Geographic Responses of Groundfish to Variation in Abundance: Methods of Detection and Their Interpretation

1994 ◽  
Vol 51 (4) ◽  
pp. 808-816 ◽  
Author(s):  
C. Tara Marshall ◽  
Kenneth T. Frank
Keyword(s):  
Large Scale ◽  
Three Dimensional ◽  
Horizontal Distribution ◽  
Melanogrammus Aeglefinus ◽  
Age Classes ◽  
Dimensional Distribution ◽  
Catch Rates ◽  
Positive Correlations ◽  
Haddock Melanogrammus Aeglefinus ◽  
Trawl Surveys

Recent published studies have used data from bottom trawl surveys of groundfish populations to test whether distributional area and abundance are correlated. Two studies that used different indices to represent the distributional area of Georges Bank haddock (Melanogrammus aeglefinus) yielded conflicting results. To determine whether this is an example of different distributional indices measuring different things, both indices were regressed against estimates of abundance of haddock from a different but neighbouring location on the southwestern Scotian Shelf. Positive correlations were observed for immature age-classes using both indices whereas only one of the two indices resulted in positive correlations for mature age-classes. The following factors contributed to the lack of agreement among distributional indices: (1) age-aggregated indices potentially obscure correlations between distributional area and abundance for individual age-classes; (2) distributional indices that depend on the magnitude of catch rates confound variation in the large-scale horizontal distribution of stocks with diurnal variation in the three-dimensional distribution of schools; (3) distributional indices that scale positively with abundance generate spurious correlations. The results suggest that the outcome of any test of whether distributional area and abundance are correlated depends on the index chosen to represent distributional area.

scholarly journals Shifting fish distributions in warming sub-Arctic oceans

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Steven E. Campana ◽  
Ragnhildur B. Stefánsdóttir ◽  
Klara Jakobsdóttir ◽  
Jón Sólmundsson
Keyword(s):  
Fish Species ◽  
Climate Warming ◽  
Large Scale ◽  
Linear Models ◽  
Three Dimensional ◽  
Species Abundance ◽  
Time Frame ◽  
Thermal Limits ◽  
Dimensional Distribution ◽  
Distribution Shifts

Abstract The distributional response of marine fishes to climate warming would be expected to be very different than that of homeothermic birds and mammals, due both to more direct thermal effects on poikilothermic fish physiology and on reduced habitat fragmentation. In this study, we use a combination of linear models and graphical tools to quantify three-dimensional distribution shifts in 82 fish species caught in 5390 standardized groundfish survey tows over a 22-year time frame in the highly-productive sub-Arctic waters around Iceland. Over a 1 °C range, temperature significantly modified the distributional centroids of 72% of all fish species, but had relatively little effect on diversity. Most of the geographic shifts were to the northwest, and there was no overall tendency to move to deeper waters. A doubling of species abundance significantly influenced the distribution of 62% of species, but lacked the poleward orientation observed with temperature increases. Stenothermal species, those near their upper or lower thermal limits, and those with restricted spatial ranges were most likely to shift their distribution in response to climate warming, while deepwater species were not. A 2–3 °C warming of marine waters seems likely to produce large-scale changes in the location of many sub-Arctic fisheries.

Recruitment to Northwest Atlantic Cod (Gadus morhua) and Haddock (Melanogrammus aeglefinus) Stocks: Influence of Stock Size and Climate

1987 ◽  
Vol 44 (1) ◽  
pp. 26-39 ◽  
Author(s):  
J. Anthony Koslow ◽  
Keith R. Thompson ◽  
William Silvert
Keyword(s):  
Large Scale ◽  
Gadus Morhua ◽  
Reproductive Output ◽  
Atlantic Cod ◽  
Low Frequency ◽  
Melanogrammus Aeglefinus ◽  
Northwest Atlantic ◽  
Biological Variables ◽  
Low Frequency Variability ◽  
Haddock Melanogrammus Aeglefinus

Year-class success of both Atlantic cod (Gadus morhua) and haddock (Melanogrammus aeglefinus) stocks in the northwest Atlantic exhibits large-scale coherence and low-frequency variability with apparent periodicities of 10–20 yr. Several physical and biological variables in the region exhibit similar large-scale coherence and apparent periodicity. Multiple regression analysis indicates that year-class success in northwest Atlantic cod stocks tends to be associated with large-scale meteorological patterns and offshore winds. Recruitment to most haddock stocks from the Scotian Shelf to Georges Bank is negatively associated with abundance of 0-group mackerel, which may be due to predation over winter and/or to a combination of environmental features including sea-surface temperature, large-scale atmospheric pressure systems, and freshwater outflows. Statistical analyses often did not define a unique set of variables that best predicted fishery recruitment due to widespread intercorrelations among environmental processes and the likelihood that not all relevant processes entered directly into the analyses. There is little evidence that stock reproductive output during the study period was significantly related to year-class success.

Local-Scale versus Large-Scale Factors Affecting Recruitment

1991 ◽  
Vol 48 (6) ◽  
pp. 1003-1006 ◽  
Author(s):  
Edward B. Cohen ◽  
David G. Mountain ◽  
Robert O'Boyle
Keyword(s):  
Large Scale ◽  
Gadus Morhua ◽  
Atlantic Cod ◽  
Scale Effects ◽  
Melanogrammus Aeglefinus ◽  
Data Set ◽  
Factors Affecting ◽  
Scale Factors ◽  
Haddock Melanogrammus Aeglefinus ◽  
Recruitment Time

Recent analyses of Atlantic cod (Gadus morhua) and haddock (Melanogrammus aeglefinus) stocks in the northwest Atlantic have indicated that large-scale factors (several hundred to thousands of kilometres) dominate over effects operating on more local scales (10 to a few hundred kilometres} in determining recruitment patterns for these stocks. Adding additional years and additional stocks to the data set, the recruitment time series for cod and haddock have been reexamined. A first differencing technique was used to remove trends in the data. The results indicate that while large-scale effects probably do affect recruitment, the dominant factors are operating on more local scales and correlations are strongest for neighboring stocks.

scholarly journals A ring in a shell: the large-scale 6D structure of the Vela OB2 complex

2019 ◽  
Vol 621 ◽  
pp. A115 ◽  
Author(s):  
T. Cantat-Gaudin ◽  
M. Mapelli ◽  
L. Balaguer-Núñez ◽  
C. Jordi ◽  
G. Sacco ◽  
...  
Keyword(s):  
Small Groups ◽  
Large Scale ◽  
Three Dimensional ◽  
Unsupervised Classification ◽  
Young Stars ◽  
Total Current ◽  
Proper Motions ◽  
Large Spatial Scale ◽  
Dimensional Distribution ◽  
Current Mass

Context. The Vela OB2 association is a group of ∼10 Myr stars exhibiting a complex spatial and kinematic substructure. The all-sky Gaia DR2 catalogue contains proper motions, parallaxes (a proxy for distance), and photometry that allow us to separate the various components of Vela OB2. Aims. We characterise the distribution of the Vela OB2 stars on a large spatial scale, and study its internal kinematics and dynamic history. Methods. We make use of Gaia DR2 astrometry and published Gaia-ESO Survey data. We apply an unsupervised classification algorithm to determine groups of stars with common proper motions and parallaxes. Results. We find that the association is made up of a number of small groups, with a total current mass over 2330 M⊙. The three-dimensional distribution of these young stars trace the edge of the gas and dust structure known as the IRAS Vela Shell across ∼180 pc and shows clear signs of expansion. Conclusions. We propose a common history for Vela OB2 and the IRAS Vela Shell. The event that caused the expansion of the shell happened before the Vela OB2 stars formed, imprinted the expansion in the gas the stars formed from, and most likely triggered star formation.

scholarly journals Radio Surveys and Large Scale Structure

1991 ◽  
Vol 44 (6) ◽  
pp. 759 ◽  
Author(s):  
PA Shaver
Keyword(s):  
Radio Source ◽  
Large Scale ◽  
Three Dimensional ◽  
Large Scale Structure ◽  
Radio Galaxies ◽  
Scale Structure ◽  
Radio Sources ◽  
Clusters Of Galaxies ◽  
Normal Galaxies ◽  
Dimensional Distribution

An analysis of the Molonglo Reference Catalogue indicates that significant departures from isotropy are present in the sky distribution of strong extragalactic radio sources. This has been shown to be due to local large scale structure, specifically a concentration to the supergalactic plane, which also influences the slope of the source counts. A study of the three-dimensional distribution of local radio galaxies shows that they are more strongly concentrated to the supergalactic plane than are optically�selected galaxies, and that the supergalactic concentration is more extensive than hitherto believed. It appears that radio galaxies (and clusters of galaxies) trace the 'skeleton' of large scale structure, about which normal galaxies are more loosely distributed. Thus, while large scale structure evidently complicates the interpretation of radio source counts, it appears that radiO surveys can be of value in exploring structures on the largest scales.

scholarly journals Determining Ω0 and λ0 from Cosmological Redshift Distortion of Galaxies and Quasars

1999 ◽  
Vol 183 ◽  
pp. 235-240
Author(s):  
Yasushi Suto
Keyword(s):  
Large Scale ◽  
Collaborative Work ◽  
Cosmological Parameters ◽  
Three Dimensional ◽  
Density Parameter ◽  
Cosmological Redshift ◽  
Peculiar Velocity ◽  
Dimensional Distribution ◽  
Space Distortion ◽  
The Universe

The three-dimensional distribution of galaxies in the redshift surveys differ from the true one since the distance to each galaxy cannot be determined by its redshift z only; for z ≪ 1 the peculiar velocity of galaxies, typically ∼ (100–1000)km/sec, contaminates the true recession velocity of the Hubble flow, while the true distance for objects at z ≳ 1 sensitively depends on the (unknown and thus assumed) cosmological parameters. This hampers the effort to understand the true distribution of large-scale structure of the universe. Nevertheless such redshift-space distortion effects are quite useful since through the detailed theoretical modeling, one can derive the peculiar velocity dispersions of galaxies as a function of separation, and also can infer the cosmological density parameter Ω0, the dimensionless cosmological constant λ0, and the spatial biasing factor b of galaxies and/or quasars, for instance. In this talk, I discuss the importance of such redshift distortion induced by the geometry of the universe, which summarizes the recent results of my collaborative work in this topic (Matsubara & Suto 1996; Nakamura, Matsubara, & Suto 1998; Magira, Matsubara, Jing, & Suto 1998).

Objective Determination of the Large-scale Distribution of Galaxies

1991 ◽  
Vol 9 (1) ◽  
pp. 49-51
Author(s):  
R. J. Dodd ◽  
H. T. MacGillivray
Keyword(s):  
Large Scale ◽  
Large Body ◽  
Three Dimensional ◽  
Surface Distribution ◽  
Visible Part ◽  
Royal Observatory ◽  
The Galaxy ◽  
Dimensional Distribution ◽  
Objective Prism

AbstractObservations of the large-scale organisation of matter in the Universe are of great importance in present day astronomy. In the visible part of the spectrum such observations are mainly of the distribution of galaxies on the plane of the sky.Direct and objective prism plates obtained using large Schmidt telescopes form the bulk of the material used. The direct plates provide the observations from which the surface distribution of galaxies may be determined and the prism plates and FLAIR, via redshifts, yield extragalactic distances and hence the three dimensional distribution of galaxies.For large-scale surveys the measuring machines used need to be multi-purpose and fast such as COSMOS and SUPER-COSMOS at the Royal Observatory Edinburgh. More specific programs can make use of smaller, slower machines such as iris photometers and microdensitometers.The method of analysing the data produced rely on seeking density enhancements in the general field of galaxies for cluster detection or using correlation techniques for analysis of the galaxy distribution.A description is given of a southern sky catalogue containing 109 objects recently completed and an outline of some of the extragalactic projects underway using this large body of data.

Recruitment Patterns in Northwest Atlantic Fish Stocks

1984 ◽  
Vol 41 (12) ◽  
pp. 1722-1729 ◽  
Author(s):  
J. Anthony Koslow
Keyword(s):  
Large Scale ◽  
Gadus Morhua ◽  
Principal Component ◽  
Clupea Harengus ◽  
Melanogrammus Aeglefinus ◽  
Biological Interactions ◽  
Data Set ◽  
Northwest Atlantic ◽  
Physical Forcing ◽  
Positive Correlations

By analysing recruitment time series for 14 stocks of northwest Atlantic fish, I have found consistent positive correlations in recruitment among stocks within such species as cod (Gadus morhua), haddock (Melanogrammus aeglefinus), and herring (Clupea harengus). Significant positive correlations are also often found in recruitment among demersal, offshore-spawning species (cod, haddock, and redfish (Sebastes spp.)), and recruitment in these groups tends to be negatively correlated with that of pelagic species, which spawn inshore (herring) or in restricted waters (mackerel (Scomber scombrus)). These patterns emerge as well from a principal component (PC) analysis of the recruitment data. Three dominant patterns (PC 1–3) explain 78% of the variance of the data set. I suggest that the spatial extent of these patterns, which span the region from west Greenland to Georges Bank, indicates that large-scale physical forcing, rather than local biological interactions, predominantly regulates recruitment to northwest Atlantic fisheries.

Acoustic Observations of Patterns of Aggregation in Haddock (Melanogrammus aeglefinus) and Their Significance to Production and Catch

1992 ◽  
Vol 49 (1) ◽  
pp. 23-31 ◽  
Author(s):  
Paul R. Boudreau
Keyword(s):  
Body Size ◽  
Spatial Scales ◽  
Time Of Day ◽  
Melanogrammus Aeglefinus ◽  
Biomass Density ◽  
Dual Beam ◽  
Local Aggregation ◽  
Catch Rates ◽  
High Degree ◽  
Haddock Melanogrammus Aeglefinus

A dual-beam acoustic system was used to collect detailed information on density and body size over a 24-h period in an area of the Scotian Shelf occupied by a population of large spawning haddock (Melanogrammus aeglefinus). The acoustic sampling showed a persistent gradient of decreasing density with distance from bottom with 50% of the fish < 2.5 m off bottom. Horizontally (scale of hundreds of metres), there was a high degree of local aggregation which changed dramatically over 24 h. Highest aggregation was in daytime, with fish more dispersed throughout the water column at night. The differences in the degree of aggregation with time of day appear to be sufficient to explain diel changes in net catch rates. On larger geographic scales (tens of kilometres), fish density was relatively uniform. Acoustics provide a method for studying the relative importance of aggregation on these various spatial scales to estimates of abundance. Haddock biomass density was also related to organism body size, as has been observed for other species in both aquatic and terrestrial situations, suggesting that haddock population density is determined by trophic interactions similar to those that underlie production of other populations of organisms.

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