Aggregating Behavior of Yellowfin and Bigeye Tuna Tagged With Coded Ultrasonic Transmitters Around FADs in Okinawa, Japan

Ohta, Itaru; Kakuma, Shinichiro; Kanashiro, Kiyoaki

doi:10.1007/978-94-017-1402-0_6

Cited by 8 publications

(5 citation statements)

References 4 publications

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“…Ohta et al. (), however, found that yellowfin tuna left and returned to FADs at night. Our results support the latter finding that long range horizontal movements occur during the daytime.…”

Section: Discussionmentioning

confidence: 64%

“…Ohta et al. () found that 85% of yellowfin tuna in a school remained for less than one hour, with the longest stay being 24 days in the waters around Okinawa. Ohta and Kakuma () showed that the average single stay at a surface FAD was 4–5 days.…”

Section: Discussionmentioning

confidence: 99%

“…Ohta et al. () and Ohta and Kakuma () in Okinawan waters, but none has been attempted in Taiwanese waters.…”

Section: Introductionmentioning

confidence: 99%

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Fine-scale vertical and horizontal movements of juvenile yellowfin tuna (Thunnus albacares ) associated with a subsurface fish aggregating device (FAD) off southwestern Taiwan

et al. 2013

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Summary An increase in yellowfin tuna (Thunnus albacares) catch by danish seine fisheries around the subsurface fish aggregating devices (FADs) in southern Taiwan waters has been a concern of local government and environmental groups. However, the attraction mechanism of aggregating tunas at the subsurface FADs is still poorly understood. The objective of this study is to examine the fine‐scale vertical and horizontal movements of juvenile yellowfin tunas around a subsurface FAD. In total, 53 tunas (35–81 cm fork length) were tagged with ultrasonic telemetry tags and released at a subsurface FAD in the waters off Shiao‐Liu‐Chiu Island, southwestern Taiwan from October 2008 to December 2009. These tunas stayed at the subsurface FAD for up to 31 days, with daytime vertical movement depths averaging 60–80 m at a maximum depth of 250 m. At night, the tuna gathered at a shallow depth of 40 m. The mean depth of vertical movement in the daytime is significantly different from that of the nighttime (P < 0.05). The maximum detectable distance of horizontal movement was 1.6 km, with 80% of the long horizontal movements occurring in the daytime. It is likely that the purpose of these vertical and horizontal movements was for feeding or avoiding predators. Moreover, the tagged tunas did not depart from the subsurface FAD simultaneously, suggesting distinct behaviors in their movements.

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Section: Discussionmentioning

confidence: 64%

Section: Discussionmentioning

confidence: 99%

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Fine-scale vertical and horizontal movements of juvenile yellowfin tuna (Thunnus albacares ) associated with a subsurface fish aggregating device (FAD) off southwestern Taiwan

et al. 2013

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“…Based on observations of residence time of tropical tuna around anchored FADs (Ohta et al 2001, Itano et al 2004 or aggregated at seamounts (Holland et al 1999, Klimley et al 2003, only tuna for which time at liberty was larger than 5 d were considered suitable for the purpose of the analysis (even if it was unclear whether residency under drifting FADs can be considered the same as under anchored FADs or at seamounts). To minimize measurement errors, unrealistic growth rates (i.e.…”

Section: Datamentioning

confidence: 99%

Drifting fish aggregation devices could act as an ecological trap for tropical tuna species

Hallier¹,

Gaertner²

2008

Mar. Ecol. Prog. Ser.

166

152

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Purse seine fishing on fish aggregating devices (FADs) has expanded considerably during the last 15 yr in tropical tuna purse seine fisheries, and FADs currently account for about 70% of their reported tuna catches. The scientific community has expressed concern over the consequences of this fishing practice in terms of yield per recruit and suspected detrimental effects on FADassociated tunas. To explore possible detrimental effects, we compared stomach fullness, fish plumpness, growth rate, and migration behaviour between free school and drifting FAD-associated tunas for skipjack tuna Katsuwonus pelamis and yellowfin tuna Thunnus albacares caught in the Atlantic and Indian Oceans. Significant differences in fish plumpness and individual growth rates were found, suggesting that individuals associated with drifting FADs were less healthy than those in free schools. Since stomach fullness indicated that tunas associated with FADs eat less than those in free schools, the difference in growth rate and condition could be the consequence of altered feeding patterns. For each species, significant changes in migratory direction and displacement rates were observed in the presence of drifting FADs. These findings support the hypothesis that FADs act as a super-stimulus, misleading tunas to make inappropriate habitat selection. However, further studies are required to investigate the long-term effect of FADs on the entire life cycle of tunas.

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“…Recently, archival tags have been applied for investigating the behavior of tuna species, including bigeye tuna (Schaefer and Fuller, , , ; Musyl et al ., ; Evans et al ., ; Schaefer et al ., ). Several studies on the behavior of this species have employed ultrasonic telemetry (Holland et al ., ; Dagorn et al ., , ; Ohta et al ., ; Ohta and Kakuma, ) and pop‐up tags (Matsumoto et al ., ; Arrizabalaga et al ., ; Howell et al ., ). Several studies reported clear diurnal patterns in swimming depth; that is, the fish stay in the upper layer during the night and dive deep during the daytime.…”

Section: Introductionmentioning

confidence: 99%

Vertical behavior of bigeye tuna (Thunnus obesus) in the northwestern Pacific Ocean based on archival tag data

Matsumoto

Kitagawa

Kimura

2013

Fisheries Oceanography

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The behavior of bigeye tuna (Thunnus obesus) in the northwestern Pacific Ocean was investigated using archival tag data for 28 fish [49–72 cm fork length (FL) at release, 3–503 days] released in Japanese waters around the Nansei Islands (24–29°N, 122–132°E) and east of central Honshu (Offshore central Honshu, 32–36°N, 142–148°E). Vertical behavior was classified into three types based on past studies: ‘characteristic’ (non‐associative), ‘associative’ (associated with floating objects) and ‘other’ (behavior not fitting into these two categories). The proportion of fish showing associative behavior decreased and that of characteristic behavior increased as fish grew, and this shift was pronounced at 60–70 cm FL. The fish usually stayed above the 20°C isotherm during the daytime and nighttime when showing associative behavior and below the 20°C isotherm during daytime for characteristic behavior. A higher proportion of characteristic behavior was seen between December and April around the Nansei Islands, and between September and December for offshore central Honshu. Seasonal changes in vertical position were also observed in conjunction with changes in water temperature. In this study, ‘other’ behavior was further classified into five types, of which ‘afternoon dive’ behavior, characterized by deep dives between around noon and evening, was the most frequent. The present study indicated that in the northwestern Pacific Ocean, the vertical behavior of bigeye tuna changes with size, as well as between seasons and regions.

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Aggregating Behavior of Yellowfin and Bigeye Tuna Tagged With Coded Ultrasonic Transmitters Around FADs in Okinawa, Japan

Cited by 8 publications

References 4 publications

Fine-scale vertical and horizontal movements of juvenile yellowfin tuna (Thunnus albacares ) associated with a subsurface fish aggregating device (FAD) off southwestern Taiwan

Fine-scale vertical and horizontal movements of juvenile yellowfin tuna (Thunnus albacares ) associated with a subsurface fish aggregating device (FAD) off southwestern Taiwan

Drifting fish aggregation devices could act as an ecological trap for tropical tuna species

Vertical behavior of bigeye tuna (Thunnus obesus) in the northwestern Pacific Ocean based on archival tag data

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