmin edilmişti

Relationships between body size - otolith size for seven demersal fish species from the Marmara Sea, Turkey

The total length-otolith length (TL-OL), total length-otolith width (TL-OWi), total length-otolith weight (TL-OW) and total weight-otolith weight (TW-OW) relationships of seven fishes in the Marmara Sea, Turkey were calculated. Measurements of sagittal otoliths (length, width and weight) and individuals (total length and total weight) from these species (Gaidropsarus biscayensis, Mediterranean bigeye rockling; Arnoglossus kessleri, Scaldback; Solea solea, Common sole; Uranoscopus scaber, Stargazer; Lophius budegassa, Blackbellied angler, Lepidorhombus boscii, The four-spot megrim and Lesueurigobius friesii, Fries's goby) were given. Linear regression analysis (y = bx + a) was used to determine the relationship between each morphometric character and the coefficient of determination (r(2)) were calculated. Highest determination coefficient were determined for L. budegassa and A. kessleri to TW-OW, for S. solea, and U. scaber to TL-OL, for G. biscayensis and L. boscii to TL-OWi, for L. friesii to TL-OW. The relatively lower determination coefficients were found for G.biscayensis, compared with others. These relationships provide vital information on species identification and size estimation of fish in predator-prey studies, we believe these results will be useful in future studies of stomach contents.General Directorate of Agricultural Research and Policy of Turkey [TAGEM/HAYSUD/2011/09/02/04]This project supported by General Directorate of Agricultural Research and Policy of Turkey with the project number TAGEM/HAYSUD/2011/09/02/04. The authors would like to thank the researchers, Sukriye Ana vessel captain and crew

POPULATION STRUCTURE OF WEDGE CLAM, DONAX TRUNCULUS (BIVALVIA, DONACIDAE), IN THE SOUTHERN SEA OF MARMARA, TURKEY

The growth, reproduction, and density of wedge clam (Donax trunculus) were studied at a depth of 0.5-2 m in Denizkent in the Southern Sea of Marmara, Turkey. Samples were collected monthly between May 2017 and July 2018. The average density of the studied population ranged between 118 individuals m(-2)(November) and 245 individuals m(-2) (July). von Bertalanffy growth parameters using the length-frequency distribution of Donax trunculus were estimated at L-x = 43.85 mm and the rate at which the asymptotic length (L-x) is approached (K) = 0.73y(-1). The slowest growth period was in Janu- ary. Growth performance index, potential longevity and maximum length derived from seasonal parameters were calculated as 3.15, 4.11 y and 42 mm, respectively. The growth pattern showed negative allometric growth (slope [b] = 2.71), the spawning period occurred from April to July and peaked between May and June.Scientific Research Fund of Canakkale Onsekiz Mart University [FBA-2017-1163]This study was financially supported by Scientific Research Fund of Canakkale Onsekiz Mart University (Project No: FBA-2017-1163)

Benthic marine litter in the Marmara Sea, Turkey

This study presents the first data on benthic marine litter in the Marmara Sea, Turkey. To obtain the data, bottom trawl surveys were conducted at 34 sites between May 2017 and February 2018. The litter items were sampled and sorted following the MEDITS' relevant instructions. 660 pieces of litter, weighing 434.9 kg, were sampled. The litter density was found to range between 27.5 n/km(2) and 661.2 n/km(2), averaging 73.9 n/km(2), and the obtained items' weights ranged between 0.03 kg/km(2) and 1597.8 kg/km(2), averaging 48.7 kg/km(2). The plastic group L1 constituted 71.7% of the trawled litter. The highest mean litter density was detected in the Northeastern Marmara Sea in the spring and summer of 2018. The mean benthic litter density was found to be higher than the nearby areas. It was concluded that more effort should be invested in reducing marine pollution.(TAGEM) General Directorate of Agricultural Research and Policy [TAGEM/HAYSUD/2014/05/01]This research is supported by (TAGEM) General Directorate of Agricultural Research and Policy with the Project Number: TAGEM/HAYSUD/2014/05/01. The authors would like to thanks Hasim Inceoglu, Alpaslan Kara, Engin Kocabas, Habip Bal, Ahmet Oktener, Guzin Gul, Koray Cabbar, Gurkan Ali Yazici and G. Erman Ugur for their contributions in the field samplings

Age, growth and reproductive biology of the saddled seabream (Oblada melanura) in the North Aegean Sea, Eastern Mediterranean

This study determines the length distribution, length-weight relationship, age, growth parameters, mortality rate, sex ratios, length at first maturity and reproduction of saddled seabream (Oblada melanura) collected monthly by fishermen around the Northern Aegean Sea between November 2017 and October 2018. The length-weight relationship was calculated as W = 0.0091 x L-3.11 (R-2 = 0.95) and positive allometric growth was found. The condition factor and GSI varied between 0.81-1.58 and 0.01-9.61, respectively. The spawning season extended from May to July and peaked in June. Total lengths at 50% maturity were 18.97 cm for males and 18.83 cm for females. Parameters of the von Bertalanffy growth equation were: L-infinity = 29.91 cm, K = 0.27 per year, t(0) = -0.82 year and age varied between 1 and 8. The instantaneous rates of total mortality (Z) and natural mortality (M) were 1.36 and 0.58 per year, respectively. Rates for fishing mortality F and exploitation E were 0.78 and 0.57 per year, respectively. The mean absolute fecundity (F) was 117 075 +/- 23 243 oocytes, ranging from 19130 to 470 132.Scientific Research Projects Coordination Unit of Canakkale Onsekiz Mart University [FBA-2017-1283]The authors thank Genctan Erman Ugur and Buminhan Burkay Selcuk for their valuable help during the laboratory study. This work was supported by the Scientific Research Projects Coordination Unit of Canakkale Onsekiz Mart University, Project number: FBA-2017-1283

Otolith morphometry and population parameters of red porgy, Pagrus pagrus (Linnaeus, 1758) in Saros Bay (North Aegean Sea)

Bu çalışmada, Kuzey Ege Denizi’nde (Saroz Körfezi) Fangri balığının toplam boy (TL) ile toplam ağırlık (TW) arasındaki ilişki, yaş, büyüme ve otolit boyu (OL) - otolit ağırlığı (OW), balık boyu (TL) - otolit boyu (OL), balık ağırlığı (TW) - otolit boyu (OL), otolit boyu (OL) - otolit genişliği (OWi) arasındaki morfometrik ilişkiler incelenmiştir. Toplam 100 adet balık üzerinde yapılan ölçümlerde minimum boy 9,6 cm, maksimum boy 44,4 cm; minimum ağırlık 17,1 g, maksimum ağırlık 1372,5 g olarak tespit edilmiştir. Otolit ağırlığı minimum 0,0181 g, maksimum 0,1456 g; otolit boyu minimum 0,52 cm, maksimum 1,17 cm olarak ölçülmüştür. Boy-ağırlık ilişkisi TW=0,021*TL2,885 (r2=0,98), otolit boyu - otolit ağırlığı OW=0,105*OL2,609 (r2=0,92), toplam boy - otolit boyu OL=0,024*TL+0,249 (r2=0,83) otolit boyu - toplam ağırlık OL=0,235*TW0,237 (r2=0,81) otolit boyu - otolit genişliği OWi=0.501*OL+0.116 (r2=0.832) ilişkileri tespit edilmiştir. En büyük yaş 9 olarak belirlenmiş, von Bertalanffy büyüme parametreleri L?=51,59 cm, K=0,12 yıl-1ve t0= -1,13 yıl olarak hesaplanmıştır