Acoustic evidence for unusual diel behaviour of a mesopelagic fish (Vinciguerria nimbaria) exploited by tuna

Marchal, Émile; Lebourges, Anne

doi:10.1006/jmsc.1996.0062

Cited by 48 publications

(29 citation statements)

References 1 publication

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“…Thus our results support the notion that there is a high degree of net avoidance by myctophids in the upper regions of the water column during periods of high daylight intensity (Collins et al, 2008). Other studies have reported daylight near-surface schooling of mesopelagic fish that perform DVM in high latitude and equatorial regions and it has been suggested that this could be related to local light regimes (Alverson, 1961;Kaartvedt et al, 1998;Marchal and Lebourges, 1996). For example, both these regions represent an extreme regarding light climate, such as the absence of darkness in summer at high latitudes and rapid changes between daylight and darkness in equatorial regions.…”

Section: Insight Into Myctophid Ecologysupporting

confidence: 89%

School characteristics of mesopelagic fish at South Georgia

Saunders

Fielding

Thorpe

et al. 2013

Deep Sea Research Part I: Oceanographic Research Papers

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In this paper, we describe the variation in myctophid schools characteristics at South Georgia using multi-frequency acoustic data collected annually between November 2007 and January 2012. We studied the relationship between the proximity of land and the distribution and schooling characteristics of myctophid fish. We also examined patterns in schooling behaviour in relation to oceanographic data. Fish schools were identified using a dualfrequency dB identification method (S v120-38 kHz ), where negative S v120-38 kHz is indicative of gas-bearing organisms, such as swimbladdered fish. Available net data were used to provide information on the meosopelagic fish community in the region. School morphometrics (e.g. length, thickness, area) data were extracted and pooled according to their distance from the shore (0-30 km, 30-60 km, 60-90 km, 90-120 km). A total of 578 schools were detected in the survey region and there was high variation in school backscattering strength (NASC), length, height, perimeter, depth and horizontal distribution between surveys, including distinct inter-annual variation in these parameters when surveys were conducted in the same season (2009)(2010)(2011)(2012). Schools were distributed predominantly on-shelf (0-500 m isobaths) during some summer surveys (2007 and 2012) and predominantly off-shelf on others (>500 2 m isobaths; 2009, 2010 and 2011). There was also evidence of bathymetric separation in the horizontal distribution of schools. Schools observed in the late-season in 2008 had the greatest NASC, largest height and the deepest depth distribution. Most schools occurred at depths between ~60-300 m, but they did not occupy the same water masses during each survey. Schools became progressively thinner, shallower and acoustically weaker with increasing distance to land, whilst school length and perimeter increased correspondingly.The change in fish schooling behaviour between environments could be a response to a combination of local predatory threats over short spatial/temporal scales and differences in oceanographic conditions, such as current velocity. The trend could also be evidence of spatial habitat partitioning of myctophids, with different schooling species, or different lifestages, orientating along a bathymetric gradient at South Georgia.

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Section: Insight Into Myctophid Ecologysupporting

confidence: 89%

School characteristics of mesopelagic fish at South Georgia

Saunders

Fielding

Thorpe

et al. 2013

Deep Sea Research Part I: Oceanographic Research Papers

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show abstract

“…data). It has been observed elsewhere that mesopelagic fish can form diurnal surface aggregations under specific oceanographic conditions (Marchal & Lebourges 1996, Bertrand et al 2002a. Where prey were available, jack mackerel aggregated and foraged during the daytime.…”

Section: Discussionmentioning

confidence: 91%

Determinism and plasticity of fish schooling behaviour as exemplified by the South Pacific jack mackerel Trachurus murphyi

Bertrand¹,

Barbieri²,

Gerlotto³

et al. 2006

Mar. Ecol. Prog. Ser.

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Pelagic fish schools are thought to show a general pattern of dispersion at night and aggregation within schools during the day. This pattern is often accepted as the major rule driving most of the other physiological, biological and ecological processes. Foraging on mobile prey, for instance, is assumed to be enhanced by schooling behaviour. Current theory assumes then that foraging is only possible for obligatory gregarious predatory fish from dawn to dusk. However, offshore mesopelagic communities perform vertical migrations and are out of reach for most oceanic pelagic predators during the day (with the exception of some apex predators, e.g. swordfish or bigeye tuna). To investigate how fish may overcome this apparent contradiction, we studied the 3-dimensional spatial strategy of the South Pacific jack mackerel Trachurus murphyi according to the abiotic and biotic conditions of the habitat. Data came from acoustic surveys performed in central Chile in 1997Chile in , 1998Chile in and 1999. Our results show that the jack mackerel distribution was driven by prey during the night when foraging, and related to the hydrology when resting during the day in the upper part of the oxycline. Fish were more aggregated at night than during the day, probably because jack mackerel cycles of schooling behaviour depend primarily on prey availability. This 'atypical' behaviour could be an adaptation of gregarious pelagic fish to an oceanic ecosystem. Fish schooling behaviour is not necessarily driven directly by the diel cycle; rather, it can be functional and depends on prey availability.

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“…Acoustic surveys, on the other hand, allow a 2-dimensional and continuous approach to the pelagic habitat and are a good tool when studying the distribution of micronekton. For example, Marchal et al (1993), Roger & Marchal (1994) and Marchal & Lebourges (1996) used acoustics to study the behaviour and distribution of Vinciguerria nimbaria, the main tuna prey south of Libena in the Tropical Atlantic. This method was also used on dolphin prey by Fiedler et al (1998).…”

Section: Introductionmentioning

confidence: 99%

Acoustic characterisation of micronekton distribution in French Polynesia

Bertrand¹,

Borgne²,

Josse³

1999

Mar. Ecol. Prog. Ser.

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Tuna distribution may be directly linked to food ava~labllity, the density of which can be assessed by echo-sounding. A study was performed in the French Polynesian EEZ (Economic Exclusive Zone) between 1995 and 1997 with a 38 kHz echo sounder working down to 500 m depth. With the settings used, acoustic back-scattered energy may be considered as representative of micronektonic fish biomass and provided information on horizontal and vertical micronekton variabilities and the structure of the echograms. Three different zones were defined by multivanate analysis. The classical biomass decreasing gradient from the equator to higher latitudes did not appear. Instead, the maximum micronekton abundance was found between Marquesas Archipelagos and a west-northwest/eastsoutheast oriented line stretching between l1 and 14"S, i.e. in a weak convergence, favourable to micronekton development due to the concentration of lower trophic levels with no oxygen limitation in the deep layers. Two zones with very different hydrological features, but with comparable micronektonic abundances, surround the richest micronekton zone. To the north, waters are enriched by the equatorial upwelling, but intense organic matter remineralisation limits oxygen availability under the therrnocline. To the south, waters are influenced by the great southern gyre and present oligotrophic characteristics less favourable to rnicronekton development. The present results suggest that prediction of tuna forage distribution should take not only trophic parameters into account, but also environmental ones. They also suggest that echo-sounding data should be used more extensively in the validation of models predicting tuna forage.

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Acoustic evidence for unusual diel behaviour of a mesopelagic fish (Vinciguerria nimbaria) exploited by tuna

Cited by 48 publications

References 1 publication

School characteristics of mesopelagic fish at South Georgia

School characteristics of mesopelagic fish at South Georgia

Determinism and plasticity of fish schooling behaviour as exemplified by the South Pacific jack mackerel Trachurus murphyi

Acoustic characterisation of micronekton distribution in French Polynesia

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