JournalTOCs

Acta Biologica Turcica
Number of Followers: 1

This is an Open Access Journal

Open Access journal
ISSN (Online) 2458-7893
Published by Nevsehir Haci Bektas Veli University

[1 journal]

Biometrical distribution of sharks in a low Elasmobranches-diversified
shelf, the eastern Mediterranean Sea
- Authors: Erhan MUTLU, Mehmet Cengiz DEVAL, Claudia MIGLIETTA, İsmet SAYGU, Ilaria de MEO
  Abstract: Spatiotemporal distribution of sharks collected by the Otter trawl in 2009-2001 and 2014-2015 was studied for their biometrical characteristics, and fish assemblage and ecology in shelf-slope of Antalya Gulf. Four species was found only on the shelf, two species from middle shelf to shelf break and three species from shelf edge to shelf break. Scyliorhinus canicula was the most dominant and the most frequently occurred species during 2009-2010 and then occurrence of Scyliorhinus canicula decreased. The rarest species were Etmopterus spinax and Oxynotus centrina. Annual average abundance was above 800 ind/km2 in 2010-2011 and below 50 ind/km2 in 2014-2015. Species richness decreased from winter to spring. Abundance ranged from 5 ind/km2 in June to 964 ind/km2 in August. Sallower zone inhabited lower number of species than the deeper zone. Abundance increased from shallower to the deeper waters. The species had a positive allometric or isometric growth. Unimodal species peaked at 75-100 m and at 300 m. Ubiquitous species had a bimodal distribution. The species were discriminated from the deeper water to the shallower water. The species-environment relation was correlated positively by the bottom depths, followed negatively by Secchi disk depth, and water salinity and positively by near-bottom chl-a and finest bioseston.
  PubDate: 2022-03-17
  Issue No: Vol. 35, No. 2 (2022)
Identification of critical demersal fish habitats in the Northeast
Mediterranean - with an emphasis on Mullus barbatus
- Authors: Ali Cemal GÜCÜ, Ferit BİNGEL
  Abstract: The study determines the spawning and the nursery grounds of the important demersal fishes evaluating the fisheries data collected in 1983-1984. For this purpose, the spatial distribution of mean size, abundance, and biomass of fish communities on the northeastern corner of the Mediterranean Sea was evaluated. The emphasis has been given to red mullet, Mullus barbatus. During the spawning season, it was not possible to draw a clearcut bounderies for the spawning ground; rather, the stocks were distributed along the basin on an offshore band around 50 – 80 m depth. After the spawning season, the fishes were aggregated on the shallow waters (5-15 m). Among them, the most important nursery sites were found near the rivers, where the highest biomass and abundance values were recorded throughout the study. The paper also discusses the impact of Lessepsian species on critical habitats.
  PubDate: 2022-03-11
  Issue No: Vol. 35, No. 2 (2022)
Recovery potential and management options for European hake, Merluccius
merluccius (Linnaeus, 1758), stocks in Turkish waters
- Authors: Nazli DEMIREL, Güzin GÜL, Ahsen YÜKSEK
  Pages: 3 - 1-9
  Abstract: Overfishing has been a topic of fierce discussion over the past several decades. However, a lack of information regarding fish stocks makes proper stock assessment through good fisheries management difficult. This study addresses a problematic question for declining European hake, Merluccius merluccius (Linnaeus, 1758), stocks in the Turkish Aegean, Mediterranean, and Marmara seas. The present stock status and fisheries reference points were estimated using novel, data-limited assessment methods with recovery potential and management options for European hake stocks under different exploitation scenarios for each sea. Assessment results show that the ratio of the biomass (B) corresponding to the maximum sustainable yield (MSY) (B/BMSY) was under the threshold, and the ratio of fishing mortality (F) corresponding to the MSY (F/FMSY) was over the threshold, indicating that hake stocks were under ongoing overfishing since 2002 in each sea. After that, the biomass values gradually decreased from outside the safe biological limits, under the critical limits of 0.5 BMSY, while fishing mortality continued over the threshold. Reducing the fishing mortality to half of the estimated FMSY could lead to Marmara Sea hake stocks gradually increase in biomass and close to reaching its BMSY. Reducing fishing mortality to its 0.8 FMSY for Aegean Sea stock, and 0.5 FMSY for Mediterranean stock may help rebuild stocks until 2025. However, even the current estimated FMSY (0.95 FMSY is presented as FMSY), cannot assist in rebuilding any European hake stocks in 15 years projection. It is obvious to say that fisheries regulations must be carefully considered and rearranged, especially for depleted stocks such as those of European hake in Turkish waters.
  PubDate: 2022-03-18
  Issue No: Vol. 35, No. 2 (2022)
Historical roots of anchovy fishing
- Authors: Mustafa ZENGİN
  Pages: 4 - 1-24
  Abstract: It is not known whether there are any other fish species in the world's seas, where anchovy has a place in the life and culture of Black Sea residents. But in our country, it is very difficult for other fish to conquer the anchovy's reign. This fact has never changed throughout our fishing history. The pearl of the Black Sea, anchovy, has become so part of life in trade, social life, art and literature that it has become a part of culture. Anchovy has never been integrated and intertwined with the life of the local people, and even an indispensable element of daily life, has not become a lifestyle, as in the Black Sea region. In this study, the historical, cultural, sociological and economic adventure of anchovy, which forms the basis of fishing in the Black Sea, has been discussed with a long past perspective and tried to be revealed with a monolith text. Anchovy is neither a commercial commodity hunted by fishermen in the sea, nor a type of food consumed by every economic class in the society, nor is it a sea creature that has completed its history. Anchovy is a way of life for Black Sea people. In this text, the journey of anchovy from past to present and still continuing is tried to be conveyed to the reader by coloring it with traditional and authentic cultural elements.
  PubDate: 2022-03-18
  Issue No: Vol. 35, No. 2 (2022)
A comparative assessment of the Black Sea anchovy stock using holistic
production and analytical age structure models
- Authors: Gizem AKKUŞ, Ali Cemal GÜCÜ
  Pages: 5 - 1-12
  Abstract: The Black Sea anchovy (Engraulis encrasicolus) is economically and ecologically the most important commercial fish species in the Black Sea. Therefore, a management plan targeting the maximum sustainable yield has gained importance in recent years. The present study aims to provide a comprehensive assessment by using only Turkish data to evaluate the status of the Black Sea anchovy stock and compare the different approaches outcomes. For this, ASPIC (1968-2014) as a holistic production model and XSA (2005-2014) as an age-structured model are used. ASPIC estimates that the Black Sea's carrying capacity (K) is 1.2 million tons of anchovy, and to achieve the MSY of 244kton fish, 610kton (BMSY) fish must be present in the sea. It is estimated B2015 is 399ktons; this shows, now, there are 35% fewer fish present in the sea. Hence, the Black Sea anchovy is exposed to low overfishing. In XSA, the stock-recruitment relationship could not be established. Therefore, the current status of anchovy stock is estimated by Patterson’s (1992) precautionary exploitation rate of Etarget=0.4 as a reference point. Accordingly, the current exploitation rate is calculated as Ecurrent=0.5, which is 25% higher than the Etarget. Hence, XSA results also suggest that the Black Sea anchovy is exposed to low overfishing. This result and the other comparable parameter of F of the two models show the concordance and comparability of holistic (ASPIC) and analytic (XSA) models.
  PubDate: 2022-03-18
  Issue No: Vol. 35, No. 2 (2022)
Some biological characteristics of surmullet, Mullus surmuletus Linnaeus,
1758 in the Sea of Marmara
- Authors: Murat ŞİRİN, Mukadder ARSLAN İHSANOĞLU, İsmail Burak DABAN, Ali İŞMEN, Haşim İNCEOĞLU, Engin KOCABAŞ, Gençtan Erman UĞUR, Alpaslan KARA, Habib BAL
  Pages: 6 - 1-12
  Abstract: Mullus surmuletus is one of the economically important species which was investigated in this study. Length-weight relationship, age, growth parameters, reproductive season, length-at –first maturity and mortality parameters were determined in the Sea of Marmara. Samples were collected between March 2017 and December 2018 at 34 stations with trawl net. In totally 2486 Mullus surmuletus were sampled, total length and weight ranged from 8.7 cm to 23.7 cm in total length (TL) and from 6.01 g to 141.92 g in weight. The length-weight relationships were estimated as W=0.0084*L3.09, W=0.0081*TL3.10, W=0.0099*TL3.03 for both sexes, females, and males respectively. The growth parameters were calculated for females L∞=25.60 cm TL, K=0.21 y-1 and t0=-2.69 y, and for males as L∞=17.72 cm TL, K=0.34 y-1 and t0=-2.78 y. The length-at-first maturity for female and male individuals were determined as L50 = 12.5 cm, L50 = 11.9 cm, respectively. According to monthly values of the gonadosomatic index and gonad stages, spawning period of M.surmuletus was found from May to July.
  PubDate: 2022-03-22
  Issue No: Vol. 35, No. 2 (2022)
Growth of larval anchovy (Clupeiformes: Engraulis encrasiclus L.) in
İskenderun Bay, the Northeastern Mediterranean
- Authors: Sinan MAVRUK, Ahsen YÜKSEK, İsmet SAYGU, Dursun AVŞAR
  Pages: 7 - 1-10
  Abstract: In this study, growth patterns of larval anchovy (Engraulis encrasicolus L., 1758) was investigated based on otolith microstructure analyses and a meta-analysis of previously recorded growth rate estimates. For this purpose, samples were collected from Iskenderun Bay, the northeastern corner of Levant Basin, between 21-22 April 2017 and stored at -20 °C. The average temperature weighted with the abundance of larval anchovy was 18.0 ±0.24 °C (± standard deviation). In context of the study, a total of 76 larvae were investigated, standard lengths (SL) of which ranged between 2.78 and 18.61 mm with an average value of 8.24 ±3.35 mm. The number of increments on the sagittal otoliths (A) ranged from 4 to 30 with an average value of 13 ±7. No significant difference was found between the morphometrics of left and right sagitta. Positive allometric relationships were detected between otolith radius (OR) - SL (OR=0.33SL1.87; R2=0.87) and OR - A (OR=0.95A1.24; R2=0.75). The length at age relationship was SL=2.87+0.47A (R2=0.85). In the meta-analysis, larval anchovy growth rates varied in a wide range without a clear spatial pattern regardless of coupling temperature conditions.
  PubDate: 2022-03-24
  Issue No: Vol. 35, No. 2 (2022)
Juvenile fısh fauna of the transitional waters on the Mediterranean
coasts of Turkey; a structural and environmental assessment
- Authors: Deniz İNNAL
  Pages: 8 - 1-11
  Abstract: While transitional waters create important areas for fish breeding, feeding and growth, these are also the areas where the physiological preparation for migration is made. Transitional waters allow juvenile fish to grow faster. Juvenile fish predation is also considerably lower than in the marine environment, as large carnivorous fish are less common in transitional waters than in open seas. In this respect, transitional waters represent important protection areas for juveniles. For the protection and long-term management of fish stocks of transitional waters, it is necessary to identify the fish species living in these systems and to know the human activities affecting the fauna. In this study, the systematic status of juvenile fish species, habitat categories, population sources and risk categories of the Manavgat, Göksu, Seyhan and Ceyhan transitional waters on the Mediterranean coasts of Turkey were determined, and human activities affecting natural fish species and their results were evaluated. During the study, a total of 28 juvenile species were identified in transitional waters. 7 (25%) of these species are found to be common in the transitional waters of 4 river systems. Marine species are represented by more juvenile species in the transition waters of Manavgat, Göksu, Seyhan and Ceyhan rivers.
  PubDate: 2022-03-30
  Issue No: Vol. 35, No. 2 (2022)