The red cornetfish (Fistularia petimba Lacepède, 1803) is an invasive fish species commonly found along the eastern Mediterranean coast of Türkiye. This study examined the length-weight relationship (LWR), condition factor (Fulton-K), and hepatosomatic index (HSI) of F. petimba specimens by sex. Between 2021 and 2024, 306 individuals (♀: 224, ♂: 56, juvenile: 26) were collected as bycatch from commercial fishing vessels in Taşucu Bay, Mersin Province. The sex ratio was 1:0.3 (♀:♂). The length-weight relationship was W = 0.0002×L3.289 (r2 = 0.952) for all individuals, W = 0.0002×L3.222 (r2 = 0.949) for females, and W = 7E-05×L3.514 (r2 = 0.951) for males. Positive allometric growth was detected. Fulton-K condition factor values were 0.49±0.03 for all individuals, 0.50±0.03 for females, and 0.47±0.06 for males. Hepatosomatic index (HSI) values were 0.85±0.05 for all individuals, 0.94±0.06 for females, and 0.57±0.08 for males. The data from this study on the red cornetfish population in Taşucu Bay, Mersin Province, may contribute significantly to understanding the body dynamics of the species.

This study evaluates the biodiversity of fish species caught using different fishing methods in relation to habitat distribution, based on 34 length-weight studies conducted in İzmir Bay between 1990-2024. The obtained data has been analysed in terms of traditional and modern fishing methods' species distributions in coastal and offshore habitats and the state of the bay ecosystem. This study examines how fish species diversity in the bay fluctuates over time, analyzing the impact of habitat characteristics and fishing practices on these variations. In the study, data from 170,466 fish specimens belonging to 139 species were analyzed using the Biodiversity Pro program. According to Simpson’s Reciprocal Index analysis, trawling is the most dominant fishing method with 20.81% in terms of number of individuals, followed by trammel net with 13.12%. While trawling, the bay's most effective fishing gear, catches 97 species, trammel net catches 28 species. The fishing method capturing the least number of individuals is fishnet with 1%. According to life forms, demersal species constitute the dominant group (18.157%) in the bay, while bathypelagic species showed the lowest diversity (1%). According to the Margalef index, the highest species richness was observed in demersal species (M: 28.265), while the lowest was in bathydemersal species (M: 43.792). According to studies between 1990-2024, fish populations with a b value above 3 comprise 68.61% in İzmir Bay. The average b value of 3.078 indicates that fish populations in the bay consist of species prone to positive allometric growth. The findings provide important contributions to understanding the ecological preferences of fishing methods and fish species. These data offer significant recommendations for sustainable fishery and species diversity management in İzmir Bay.

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 2020-2021. The eels' total lengths and weights were measured in the laboratory before they were dissected to examine gonad development. The total length and weight values of the specimens ranged from 19.2-72.5 cm (average: 46.77 cm) and 10.1-1002.4 g (average: 254.69 g) respectively. The ratio of female to male eels was 1:1.28. The chi-square test revealed no significant difference between female and male individuals (χ² calculation: 0.625 < χ² table: 3.841). The Gonadosomatic Index (GSI) value of the species was found to be between 0.22-0.47, peaking in the fall (0.47). Upon histological examination of the females' ovaries, two phases were identified - immature and maturing. Oocytes in the ovary consisted of pre-vitellogenic and early vitellogenic phases. The pre-vitellogenic phase featured a large nucleus situated in the centre of dense cytoplasm. The diameter of oocytes in this stage was measured between 90-200 µm. The early vitellogenic stage was characterized by larger oocytes located primarily in the peripheral zone of the ovarian stroma, containing a high amount of adipose tissue. The oocytes in this stage had a diameter ranging from 210-280 µm.

The African Softshell Turtle, Trionyx triunguis (family Trionychidae), is a large (up to >100 cm straight-line carapace length), fresh- and salt-water tolerant species predominantly found in moderately deep streams, rivers, estuarine systems, and lakes. It is the most widely distributed turtle in Africa, ranging from the mouth of the Nile River system south to Lakes Turkana (Rudolf) and Albert in eastern Africa, and from the Cunene River in northern Namibia to Senegal in western Africa. Additionally, it is found in the western Mediterranean region from the Turkish coastal zone to Israel. African populations are thought to have experienced significant declines in recent decades and Mediterranean populations have been considered Critically Endangered by the IUCN. While there is little published about the habitat preferences and ecology of the species, it appears to prefer medium to large sized rivers and permanent waterbodies with muddy, organic substrates, abundant emergent vegetation, and forested banks. Most accounts of nesting come from Mediterranean populations, where nesting takes place between May and July–August, with hatchling emergence from July to September after an incubation of 54–75 days. Clutch sizes seem to be highly variable between studies, seasons, and countries, with clutch size averages ranging from 23.0–44.7 eggs; up to 66 eggs have been recorded. The near spherical eggs are roughly 30–35 mm in diameter and weigh ~20 g. Most nests are between 20–40 cm deep and laid within 15 m of the water’s edge. As seen in all other trionychids, T. triunguis does not exhibit temperature-dependent sex determination. Optimal nest temperatures are between 24–33ºC, with around 30ºC producing maximum hatching success. Nest predation seems to be high where nesting has been recorded, with monitor lizards, domestic dogs, weasels, foxes, and jackals reported as the predominant predators. Hatchlings typically measure 40–51 mm SCL and weigh 10–15 g. Double and triple clutching have been noted in the species (though the frequency of multiple clutches remains unknown). Other than high nest predation rates, threats include entanglement in fishing gear, subsistence hunting, targeted hunting for the bushmeat trade, wanton killing, pollution, sand mining, and destruction of nesting beaches and sandbanks. The species is estimated to be Vulnerable and decreasing throughout its range and increased conservation efforts are warranted.

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, as well as being connected to the swimming speed which is effective in executing escape movements from existing predators in their natural environments. This study presents body surface area and aspect ratio values for nine Syngnathiformes species caught off Turkish coasts. It aims to provide a comparative scientific contribution for members of this order.

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 includes 20 species of cartilaginous fish and 8 species of bony fish listed as endangered on the IUCN Red List, alongside 54 non-native fish species. Prepared according to museum standards by Ege University Fisheries Faculty’s Scientific Material (ESFM), this collection of Turkish marine fish constitutes 66% of all Turkish marine fish fauna. This makes it the largest and oldest marine fish collection in Türkiye. Considering Türkiye’s maritime borders with neighboring countries, this collection is significant nationally and globally. Given the diverse marine fish species in Turkish seas over the past half-century, this preserved material is a vital reference for local and foreign ichthyologists. If organized and transformed into a visitable museum, this extensive collection could raise awareness about the diversity of marine fish species in our seas. As a result, we have established the ” biological repository of Turkish Marine Fish Department” in the Faculty Museum, now known as the Fisheries Faculty’s Scientific Material (ESFM) at Ege University. We present the fish in the collection as a species list.

The Mediterranean is a significant region for marine (Yildiz et al., 2020) fish particularly flatfish species with high commercial value. The common sole, Solea sp. (Linnaeus 1758) is a flat fish species that has high commercial importance in Turkey as well as in the whole world. Turkey's most important sole fishing areas are Gulluk Bay, Karina and Izmir Bay in Aegean Sea (Uluturk et al., 2012). As known, morphological characteristics are crucial in defining species or subspecies and serve as the primary basis of systematic science (Chan, 2001). However, biometric characters' similarities or differences vary due to geographical variations (Ezzat et al., 1975). Therefore, understanding population characteristics and growth dimorphisms between sexes across various geographical areas is vital for these economically important flatfish species. Although studies on biological characteristics of Solea solea exist (Amara et al., 2007; Parma et al., 2019; Cerim and Ates, 2020), research on whether growth causes any morphometric differentiation in both sexes is insufficient, considering the length groups. This study aims to determine the dimorphism in growth and geographic characters in the S. solea, caught from the Aegean Sea off the coast of Turkiye, depending on sexes and length groups, using morphometric combinations, which are an integral part of biological studies.

In this study, we aimed to state how we can contribute to an effective population management and protection by determining the morphometric characteristics of European yellow eels, Anguilla anguilla Linnaeus 1758, in the Aegean Sea population, Izmir Bay. It was found that the eye index and condition values of the female specimens are higher than those of the males. While it was determined that there was a significant difference between both sexes in 19 of 20 morphometric measurements of the head region, there was no statistical difference only in the height measurement at the nostril level of the head. In our study, the fact that specimens with ovaries were seen among the females longer than 34 cm (length group II) is remarkable in terms of early maturation in the region. The differences in head measurements between sexes indicate the existence of a dimorphic structure and these differences are in favor of female specimens.

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 of Türkiye. The biological indices determined were: FI- Fullness index, HSI-Hepatosomatic index, GSI-Gonadosomatic index, EQ-Encephalization quotient, VSI-Visceral index, IWL-Zihler index, Fulton-K: Fulton-Condition. For this study, 65 red cornetfish specimens (♀:40, ♂:23, immature: 2) caught as by-catch in the nets of commercial trawlers, operating in the study area in the winter of 2021 were studied. The estimated length-weight relationship (LWR) was W=0.0001L3.34 (R2= 0.89) and the species exhibits a positive allometric growth. The mean index (M±SD) and range values calculated from the obtained data are as follows: FI 1.05±0.13 (0.83-1.26); HSI 0.43±0.05 (0.23-0.62); GSI 1.27±0.20 (1.08-1.46); EQ 0.0024±0.0003 (0.0022-0.0025); VSI 3.14±0.39 (2.08-4.20); IWL 12.37±1.54 (4.41-20.3) and Fulton-K 0.47±0.06 (0.43-0.51). According to these results, it can be hypothesized that this Lessepsian species is well established and thrives in the eastern Mediterranean coasts of Türkiye. Although it is evaluated as the least concern category (LC) in the IUCN Red List 2013, we believe that the species has an invasive potential. Therefore, this study, in which biological index parameters were presented for Fistularia petimba, may be important in terms of fisheries management, planning measures to reduce distribution and combating invasiveness.

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 one specimen (TL: 48.5 cm and TW: 247.12 g) had 23 swim bladder parasites (adult nematodes: 15, larvae: 8) and similarly, only one parasite was found in one specimen (TL: 37.5 cm and TW: 88.47 g) of 8 eels caught in spring. No parasite was found in the female eels. At the examinations, it was determined that all adult Anguillicola crassus specimens were females and the minimum-maximum and average length values in adult and larval parasites were, respectively, 1.5-2.5 cm (1.99 ± 0.31) and 0.7-1.3 cm (1.025 ± 2.40). Consequently, the species A. crassus, a swim bladder parasite, was found in European eels from the locality Çamalti Tuzla in two seasons (winter and spring) and this parasitic nematode were only in male eels. This study is a first and remarkable one having evidential value, which shows the presence of the species A. crassus among the eel population in the locality Çamalti Tuzla of Izmir Bay. Besides, it is a population that should be monitored due to the status of Anguilla anguilla on the IUCN red list.

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 (female: 94, male: 19, immature: 9) common sole were evaluated. Total length-weight relationships were calculated as W = 0.085TL(3.01) and W = 0.0547TL(2.40) in females and males, respectively, whereby isometric growth was observed in females and negative allometric growth was observed in males. While there was no statistically significant difference was observed between the FI, HSI, Viscerosomatic Index (VSI), RGL and GSI values of both sexes, however, there was a statistically significant difference in terms of Fulton K values (P < 0.05). In addition, there are statistical differences between the sexes total lengths and the values of RGL, FI, HSI, VSI, and Fulton-K (P < 0.05), as it is discernible in their HSI and VSI index values according to the month the specimens were obtained (P < 0.05). According to the results of the analysis, it has been determined that the female common sole along the Aegean coast adjust their energy temporally and store the energy they obtain from vegetative and carnivorous feeding. Contrary to the situation seen in females, the male individuals invest in energy through omnivorous feeding, according to the diet in the active process. Based on the results, it can be stated that the VSI and HSI are both important indicators of fish condition status. The results found here may be useful in both fishery research and fishery management.

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 testicles were weighed as 20.77 g and are in the third maturity stage. Additionally, during scuba diving to the underwater cave of Mersin Silifke, Beşparmak Island, a group of devil firefish was photographed at depths less than 15 meters. Contrary to many records on the hard rocky bottom at depths more than 20 meters, it has been observed by us that many anglers on the dock of Mersin Taşucu port were catching the devil firefish together with sympatric pufferfish (Lagocephalus sceleratus) in shallow waters of sandy bottom less than 3 meters at depth.

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 insignificant (p>0.05). This was highest in autumn and lowest in winter, while there were no differences between the sexes (p>0.05). A sequential spiral of developing oocytes was observed from the earliest stage in the germinal ridge to the mature edge with the largest oocyte. Mature oocytes were found in histological sections during the summer season and the results obtained from gonadosomatic index values confirmed that the summer season is the breeding period of H. hippocampus at the eastern Black Sea shore of Turkey.

This study aims to determine the presence of sexual dimorphism based on morphometric characteristics in 69 (female: 44 male: 25) Syngnathus abaster specimens captured with seine-net from Lake Bafa's coasts (Mugla) between November 2014 and March 2016. Female/Male ratio of samples is 1/0.6. Based on morphometric measurements, the presence of sexual dimorphism was determined in among specimens pooled according to total length groups (I: 50-74 mm; II: 75-99 mm; III: 100-124 mm IV: 125 mm>). Thus, a statistical difference (p <0.05) is present between sexes in terms of body height (BH). Total length of males having a positive allometric growth is greater than that of female specimens, whereas females are higher than males. According to size groups, statistical sexual differences (p <0.05) were observed among length groups II and III of females and length group I of males. In conclusion, the species Syngnathus abaster, which is included in the Least Concern (LC) category of IUCN Red List, appears to have sexual dimorphism in the Lake Bafa's coasts in terms of body height.

In this research, gut lengths and numerical occurrence of gut contents (NO%) of Syngnathus acus, Syngnathus typhle and Nerophis ophidion were examined. The specimens were captured with beach seine net in different habitats (vegetated and sandy-vegetated etc.) at the coasts of Aegean Sea between 2006-and 2008. The zooplanktonic preys were mostly consumed by Syngnathus acus and Nerophis ophidion, whereas, Syngnathus typhle showed the most prey diversity. Thus, zooplanktonic organisms and other vegetative materials were consumed by three pipefish, however, vegetative tissues were mostly preferred by Syngnathus typhle. Feeding habits of three pipefish species are associated with gut lengths that show differences in increases or decreases depending on fish size and shape. In this study, S. typhle that has longer gut length than the other pipefish species explains the situation of being rich in organic gut content such as benthic zooplankton. Accordingly, probable presence or absent of the relationships between gut length and prey groups for three pipefish were discussed. The obtained results have supported low index values explaining the exact feeding habits of the pipefish.

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 January-February 2019. After the fork length and total length together with their weight measurements, the specimens were dissected in the laboratory. The adult females’ gonads were then fixed in 4% formalin solution for fecundity. A total of 170 individuals was examined and the values of their fork length, total length and weight were computed as 9.7-13.4 cm (mean: 11.16±0.81), 10.5-15 cm (mean: 12.3±0.89), 8.06-23.7 g (mean: 12.7±2.93), respectively. 44 of the supplied specimens were male (25.9%), 122 female (71.8%) and 4 (2.3%) uncertain, thus, the female: male ratio was determined as 2.77:1. According to χ2 test results, a statistically significant difference was observed among individuals. For the specimens examined, the fork length-weight relationship was calculated as W = 0.0098FL2.96, while total length-weight relationship was W = 0.0071TL2.97. In order to calculate the fecundity, sub-samples were taken from the anterior, median and posterior parts of 15 ovaries in the ration of 2 - 5% of the ovary weight and the mature oocytes were counted. As a result, the species’ fecundity was found to be between 4,600-9,800 (6,110±1,755). The relationship between total length and fecundity was computed as W= 1,640.7 TL-13,907 and a linear relationship was determined.

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 Fulton condition factor were W = 2E - 0.94.01, 0.035 ± 0.009 in S.abaster specimens. Also LW relationships and condition factor were W = 8E-0.93.83 , 0.033 ± 0.01 in S. acus. On the other hand mean ± SD of HSI and GSI values were 2.18 ± 1.65 and 7.69 ± 7.12 respectively. In S.acus values 3.22 ± 3.13 and 5.49 ± 5.12 as well. The decrease in HIS and K values, provides sufficient information to claim that species in the lake spend all energy requirement obtained with proper feeding to growth and gonad development.