Patterns in the distribution of myctophid fish in the northern Scotia Sea ecosystem

Collins, Martin A.; Xavier, José C.; Johnston, Nadine M.; North, A. W.; Enderlein, Peter; Tarling, Geraint A.; Waluda, Claire M.; Hawker, Elizabeth J.; Cunningham, Nathan

doi:10.1007/s00300-008-0423-2

Cited by 112 publications

(110 citation statements)

References 27 publications

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“…There are consequently few robust net data on myctophids available from these surveys. However, we draw upon published data from myctophid surveys conducted around South Georgia during time periods coinciding with the present study to support our observations where possible Collins et al, 2008). Although these surveys were not conducted during our WCB surveys, the data are the most contemporary and comprehensive available for meosopelagic fish in the region to date.…”

Section: Survey Detailssupporting

confidence: 73%

“…Ground-truthed acoustic observations also showed that aggregations of squid in the region tended to have a relatively weak acoustic response and exhibit positive S v120-38 kHz backscatter (Goss et al, 2001;), so we advocate that squid were an unlikely source of bias in the study. All available net data from around South Georgia collected around the timeframe of the study period showed that the dominant group of swimbladdered fish in the mesopelagic community was Myctophidae Collins et al, 2008). Other swimbladdered fish groups, such as some Bathylagidae, were observed in the region, but these groups were comprised of predominantly deep-dwelling fish that occurred below our vertical observation window (>600 m) Collins et al, 2008).…”

Section: Target Identificationmentioning

confidence: 78%

“…In this paper, we identified mesopelagic fish schools using a validated dual-frequency technique (Madureira et al, 1993;Watkins and Brierley, 2002) and we attributed these schools to the myctophid component of the South Georgia fish community based on available net data obtained during the study and from published sources Collins et al, 2008). Biological targets with negative S v120-38 kHz backscatter around South Georgia are most likely to be organisms with gas-filled organs such as siphonophores, swimbladdered fish, or possibly squid (Korneliussen and Ona, 2003;Madureira et al, 1993;Martin et al, 1996;Woodd-Walker et al, 2003).…”

Section: Target Identificationmentioning

confidence: 99%

“…All available net data from around South Georgia collected around the timeframe of the study period showed that the dominant group of swimbladdered fish in the mesopelagic community was Myctophidae Collins et al, 2008). Other swimbladdered fish groups, such as some Bathylagidae, were observed in the region, but these groups were comprised of predominantly deep-dwelling fish that occurred below our vertical observation window (>600 m) Collins et al, 2008). These groups often occur only in relatively low abundance at South Georgia and they are not known to exhibit daytime vertical migrations that would result in them being detected above 500 m during our surveys Gon, 1990).…”

Section: Target Identificationmentioning

confidence: 99%

“…Myctophids are the most dominant mesopelagic fish families in the South Georgia region in terms of abundance and diversity Collins et al, 2008;Hulley, 1981).…”

Section: Introductionmentioning

confidence: 99%

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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: Survey Detailssupporting

confidence: 73%

Section: Target Identificationmentioning

confidence: 78%

Section: Target Identificationmentioning

confidence: 99%

Section: Target Identificationmentioning

confidence: 99%

“…Myctophids are the most dominant mesopelagic fish families in the South Georgia region in terms of abundance and diversity Collins et al, 2008;Hulley, 1981).…”

Section: Introductionmentioning

confidence: 99%

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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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Spatial and Temporal Operation of the Scotia Sea Ecosystem

Murphy

Watkins

Trathan

et al. 2012

Antarctic Ecosystems

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Life Beyond the Ice

Xavier

Peck

2015

Exploring the Last Continent

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The Antarctic Circumpolar Current isolates Antarctic waters and their living organisms from warmer waters to the north. Over the last 25-35 million years, this isolation has led to specific environmental conditions, including a sharp drop in water temperatures south of the Polar Frontal Zone and the formation of sea ice during winter. Three key factors control productivity in the Southern Ocean today. Firstly, the Southern Ocean contains about 1.8 times as much oxygen as tropical seawater because more oxygen can dissolve in water at lower temperatures. Secondly, upwelling currents bring nutrients from the seabed to feed microscopic algae at the surface, and, lastly, the seasonal formation of sea ice has a profound impact on marine life. In addition, there is a long period of low or no light in winter, extreme physical disturbance from icebergs and a very high level of coastal productivity. All these factors have been important in the evolution of the characteristic Southern Ocean species and have resulted in a high degree of endemism, particularly in certain groupings of Antarctic organisms such as crustaceans and fish. The Southern Ocean represents 9.6 % of the world's oceans and is a key part of Earth's system. As the climate changes and sea level rises, the behavior of deepocean currents associated with the global thermohaline conveyor belt is altered and marine organisms respond. Our knowledge of the Southern Ocean has increased considerably in the last 20 years, but our understanding of adaptations, biological cycles and responses to change is still poor and more research is needed.

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Patterns in the distribution of myctophid fish in the northern Scotia Sea ecosystem

Cited by 112 publications

References 27 publications

School characteristics of mesopelagic fish at South Georgia

School characteristics of mesopelagic fish at South Georgia

Spatial and Temporal Operation of the Scotia Sea Ecosystem

Life Beyond the Ice

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