Vertical distribution of Atlantic bluefin tuna Thunnus thynnus and bonito Sarda sarda larvae is related to temperature preference

Reglero, Patricia; Blanco, Edurne; Alemany, Francisco; Ferrà, Carmen; Alvarez-Berastegui, Diego; Ortega, Aurelio; Gándara, Fernando de la; Aparicio‐González, Alberto; Folkvord, Arild

doi:10.3354/meps12516

Cited by 18 publications

(8 citation statements)

References 43 publications

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“…Because more than 95% of the larval tuna and P. noctiluca early life stages permanently remain in the top 30 m of the water column (Fig. S2; Reglero et al 2018 a ; Ottmann et al 2021), we selected samples of 540 oblique bongo tows (90 cm diameter and 500 μ m mesh size) deployed down to 30 m depth in 2012–2017 and consider them representative of both populations. Immediately after each tow, samples were preserved in 4% formalin buffered with borax for quantitative analysis.…”

Section: Methodsmentioning

confidence: 99%

Spawning site distribution of a bluefin tuna reduces jellyfish predation on early life stages

Ottmann

Fiksen

Martín

et al. 2021

Limnology & Oceanography

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Bluefin tunas across the world migrate long distances to spawn in particularly warm and oligotrophic areas constrained by oceanographic fronts. The low abundance of predators in these areas increases survival chances of their early life stages, but its importance for choice of spawning habitat is unknown. Here, we use estimated clearance rates and data on spatial distributions of Atlantic bluefin tuna larvae Thunnus thynnus and metaephyrae of the jellyfish Pelagia noctiluca to quantify predation at a major spawning ground in the Mediterranean Sea. We found that high densities of P. noctiluca can rapidly deplete tuna eggs and preflexion larvae, but their patchy distribution and low spatial and temporal overlap results in overall low predation. The specific distribution of the spawning sites suggests that bluefin tunas may use local oceanography as cues to spawn outside areas with high predator densities.

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Section: Methodsmentioning

confidence: 99%

Spawning site distribution of a bluefin tuna reduces jellyfish predation on early life stages

Ottmann

Fiksen

Martín

et al. 2021

Limnology & Oceanography

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“…larvae and 25 m depth for skipjack larvae. These depths were selected because they represent the mid-point of observed vertical distributions for these taxa 28,29,60 . The particles were tracked backwards in time for 15 days from collection date, with a model time step of 20 minutes.…”

Section: Methodsmentioning

confidence: 99%

Evidence and patterns of tuna spawning inside a large no-take Marine Protected Area

Hernández

Witting

Willis

et al. 2019

Sci Rep

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The Phoenix Islands Protected Area (PIPA), one of the world’s largest marine protected areas, represents 11% of the exclusive economic zone of the Republic of Kiribati, which earns much of its GDP by selling tuna fishing licenses to foreign nations. We have determined that PIPA is a spawning area for skipjack ( Katsuwonus pelamis ), bigeye ( Thunnus obesus ), and yellowfin ( Thunnus albacares ) tunas. Our approach included sampling larvae on cruises in 2015–2017 and using a biological-physical model to estimate spawning locations for collected larvae. Temperature and chlorophyll conditions varied markedly due to observed ENSO states: El Niño (2015) and neutral (2016–2017). However, larval tuna distributions were similar amongst years. Generally, skipjack larvae were patchy and more abundant near PIPA’s northeast corner, while Thunnus larvae exhibited lower and more even abundances. Genetic barcoding confirmed the presence of bigeye ( Thunnus obesus ) and yellowfin ( Thunnus albacares ) tuna larvae. Model simulations indicated that most of the larvae collected inside PIPA in 2015 were spawned inside, while stronger currents in 2016 moved more larvae across PIPA’s boundaries. Larval distributions and relative spawning output simulations indicated that both focal taxa spawned inside PIPA in all 3 study years, demonstrating that PIPA is protecting viable tuna spawning habitat.

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“…Atlantic bluefin tuna (BFT), as with other tuna species, reproduce in temperatures above 20 • C conducive for survival and development of eggs and larvae [24,25]. Therefore, temperature is often the primary variable used to explain the shallow depth distribution of tuna larvae in environments with a strong seasonal thermocline where temperatures of 20 • C occur at around 20 m depth (e.g., Pacific bluefin tuna in the Nansei area [26]; Albacore and BFT in the NW Mediterranean [27]). However, tunas also reproduce in areas that lack a strong near-surface seasonal thermocline and where temperatures above 20 • C are mixed throughout the upper water column.…”

Section: Introductionmentioning

confidence: 99%

“…Pacific bluefin tuna larvae, Thunnus orientalis, is the only species for which the vertical distribution has been compared across two spawning areas with different scenarios showing a shallower and narrower distribution in areas with a strong thermocline [28]. Laboratory experiments show that BFT and bonito larvae occupy a wider depth range when temperatures are vertically homogeneous compared to when waters are stratified, in which case BFT larvae are confined to the surface mixed layer [27]. Vertical temperature distributions may then play a major role on the vertical distribution of tuna species and companion species, a task that has received little attention in the literature.…”

Section: Introductionmentioning

confidence: 99%

Influence of the Seasonal Thermocline on the Vertical Distribution of Larval Fish Assemblages Associated with Atlantic Bluefin Tuna Spawning Grounds

Álvarez

Rasmuson

Gerard

et al. 2021

Oceans

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Temperature is often an important variable influencing the vertical position of fish larvae in the water column. The same species may show different vertical distributions in areas with a strong near-surface seasonal thermocline compared to isothermal near-surface regions. In areas with a strong surface thermocline, tuna larvae show a significant preference for the near-surface warmer layers. Little is known regarding larval tuna vertical distribution in isothermal waters and on the vertical distribution of the associated larval fish assemblages. We conducted vertical stratified sampling using the same methodology and fishing device (MOCNESS) in the two major spawning areas of Atlantic bluefin tuna (BFT): western Mediterranean Sea (MED), characterized by a surface thermocline, and the Gulf of Mexico (GOM) which lacks thermal stratification. Tuna larvae occupied the upper 30 m in both areas, but the average larval depth distribution was consistently deeper in the GOM. In the MED, vertical distribution of larval fish assemblages was explained by temperature, and species such as BFT, Thunnus alalunga, and Ceratoscopelus maderensis, among others, coexist above the thermocline and are separated from species such as Cyclothone braueri and Hygophum spp. (found below the thermocline). In the GOM, the environmental correlates of the vertical distribution of the larvae were salinity and fluorescence. Mesopelagic taxa such as Ceratoscopelus spp. and Cyclothone spp., among others, had a shallower average distribution than Lampanyctus spp., Hygophum spp., and Myctophum spp.

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Vertical distribution of Atlantic bluefin tuna Thunnus thynnus and bonito Sarda sarda larvae is related to temperature preference

Cited by 18 publications

References 43 publications

Spawning site distribution of a bluefin tuna reduces jellyfish predation on early life stages

Spawning site distribution of a bluefin tuna reduces jellyfish predation on early life stages

Evidence and patterns of tuna spawning inside a large no-take Marine Protected Area

Influence of the Seasonal Thermocline on the Vertical Distribution of Larval Fish Assemblages Associated with Atlantic Bluefin Tuna Spawning Grounds

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