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1. Mass Mortality of the Invasive Sea Urchin Diadema setosum in Türkiye, Eastern Mediterranean Possibly Reveals Vibrio Bacteria Infection.

Author

Dinçtürk, Ezgi, Öndes, Fikret, Alan, Vahit, and Dön, Emre

Subjects
*SEA urchins, *VIBRIO infections, *MARINE ecology, *SPRING, *AUTUMN
Abstract

ABSTRACT The invasive Diadema setosum (Leske, 1778) long‐spined sea urchin has been in the Mediterranean Sea since 2006, and then, it has been known that its population density has reached high values on the southern Aegean coasts of Türkiye. This study aimed to report the mass mortality event of D. setosum with the determined agent on the Aegean coast of Türkiye. In addition, it was targeted to provide information on the current status of its density based on seasonal SCUBA diving observations for the period between January 2023 and November 2023. The results showed that the mass mortality of D. setosum was determined in Muğla, Aegean Sea, in August 2023. Spine loss, the mucoid layer at the bottom of the appendages, and the outer body surface were observed as the clinical symptoms of the diseased samples. Bacterial growth was detected on Vibrio‐selected TCBS agar plates, while no other parasitic agents were determined in the coelomic fluid of sea urchins. The results of the biochemical (API 20E) and molecular tests confirmed the isolated bacteria as Vibrio spp. The density of D. setosum showed statistically significant temporal changes, and the highest and lowest mean density values were recorded in autumn and spring, respectively. Environmental stressors, such as increasing sea temperature levels, affect the marine ecosystem and lead to opportunistic pathogens. Long‐term monitoring of disease outbreaks is necessary to understand the interactions between species and the ecosystem. [ABSTRACT FROM AUTHOR]

Published
2024
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4. Mass mortality of the keratose sponge Sarcotragus foetidus in the Aegean Sea (Eastern Mediterranean) correlates with proliferation of Vibrio bacteria in the tissues.

Author

Dinçtürk, Ezgi, Öndes, Fikret, Leria, Laia, and Maldonado, Manuel

Subjects
VIBRIO, OCEAN temperature, SPONGES (Invertebrates), BACTERIA, TISSUE culture
Abstract

In the last two decades, episodes of mass mortality in benthic communities have often been associated with climatic anomalies, but the ultimate mechanisms through which they lead to death have rarely been identified. This study reports a mass mortality of wild sponges in the Aegean Sea (Turkey, Eastern Mediterranean), which affected the keratose demosponge Sarcotragus foetidus in September 2021. We examined the occurrence of thermo-dependent bacteria of the genus Vibrio in the sponges, identified through 16S rRNA of colonies isolated from sponge tissue in specific culturing media. Six Vibrio sequences were identified from the sponges, three of them being putatively pathogenic (V. fortis, V. owensii, V. gigantis). Importantly, those Vibrios were isolated from only tissues of diseased sponges. In contrast, healthy individuals sampled in both summer and winter led to no Vibrio growth in laboratory cultures. A 50  years record of sea surface temperature (SST) data for the study area reveals a progressive increase in temperature from 1970 to 2021, with values above 24°C from May to September 2021, reaching an absolute historical maximum of 28.9°C in August 2021. We hypothesize that such elevated SST values maintained for several months in 2021 promoted proliferation of pathogenic Vibrio species (thermo-dependent bacteria) in S. foetidus, triggering or aggravating the course of sponge disease. Thus, vibrioisis emerges as one of the putative mechanisms through which global water warming in the Mediterranean Sea translates into sponge mortality. The historical time course of temperature data for the studied area in the Aegean Sea predicts that recurrent waves of elevated SST are likely to occur in the coming summers. If so, recurrent disease may eventually eliminate this abundant sponge from the sublittoral in the midterm, altering the original bathymetric distribution of the species and compromising its ecological role. [ABSTRACT FROM AUTHOR]

Published
2023
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11. The dominance of non-indigenous species in the catch composition of small-scale fisheries: A case study from the Kaş-Kekova Special Environmental Protection Area, Türkiye, Eastern Mediterranean.

Author

Öndes, Fikret and Ünal, Vahdet

Abstract

This study aimed to determine the catch composition and compare the catch per unit effort (CPUE) of indigenous and non-indigenous species in longline and trammel net fisheries in the Mediterranean coasts of Türkiye. The data were collected weekly from May 2020 to September 2021 by commercial fishing vessels (n = 62 days for trammel nets, n = 75 days for longlines). The results of the study indicated that more than 90% of the catch composition consisted of non-indigenous species in trammel net fishery and Pterois miles (Bennett, 1828), Siganus rivulatus Forsskål et Niebuhr, 1775, Siganus luridus (Rüppell, 1829), and Scarus ghobban Forsskål, 1775 were the most commonly caught species. Although indigenous species were more common in longlines compared with trammel nets, non-indigenous species Lagocephalus sceleratus (Gmelin, 1789) and Lagocephalus suezensis Clark et Gohar, 1953 were represented by relatively high catch ratios. The results also revealed that the CPUE of non-indigenous species exhibited seasonal differences. Although some non-indigenous species caught within this study have a market value, some other highly invasive species do not. Therefore, it is critically important to develop effective management tools to control bio-invasion. This study provides the first comprehensive research by utilizing basic data with relatively long-term surveys in the small-scale fishery on the Mediterranean coasts of Türkiye. The outcomes of this study can provide guidance to decision-makers. [ABSTRACT FROM AUTHOR]

Published
2023
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12. Distribution and Fishery of the Invasive Blue Crab (Callinectes sapidus) in Turkey Based on Local Ecological Knowledge of Fishers

Author

ÖNDES, Fikret and GÖKÇE, Gökhan

Subjects
Fen, lagoon fishery,marine invasion,invasive species,Callinectes sapidus,fisheries management,local ecological knowledge, Science, dalyan balıkçılığı,denizel istila,istilacı türler,Callinectes sapidus,balıkçılık yönetimi,local ekolojik bilgi
Abstract

Bu çalışma, Callinectes sapidus’un Türkiye’deki dağılımı, ekolojisi, uzatma ağlarındaki (fanyalı ve sade ağlar) günlük maksimum avı ve dalyanlardaki ticari balıkçılığı hakkında bilgi sağlamaktadır. Veriler, 2020 yılında yapılan telefon anketleri ile toplanmıştır. Dalyanlarda balıkçılık yapan 6 balıkçı ve Türkiye’nin Akdeniz, Ege, Marmara ve Karadeniz kıyılarını kapsayan toplam 28 ildeki su ürünleri kooperatifi başkanları ya da kooperatif üyeleri (örneklem sayısı = 104) anketleri cevaplamıştır. Bulgular, C. sapidus türünün Türkiye’nin Akdeniz ve Güney Ege kıyılarında yaygın olduğunu, Marmara ve Karadeniz kıyılarında ise nadiren gözlemlendiğini göstermiştir. Bu türün Karadeniz’de son 10 yıldır görüldüğü balıkçılar tarafından rapor edilmiştir. Uzatma ağlarındaki günlük maksimum yengeç avı Akdeniz ve Ege Denizi’nde anlamlı fark göstermiştir. Çoğu kıyı balıkçısı (%79), C. sapidus türünün ağları parçaladığını ve ekonomik kayba neden olduğunu belirtmiştir. Yumurtalı yengeçler Mart ve Ekim ayları arasında gözlemlenmiş olup, mevcut balıkçılık sezonu dâhil olmak üzere yönetim ile ilgili konular değerlendirilmiştir., This study provides information on the distribution and ecology of Callinectes sapidus in Turkey, as well as its maximum daily catch in set nets (trammel nets and gillnets), and its commercial fishery in lagoons. Data were collected in 2020 by utilizing a telephone based questionnaire survey. Responses were gathered from fishers (n = 6) who fish in the lagoons and the head of fishery cooperatives or its members (n = 104) in 28 cities, including the coastal regions of the Mediterranean Sea (Levantine), Aegean Sea, Sea of Marmara and the Black Sea in Turkey. Results indicated that C. sapidus is commonly distributed along the Levantine and Southern Aegean coasts of Turkey, whilst it is rarely observed in the Sea of Marmara and the Black Sea. It has been reported by fishers that this species has been seen in the Black Sea for the last decade. The maximum daily catch of blue crab in set nets showed a significant difference in the Levantine and Aegean coasts. The species is mainly produced in the lagoons, whereas many coastal fishers returned it as discard and 79% of fishers emphasized that C. sapidus shred the nets and caused an economic loss. Ovigerous females have been observed between March and October and we have discussed related management issues including current fishery season.

Published
2021

18. Socio-economic Characteristics and Catch Composition of Recreational Angling in Bandırma Bay and the Kapıdağ Peninsula (Sea of Marmara, Turkey)

Author

ÖNDES, Fikret

Subjects
Fen, Balıkçılık yönetimi,balıkçılık ekonomisi,denizel amatör balıkçılık,Türkiye, Science, Fisheries management,fisheries economy,marine recreational fisheries,Turkey
Abstract

Bu çalışma, Bandırma Körfezi ve KapıdağYarımadası’ndaki amatör balıkçıların sosyo-demografik özelliklerini, balıkçılıkharcamalarını, birim çabaya düşen av miktarı ile av kompozisyonunu tespitetmeyi amaçlamıştır. Veri temini, yüz yüze yapılan anketler ile (n=120)Eylül-Aralık 2018 tarihleri arasında gerçekleştirilmiştir. Anketler ilebalıkçıların demografik özellikleri, balıkçılık aktivitesi için yaptıklarımasraflar, aktivitenin zamansal değişimi, birim çabaya düşen av miktarı, avkompozisyonu ve başlıca sorunlar ile balıkçıların balıkçılık yönetimindepotansiyel düzenlemelere karşı bakış açıları hakkında verilere ulaşılmıştır.Balıkçıların ortalama yaşı 46 ± 14 yıl olarak tespit edilmiş ve büyük birkısmının lise mezunu evli erkeklerden oluştuğu gözlemlenmiştir. Bir balıkçınınortalama 1 470 ± 189 TL yıllık masrafının olduğu tespit edilmiş ve avekipmanları en büyük harcama kalemidir. Birim çabaya düşen av miktarı ortalama 0,46kg/saat olarak tespit edilmiştir. Çalışmada toplam 29 tür rapor edilmiş, enyaygın tutulan türler sırasıyla Trachurusmediterraneus, Lithognathus mormyrusve Pomatomus saltatrix’ dir. Amatörbalıkçıların %55’i ticari balıkçılar ile çıkar çatışması yaşadıklarını bildirmiştir.Ankete katılanların büyük çoğunluğu amatör balıkçılıkta uygulanan mevcut tebliğhakkında yeterli bilgilerinin olmadığını ve olası yer ve zaman yasaklarınıgereksiz bulduklarını belirtmiştir. Denizel kaynakların sürdürülebilirkullanımı için amatör balıkçıların, tebliğ hakkında bilgilendirilmelerinin veyaptıkları aktivitenin denetlenip, izlenmesinin büyük önemi bulunmaktadır., This study aimed to determine the socio-demographic characteristics ofrecreational fishers, fisheries expenditures, catch per unit effort and catchcomposition around Bandırma Bay and Kapıdağ Peninsula. Data were collectedbased on face to face questionnaires (n=120) between September and December2018. With the data obtained from the research, demographic characteristics,fishing expenditures, temporal changes in fishing, catch per unit effort, catch composition, main problems and perspectivesof fishers on the potential regulations related to fisheries management wereinvestigated. The mean age of fishers was 46 ± 14 years and most fishers weremarried and they had a high school degree. Mean annual expenses on recreationalfishing activity was 1 470 ± 189 TL and the highest expenditure was the fishingequipment. The mean catch per unit effort was estimated as 0.46 kg/h. A total of 29 species were reported and Trachurus mediterraneus, Lithognathus mormyrus and Pomatomus saltatrix were the most commonspecies respectively. The recreational fishers (55%) declared that they had aconflict with commercial fishers. Many respondentsreported that they did not have enough information on the current notification andthey considered that spatial and temporal closures were not necessary forrecreational fishing. It is critically important that recreational fishers areinformed about the fishing notification, their activity is audited and monitoredfor the sustainable use of marine resources.

Published
2019

19. Charter fishing in the Aegean Sea (Turkey), Eastern Mediterranean: The missing point of fisheries management

Author

Öndes, Fikret, Ünal, Vahdet, Öndes, Hakan, Gordoa, Ana, Öndes, Fikret, Ünal, Vahdet, Öndes, Hakan, and Gordoa, Ana

Abstract

This study attempts to improve the scientific knowledge of charter fishing on the Aegean coast of Turkey, where fishing activity and ecological indicators were investigated. Fishing and socio-economic data from both charter boat owners and charter fishers were collected using on-site questionnaires, and seasonal on-board surveys during 2017. No differences were observed between CPUE estimates from the questionnaire and the on-board surveys. The highest and lowest fishing activity were found in autumn and summer respectively. Charter owners reported conflicts with both private boat owners as well as commercial fishers. The annual activity was estimated to be 9246 charter trips hosting 138,690 charter fishers, who caught 277−305 tonnes. The total annual fisher and boat owner expenditure was estimated at €3.5 million and €0.6 million respectively. A total of 38 species were identified; most of the catch was represented by sparids, of which there were several species, such as Diplodus vulgaris, Sparus aurata, and Pagellus erythrinus, all of which were highly undersized. The results highlighted that the fishers and boat owners had limited knowledge of fishing policies. We conclude that managers should pay more attention to this activity and revise the existing regulations of charter fishing to improve fisheries management.

Published
2019

21. By-catch and monetary loss of pufferfish in Turkey, the Eastern Mediterranean

Author

Öndes, Fikret, Ünal, Vandet, Özbilgin, Yeliz, Deval, Cengiz, Turan, Cemal, Deniz Bilimleri ve Teknolojisi Fakültesi -- Deniz Bilimleri Bölümü, and Turan, Cemal

Subjects
Local ecological knowledge, Actinopterygii, Tetraodontidae, Silver-Cheeked toadfish, Fisheries, Pufferfish, Lagocephalus-Sceleratus gmelin, Iskenderun Bay, Knowledge, By-catch, Lagocephalus sceleratus, 1st record, Mediterranean Sea, Marine & Freshwater Biology, Monetary loss
Abstract

WOS: 000456094500001, Non-native pufferfish have been a part of the Mediterranean marine ecosystem since the 1930s. However, there is a lack of knowledge regarding the by-catch of these species. This study aimed to compare the by-catch of pufferfish species between different types of fishing gear and to determine the monetary losses due to pufferfish on the Aegean (west) and Mediterranean (south) coasts of Turkey. A total of 467 commercial and recreational fishers (n= 244 and n=223 respectively), based in the 7 coastal cities were interviewed in the period of June - December 2017. A semi-structured questionnaire provided detailed information on by-catch amount of pufferfish in fishing gears, and economic loss caused by pufferfish. The most commonly caught pufferfish species was Lagocephalus sceleratus. The by-catch amount of pufferfish is higher on the Mediterranean coast in comparison with the Aegean coast. The highest pufferfish by-catch was recorded in purse seines and trawls on the south coasts, but in set nets on the west coasts. When seasonal changes were considered, the highest by-catch was occurred in the summer months for both commercial and recreational fisheries. Regarding the damages caused by pufferfish species in the small-scale fisheries, 92% and 90% of fishers, who fished on the south coasts, claimed that pufferfish species damage their fishing gears and fish entangled to these fishing gears, respectively. In conclusion, pufferfish species (e.g. L. me/era:us) are part of the ecosystem with their unknown quantified impacts. In fact, such information is required for fisheries management to mitigate the impacts of these species. The present study contributes to filling the gaps in this area.

Published
2018

24. THE CATCH CHARACTERISTICS OF A SET LONGLINE FISHERY IN THE FOÇA SPECIAL ENVIRONMENTAL PROTECTION AREA, TURKEY.

Author

GÜÇLÜSOY, Harun, ÖNDES, Fikret, and TOSUNOĞLU, Zafer

Subjects
ENVIRONMENTAL protection, FISHERIES, MARINE parks & reserves, EUROPEAN seabass, MANN Whitney U Test, SPARUS aurata, SMALL-scale fisheries
Abstract

Background. Fisheries activities are rarely documented in the marine and coastal protected areas in Turkey. This study aimed to determine the catch composition of set longline fishery in the Foça Special Environmental Protection Area (Turkey), and to understand the effects of factors (e.g., bait type, hook size, and soak time) on the catch per unit effort (CPUE) and the size of species caught. Material and methods. Samples were collected by small-scale fishing boats in 2007 at depths ranging from 1 to 50 m. Kruskal-Wallis test was used to understand if the CPUE changes depended on the fishery specific factors (hook size and bait type). Mann-Whitney U test was used to test if CPUE changes depended on sampling seasons (autumn and summer). Chi-square test was used to determine whether hook size influenced the body size of two commonly caught species. Results. The following 25 fish species were caught, Diplodus sargus, Sparus aurata, Diplodus vulgaris, Boops boops, Lithognathus mormyrus, Oblada melanura, Conger conger, Trachurus sp., Spondyliosoma cantharus, Pagellus erythrinus, Pagrus pagrus, Dentex dentex, Sciaena umbra, Scorpaena scrofa, Belone belone, Serranus sp., Myliobatidae gen. sp., Muraena helena, Sarpa salpa, Diplodus annularis, Coryphaena hippurus, Diplodus puntazzo, Chelidonichthys lucerna, Scomber japonicus, and Dicentrarchus labrax. The most commonly caught species were white seabream, Diplodus sargus and gilthead seabream Sparus aurata. The hook size and bait type were important factors that influenced the CPUE. Moreover, the hook size significantly influenced the body size of caught white seabream and gilthead sea bream. Conclusions. The discard level was low in the set longline fishery in the Foça Special Environmental Protection Area. We recommend using 12 sized hooks rather than 13 to reduce the discards of the main target species in the Foça SEPA. Nevertheless, this also needs an economic assessment, and also identification and use any incentives to promote the shift in the use of larger size hooks. Minimum size limits to be set in the fisheries legislation and alternative bait use studies were also recommended. [ABSTRACT FROM AUTHOR]

Published
2020
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25. Human impacts on the endangered fan mussel, Pinna nobilis.

Author

Öndes, Fikret, Kaiser, Michel J., and Güçlüsoy, Harun

Subjects
MUSSELS, ECOLOGICAL surveys, BEACHES, DATA distribution, PROTECTED areas, BYCATCHES, EDUCATIONAL benefits
Abstract

Pinna nobilis is a sensitive and vulnerable species and is hence considered a good indicator of anthropogenic pressures on marine ecosystems.This study provides novel data on the density and distribution of endangered P. nobilis on the Turkish coasts. Threats to the status of P. nobilis, including by‐catch and illegal collection, were assessed, as was the general awareness of people about the endangered status of fan mussels.The data sources consisted of direct observations from diving surveys and the local ecological knowledge (LEK) of fishers and scuba‐divers.Results demonstrated that the density of P. nobilis significantly changed with environmental parameters, such as depth, and among different sampling areas. The number of damaged individuals was lowest in the areas that were distant from human influences such as ports and tourist beaches. The density estimations of P. nobilis across a wide geographic area around the Turkish coasts revealed that the density of fan mussels was highest around western coasts in comparison with southern coasts.Fishers and divers indicated that the population of this species has decreased during the last decade. The main causes of this decline were suggested to be the impacts of fishing gear, poaching, pollution, and boat anchoring. The highest volume of by‐catch was estimated to be taken by trawls. In general, the knowledge and local awareness of the conservation importance and status of fan mussels was poor.The study has identified those areas where fan mussels occur at a high density, and hence may indicate areas for possible conservation protection status. Second, areas exposed to the illegal harvesting of fan mussels were highlighted. Societal concern would benefit from educational activities to raise awareness of the ecological importance and conservation needs for fan mussels in Turkey. [ABSTRACT FROM AUTHOR]

Published
2020
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29. Occurrence of the squat lobster Munida curvimana A. Milne Edwards & Bouvier, 1894 and Colombus crab Planes minutus (Linnaeus, 1758) in Turkey.

Author

Irmak, Erhan and Öndes, Fikret

Subjects
*LOGGERHEAD turtle, *LOBSTERS, *CRABS, *DECAPODA
Abstract

The present study reports the first record of Munida curvimana and second record of Planes minutus in Turkish waters. A male specimen of M. curvimana was collected by a commercial set net in Antalya Bay, Turkey in 2007. A male specimen of P. minutus was found on the loggerhead sea turtle that was captured by driftnet as a bycatch in Fethiye Bay in 2005. The morphometric characteristics and the updated distribution of squat lobster and Columbus crab in the Mediterranean Sea are presented. [ABSTRACT FROM AUTHOR]

Published
2019

30. The catch characteristics and population structure of the brown crab (Cancer pagurus) fishery in the Isle of Man, Irish Sea.

Author

Öndes, Fikret, Emmerson, Jack A., Kaiser, Michel J., Murray, Lee G., and Kennington, Kevin

Abstract

Brown crab contributes to small-scale fisheries in the Isle of Man and landings (495 t) were worth in excess of £0.5 million in 2012. The present study sought to fill evidence gaps needed to improve the scientific understanding of this fishery. Observer data were collected to examine the spatial and temporal variations in the size distribution and sex ratio of crabs around the Isle of Man. This study also aimed to evaluate the catch characteristics of brown crab using logbook data (2007–2012), observer data (2012–2013) and questionnaire survey data (2013). The sex ratio is highly variable in different areas across seasons and was perhaps indicative of migration patterns in relation to mating. This change was most notable with a strong increase in the proportion of females to the south and west of the Isle of Man in the autumn months. The depth and pot volume were important factors that influenced the catch per unit effort (CPUE). Future survey designs would need to ensure adequate spatial coverage of the east and west coast of the Isle of Man together with a seasonal sampling regime that captures the spatial change in the distribution and abundance of male and female crabs. [ABSTRACT FROM AUTHOR]

Published
2019
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31. Fish and invertebrate by-catch in the crab pot fishery in the Isle of Man, Irish Sea.

Author

Öndes, Fikret, Kaiser, Michel J., and Murray, Lee G.

Abstract

Baited trap or pot fisheries are considered to have relatively few wider ecosystem effects on the marine environment, particularly when compared with towed mobile fishing gear. However, this assumption is rarely tested in the field. This study aimed to determine the composition of non-target species that occur in crustacean pots and to assess spatial and temporal differences in catches in the waters around the Isle of Man, Irish Sea. The data were collected using fishery independent surveys and a questionnaire study. Based on fishery independent surveys, a total of five taxonomic groups and 43 species occurred as by-catch. The dominant by-catch species was velvet crab Necora puber. The by-catch per unit effort (BPUE) for all of the non-target species was low particularly in comparison to towed bottom gear fisheries around the Isle of Man. BPUE of species composition varied considerably between different locations around the Isle of Man. The results of both the fishery independent and questionnaire data suggested that the by-catch rates varied with season with peak BPUE occurring in spring which then declined into autumn and winter. By-catch composition did not decrease significantly with an increasing target species catch. Overall, by-catch was low relative to target species catch which may be partially attributable to the use of escape panels in pot fisheries in the Isle of Man. [ABSTRACT FROM AUTHOR]

Published
2018
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32. Reproductive Ecology, Fecundity, and Elemental Composition of Eggs in Brown Crab Cancer pagurus in The Isle of Man

Author

Öndes, Fikret, Kaiser, Michel J., Murray, Lee G., Torres, Gabriela, Öndes, Fikret, Kaiser, Michel J., Murray, Lee G., and Torres, Gabriela

Abstract

The brown crab is an important fishery resource in northern Europe. Understanding factors that affect fecundity in this species is complicated by the fact that ovigerous females enter traps infrequently. This study aimed to understand factors that affect brown crab fecundity and egg quality for crabs sampled from the waters around the Isle of Man. The size-fecundity relationship for the Isle of Man matched closely with those published for other geographical areas where a fishery exists for this species. Ovigerous crabs varied in size from 134 to 215 mm carapace width and each individual carried an estimated 0.4–3.0 million eggs. Fecundity was not affected by factors such as sampling season, location, loss of chelae, or black spot disease. Egg volume was independent of the number of eggs per batch or female body size. Egg volume was reduced significantly in crabs that had lost chelae. Egg dry weight, C and N composition did not vary with body size or any other explanatory factors such as chelal loss or the occurrence of black spot disease. Although the importance of the effect of claw loss on egg volume remains unclear, it may be an important consideration in fisheries in which the landing of claws is permitted.

Published
2016

34. İzmir Körfezi midye (Mytilus galloprovincialis Lamarck, 1819) fasiesinde bulunan tanaid (Crustacea,Tanaidacea) türlerinin bazı biyolojik özellikleri

Author

Öndes, Fikret, Katağan, Tuncer, and Su Ürünleri Temel Bilimleri Anabilim Dalı

Subjects
Su Ürünleri, Crustacea, Aquatic Products, İzmir Bay
Abstract

Bu çalışmada, İzmir Körfezi'nin midye fasiesinde (Mytilus galloprovincialis) bulunan tanaid türlerinin bazı biyolojik ve üreme özellikleri incelenmiştir. Bu amaç doğrultusunda iç körfezdeki 3 istasyondan bir yıl boyunca (Nisan 2008 ? Mart 2009) aylık örnekleme yapılmış ve 2 tanaid türüne ait 3176 birey tespit edilmiştir. Tanais dulongii toplam birey sayısının %94.96'sını, Leptochelia savignyi ise %5.03'ünü kapsamaktadır. Türlerin üreme periyotları, erkek- dişi oranları, yumurta çapları, total boyları ve biyokütleleri belirlenmiştir. T. dulongii'nin en yüksek populasyon yoğunluğu (17600 birey.m-²) İnciraltı istasyonunda Mayıs ayında, L. savignyi'nin ise en yüksek populasyon yoğunluğu (2350 birey.m-²) İnciraltı istasyonunda Ocak ayında tespit edilmiştir. Ayrıca her ay yapılan örneklemeler ile tanaid populasyonlarının mevsimsel değişimleri izlenmiş ve ortamın bazı çevresel faktörlerin (su sıcaklığı, tuzluluk, pH, çözünmüş oksijen, midye biyokütlesi ve midye sayısı) tanaid populasyonlarına olan etkileri saptanmıştır.Anahtar Sözcükler: Tanaidacea, Tanais dulongii, Leptochelia savignyi, biyo-ekoloji, biyometri, İzmir Körfezi. AThis study focused on some biological and reproductive properties of tanaid species which were collected from mussel fasies (Mytilus galloprovincialis) in İzmir Bay. For this purpose, samples were collected from 3 stations monthly between April 2008 ? March 2009 in inner bay. A total of 3176 individuals belonging to 2 tanaid species were determined. Tanais dulongii accounts for 94.96 % of total number of species and Leptochelia savignyi for 5.03 % of the total number of species. Reproduction period, the proportion of males/ females, egg diameter, biomass and total length were determined. The highest population densities of T. dulongii were estimated as 17600 ind.m-2 at the station of İnciraltı in May and those of L. savignyi as 2350 ind.m-² at the same station in January. Seasonal variations of tanaids population were monitored by monthly collections and some environmental factors (temperature, salinity, pH, dissolved oxygen, biomass of mussel and number of mussel) affecting the population of tanaids were established.Keywords: Tanaidacea, Tanais dulongii, Leptochelia savignyi, bio-ecology, biometry, İzmir Bay. 84

Published
2011

35. Ege Denizi küçük ölçekli balıkçılığının sosyo-ekonomik açıdan değerlendirilmesi

Author

Birkan, Riza, Öndes, Fikret, and Su Ürünleri Anabilim Dalı

Subjects
Deniz Bilimleri, Marine Science
Abstract

Bu çalışmanın amacı; Ege Denizi'ndeki küçük ölçekli balıkçılık yapan balıkçıların sosyo-demografik durumlarını ve karşılaştıkları başlıca sorunları tespit etmektir. Veriler, 2018 yılında küçük ölçekli balıkçılar ile yüz yüze yapılan anketler ile 3 alt bölgeden (Kuzey Ege, Orta Ege ve Güney Ege) (n=190) temin edilmiştir. Anketler ile balıkçı teknelerinin genel özellikleri, balıkçıların demografik özellikleri, balıkçılık aktivitesi için yaptıkları masraflar, birim çabaya düşen av miktarı ve başlıca sorunlar hakkında verilere ulaşılmıştır. Ayrıca, aynı araştırma alanında daha önceden yapılmış çalışmalar ile bazı demografik (örn. yaş, evli oranı) ve balıkçılık ile ilgili (örn. aktif balıkçı oranı, sadece balıkçılıktan geçinen balıkçı oranı) kriterlerde zamansal değişim olup olmadığı araştırılmıştır. Balıkçıların ortalama yaşı 50 ± 10 yıl olarak tespit edilmiş ve büyük bir kısmının ilkokul mezunu evli erkeklerden oluştuğu gözlemlenmiştir. Balıkçılık kaynaklı harcama kalemleri içerisinde en yüksek kalem personel ücreti olarak tespit edilmiştir. Balıkçılık kaynaklı harcamalar ile ilgili alt coğrafik bölgelere göre istatistiksel açıdan anlamlı farklar bulunmamış fakat yapılan balıkçılık türüne (uzatma, alamana, paragat) göre fark tespit edilmiş olup, alamana balıkçılığı yapan balıkçıların harcamalarının diğerlerine kıyasla yüksek olduğu saptanmıştır. Bulgular göstermiştir ki kooperatiflerdeki aktif balıkçı oranı ve geçimini sadece balıkçılıktan sağlayan balıkçıların oranı son 10 yılda anlamlı bir şekilde düşüş gösterirmiştir. Ayrıca, kullanılan teknelerin motor gücünde (HP) son 15-16 yılda istatistiksel açıdan anlamlı bir artış tespit edilmiştir. Başlıca sorunlar arasında denetim eksikliği, yasadışı avcılık ve stoklardaki düşüş belirtilmiştir. Denizel kaynakların sürdürülebilir kullanımı için su ürünleri denetiminin arttırılması ve balıkçıların eğitilmeleri önem arz etmektedir The aim of this study was to determine the socio-demographic status and main problems of small scale fishers in the Aegean Sea. Data were collected from small scale fishers (n = 190) using face-to-face questionnaires from 3 sub-regions (North Aegean, Central Aegean and South Aegean) in 2018. The questionnaire included information on main characteristics of fishing boats, demography of fishers, fisheries expenditures, catch per unit effort, and main problems. Furthermore, in this study some demographic characteristics (e.g. age and married ratio) and fishery specific characteristics (e.g. active fisher ratio, the ratio of fishers who do not have other income) were compared with previous studies which were carried out in the sampling area to reveal if any changes have prevailed historically. The mean age of fishers was 50 ± 10 years and many of them were married males who had primary school diplomas. The highest fisheries expenditures was personnel expenses. The fisheries expenditures did not show a statistically significant difference in terms of different geographic areas. However, there was a significant difference in fisheries expenditures depending on fishery type; fishers, who use encircling net, reported higher expenditures in comparison with other fishing types. Results showed that the active fisher ratio and the ratio of fishers who do not have other income decreased significantly during the last 10 years. In addition, HP showed a significant increase for the last 15-16 years. The main problems were lack of control, illegal fisheries, and decrease in stocks. For the sustainable use of marine resources, it is important to increase the control of fishing activities and training of fishers. 55

Published
2019

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