scholarly journals Decadal‐Scale Variation in Mean Trophic Level in Beibu Gulf Based on Bottom‐Trawl Survey Data

2021 ◽  
Vol 13 (3) ◽  
pp. 174-182
Author(s):  
Li Su ◽  
Zuozhi Chen ◽  
Kui Zhang ◽  
Youwei Xu ◽  
Shannan Xu ◽  
...  
Keyword(s):  
Survey Data ◽  
Trophic Level ◽  
Bottom Trawl ◽  
Beibu Gulf ◽  
Trawl Survey ◽  
Bottom Trawl Survey ◽  
Decadal Scale ◽  
Mean Trophic Level ◽  
Scale Variation

Validation of deep-sea coral and sponge distribution models in the Aleutian Islands, Alaska

2017 ◽  
Vol 75 (1) ◽  
pp. 199-209 ◽  
Author(s):  
Christopher N Rooper ◽  
Rachel Wilborn ◽  
Pamela Goddard ◽  
Kresimir Williams ◽  
Richard Towler ◽  
...  
Keyword(s):  
Survey Data ◽  
Deep Sea ◽  
Goodness Of Fit ◽  
Bottom Trawl ◽  
Aleutian Islands ◽  
Trawl Survey ◽  
Bottom Trawl Survey ◽  
Spatial Management ◽  
Model Predictions ◽  
Deep Sea Corals

Abstract Spatial management of vulnerable benthic ecosystem components such as deep-sea corals and sponges requires adequate maps of their distribution. These maps are often based on statistical models of survey data. The objective of this project was to validate the predictions of existing presence or absence and abundance models of deep-sea corals and sponges in the Aleutian Islands that were based on bottom trawl survey data. Model validation was conducted by comparing bottom trawl survey model predictions to the observations of an in situ camera survey conducted at randomly selected locations. The measures of goodness of fit (area-under-the-receiver-operator-curve, AUC) for the bottom trawl survey model predictions of camera survey observations ranged from 0.59 to 0.77 (for sponges and coral, respectively) and indicated that the bottom trawl survey models predicted the probability of presence for corals accurately across the Aleutian Islands. The bottom trawl survey models explained as little as 3% of the variability in Stylasteridae density and up to 17% of the variability in coral density. These results indicate that models of deep-sea coral distributions based on presence and absence data from bottom trawl surveys can be accurate and can provide useful information for spatial management of these vulnerable taxa. However, for some other taxa, such as sponges, care should be taken interpreting the results of bottom trawl survey models. An interesting finding of this study was that the residuals from the bottom trawl survey model-camera density relationships were negative in areas that remained open to fishing after 2005, possibly indicating an effect of continued bottom trawling on the abundance of corals in these areas. This study highlights the importance of validating models of species distribution using independent surveys, so that the results can be used with confidence to support decision-making processes.

Decomposing and explaining the variability of bottom trawl survey data from the Barents Sea

Sarsia ◽  
2004 ◽  
Vol 89 (3) ◽  
pp. 196-210 ◽  
Author(s):  
Vidar Hjellvik ◽  
Olav Rune Godø ◽  
Dag Tjøstheim
Keyword(s):  
Survey Data ◽  
Barents Sea ◽  
Bottom Trawl ◽  
Trawl Survey ◽  
Bottom Trawl Survey ◽  
The Barents Sea

scholarly journals The influence of warp length on trawl dimension and catch of walleye pollock Theragra chalcogramma in a bottom trawl survey

2005 ◽  
Vol 71 (4) ◽  
pp. 738-747 ◽  
Author(s):  
Yasuzumi FUJIMORI ◽  
Kenji CHIBA ◽  
Tatsuki OSHIMA ◽  
Kazushi MIYASHITA ◽  
Satoshi HONDA
Keyword(s):  
Walleye Pollock ◽  
Bottom Trawl ◽  
Theragra Chalcogramma ◽  
Trawl Survey ◽  
Bottom Trawl Survey ◽  
Walleye Pollock Theragra Chalcogramma

scholarly journals Protocols of the EU bottom trawl survey of Flemish Cap

2014 ◽  
Vol 46 ◽  
pp. 3-51
Author(s):  
A Vazquez ◽  
J M Casas ◽  
A Alpoim
Keyword(s):  
Bottom Trawl ◽  
Trawl Survey ◽  
Bottom Trawl Survey ◽  
The Eu

Catchability of snow crab (Chionoecetes opilio) by the eastern Bering Sea bottom trawl survey estimated using a catch comparison experiment

2013 ◽  
Vol 70 (12) ◽  
pp. 1699-1708 ◽  
Author(s):  
David A. Somerton ◽  
Kenneth L. Weinberg ◽  
Scott E. Goodman
Keyword(s):  
Experimental Data ◽  
Bering Sea ◽  
Weighted Average ◽  
Assessment Model ◽  
Bottom Trawl ◽  
Snow Crab ◽  
Trawl Survey ◽  
Chionoecetes Opilio ◽  
Bottom Trawl Survey ◽  
Eastern Bering Sea

Catchability of the eastern Bering Sea (EBS) bottom trawl survey for snow crab (Chionoecetes opilio) was estimated from experimental data to provide a constraint on the survey catchability parameters in the stock assessment model. The experiment utilized a second fishing vessel to conduct side-by-side trawling with each of two survey vessels at 92 stations using an experimental trawl assumed to capture all crabs in its path. Trawl efficiency, or the captured proportion of crabs in the trawl path, was estimated for the 83-112 Eastern otter trawl from experimental data using a nonparametric smooth function of carapace width, sediment size, and depth. Survey catchability was then estimated as the catch-weighted average of the predicted trawl efficiency at all 275 survey stations where snow crabs were captured. The fitted model indicated that trawl selectivity was greater in sand than mud and greater in shallow water than deep. At a carapace widths >95 mm, the minimum commercial size limit, the estimated survey catchability of males is considerably less than previously reported.

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