Ertan Taskavak

• Professor
• Professor (Full) at Ege University

Anguilla anguilla, a catadromous species, is believed to undergo significant morphological and physiological changes in the final stage of its freshwater life. These changes are closely associated with gonad development and enable adaptation for long migration. This study examined 89 eels from the Gediz Delta, caught by commercial fishermen between...

Swimming ability in fish is directly related to body shape, manifesting in various values for swimming speed and body surface area. The constant value used in calculating body surface area derived from length or weight measurements differs between pelagic and benthic species. Furthermore, the aspect ratio is closely related to the feeding pattern,...

This study aims to analyse the eye diameter measurements of different species within the Syngnathiformes order that are found in the seas of Turkey. The eye diameter values have been calculated as percentages in relation to the total length (TL) and head length (HL). Additionally, the study also explores the correlations between the eye diameter (E...

In this study, cellular changes and biological indices in the liver tissue of the common sole, Solea solea (L. 1758), are investigated based on sex, size groups, and seasons. The specimens used in the study were obtained monthly between 2019 and 2020 from commercial trawlers and small scale–fishing operations in the fishing grounds of Izmir Bay, th...

This study examined preserved marine fish specimens collected from numerous field surveys conducted along Türkiye’s Black Sea, Marmara, Aegean, and Mediterranean coasts since 1965. Our review and categorization of these materials revealed that the specimens belong to 360 species from 131 families. Current data shows that the museum collection inclu...

The Lessepsian migrants of the family Fistulariidae, which are widely distributed in the Eastern Mediterranean coasts of Türkiye, are represented by two species, Fistularia commersonii and Fistularia petimba. This study focused on estimating various biological indices of red cornetfish Fistularia petimba Lacepède 1803, eastern Mediterranean coast o...

We, here, aimed to determine the presence of Anguillicola crassus, a swim bladder parasite, in 89 (male: 45, female: 44) dead European eel specimens obtained seasonally between 2020-2021 from a regional fisherman, who has fished with fyke net in the locality Tuzla of Izmir Bay, Eastern Aegean Sea. Out of 21 male European eels caught in winter, only...

Temporal changes of the morphological indices (Relative Gut Length (RGL), Fullness Index (FI), Hepatosomatic Index (HSI), Visceral Index (VSI), Gonadosomatic Index (GSI) and Fulton condition)) in 122 (♂: 94, ♀: 19, immature: 9) common sole were evaluated. Total length-weight relationships were calculated as W = 0.085TL3.01 and W = 0.0547TL2.40 in f...

In this study, we discussed the size of devil firefish Pterois miles (Bennett, 1828) specimen obtained from commercial fishermen who trawl off the coast of Taşucu, Silifke (36°3'32.70"N; 34°3'51.33"E). The obtained specimen was 335 mm in total length, 258 cm in standard length, and 0.696 kg in weight. The dissected specimen was a mature male. The t...

This study aims to determine the presence of sexual dimorphism based on morphometric charac-teristics in 69 (female: 44 male: 25) Syngnathus abaster specimens captured with seine-net from Lake Bafa’s coasts (Muğla) between November 2014 and March 2016. Female/Male ratio of sam-ples is 1/0.6. Based on morphometric measure-ments, the presence of sexu...

The reproductive characteristics of the Short-snouted Seahorse, Hippocampus hippocampus, was studied in the eastern Black Sea shore over a one-year period. Average standard length was 10.38 cm (6.15–13.3 cm) and weight 1.88 g (0.68–3.02 g). Males were slightly more common than females (females: 48%), but the difference was statistically insignifica...

Sardina pilchardus is a multiple spawning fish, i.e., the species that spawns periodically during the spawning period. In order to examine the reproduction biology of the species, the specimens were obtained in the known spawning period indicated by the current literature obtained from fishers who were commercially fishing in December 2018 and Janu...

In this study, together with of liver, gonad, condition values, it was aimed to determine various morphometric measurements of some body parts of Short snouted seahorse, Hippocampus hippocampus, distributed in the vegetated shores of the county Tirebolu for 4 months in 2014. A total of 131 (♀: 70, ♂: 61) specimens was obtained from fishermen fishin...

Liver, Ovary and Body Weights for Short snouted seahorse

This study aims to determine various relationships between liver, gonad and body weights of the two pipefish species caught in two breeding seasons from the Bafa Lake (Muğla) coasts between 2014 -2016. Using beach seine-net in the lake, a total of 208 pipefish specimens (79 Synathus abaster and 129 Synathus acus) were sampled. L-W relationship and...

Turtle Excluder Devices Developed For Shrimp Trawl Used In Eastern Mediterranean

In this research, a preliminary study was carried out in January and February 2014 to determine the fecundity of the whiting species in Tirebolu, Eastern Black Sea. After the total length (cm) and weight (0.01 g) of the 70 fish specimens were measured in the laboratory, they were dissected for sex determination. Using the 20 ovaries at the third an...

A total of 1492 specimens of sand smelt, Atherina boyeri, was collected from the coasts of Candarlı Bay (North Aegean Sea, Turkey) during 2007-2008, to determine their stomach content compositions. Of the 460 stomachs examined, 258 (56.1%) were found with prey items. Zooplanktonic organisms were the main prey items in terms of abundance for the aut...

In this research, a preliminary study was carried out in January and February 2014 to determine the fecundity of the whiting species in Tirebolu, Eastern Black Sea. After the total length (cm) and weight (0.01 g) of the 70 fish specimens were measured in the laboratory, they were dissected for sex determination. Using the 20 ovaries at the third an...

SOME REPRODUCTIVE FEATURES OF GREAT PIPEFISH IN COASTS OF TİREBOLU (EAST BLACK SEA)

Fecundity of Whiting Merlangius merlangus euxinus (L., 1758) in coast of Tirebolu (Eastern Black sea)

This study aims to contribute solution of the problems in the taxonomic status and distribution of E. orbicularis in the Aegean and Central Anatolian regions of Turkey

We assessed the size of the population of the African Softshell Turtle, Trionyx triun- guis, in Dalaman (Muğla, Turkey), which is considered to be the largest population of the species in the Mediterranean, by using the Jolly-Seber mark-recapture method. A total of 415 individuals were caught during the summer months of 2009 to 2011, of which 148 w...

This investigation aims to examine histologically the ovary structure of H.hippocampus.

In this study, the prey composition of broadnosed pipefish (Syngnathus typhle) that has distributed in the Aegean Sea coasts was seasonally determined between the years of 2007 and 2008. The seasonal differences were determined in gut contents. In Spring, unidentified and vegetative tissues were the most important prey group in ten prey groups X2=1...

The aquaponics is a bio-integrated food production system that, aquaculture (fish production in intensive culture ponds) and hydroponics (plant growing in water with nutrient solution) plant production are made together. This study was designed in the shape of a closed system; two different feeding dose (3% and 4% of the live weight of the pool) Gr...

The Euphrates Softshell Turtle, Rafetus euphraticus (Family Trionychidae), is a medium-sized (maximum recorded carapace length 680 mm), freshwater turtle thought to be most closely related to the eastern Asian species Rafetus swinhoei. The species inhabits diverse habitats, including rivers, streams, ponds, lakes, reservoirs, marshlands, and artifi...

The Morocco dentex, Dentex maroccanus, is an important demersal commercial sparid species inhabiting throughout the Mediterranean at the depths from 20 to 500 m. Morocco dentex ecologically prefers deep and higher salinity waters. In the Aegean Sea (Izmir Bay), a basin of the eastern-central Mediterranean, the sparids represent important components...

In this research, stomach lengths and occurence of gut contents (NO) of Syngnathus acus, Syngnathus typhle and Nerophis ophidion was examined in which collected between 2006 and 2008 years in different habitats (vegetated and sandy-vegetated etc.) from coasts of Aegean Sea by using beach seine net. The zooplanktonic preys were mostly consumed by Sy...

Male tortoises are occasionally presented with a prolapsed phallus (penis). The penis is retracted except during mating, trauma, or death; it lies in the ventral floor of the cloaca. Male Euphrates soft-shelled turtle constituted the study material. Clinically, necrotic areas in the phallus were observed. After the local anesthesia and analgesia, p...

Leatherback sea turtle, Dermochelys coriacea, is a pelagic and circumglobal species and listed Vulnerable in IUCN Red List. Although the species mainly inhabits the Atlantic and Paci c Oceans and occasionally enters the Mediterranean Sea. Most of the sightings have been made in the western part of the Mediterranean. More than a decade after the spe...

About knowledge of reproductive success of broad-nosed pipefish, Syngnathus typhle, has not yet determined for the Turkish coasts, Aegean Sea. Three groups of oocyte in the ovaries of females were determined in the present study. In the study, egg diameter in pregnant males was approximately equal in females. Average hydrated oocyte diameters were...

The endangered Euphrates soft‐shelled turtle, Rafetus euphraticus , is endemic to the Mesopotamian River Basin in the Middle East. Within recent decades, populations of this aquatic species have been heavily depleted and severely fragmented owing to habitat alteration and destruction by drainage and hydroelectricity dam constructions. Continuing ha...

Background: The family Syngnathidae exhibits one of the most specialized forms of parental care with the female depositing egg in a specialized incubating area, located either on the abdomen or tail of the male who, according the each species. In Syngnathus typhle, all the eggs in male’s brood pouch are usually at the same developmental stage, even...

zet: Ege Denizi'nde bulunan beş derin deniz balığı: Argentina sphyraena, Glossanodon leioglossus, Chlorophthalmus agassizi, Hoplostethus mediterraneus ve Capros aper 2003 bahar mevsimi süresince ticari trol balıkçıları tarafından hedef dışı av olarak elde edilen örnekler olarak çalışılmıştır. Türlerin besin kompozisyonlarını belirlemek için mide iç...

This paper presents the first attempt to use an ethnoecological approach to examine issues relevant to seahorse conservation and management in Turkey. Between 1999 and 2008, we visited 32 localities, and interviewed 394 people involved in artisanal fishery. We considered the following aspects as positive for the conservation of seahorses and th...

We present a detailed morphological review of the leaf-toed gecko, Asaccus elisae from Birecik, Şanliurfa (Southeastern Anatolia), as well as a comparison with specimens from Iran, Iraq, and Syria. The great majority of morphological characteristics of the Birecik sample are in accordance with those given for A. elisae (Werner, 1895).

The relationships of length—weight and age, and otolith length—total length in Solea solea were examined. The length and age of wild-caught specimens were compared with the length and age calculated theoretically, together with the results from the back-calculated lengths-at-age. Five different groups of total length were designated, and otolith le...

1. The aim of the study was to investigate nearshore fish community structure in the different habitat types (sand, gravel, and seagrass) in Çandarlı Bay (Northern Aegean Sea) from May 2007 to June 2008. 2. The samples were collected with beach seine net at the depths of 0.5 to 1.5 m. Evenness and Shannon-Weaver diversity indices were calculated to...

Seahorses (genus: Hippocampus) are traded globally for use in traditional medicines, souvenirs and as aquarium fishes. Between 1999 and 2008, surveys were made in order to expose the situation (species distribution, seahorse fishery and trade etc.) of seahorses in Turkey. The surveys were conducted on south and west coasts of Turkey where fisheries...

zet: Bu araştırmada, İzmir Körfezi'nde dağılım gösteren gümüş balığı Atherina boyeri Risso, 1810'nın bazı biyometrik özellikleri incelenmiştir. Aralık 2002-Ekim 2003 tarihleri arasında incelenen toplam 596 örneğin en küçük ve en büyük tam boy değerleri sırasıyla, 43 mm, 97 mm olarak belirlenmiştir. Türün tam boy-ağırlık ilişkisi ise W=0.000003*L 3....

Females of Syngnathus typhle have larger mouth structure than males, resulting in pronounced sexual dimorphism with respect to the mouth width/mouth height in length group II (0.54 and 0.67 respectively). The mouth was relatively wider in females compared with males (1.32mm female; 1.25mm male) and higher (2.67mm female; 2.33mm male). Additionally...

This study investigates the diet of adult wild seahorses, Hippocampus hippocampus and Hippocampus guttulatus from the Aegean Sea, along the coasts of Turkey. A total of 47 fish stomachs (H. hippocampus = 25, H. guttulatus = 22) were analyzed to determine diet according to fish size and sex. Twenty one of specimens of H. hippocampus (84%) had prey i...

This study examined the gut content of 43 Nerophis ophidion individuals obtained from Izmir Bay, Eastern Aegean Sea. A four season sampling process provided 7 groups of prey: Ostracoda, Amphipoda, Gastropoda, Cirripedia, Decapod crustacea, bentic Cinideria and Copepoda (Calanoid, Harpacticoid, Cyclopoid-Sapphirina sp., E. acutifrons and Monstrilloi...

Seasonal Condition Factors of Syngnathid Species Caugth from Aegean Sea Coasts. In this research, 1122 syngnathid fish samples (total fish size 1130) were obtained between 2002-2006 to examine the seasonal condition factors which were found in vegetated coasts of Aegean Sea. As a result of present study 4 pipefish species Syngnathus abaster (n=8),...

Length- weight relationships were calculated for 22 fish species caught from Candarli Bay in the north Aegean Sea, Turkey. Between December 2006 and January 2008 beach seine net was use to capture specimens and sampling was made in vegetated and sandy bottoms at the depths up to 1.5 m. A total of 2605 fish specimens were weighed and measured. The s...

In the last decade, Asian populations of Testudo graeca were split into as many as 10 species based on morphology and morphometry and then subsequently synonymized based on genetic evidence. We generate new morphometric data for six of these disputed species from Turkey, a major center of morphological and genetic diversity for Asian T. graeca. We...

Length- weight relationships were calculated for 22 fish species caught from Candarli Bay in the north Aegean Sea, Turkey. Between December 2006 and January 2008 beach seine net was use to capture specimens and sampling was made in vegetated and sandy bottoms at the depths up to 1.5 m. A total of 2605 fish specimens were weighed and measured. The s...

A total of 112 stomachs of the Great Pipefish, Syngnathus acus Linnaeus, 1758 (56 females and 38 males), was collected in İzmir Bay (Aegean Sea) and analysed in order to determine the feeding habits. 95 specimens (85.6%) were found with prey items in their stomachs. Zooplanktonic organisms were the main food and in terms of numerical (NO%) and freq...

Age and feeding habits of Atlantic spotted flounder, Citharus linguatula, from Izmir Bay (central Aegean Sea coast of Turkey) were studied. Total length ranged between 6.8 and 23.2 cm. Overall female: male ratio was 1:1.34 and age distribution of the samples I and IV years (otolith readings). Atlantic spotted flounder grew positively allometrically...

The Nile soft-shelled turtle, Trionyx triunguis is known from the riverine and coastal environments of eastern Mediterranean countries (Turkey, Syria, Lebanon and Israel) and most of Africa, except for the waterways of the southern, north-western, and northern part of the continent. Trionyx triunguis is a mainly freshwater species adapted to modera...

Age and feeding habits of Atlantic spotted flounder, Citharus linguatula, from Izmir Bay (central Aegean Sea coast of Turkey) were studied. Total length ranged between 6.8 and 23.2 cm. Overall female: male ratio was 1:1.34 and age distribution of the samples I and IV years (otolith readings). Atlantic spotted flounder grew positively allometrically...

With the aim of determining the reproductive characteristics and mating periods specific to Syngnathus acus, a study was carried out from December 2001 to November 2002 in the Camalti Lagoon (Izmir Bay, Aegean Sea). Study material consisted of 605 individuals that were captured using a beach seine in areas with vegetation. 43% (n=261) of the captur...

Stomach contents of 148 hollowsnout grenadier, Caelorinchus caelorhincus (RISSO, 1810), were examined. Crusta- ceans were found to be most important prey group in the diet. Polychaetes constituted the second most important prey group. Cha- etognathans were only occasionally eaten.

Length–weight relationships of three macrourid fishes (saddled grenadier Caelorinchus caelorhincus, glasshead grenadier Hymenocephalus italicus and bluntsnout grenadier Nezumia sclerorhynchus) from Sigacik Bay on the Turkish coast of the Aegean Sea are presented. Overall, 923 specimens of three different species of the family Macrouridae were weigh...

The age, length-weight relationship and diet composition of Arnoglossus laterna from the Izmir Bay were examined in specimens caught on a seasonal basis from January 2002 to March 2003. The ratio of male to female of 1081 scaldfish captured by trawl netting was 1:1.62 and their total lengths varied from 5.6-15.7 cm and total weights from 1.2-31.51...

Length-weight relationships were estimated for Citharus linguatula, Arnoglossus kessleri, Arnoglossus laterna, Arnoglossus thori, Buglossidium luteum, Microchirus variegatus and Solea solea sampled from Izmir Bay, Aegean Sea, Turkey. The slopes (b) of the length-weight relationship ranged between 2.160 and 3.416 with a mean of 2.790. Negative allom...

Three fish species, Bregmaceros atlanticus Goode et Bean, 1886 (Bregmacerotidae), Echiodon dentatus (Cuvier, 1829) (Carapidae), and Nemichthys scolopaceus Richardson, 1848 (Nemichthyidae) were recorded in the Sığacık and Kuşadası Bays (Eastern Aegean Sea, Turkey). B. atlanticus and E. dentatus constitute new records for the Turkish waters and the A...

In this paper we present length–weight relationships of three pipefishes, Syngnathus acus, Syngnathus typhle Nero-phis ophidion, and two seahorse species, Hippocampus hippocampus, Hippocampus guttulatus from İzmir Bay, on the Turkish coasts of the Aegean Sea. Overall, 1010 specimens of five different species of Syngnathidae were weighed and measure...

Length-weight relationships were calculated for 47 fish species from the Izmir Bay in the Aegean Sea, Turkey. A total of 13243 fish specimens were sampled with several fishing gears in 1998-2001. The sample size ranged from 11 individuals for Nerophis ophidion to 1197 for Boops boops. The r 2 values ranged from 0.82 for Nerophis ophidion to 0.99 fo...

The investigation of biometric characteristics of seahorse species [Hippocampus hippocampus (Linnaeus, 1758) and Hippocampus guttulatus Cuvier, 1829] in Izmir Bay. In this study, the biometric features of the seahorse species belong to family Syngnathidae was investigated in İzmir Bay. Two seahorse species, Hippocampus hippocampus (29) Hippocampus...

The investigation of biometric characteristics of seahorse species [Hippocampus hippocampus (Linnaeus, 1758) and Hippocampus guttulatus Cuvier, 1829] in Izmir Bay. In this study, the biometric features of the seahorse species belong to family Syngnathidae was investigated in İzmir Bay. Two seahorse species, Hippocampus hippocampus (29) Hippocampus...

in Turkish.

This study presents the relationships of length-weight, age and otolith length-total length in Merluccius merluccius . The length and age of the 316 wild-caught specimens were compared with the length and age calculated theoretically, together with the results from the back-calculated lengths-at-age. Lengths of the specimens captured by bottom traw...

Males of the smallspotted catshark, Scyliorhinus canicula, have a longer and narrower mouth than females, resulting in pronounced sexual dimorphism. The length/width ratio of the mouth is 0.55 in males and 0.50 in females. Other head measurements also significantly differ between the sexes, i.e., the snout-spiracle and snout-pectoral distances. Bod...