scholarly journals A review of the fisheries, life history and stock structure of tropical tuna (skipjack Katsuwonus pelamis, yellowfin Thunnus albacares and bigeye Thunnus obesus) in the Indian Ocean

2020 ◽  
Author(s):  
Iraide Artetxe-Arrate ◽  
Igaratza Fraile ◽  
Francis Marsac ◽  
Jessica H. Farley ◽  
Naiara Rodriguez-Ezpeleta ◽  
...  
Keyword(s):  
Life History ◽  
Indian Ocean ◽  
Thunnus Albacares ◽  
Stock Structure ◽  
Katsuwonus Pelamis ◽  
Thunnus Obesus ◽  
The Indian Ocean ◽  
Tropical Tuna

scholarly journals IDENTIFIKASI STRUKTUR STOK IKAN CAKALANG (Katsuwonus pelamis Linnaeus, 1758) DI SAMUDRA HINDIA (WPP NRI 573) MENGGUNAKAN ANALISIS BENTUK OTOLITH

2017 ◽  
Vol 23 (2) ◽  
pp. 77
Author(s):  
Arief Wujdi ◽  
Bram Setyadji ◽  
Suciadi Catur Nugroho
Keyword(s):  
Indian Ocean ◽  
Canonical Analysis ◽  
Sampling Location ◽  
Discrete Wavelet ◽  
Stock Structure ◽  
Katsuwonus Pelamis ◽  
Multivariate Statistic ◽  
Otolith Shape ◽  
The Indian Ocean ◽  
Outline Analysis

Ikan cakalang (Katsuwonus pelamis Linnaeus, 1758) yang tersebar luas di Samudra Hindia selatan Jawa, Bali dan Nusa Tenggara telah dieksploitasi secara terus menerus dengan berbagai alat tangkap. Pengelolaannya saat ini belum rasional karena masih diasumsikan sebagai unit stok tunggal tanpa adanya bukti ilmiah sehingga rentan mengalami lebih tangkap. Penelitian ini bertujuan untuk mengindentifikasi struktur stok ikan cakalang dengan teknik analisis bentuk otolith. Sampel otolith (saggittae) dikumpulkan pada bulan April, Agustus, dan September tahun 2016 di 4 lokasi, yaitu: Binuangeun, Sadeng, Prigi, dan Labuhan Lombok. Rekonstruksi bentuk otolith dilakukan dengan pendekatan outline analysis menggunakan teknik transformasi discrete wavelet. Uji statistik multivariate dengan kluster analisis menggunakan canonical analysis ofprincipal (CAP) dan uji ANOVA-like permutation juga diterapkan untuk menentukan signifikansi antar populasi. Hasil penelitian menunjukkan bahwa analisis bentuk otolith dapat digunakan sebagai penanda yang akurat untuk mengidentifikasi struktur stok. Bentuk otolith ikan cakalang bervariasi khususnya pada bagian rostrum, namun tidak berbeda nyata antar populasi (p>0,001). Hal tersebut berarti struktur stok ikan cakalang di Samudra Hindia (WPP NRI573) terdiri dari 1 populasi yang bergerak mengikuti pola perubahan lingkungan perairan di sepanjang Samudra Hindia. Skipjack tuna (Katsuwonus pelamis Linnaeus, 1758) distributed vastly along the Indian Ocean south of Java, Bali and Nusa Tenggara. It has been exploited by various fishing gear yet it always assumed to be a single stock. It was not based on scientific evidence but merely based on “a scientific assumption”, so that vulnerable to subject of overfishing. This research aims to examine the alternative tool for identifying the stock structure based on the otolith shape. Sampling location took place in four regions, namely: Binuangen, Sadeng, Prigi and Labuhan Lombok. The otolith (sagittae) samples was collected during April, August, and September 2016. The otolith shape was reconstructed using outline analysis with discrete wavelet transformation technique. A multivariate statistic using canonical analysis of principal (CAP) and ANOVA-like permutation test were also used to determine the signification among populations. The result showed that skipjack’s otolith shape was varied from one and another, especially in the rostrum. But it was not statistically different among regions (p>0.001), which means a single stock for skipjack in the Indian Ocean (Indonesian territory of FMA 573). This study also proved that otolith shape can be useful marker tool to identify stock structure for management purpose.

scholarly journals Comparison of handline tuna catches in Indian Ocean and Banda Sea waters

2021 ◽  
Vol 322 ◽  
pp. 03004
Author(s):  
Ignatius Tri Hargiyatno ◽  
Regi Fiji Anggawangsa ◽  
Moh. Natsir ◽  
I. Gede Bayu Sedana ◽  
Agustinus Anung Widodo ◽  
...  
Keyword(s):  
Indian Ocean ◽  
Average Length ◽  
Fishing Ground ◽  
Katsuwonus Pelamis ◽  
Thunnus Obesus ◽  
Significant Difference ◽  
Landing Sites ◽  
The Indian Ocean ◽  
Catch Composition ◽  
First Maturity

There are two essential landing sites for handline tuna in Indonesia: Palabuhanratu (in the Indian Ocean) and Kendari (in the Banda Sea). This paper analyzes handline catches from the Indian Ocean and Banda Sea waters as the main fishing ground. The catch composition of the handline tuna landed in Kendari is more varied than Palabuhanratu. Several species commonly caught are yellowfin tuna (Thunnus albacares), skipjack tuna (Katsuwonus pelamis), bigeye tuna (Thunnus obesus) as a target species, and some billfish species as bycatch. Mean CPUE for handline tuna landed in Palabuhanratu is lower than Kendari. A significant difference is based on the monthly mean CPUE variation between Palabuhanratu and Kendari landing sites (p < 0.001). Handline catches in Palabuhanratu had a more comprehensive range of length sizes than Kendari, using a two-sample K-S test showed significant differences (p < 0.001). The fish size landed in Kendari is relatively smaller than Palabuhanratu. The average length of fish caught by handline is smaller than the length at first maturity (Lm) value in both landing sites. The use of large size hook for hand lines is recommended for catching tunas in this area.

scholarly journals Otolith microchemistry: a useful tool for investigating stock structure of yellowfin tuna (Thunnus albacares) in the Indian Ocean

2019 ◽  
Vol 70 (12) ◽  
pp. 1708 ◽  
Author(s):  
Iraide Artetxe-Arrate ◽  
Igaratza Fraile ◽  
David A. Crook ◽  
Iker Zudaire ◽  
Haritz Arrizabalaga ◽  
...  
Keyword(s):  
Stable Isotopes ◽  
Indian Ocean ◽  
Yellowfin Tuna ◽  
Thunnus Albacares ◽  
Stock Structure ◽  
North West ◽  
Natal Origin ◽  
Oxygen Stable Isotopes ◽  
West Indian Ocean ◽  
The Indian Ocean

A better understanding of the stock structure of yellowfin tuna (Thunnus albacares) in the Indian Ocean is needed to ensure the sustainable management of the fishery. In this study, carbon and oxygen stable isotopes (δ13C and δ18O) and trace elements (138Ba, 55Mn, 25Mg and 88Sr) were measured in otoliths of young-of-the-year (YOY) and age-1 yellowfin tuna collected from the Mozambique Channel and north-west Indian Ocean regions. Elemental profiles showed variation in Ba, Mg and Mn in YOY otolith composition, but only Mn profiles differed between regions. Differences in YOY near-core chemistry were used for natal-origin investigation. Ba, Mg and Mn were sufficiently different to discriminate individuals from the two regions, in contrast with carbon and oxygen stable isotopes. A linear discriminant analysis resulted in 80% correct classification of yellowfin tuna to their natal origin. Classification success increased to 91% using a random forest algorithm. Finally, a unique larval source was detected among age-1 yellowfin tuna. The signal of these fish resembled that of YOY from a north-west Indian Ocean origin, highlighting the importance of local production. The present study supports the use of otolith chemistry as a promising approach to analyse yellowfin stock structure in the Indian Ocean.

scholarly journals Otolith chemical fingerprints of skipjack tuna (Katsuwonus pelamis) in the Indian Ocean: First insights into stock structure delineation

PLoS ONE ◽  
2021 ◽  
Vol 16 (3) ◽  
pp. e0249327
Author(s):  
Iraide Artetxe-Arrate ◽  
Igaratza Fraile ◽  
Jessica Farley ◽  
Audrey M. Darnaude ◽  
Naomi Clear ◽  
...  
Keyword(s):  
Chemical Composition ◽  
Indian Ocean ◽  
Equatorial Indian Ocean ◽  
Otolith Microchemistry ◽  
Stock Structure ◽  
Skipjack Tuna ◽  
Katsuwonus Pelamis ◽  
Nursery Areas ◽  
Chemical Signatures ◽  
The Indian Ocean

The chemical composition of otoliths (earbones) can provide valuable information about stock structure and connectivity patterns among marine fish. For that, chemical signatures must be sufficiently distinct to allow accurate classification of an unknown fish to their area of origin. Here we have examined the suitability of otolith microchemistry as a tool to better understand the spatial dynamics of skipjack tuna (Katsuwonus pelamis), a highly valuable commercial species for which uncertainties remain regarding its stock structure in the Indian Ocean. For this aim, we have compared the early life otolith chemical composition of young-of-the-year (<6 months) skipjack tuna captured from the three main nursery areas of the equatorial Indian Ocean (West, Central and East). Elemental (Li:Ca, Sr:Ca, Ba:Ca, Mg:Ca and Mn:Ca) and stable isotopic (δ13C, δ18O) signatures were used, from individuals captured in 2018 and 2019. Otolith Sr:Ca, Ba:Ca, Mg:Ca and δ18O significantly differed among fish from different nurseries, but, in general, the chemical signatures of the three nursery areas largely overlapped. Multivariate analyses of otolith chemical signatures revealed low geographic separation among Central and Eastern nurseries, achieving a maximum overall random forest cross validated classification success of 51%. Cohort effect on otolith trace element signatures was also detected, indicating that variations in chemical signatures associated with seasonal changes in oceanographic conditions must be well understood, particularly for species with several reproductive peaks throughout the year. Otolith microchemistry in conjunction with other techniques (e.g., genetics, particle tracking) should be further investigated to resolve skipjack stock structure, which will ultimately contribute to the sustainable management of this stock in the Indian Ocean.

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