Regional patterns in mercury and selenium concentrations of yellowfin tuna (Thunnus albacares) and bigeye tuna (Thunnus obesus) in the Pacific Ocean

2011 ◽  
Vol 68 (12) ◽  
pp. 2046-2056 ◽  
Author(s):  
Bridget E. Ferriss ◽  
Timothy E. Essington
Keyword(s):  
Pacific Ocean ◽  
Trophic Level ◽  
Equatorial Region ◽  
Yellowfin Tuna ◽  
High Trophic Level ◽  
Thunnus Albacares ◽  
Bigeye Tuna ◽  
Central Pacific ◽  
Regional Patterns ◽  
Thunnus Obesus

Mercury (Hg) concentrations in high trophic level fish, such as bigeye tuna ( Thunnus obesus ) and yellowfin tuna ( Thunnus albacares ), can often exceed consumption advisories. Here we sampled 444 yellowfin and bigeye tuna to determine whether tuna Hg concentration varies regionally in the eastern and central Pacific Ocean and whether this variation corresponds to environmental characteristics that promote the bioavailability of Hg. Of the five regions sampled, we found significantly higher Hg concentrations in the eastern equatorial region (5°S–5°N; 110°W–120°W) for both species. Hg concentrations in this region were elevated by 0.22 and 0.17 µg·g–1for yellowfin and bigeye tuna, respectively, compared with Hg concentrations in the other regions. Tuna selenium concentrations, which may alter the toxicity of Hg, did not vary by region. Oceanographic data indicated that the eastern equatorial region had elevated chlorophyll a concentrations and shallow minimum oxygen depths, both of which promote Hg methylation. These findings suggest that methylation-promoting mechanisms may translate into regional variation in the Hg concentrations of highly mobile, high trophic level fish.

scholarly journals Influence of oceanographic variability on recruitment of yellowfin tuna (Thunnus albacares) in the western and central Pacific Ocean

2009 ◽  
Vol 66 (9) ◽  
pp. 1462-1477 ◽  
Author(s):  
Adam Langley ◽  
Karine Briand ◽  
David Seán Kirby ◽  
Raghu Murtugudde
Keyword(s):  
Pacific Ocean ◽  
Stock Assessment ◽  
Equatorial Region ◽  
Yellowfin Tuna ◽  
Assessment Model ◽  
Thunnus Albacares ◽  
Central Pacific ◽  
Central Pacific Ocean ◽  
Oceanographic Variables ◽  
Recruitment Model

Recruitment estimates for yellowfin tuna ( Thunnus albacares ) in the western and central Pacific Ocean (WCPO), derived from a stock assessment model, are highly variable seasonally, interannually, and over decadal periods. A generalized linear model (GLM) was developed that predicts the variation in yellowfin tuna recruitment in response to a range of oceanographic variables. The GLM model accounted for 54% of the variation in quarterly recruitment for the period 1980–2003, with the inclusion of seven different oceanographic variables derived from a zone within the northwestern equatorial region of the WCPO. The robustness of the recruitment model was investigated by cross-validation. The GLM was complemented by a cluster analysis approach that identified five principal oceanographic states within the northwestern zone selected by the GLM. Incorporation of the recent GLM recruitment indices in the yellowfin tuna stock assessment model is likely to improve the precision of estimates of current and projected (next 1–2 years) biomass and exploitation rates. In a broader context, the recruitment model provides a tool to investigate how yellowfin tuna recruitment might vary in response to short- and long-term variation in the oceanographic conditions of the WCPO.

scholarly journals KOMPOSISI JENIS DAN DISTRIBUSI UKURAN IKANPELAGIS BESAR HASILTANGKAPANPANCINGULURDI SENDANGBIRU, JAWATIMUR

2017 ◽  
Vol 3 (6) ◽  
pp. 377
Author(s):  
Ria Faizah ◽  
Aisayah Aisayah
Keyword(s):  
Species Composition ◽  
Size Distribution ◽  
Landing Site ◽  
Pelagic Fish ◽  
Yellowfin Tuna ◽  
Thunnus Albacares ◽  
Bigeye Tuna ◽  
Katsuwonus Pelamis ◽  
Individual Weight ◽  
Thunnus Obesus

Sendang Biru merupakan salah satu tempat pendaratan ikan pelagis besar di Jawa Timur. Penelitian tentang komposisi jenis dan ukuran ikan pelagis besar hasil tangkapan pancing ulur yang didaratkan di PPI Pondok Dadap, Sendang Biru, Jawa Timur, dilakukan pada bulanApril dan Oktober 2010. Hasil penelitian menunjukkan hasil tangkapan pancing ulur didominasi oleh jenis tuna (Thunnus albacares dan Thunnus obesus) 45%, cakalang (Katsuwonus pelamis) sebesar 38 %, dan lainnya (marlin, lemadang, lauro) sebesar 1,7 %. Ikan tuna yang didaratkan terdiri dari jenis yellowfin tuna (Thunnus albacares) dan bigeye tuna (T. obesus) dengan ukuran panjang cagakmasing –masing berkisar antara 40 - 170 cmFL dan 40 - 140 cmFL. Berat individumasing-masing berkisar antara 0.1 - 71 kg dan 0.5 - 43 kg. Sendang Biru is one of big pelagic’s landing site in East Java. Tuna on this research are caught by handline that landing in PPI Pondok Dadap, Sendang Biru, East Java. Research on the species composition and size distribution of big pelagic fish caught by handline were carried out during April and October 2010 at Sendang Biru, East Java. The result showed that Thunnus sp. are the most landed (45%) followed by Katsuwonus pelamis (38 %) and others (Xiphias gladius, Coriphaena sp., Elagatis bipinnulatus) of 1.7 %. The dominant fork lengthof Thunnus albacares and Thunnus obesus ranged from about 40 - 170 cm and 40 – 140 cm. Individual weight ranged between 0.1 - 71 kg and 0.5 - 43 kg respectivelly.

A spatially disaggregated, length-based, age-structured population model of yellowfin tuna (Thunnus albacares) in the western and central Pacific Ocean

2001 ◽  
Vol 52 (7) ◽  
pp. 937 ◽  
Author(s):  
John Hampton ◽  
David A. Fournier
Keyword(s):  
Pacific Ocean ◽  
Yellowfin Tuna ◽  
Growth Patterns ◽  
Thunnus Albacares ◽  
Central Pacific ◽  
Data Set ◽  
Structured Population Model ◽  
Central Pacific Ocean ◽  
Age Structured ◽  
The Impact

A spatially disaggregated, length-based, age-structured model for yellowfin tuna (Thunnus albacares) in the western and central Pacific Ocean is described. Catch, effort, length-frequency and tagging data stratified by quarter (for the period 1962–99), seven model regions and 16 fisheries are used in the analysis. The model structure includes quarterly recruitment in each region, 20 quarterly age classes, independent growth patterns for juveniles and adults, structural time-series variation in catchability for all non-longline fisheries, age-specific natural mortality, and age-specific movement among the model regions. Acceptable fits to each component data set comprising the log-likelihood function were obtained. The model results suggest that declines in recruitment, and as a consequence, population biomass, have occurred in recent years. Although not obviously related to over-exploitation, the recruitment decline suggests that the productivity of the yellowfin tuna stock may currently be lower than it has been previously. Recent catch levels appear to have been maintained by increases in fishing mortality, possibly related to increased use of fish aggregation devices in the purse-seine fishery. A yield analysis indicates that average catches over the past three years may have slightly exceeded the maximum sustainable yield. The model results also reveal strong regional differences in the impact of fishing. Such heterogeneity in the fisheries and the impacts on them will need to be considered when future management measures are designed.

scholarly journals Pelagic longline fishery for albacore tuna (Thunnus alalunga) yellowfin tuna (Thunnus albacares) and bigeye tuna (Thunnus obesus) in the high seas of eastern Pacific ocean.

2018 ◽  
Author(s):  
Bruno Thierry Nyatchouba Nsangue ◽  
Zhou Cheng ◽  
Liuxiong Xu ◽  
Richard Kindong
Keyword(s):  
Pacific Ocean ◽  
Condition Factor ◽  
Yellowfin Tuna ◽  
Eastern Pacific ◽  
Bigeye Tuna ◽  
Eastern Pacific Ocean ◽  
Albacore Tuna ◽  
Thunnus Obesus ◽  
Hook Depth ◽  
High Seas

This study highlighted the occurrence of a pelagic long line fishery targeting albacore tuna, yellowfin tuna and bigeye tuna in the high seas of eastern Pacific Ocean. Species selectivity of the fishing method was assessed. Hook depth, statistics of at-vessel survival rate grouped by hooks number, length frequency, weight frequency, length weight relationship, relative condition factor and Fulton’s condition factor were estimated for the target species. This fishing method proved highly selective for albacore tuna, where catches accounted for about 85% of catches, while other resources such as yellowfin tuna amounted to 4.8% and big eye tuna accounted for 9.70%. The results showed that, fish size increased with deeper depths. Hook No. 8 located at a critical depth indicated that fork lengths of tuna registered above this depth were significantly smaller than that those captured below it. Logistic regression model suggested a significant effect of hook depth on the catch efficiency. The highest density of catch efficiency was located at the depth of 167.57 m. An alternative strategy showed that hooks deployed at the depths ranging from 124 to 211 m will result in a more considerable fishing efficiency. The analyses also showed that the relative condition factors (Krel) of the three fish species were greater than (1) implying that they were in good physiological condition at the time of capture.

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