Nuri Başusta

Age and growth of the common guitarfish, Rhinobatos rhinobatos , in Iskenderun Bay (north-eastern Mediterranean, Turkey)

Age and growth of the common guitarfish (Rhinobatos rhinobatos) were estimated from the north-eastern Mediterranean coast of Turkey. A total of 115 common guitarfish (66 females and 49 males) were sampled. Age determinations were carried out using vertebral sections. Alcian blue dying techniques were used to enhance the visibility of the band on vertebrae. The techniques have been used for the first time on elasmobranchs vertebrae successfully in this study. A total of 97 vertebrae of 115 were visible on the vertebral band in this study. Male and female common guitarfish ranged in age from i to 15 and i to 24 y respectively. Total length ranged from 42 to 147 cm for females and 39 to 124 cm for males. The relationships between total length (TL) and total weight (TW) were presented as TW = 0.0054*TL 3.672 (R 2 = 0.98) for females, TW = 0.0012 *TL 3.1947 (R 2 = 0.98) for males and TW= 0.0012*TL 3.1915 (R 2 = 0.98) for both sexes. The parameters for von Bertalanffy growth curves were estimated as L inf = 137.70 + 9.38 cm, K = 0.159 + 0.047, to - 2.180 + 0.90 for pooled data.

Biological observations on the common guitarfish Rhinobatos rhinobatos from İskenderun Bay (Turkey, Eastern Mediterranean)

Histological examination of the gonads showed that spermatogenesis occurs in every male R. rhinobatos collected in autumn and winter months of the year. Th e testis was composed of lobes having numerous spermatocysts in a dorsoventral zonated arrangement. Present results suggest that since R. rhinobatos have a cystic mode of spermatogenesis it can be used as a model for biomedical and toxicological studies. Eight stages of maturation for females and seven stages of maturation for males were identifi ed. Moreover, vitellogenic oocytes were consistently found in every female collected during the summer months. In vitellogenic oocytes, yolk is present as pleomorphic droplets and very often; small yolk droplets have a crystalline confi guration. Th ese data suggest that both sexes are reproductively active at diff erent times of the year. Both, the right ovary/testis and the left ovary/testis were functional. Ripe oocytes in the ovaries were usually symmetrically distributed. Th e population consisted of aplacental viviparous individuals with lecithotrophic embryo development. Although, sex ratios of R. rhinobatos were not signifi cantly diff erent from the expected 1:1 ratio (p>0.05), slightly female biased sex ration were recorded.

LENGTH-WEIGHT RELATIONSHIP OF STREAKED GURNARD (Trigloporus lastoviza (BONNATERRE, 1788)) CAUGHT FROM NORTH-EASTERN MEDITERRANEAN

Aim of this study is to determine the length-weight relationships of streaked gurnard, Trigloporus lastoviza, caught from northeastern Mediterranean. T. lastoviza specimens were captured by commercial bottom trawler at depth of 155 to 212m off the Iskenderun Bay, Turkey. A total of 84 specimens (52 females and 32 males) were collected. Minimum-maximum length and weight of them were determined as 10.5-26.1cm and 5.92-163.8g for females and 6.41-22.0cm and 4.91-92.96g for males respectively. Length-weight relationships of T. lastoviza were found as W=0.0055*L 3.104 , R 2 =0.793, SEb=0.175 for all individuals, W=0.0076*L 2.972 , R 2 =0.84, SEb=0.258 for females and W=0.0076*L 2.972 , R 2 =0.75, SEb=0.245 for males. The type of growth for all inviduals, females and males were isometric growth (b=3).

Near-term embryos and gravid females of Lusitanian cownose ray (Rhinoptera marginata) in Mersin Bay, eastern Mediterranean Sea

Batoid chondrichthyans are vulnerable to commercial fisheries even though they are often not targeted. A greater understanding of their reproductive biology is important to facilitate their conservation. In February 2013, 89 female and 40 male Lusitanian cownose ray (Rhinoptera marginata) specimens were accidentally caught in Mersin Bay in the eastern Mediterranean Sea. Thirty-six fish were gravid, each bearing one embryo. Of the remaining females, 39 were sexually mature but not gravid and 14 were immature. There were 28 mature and 12 immature males. The average disc width (DW) of both mature females (80.2cm) and males (74.2cm) was significantly higher than that of immature females (60.7cm) and males (60.3cm). For all rays, DW and total weight (TW) were in the range 55.7–98.2cm and 1802–13600g. The DW and TW measured for all 16 female and 20 male embryos were in the range 15.6–29.2cm and 57–281g. Such a large single haul sample, including many gravid specimens and mature males, indicates a schooling formation at capture. The location in Mersin Bay near the estuaries of the Tarsus and Seyhan rivers, and its relative closeness to the sampling location of a previously reported neonate, suggests that this region may be a nursery area for Lusitanian cownose rays in the eastern Mediterranean.

Length-Weight Relationship of Brown Comber, Serranus hepatus, Linnaeus, 1758 from Iskenderun Bay, Northeastern Mediterranean, Turkey

This study describes the length-weight relationship (LWR) for Serranus hepatus from Iskenderun Bay, Northeastern Mediterranean, Turkey. A total of 202 individuals were caught from Iskenderun Bay, during the 2015-2016 fishing season. The total length ranged from 5.7-9.5 cm and body weight 2.23-12.19 g. Length-weight relationship was found as the W = 0.0172L2.9664 (R2=0.84, F1,200=21.221, P < 0.001) and SEb= 0.091 (t-test: 32.706 p < 0.01). The types of growth were found isometric growth for all indivuduals of S. hepatus.

Age determination with alcian blue staining technique for Lagocephalus sceleratus in Mersin Bay, Turkey, northeastern Mediterranean

In this study, alcian blue staining technique was used to enhance the visibility of the band on vertebrae of Lagocephalus sceleratus from Mersin Bay, Turkey, Northeastern Mediterranean. A total of 77 L. sceleratus samples were captured by commercial purse seine nets at depths between 24 and 50 m from Mersin Bay (Turkey). The total length ranged from 8.9 to 78.4 cm and body weight varied between 7.59-4750 g for L. sceleratus. Age determinations were carried out using whole vertebrae. A total of 4 vertebrae from each specimen were read by two independent readers. All images were taken using a Leica S8APO brand microscope with a high resolution Leica Application suit (Las V4.8) software. Vertebral images were then enhanced using Adobe Photoshop CS2 to improve sharpness and clarity. Of all the 77 staining vertebrae were readable and aged by both readers, resulting in an IAPE of 7.8 %. The maximum age was found as 10+ years old.

Kuzeydoğu Akdeniz’de yakalanan kütük balığı (Hoplostethus mediterraneus)’nın boy-ağırlık ilişkisi

Bu calisma Kuzeydogu Akdeniz’de yakalanan ve kutuk baligi olarak bilinen Hoplostethus mediterraneus turunun total boy-agirlik iliskilerinin saptanmasi amaciyla yapilmistir. Kutuk baligina ait toplam 380 ornek (143 disi-237 erkek) ticari trol teknesi ile uluslararasi sularda yapilan avcilikta yaklasik 200-380 m derinliklerde hedef disi tur olarak elde edilmistir. Yakalanan baliklarin total boy ve agirliklari sirasiyla disilerde 6,4-15,2 cm, 3,4-43,8 g ve erkeklerde 6,5-12,3 cm, 3,4-23,7 g olarak bulunmustur. Kutuk baligina ait total boy-agirlik iliskileri tum bireylerde W=0,013*L 2.9841 , r 2 =0,9493 ve SE b =0,039, disi bireylerde W=0,0128*L 2.9929 , r 2 =0,9388 ve ve SE b =0,068, erkek bireylerde W=0,0131*L 2.9827 , r 2 =0,9446 ve SE b =0,047 olarak bulunmustur. H. mediterraneus turunun b degerine gore erkek, disi ve tum bireylerde izometrik buyume gozlenmistir ( t -test: P > 0,05).