Age, growth and preliminary estimates of maturity of bigeye tuna, Thunnus obesus, in the Australian region

2006 ◽  
Vol 57 (7) ◽  
pp. 713 ◽  
Author(s):  
Jessica H. Farley ◽  
Naomi P. Clear ◽  
Bruno Leroy ◽  
Tim L. O. Davis ◽  
Geoff McPherson

Biological parameters such as age, growth and age (or size) at maturity are vital for accurate stock assessments and management plans to ensure that fisheries develop sustainably. Despite this, very few validated age studies have been conducted for large tropical pelagic species within the Australian region. Age and growth parameters were estimated for bigeye tuna, Thunnus obesus (Lowe, 1839), sampled from longline fisheries in the Australian region using validated techniques based on counts of annual increments. Poor increment clarity reduced the number of otoliths included in the final analysis to only 50% of the 3200 selected for reading (39–178-cm fork length). Microincrement analysis confirmed the position of the first two annual increments in these otoliths. A maximum age of 16 years was obtained, but over 80% of fish in the Australian catch were <5 years old. Growth is most rapid in the first few years of life and asymptotic length is reached at about age 9 to 10 years. The von Bertalanffy growth parameters were estimated at L∞ = 169.09, k = 0.238, and to = –1.706 for the south-west Pacific Ocean and L∞ = 178.41, k = 0.176, and to = –2.500 for the eastern Indian Ocean. These parameters were significantly different, suggesting that there is little mixing between populations in the Pacific and Indian Oceans. Length at 50% maturity for females sampled in northern Queensland was estimated to be 102.4-cm fork length.

2012 ◽  
Vol 10 (1) ◽  
pp. 148-158 ◽  
Author(s):  
Paulo Duarte-Neto ◽  
Fábio M. Higa ◽  
Rosangela P. Lessa

The purpose of the current study was to supply the first information on age and growth for Thunnus obesus caught in the equatorial south-western Atlantic using dorsal spines, an approach that has been successfully employed for ageing tuna species. The study was conducted using a multi-model inference based on information theory for back-calculated and observed length-at-age data. Uncertainty associated with the parameter estimation was verified and results were compared to other accounts on the species, considering both the statistical and methodological contexts. Samples were collected in Natal city (Rio Grande do Norte State, Brazil) from February 1999 to January 2000, of tuna vessels and from surveys, aimed at providing information on the Brazilian Exclusive Economic Zone (EEZ) in the area around São Pedro and São Paulo Archipelago. Validation using marginal increment indicated that one ring is deposited per year. Mean length-at-age ranged of 54.3 to 177.5 cm (fork length) for ages 1 to 9 years. Von Bertalanffy, Richards, and Gompertz models were considered suitable for the bigeye tuna. Hence, the model-averaged asymptotic length ¯L∞ was estimated. The averaged model generated in the present study by back-calculation was considered appropriate for describing the growth of T. obesus.


2009 ◽  
Vol 1 (1) ◽  
Author(s):  
Henry M. Manik

A preliminary research programme was carried out in order to study the acoustic wave reflection or target strength (TS) of tuna fish using a quantitative echo sounder (QES). The relationships between TS to fork length (FL) and swimbladder volume, for bigeye tuna (Thunnus obesus) and yellowfin tuna (T. albacares) are investigated. The TS of bigeye tuna was about 3 dB higher than yellowfin tuna when comparing species at the same size. The result can be correlated to the swimbladder volume differencebetween species. The relationship between TS and swimbladder volume was quantified for both species.Keywords: tuna fish, target strength, quantitative echo sounder


2009 ◽  
Vol 60 (5) ◽  
pp. 394 ◽  
Author(s):  
Francisco Cerna ◽  
Roberto Licandeo

The shortfin mako, Isurus oxyrinchus, is a large pelagic shark with a widespread global distribution. However, very little is known about most aspects of this species for the south-eastern Pacific. In the present paper, the age and growth parameters of the shortfin mako, caught by Chilean swordfish longline fisheries from 2004 to 2005, are reported. Ages were estimated by counting band-pairs from sections of vertebral centra from 547 individuals, ranging from 76 to 330 cm in total length (TL). Trends in the proportion of opaque edges for all ages combined and grouped into ages 0–6 and 7–26 years indicated that they are formed during summer and showed that annually, one band-pair is formed in the vertebrae of shortfin makos. Modal-progression analysis was used to verify the first three age classes (ages 0–2 years). For both sexes, the oldest estimated age was 25+ years. Von Bertalanffy growth parameters were estimated at L∞ = 325.29 cm TL, K = 0.076 year–1 and t0 = –3.18 years for females and L∞ = 296.60 cm TL, K = 0.087 year–1 and t0 = –3.58 years for males. The results indicated that this species is highly vulnerable to exploitation and, thus, urgent conservation measures are required.


2018 ◽  
Vol 59 (1) ◽  
pp. 97-110 ◽  
Author(s):  
Mado Kotsiri ◽  
Ioannis E. Batjakas

The otoliths of the Atlantic bonito, Sarda sarda (Bloch, 1793), were examined with the aim to estimate the age and growth of the species in the eastern Mediterranean Sea and to reveal possible relationships between otolith shape or size and age. All specimens used in this study, ranging from 7.2 to 70.4 cm in fork length and from 20 to 4889 g in total weight, were caught in the Aegean and Ionian Seas during the period 1997-2010. Otolith morphometry was studied using image analysis techniques for all intact sagittae ranging in weight from 0.6 to 11.3 mg and four shape indices were calculated. No statistical significant differences between left and right otolith morphometric variables were found. The age of fish was estimated by counting the pairs of opaque and translucent bands in transversal thin sections of otoliths. The estimated ages ranged from 0+ to 7 years and the von Bertalanffy growth parameters were determined \((L∞=79.9 cm, k=0.261 and to=-1.230 years)\). The examination of the type of growth bands at the outside margin of each otolith per month showed that one translucent band is formed annually during the cold season. The results revealed statistically significant relationships between otolith morphometric variables and fish length or age. Among the variables, otolith weight was the one that showed the highest correlation with age (R=0.77). Therefore, otolith weight could represent a valuable criterion for age estimation in Atlantic bonito that is objective, economic and easy to perform compared to annuli counting method in hard parts.


2014 ◽  
Vol 71 (10) ◽  
pp. 1529-1543 ◽  
Author(s):  
Chi Hin Lam ◽  
Benjamin Galuardi ◽  
Molly E. Lutcavage

To address the lack of fisheries-independent information for Atlantic bigeye tuna (Thunnus obesus), we released 21 adults (131 ± 12 cm curved fork length) between 2008 and 2010 in the Sargasso Sea and Northwest Atlantic. Data from nine tags (range: 1–292 days; mean: 89 days) revealed (i) pronounced north–south movements in pelagic waters between areas including Georges Bank, Mid- and South Atlantic Bight, Caribbean Sea, and Brazilian shelf, (ii) a lack of east–west exchange, and (iii) a high-use area in the Hatteras Plain, centered southwest of Bermuda. Bigeye tuna occupied water masses of 2.7–28.2 °C and depths of 0–1280 m, with deeper depths in the daytime (daily mean ± standard deviation: 196 ± 92 m) than at nighttime (45 ± 29 m). Even though bigeye tuna are assumed to forage on the deep scattered layer during the day, generalized additive mixed models did not identify the deep scattered layer as an important predictor of daytime swimming depth. Model results highlight the importance of geographic location in influencing habitat utilization, and thus suggest the need for fisheries-independent monitoring in high-catch areas, such as the central and equatorial Atlantic.


2017 ◽  
Vol 23 (1) ◽  
pp. 23 ◽  
Author(s):  
Pratiwi Lestari ◽  
R.J.G Lester ◽  
Craig Proctor

Tuna fish are highly migratory species. Clarifying their stock structures and migration patterns is important for tuna fisheries management. The purpose of this research was to examine the parasites of bigeye tuna (Thunnus obesus) and yellowfin tuna (Thunnus albacares) to determine which parasites may be potential stock markers for assessment of tuna migration patterns. Bigeye tuna and yellowfin tuna were collected (measured between 28-48 cm fork length) from 9 sites across Indonesia and from 2 ‘outlier sites’ (The Maldives and Solomon Islands). Organs including gills (filaments and branchial arches), stomach wall, liver, pyloric caeca, and intestines were examined. Seven types of didymozoids were distinguished including 3 Didymosulcus spp., 4 Kollikeria spp. and one acanthocephalan (Bolbosoma sp.). The results suggest these fish parasites are potentially useful markers for assessment of tuna migration pattern, contributing information needed for fisheries management in Indonesia.


2011 ◽  
Vol 9 (2) ◽  
pp. 393-401 ◽  
Author(s):  
Marília Previero ◽  
Carolina V. Minte-Vera ◽  
Matheus Oliveira Freitas ◽  
Rodrigo Leão de Moura ◽  
Claudenice Dei Tos

We determined the age and growth of the dog snapper (Lutjanus jocu), caught in the region of Abrolhos Bank, Bahia State, by the fishermen from coastal communities of Prado, Alcobaça, Caravelas, and Nova Viçosa. We examined 205 sectioned otoliths of fish caught by harpoon, longline, hand line, and gill nets (14.5 to 79.5 cm fork length). The formation of each ring was considered annual. The sectioned otoliths showed between 0 and 29 rings. Nearly half of the analyzed specimens had between 0 and 7 rings (88 of 205). Fish caught with nets in the estuarine region were the juvenile, while fish caught with lines and harpoons were the oldest. Two von Bertalanffy growth models were fitted to length-at-age data: one assuming constant variance of length-at-age (SVB) and another assuming constant coefficient of variation, i.e. variance increasing as a function of average size (CVVB). The SVB estimates were Loo = 87.82 cm, K = 0.10, and t0 = -1.486 and the CVVB estimates were Loo = 117.60 cm, K = 0.06, and t0 = -2.470. The largest Loo values estimated by the CVVB model are supported by reports from the literature of larger animals occurring in the deeper outer shelf of Abrolhos Bank. Growth parameters were also estimated for males and females separately (SVB model) (Loo = 92.80 cm, K = 0.099, and t0 = -1.680 for males, and Loo = 82.10 cm, K = 0.105, and t0 = -1.570 for females).


2007 ◽  
Vol 57 (3) ◽  
pp. 281-291 ◽  
Author(s):  
Murat Arslan ◽  
Ayhan Yildirim

AbstractAge and growth were analyzed for brown trout from the Stream Kan, upper Çoruh River, from January 2001 to December 2001. Age varied between 0-7 years and the ratio of male to female was 1:1.05. Fork length and total weight for brown trout varied by 6.9-22.1 cm and 4.9-158.5 g for males, by 6.8-26.1 cm and 4.3-211.9 g for females, respectively. Fork length and total weight at the same age classes were not statistically significant between males and females. The highest specific growth rate occurred between age 1 and age 2 for both sexes. The von Bertalanffy equations were used to determine growth in length for both sexes and overall population separately. The growth parameters for males, females and overall population were estimated as L∞ = 32.5 cm, K = 0.169, t0 = −0.978, L∞ = 36.7 cm, K = 0.139, t0 = −1.065 and L∞ = 35.9 cm, K = 0.147, t0 = −1.002, respectively. Overall growth performance (ø) suggested that difference between the growth of brown trout from Kan stream and those from some other populations was found not statistically significant.


2007 ◽  
Vol 58 (1) ◽  
pp. 34 ◽  
Author(s):  
Andrew N. Piercy ◽  
John K. Carlson ◽  
James A. Sulikowski ◽  
George H. Burgess

The scalloped hammerhead, Sphryna lewini (Griffith & Smith, 1834), is a globally exploited species of shark. In order to gain insight into the life history of this species in the USA waters, age and growth was examined from specimens (n = 307) captured from the north-west Atlantic Ocean and from the Gulf of Mexico. The von Bertalanffy growth model resulted in growth parameters of L∞ = 214.8 cm fork length (FL), k = 0.13 year–1, t0 = –1.62 year for males and L∞ = 233.1 cm FL, k = 0.09 year–1, t0 = –2.22 year for females. The oldest age estimates obtained for this population were 30.5 years for both males and females, which corresponded to FL of 234 cm and 241 cm respectively. Bowker’s test of symmetry and Index of Average Per Cent Error suggests that our ageing method represents a non-biased and precise approach to the age assessment. Marginal increments were significantly different between months (Kruskal–Wallis P = 0.017) with a distinct trend of increasing monthly increment growth beginning in January. When compared to previously published studies, our growth estimates suggest slower growth than populations in the Pacific Ocean but faster growth than previously reported in the Gulf of Mexico.


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