The comparison of population density of Holothuria tubulosa (Gmelin, 1790) and Holothuria polii (Delle Chiaje, 1823) between exploited and non-exploited areas in the Aegean Sea coast of Türkiye

Year 2022, Volume: 39 Issue: 4, 267 - 274, 15.12.2022

Altan Lök Aytaç Özgül Tuğçe Şensurat Genç Evrim Kurtay Aynur Lök

https://doi.org/10.12714/egejfas.39.4.01

Abstract

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Increasing demand from the Asian market first led to the collapse of economically valuable sea cucumber stocks in the Indo-Pacific, and then demand shifted to lower value Mediterranean species. The effect of this change in sea cucumber stocks in Türkiye started to be seen after the 2010s. To address it, we carried out a study to compare the population density of the most caught Holothuria tubulosa and Holothuria polii species between exploited and non-exploited areas in the Aegean Sea coast of Türkiye. The study was carried out between September 2018 and March 2020 at 4 stations, two of which are in Çandarlı Bay, where sea cucumber fishing is free, and two in İzmir Bay, where it is prohibited. Samplings between 0-20 m depths were carried out with underwater transect line technique, and at depths deeper than 20 m, with beam trawling operations. A total of 6 sea cucumber species were identified, including Holothuria mammata, Holothuria sanctori, Parastichopus regalis and Holothuria forskali species, apart from the target species H. tubulosa and H. polii. Only one P. regalis individual was recorded in the samplings in waters deeper than 20 m. The mean densities of H. tubulosa and H. polii were found to be higher in İzmir Bay stations than in Çandarlı Bay (p<0.05). The results of this study clearly reveal that the population density of sea cucumber in sampling areas has decreased tens of times compared to the last 5 years.

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Keywords

Holothuria sp., biometry, overexploitation, fisheries management, Aegean Sea

Supporting Institution

TÜBİTAK

Project Number

TOVAG-217O206

Thanks

This study supported by The Scientific and Technological Research Council of Turkey (Agriculture, Forestry And Veterinary Research Support Group, No: 217O206). We would like to thank our colleagues and R/V EGESÜF personnel for their contributions to the sea trials.

Türkiye'nin Ege Denizi kıyılarında Holothuria tubulosa (Gmelin, 1790) ve Holothuria polii (Delle Chiaje, 1823) populasyon yoğunluğunun av yapılan ve yapılmayan alanlar arasındaki karşılaştırılması

Abstract

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Asya pazarının artan talebi, ilk olarak İndo-Pasifik’teki ekonomik açıdan değerli deniz patlıcanı stoklarının çökmesine sebep olmuştur ve daha sonra talep daha düşük değere sahip Akdeniz türlerine yönelmiştir. Türkiye'deki deniz patlıcanı stoklarında bu değişimin etkisi 2010'lu yıllardan sonra görünmeye başlamıştır. Bunu ele almak için, Türkiye'nin Ege Denizi kıyılarında en çok avlanan Holothuria tubulosa ve Holothuria polii türlerinin popülasyon yoğunluğunu, avcılığın serbest ve yasak olduğu alanlarda karşılaştırmak için bir çalışma yaptık. Çalışma, ikisi deniz patlıcanı avcılığının serbest olduğu Çandarlı Körfezi'nde, ikisi ise yasak olduğu İzmir Körfezi'nde olmak üzere 4 istasyonda gerçekleştirilmiştir. 0-20 m derinlikler arasındaki örneklemeler sualtı çizgisel hat tekniği ile 20 m'den derindekiler ise algarna operasyonları ile gerçekleştirilmiştir. Hedef tür H. tubulosa ve H. polii dışında Holothuria mammata, Holothuria sanctori, Parastichopus regalis ve Holothuria forskali türleri olmak üzere toplam 6 deniz patlıcanı türü tespit edilmiştir. 20 m'den daha derin sularda yapılan örneklemelerde sadece bir P. regalis bireyi kaydedilmiştir. H. tubulosa ve H. polii'nin ortalama yoğunlukları İzmir Körfezi istasyonlarında Çandarlı Körfezi'ne göre daha yüksek bulundu (p<0,05). Bu çalışmanın sonuçları, deniz patlıcanı popülasyon yoğunluğunun son 5 yılda onlarca kat azaldığını açıkça ortaya koymaktadır.

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Keywords

Holothuria sp., biyometri, aşırı avcılık, balıkçılık yönetimi, Ege Denizi

Project Number

TOVAG-217O206

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