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Bilgin, Sabri; Bal, Hatice; Taşçı, Burak

doi:10.4194/1303-2712-v12_4_15

Cited by 13 publications

(4 citation statements)

References 9 publications

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“…The size range found was smaller than that previously observed in the AS [31] and similar to the Black Sea [82,83]. As already reported for other gadoids [84], the Mediterranean maximum size was much smaller than the Atlantic one [76,85,86].…”

Section: Population Biological Traitssupporting

confidence: 66%

Whiting (Merlangius merlangus) Grows Slower and Smaller in the Adriatic Sea: New Insights from a Comparison of Two Populations with a Time Interval of 30 Years

Calì,

Stranci,

La Mesa

et al. 2023

Fishes

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Nowadays, overexploitation and climate change are among the major threats to fish production all over the world. In this study, we focused our attention on the Adriatic Sea (AS), a shallow semi-enclosed sub-basin showing the highest exploitation level and warming trend over the last decades within the Mediterranean Sea. We investigated the life history traits and population dynamics of the cold-water species whiting (Merlangius merlangus, Gadidae) 30 years apart, which is one of the main commercial species in the Northern AS. The AS represents its southern limit of distribution, in accordance with the thermal preference of this cold-water species. Fish samples were collected monthly using a commercial bottom trawl within the periods 1990–1991 and 2020–2021. The historical comparison highlighted a recent reduction in large specimens (>25 cm total length, TL), which was not associated with trunked age structures, therefore indicating a decrease in growth performance over a period of 30 years (L∞90–91 = 29.5 cm TL; L∞20–21 = 22.8 cm TL). The current size at first sexual maturity was achieved within the first year of life, at around 16 cm TL for males and 17 cm TL for females. In the AS, whiting spawns in batches from December to March, showing a reproductive investment (gonadosomatic index) one order of magnitude higher in females than in males. Potential fecundity (F) ranged from 46,144 to 424,298, with it being heavily dependent on fish size. We hypothesize that the decreased growth performance might be related to a metabolic constraint, possibly related to the increased temperature and its consequences. Moreover, considering the detrimental effects of size reduction on reproductive potential, these findings suggest a potential endangerment situation for the long-term maintenance of whiting and cold-related species in the AS, which should be accounted for in setting management strategies.

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Section: Population Biological Traitssupporting

confidence: 66%

Whiting (Merlangius merlangus) Grows Slower and Smaller in the Adriatic Sea: New Insights from a Comparison of Two Populations with a Time Interval of 30 Years

Calì,

Stranci,

La Mesa

et al. 2023

Fishes

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“…Moreover, the Rn value of the non-seasonal VBG curves for S. guttatus improved by 21% after fitting a seasonal VBG curve. Seasonal changes in fish growth mostly caused by differences in water temperature and reproductive activities affecting fish feeding mechanism (Bilgin et al, 2012;Bilgin et al, 2013). In the literature, reproduction time was reported during June and July in the Bay of Bengal (Rashid et al, 2010), from January to August, with a peak in April and May off the south coast of India (Devaraj, 1987), from April to July around Rameswaram Island between India and Sri Lanka (Collette and Nauen, 1983).…”

Section: Discussionmentioning

confidence: 99%

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Ahmed¹,

Bilgin²,

Bat³

2016

Turk. J. Fish. Aquat. Sci.

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“…It is caught with gillnets in the Sea of Marmara and is among the most caught species as bycatch in shrimp fisheries by beam trawl. Previous studies on whiting were mostly concentrated in the Black Sea (Düzgüneş and Karaçam, 1990;Erkoyuncu et al, 1994;Samsun, 1995;Şahin and Akbulut, 1997;Samsun and Erkoyuncu, 1998;Kalaycı et al, 2007;Bilgin et al, 2012;Kasapoğlu and Düzgüneş, 2014;Mazlum and Bilgin, 2014;Samsun and Akyol, 2017;Taylan et al, 2018;Türker and Bal, 2018;Balık and Öztaş, 2019;Yıldız and Karakulak, 2019;Aksu, 2020).…”

Section: Introductionmentioning

confidence: 99%

Current Status, Management, and Future Prospects of Whiting (Merlangius merlangus) in the Sea of Marmara

Karadurmuş

2022

Acta Aquatica Turcica

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The current status of whiting (Merlangius merlangus Linnaeus, 1758) populations in the Sea of Marmara (Turkey) was evaluated by estimating growth and mortality rates in this study. The overall sex ratio (M:F) was calculated as 1:1.36. b value of LWR computed as 2.8904 for both sex groups, and M. merlangus showed a negative allometric growth type by Pauly's t-test result. The age of individuals in the population ranged from I to VI. The growth parameters were estimated as L∞ = 35.74 cm, k = 0.124 yr -1 , and t0 = -1.338 years for all individuals. Total mortality (Z), natural mortality (M), and fishing mortality (F) rates were calculated as 1.35 yr -1 , 0.34 yr -1, and 1.01 yr -1 , respectively. The Phi-prime growth index (φ′) and exploitation rate (E) of the population were calculated as 2.20 and 0.75 yr -1 . According to the results, it is obvious that the whiting stocks in the Marmara Sea are currently used at a high capacity (E = 0.75 yr -1 ). The impact of over-fishing can have increasingly detrimental effects on the overall population size of this population. Fisheries management practices in the Marmara Sea should be regulated by taking into account the ecosystem change, fishing fleet, and unreported catch data. In addition, temporal or spatial fishing bans can be applied by increasing the selectivity of fishing gear. Keywords Age  Growth  Exploitation rate  Marmara Sea  LWR Özet: Bu çalışmada, Marmara Denizi'ndeki (Türkiye) mezgit (Merlangius merlangus Linnaeus, 1758) popülasyonunun büyüme ve ölüm oranları tahmin edilerek mevcut durumu değerlendirilmektedir. Cinsiyet oranı (E:D) 1:1,36 olarak hesaplanmıştır. LWR b değeri her iki cinsiyet için 2,8904 olarak hesaplandı ve Pauly's t-testi sonuçlarına göre mezgit popülasyonu negatif allometrik büyüme gösterdi. Popülasyondaki bireylerin yaşları I ile VI arasında değişim göstermiştir. Büyüme parametreleri, tüm bireyler için L∞ = 35,74 cm, k = 0,124 yıl -1 , and t0 = -1,338 yıl olarak tahmin edilmiştir. Toplam ölüm (Z), doğal ölüm (M) ve balıkçılık ölüm (F) oranları sırasıyla 1,35 yıl -1 , 0,34 yıl -1 and 1,01 yıl -1 olarak hesaplanmıştır. Popülasyonun Phi-prime büyüme indeksi (φ′) ve sömürü oranı (E) 2,20 ve 0,75 yıl -1 olarak hesaplanmıştır. Sonuçlara göre Marmara Denizi'ndeki mezgit stoklarının şu anda yüksek kapasitede kullanıldığı aşikardır (E = 0,75). Aşırı avlanmanın etkisi, genel popülasyon büyüklüğü üzerinde giderek daha fazla zararlı etkiye sebep olabilir. Marmara Denizi'ndeki ekosistem değişimi, balıkçı filosu ve rapor edilmemiş av verileri dikkate alınarak balıkçılık yönetimi uygulamaları düzenlenmelidir. Av araçlarının seçiciliği artırılarak zamansal veya mekânsal avlanma yasakları uygulanabilir.

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Untitled

Cited by 13 publications

References 9 publications

Whiting (Merlangius merlangus) Grows Slower and Smaller in the Adriatic Sea: New Insights from a Comparison of Two Populations with a Time Interval of 30 Years

Whiting (Merlangius merlangus) Grows Slower and Smaller in the Adriatic Sea: New Insights from a Comparison of Two Populations with a Time Interval of 30 Years

Untitled

Current Status, Management, and Future Prospects of Whiting (Merlangius merlangus) in the Sea of Marmara

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