scholarly journals Improving the West Greenland Trawl Survey for Shrimp (Pandalus borealis)

2000 ◽  
Vol 27 ◽  
pp. 151-160 ◽  
Author(s):  
D Carlsson ◽  
P Kanneworff ◽  
O Folmer ◽  
M Kingsley ◽  
M Pennington
Keyword(s):  
Trawl Survey ◽  
The West ◽  
Pandalus Borealis ◽  
West Greenland

scholarly journals Calibration of bottom trawls for northern shrimp

2008 ◽  
Vol 65 (6) ◽  
pp. 873-881 ◽  
Author(s):  
Michael C. S. Kingsley ◽  
Kai Wieland ◽  
Bo Bergström ◽  
Michael Rosing
Keyword(s):  
Density Dependence ◽  
Bayesian Methods ◽  
The Other ◽  
Bottom Trawl ◽  
Trawl Survey ◽  
Low Density ◽  
The West ◽  
Pandalus Borealis ◽  
Northern Shrimp ◽  
Data Calibration

Abstract Kingsley, M. C. S., Wieland, K., Bergström, B., and Rosing, M. 2008. Calibration of bottom trawls for northern shrimp. – ICES Journal of Marine Science, 65: 873–881. The Skjervøy 3000 trawl used since 1988 in the West Greenland bottom-trawl survey has been replaced by a Cosmos 2000. To be able to compare old data on the northern shrimp (Pandalus borealis) with new data, calibration experiments were carried out by trawling twice consecutively along the same track, using either the same gear twice or the two different gears in one order or the other. Catch models were fitted to the shrimp data—both size-aggregated catch weights and size-specific counts—by likelihood and Bayesian methods. The catch in the second haul relative to that in the first depended not only on the gear used in the two hauls, but also on density, the second catches being a smaller proportion of first catches when densities were high, and often larger than the first catches at low-density stations. This density-dependence of the catch ratio was larger for small shrimp than for big ones. The Cosmos trawl was estimated to fish with ∼87% of the catchability of the Skjervøy trawl after correction for its greater wingspread. Catchability ratio varied with the size of shrimp caught, but the differences were not statistically significant.

scholarly journals Buffered random sampling: a sequential inhibited spatial point process applied to sampling in a trawl survey for northern shrimp Pandalus borealis in West Greenland waters

2004 ◽  
Vol 61 (1) ◽  
pp. 12-24 ◽  
Author(s):  
M.C.S. Kingsley ◽  
P. Kanneworff ◽  
D.M. Carlsson
Keyword(s):  
Random Sampling ◽  
Sampling Method ◽  
Sample Survey ◽  
Standard Errors ◽  
Trawl Survey ◽  
Pandalus Borealis ◽  
West Greenland ◽  
Northern Shrimp ◽  
Manual Adjustment ◽  
Statistical Effects

Abstract A stratified random sample survey has been carried out since 1988 as a component of the assessment of the stock of northern shrimp Pandalus borealis in offshore West Greenland waters. In 1999, the placing of stations independently and randomly was replaced by buffered random sampling, in which stations were randomly placed but prevented from being closer together than a prescribed limit. Buffered random sampling gave a more even distribution of stations within strata, and nearest-neighbour distances were on average increased by 50%. The statistical effects were difficult to determine, but did not appear to be large, and the estimated standard errors did not change much from previous years. However, the buffered sampling method generated designs in which stations were evenly distributed over the strata, and did away with the need for subjective manual adjustment of the positions of stations which independent random sampling sometimes placed too close to another station.

scholarly journals Genetic mixed-stock analysis disentangles spatial and temporal variation in composition of the West Greenland Atlantic Salmon fishery

2016 ◽  
Vol 73 (9) ◽  
pp. 2311-2321 ◽  
Author(s):  
Ian R. Bradbury ◽  
Lorraine C. Hamilton ◽  
Timothy F. Sheehan ◽  
Gerald Chaput ◽  
Martha J. Robertson ◽  
...  
Keyword(s):  
Atlantic Salmon ◽  
North American ◽  
Temporal Stability ◽  
Spatial And Temporal Variation ◽  
Published Data ◽  
The West ◽  
West Greenland ◽  
Archived Samples ◽  
Mixed Stock ◽  
Salmon Fishery

Abstract The West Greenland Atlantic Salmon (Salmo salar) fishery represents the largest remaining mixed-stock fishery for Atlantic Salmon in the Northwest Atlantic and targets multi-sea-winter (MSW) salmon from throughout North America and Europe. We evaluated stock composition of salmon harvested in the waters off West Greenland (n = 5684 individuals) using genetic mixture analysis and individual assignment to inform conservation of North American populations, many of which are failing to meet management targets. Regional contributions to this fishery were estimated using 2169 individuals sampled throughout the fishery between 2011 and 2014. Of these, 22% were identified as European in origin. Major North American contributions were detected from Labrador (∼20%), the Southern Gulf/Cape Breton (29%), and the Gaspe Peninsula (29%). Minor contributions (∼5%) were detected from Newfoundland, Ungava, and Quebec regions. Region-specific catches were extrapolated using estimates of composition and fishery catch logs and harvests ranged from 300 to 600 and 2000 to 3000 individuals for minor and major constituents, respectively. To evaluate the temporal stability of the observed fishery composition, we extended the temporal coverage through the inclusion of previously published data (1995–2006, n = 3095) and data from archived scales (1968–1998, n = 420). Examination of the complete time-series (47 years) suggests relative stability in stock proportions since the late 1980s. Genetic estimates of stock composition were significantly associated with model-based estimates of returning MSW salmon (individual years r = 0.69, and overall mean r = 0.96). This work demonstrates that the analysis of both contemporary and archived samples in a mixed-stock context can disentangle levels of regional exploitation and directly inform assessment and conservation of Atlantic Salmon in the West Greenland interceptory Atlantic Salmon fishery.

scholarly journals Topographic and Glaciological Controls on Holocene Ice-Sheet Margin Dynamics. Central West Greenland

1990 ◽  
Vol 14 ◽  
pp. 307-310 ◽  
Author(s):  
C.R. Warren ◽  
N.R.J. Hulton
Keyword(s):  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Glacial Maximum ◽  
Warm Climate ◽  
Short Term ◽  
The West ◽  
West Greenland ◽  
The Past

The retreat of the West Greenland ice sheet from its Sisimiut (Wisconsinan) glacial maximum, was punctuated by a series of Stillstands or small readvances that formed numerous moraines. These landforms have been interpreted in the past as the result of short-term, regional falls in ablation-season temperatures. However, mapping of the geomorphological evidence south of Ilulissat (Jakobshavn) suggests that retreat behaviour was not primarily governed by climate, and therefore that the former ice margins are not palaeoclimatically significant. During warm climate ice-sheet wastage, the successive quasi-stable positions adopted by the ice margin were largely governed by topography. The retreat of the inherently unstable calving glaciers was arrested only at topographically-determined locations where stability could be achieved.

scholarly journals Quaternary deposits between the Sukkertoppen ice cap and Nordre Strømfjord

1970 ◽  
Vol 28 ◽  
pp. 23-25
Author(s):  
A Weidick ◽  
N.W Ten Brink
Keyword(s):  
Land Area ◽  
The West ◽  
Quaternary Deposits ◽  
Sea Levels ◽  
West Greenland ◽  
Marine Deposits ◽  
Ice Cap

The area investigated during 1969 is located approximate1y between 66° 10' and 67° 30' N, and 50° and 52° W, the eastem half of the West Greenland ice-free land area transected by Søndre Strømfjord. The principal objectives of the work were to map and describe the glacial and emerged marine deposits for a Quatemary map at 1:500 000 scale, and to collect material for establishing a radiometric chronology of former ice-margin positions and sea levels. In order to study as large an area as possible, the investigations north of Søndre Strømfjord and Sondrestrom Airbase were conducted by A. Weidick, the area south of this by N. W. Ten Brink.

scholarly journals A pilot seismo-stratigraphic study on the West Greenland continental shelf

1989 ◽  
Vol 142 ◽  
pp. 1-16
Author(s):  
J.A Chalmers
Keyword(s):  
Petroleum Industry ◽  
Source Rocks ◽  
Tectonic Activity ◽  
The West ◽  
West Greenland ◽  
Main Site ◽  
Half Graben ◽  
Greenland Basin ◽  
Seismic Sections ◽  
Structural Closure

Seismo-stratigraphic interpretation of seismic sections dating from the mid-1970s has disclosed the existence of four megasequences of sediments, the oldest of which has not previously been reported from West Greenland. The basins containing these sediments developed as a series of coalescing half graben, in which the main site of tectonic activity changed with time. A structural closure of sufficient size to contain interesting quantities of hydrocarbons, given suitable source rocks, reservoir and seal, is identified. The study has shown that the evaluation of the West Greenland Basin during the 1970s was inadequate, and that abandonment of exploration by the petroleum industry may have been premature.

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