scholarly journals Industry survey turbot and brill in the North Sea : Set up and results of a fisheries-independent survey using commercial fishing vessels 2018-2020

2021 ◽  
Author(s):  
Edward Schram ◽  
◽  
Niels Hintzen ◽  
Jurgen Batsleer ◽  
Tony Wilkes ◽  
...  
Keyword(s):  
North Sea ◽  
Commercial Fishing ◽  
The North ◽  
Fishing Vessels ◽  
The North Sea ◽  
Industry Survey ◽  
Set Up

scholarly journals Hindcasting Soundscapes before and during the COVID-19 Pandemic in Selected Areas of the North Sea and the Adriatic Sea

2021 ◽  
Vol 9 (7) ◽  
pp. 702
Author(s):  
Hüseyin Özkan Sertlek
Keyword(s):  
North Sea ◽  
Adriatic Sea ◽  
Propagation Model ◽  
The North ◽  
Fishing Vessels ◽  
Water Test ◽  
The North Sea ◽  
Monthly Changes ◽  
Source Level ◽  
Sound Maps

The national measures in several European countries during the COVID-19 pandemic also affected offshore human activities, including shipping. In this work, the temporal and spatial variations of shipping sound are calculated for the years before and during the pandemic in selected shallow water test areas from the Southern North Sea and the Adriatic Sea. First, the monthly sound pressure level maps of ships and wind between 2017 and 2020 are calculated for frequencies between 100 Hz to 10 kHz. Next, the monthly changes in these maps are compared. The asymptotic approximation of the hybrid flux-mode propagation model reduces the computational requirements for sound mapping simulations and facilitates the production of a large number of sound maps for different months, depths, frequencies, and ship categories. After the strictest COVID-19 measures were applied in April 2020, the largest decline was observed for the fishing, passenger and recreational ships. Although the changes in the number of fishing vessels are large, their contribution to the soundscape is minor due to their low source level. In both test areas, the spatial exceedance levels and acoustic energies were decreased in 2020 compared to the average of the previous three years.

scholarly journals The Size of Diatoms II. Further Observations on Rhizosolenia styliformis (Brightwell)

1946 ◽  
Vol 26 (3) ◽  
pp. 271-284 ◽  
Author(s):  
R. S. Wimpenny
Keyword(s):  
North Sea ◽  
Indicator Species ◽  
Separate Species ◽  
Southern North Sea ◽  
Auxospore Formation ◽  
The North ◽  
The North Sea ◽  
Set Up ◽  
The Antarctic

1. Diameter measurements of Rhizosolenia styliformis from the Antarctic, the subtropical Atlantic and Pacific Oceans and from the North Sea and neighbouring waters have made it appear necessary to set up two varieties, oceanica and semispina, in addition to the type of the species R. styliformis. The type as I describe it has been called var. longispina by Hustedt, but elsewhere it has often been figured as the var. oceanica of this paper. Var. semispina is synonymous with the form represented by Karsten as R. semispina Hensen. It differs from R. semispina as drawn by Hensen and its synonym R. hebetata forma semispina Gran, but is thought likely to be linked by intermediates. If this is so R. hebetata may have to be extended to include and suppress R. styliformis, as var. semispina is linked to the type by intermediates. Var. oceanica has no intermediate forms and, if R. hebetata is to be extended, this variety should be established as a separate species.2. Var. oceanica is absent from the southern North Sea and appears to be an indicator species related to oceanic inflow.3. Auxospore formation was observed for the type in the southern North Sea in 1935 and biometric observations suggest that a period of 3-4 years elapsed between the production of auxospore generations in that area. Outside the southern North Sea for the type, measurements give no indication of auxospore generations occurring at intervals exceeding a year. While auxospore formation has been seen in var. oceanica from the Shetlands area samples of June 1935 and July 1938, this phenomenon has not been observed for var. semispina.

An "experiment" on effort allocation of fishing vessels: the role of interference competition and area specialization

2007 ◽  
Vol 64 (2) ◽  
pp. 304-313 ◽  
Author(s):  
Jan-Jaap Poos ◽  
Adriaan D Rijnsdorp
Keyword(s):  
North Sea ◽  
Gadus Morhua ◽  
Atlantic Cod ◽  
Seasonal Pattern ◽  
Interference Competition ◽  
Catch Rate ◽  
The North ◽  
Closed Area ◽  
Fishing Vessels ◽  
The North Sea

A temporarily closed area established to protect spawning Atlantic cod (Gadus morhua) in the North Sea allowed us to study the response of the Dutch beam trawl fleet exploiting common sole (Solea solea) and plaice (Pleuronectes platessa). A number of vessels left the North Sea 1 month earlier than the normal seasonal pattern. The vessels that continued fishing in the North Sea were concentrated in the remaining open areas. In the first week after the closure, the catch rate decreased by 14%, coinciding with an increase in crowding of 28%. Area specialisation affected the response of individual vessels because vessels without prior experience in the open areas showed a larger decline in catch rate compared with vessels that previously fished in these open areas and were more likely to stop fishing during the closed period. The decrease in catch rate in response to the increase in competitor density allowed us to estimate the strength of the interference competition.

scholarly journals Exit and entry of fishing vessels: an evaluation of factors affecting investment decisions in the North Sea English beam trawl fleet

2011 ◽  
Vol 68 (5) ◽  
pp. 961-971 ◽  
Author(s):  
Alex N. Tidd ◽  
Trevor Hutton ◽  
Laurence T. Kell ◽  
Gurpreet Padda
Keyword(s):  
North Sea ◽  
Choice Model ◽  
Investment Decisions ◽  
Strategic Decision ◽  
Beam Trawl ◽  
Factors Affecting ◽  
The North ◽  
Fishing Vessels ◽  
The North Sea ◽  
The Impact

Abstract Tidd, A. N., Hutton, T., Kell, L. T., and Padda, G. 2011. Exit and entry of fishing vessels: an evaluation of factors affecting investment decisions in the North Sea English beam trawl fleet. – ICES Journal of Marine Science, 68: 961–971. A profitable fishery attracts additional effort (vessels enter), eventually leading to overcapacity and less profit. Similarly, fishing vessels exit depending on their economic viability (or reduced expectations of future benefits) or encouraged by schemes such as decommissioning grants and/or when there is consolidation of fishing effort within a tradable rights-based quota system (e.g. individual transferable quotas). The strategic decision-making behaviour of fishers in entering or exiting the English North Sea beam trawl fishery is analysed using a discrete choice model by integrating data on vessel characteristics with available cost data, decommissioning grant information, and other factors that potentially influence anticipated benefits or future risks. It is then possible to predict whether operators choose to enter, stay, exit, or decommission. Important factors affecting investment include vessel age and size, future revenues, operating costs (e.g. fuel), stock status of the main target species, and the impact of management measures (e.g. total allowable catches) and total fleet size (a proxy for congestion). Based on the results, the predicted marginal effects of each factor are presented and the impact of each is discussed in the context of policies developed to align fleet capacity with fishing opportunities.

scholarly journals 7th Cambridge Diagenesis Conference 2011: an introduction

Clay Minerals ◽  
2014 ◽  
Vol 49 (2) ◽  
pp. 125-126
Author(s):  
C. V. Jeans ◽  
N. J. Tosca
Keyword(s):  
Clay Minerals ◽  
North Sea ◽  
Special Issue ◽  
Fundamental Study ◽  
Oil Companies ◽  
The North ◽  
Research Institutes ◽  
The North Sea ◽  
Set Up ◽  
Natural Laboratory

The Cambridge Diagenesis Conferences (1981–1998) were set up to act as a conduit for the interchange of clay mineral expertise between universities and research institutes on one hand, and the hydrocarbon industry on the other. At the time, oil companies were dealing with the development of the North Sea Oil Province which was turning out to be a natural laboratory for the fundamental study of authigenic clay minerals and their relationship to lithofacies, burial, overpressure, reservoir quality and hydrocarbon emplacement. This symbiosis between industry and academia flourished for nearly two decades. Each conference was followed by a special issue of Clay Minerals dealing with topics relevant to, or discussed at the particular meeting. By the late 1990s the North Sea had become a mature province and the major oil companies were looking to other parts of the world to replenish their reserves.

Change in the North Sea ecosystem from the 1970s to the 2010s: great skua diets reflect changing forage fish, seabirds, and fisheries

2018 ◽  
Vol 76 (4) ◽  
pp. 925-937 ◽  
Author(s):  
Gabriella E Church ◽  
Robert W Furness ◽  
Glen Tyler ◽  
Lucy Gilbert ◽  
Stephen C Votier
Keyword(s):  
North Sea ◽  
Anthropogenic Impacts ◽  
Marine Ecosystem ◽  
Commercial Fishing ◽  
Seabird Species ◽  
Rissa Tridactyla ◽  
Fulmarus Glacialis ◽  
The North ◽  
The North Sea

Abstract Understanding anthropogenic impacts are crucial to maintain marine ecosystem health. The North Sea has changed in recent decades, largely due to commercial fishing and climate change. Seabirds can act as useful indicators of these changes. By analyzing n = 20 013 pellets and n = 24 993 otoliths regurgitated by great skuas Stercorarius skua in northern Scotland over five decades from the 1970s to the 2010s (in 36 years 1973–2017), we reveal how the diet of this top predator has changed alongside the changing North Sea ecosystem. Sandeels Ammodytes spp. were the most common dietary item during the 1970s, but became virtually absent from the 1980s onward. Discarded whitefish dominated skua diets from the 1980s to the present day, despite long-term declines in North Sea discard production. However, the discarded fish eaten by great skuas has become smaller and the species composition changed. Skua pellets only rarely contained avian prey in the 1970s but this increased during the 1980s, and fluctuated between 10% and 20% from the 1990s to 2010s. There have also been changes in the avian prey in the diet—black-legged kittiwakes Rissa tridactyla generally being replaced by auks Alcid spp. and northern fulmars Fulmarus glacialis. The Shetland marine ecosystem has experienced steep declines in sandeel stocks and in seabirds that feed on them. Great skuas have been able to prey switch to respond to this change, supported by abundant discards, enabling them to maintain a favourable population status while other seabird species have declined.

Velocity and interface depth determination by tomography of depth migrated gathers

Geophysics ◽  
1996 ◽  
Vol 61 (5) ◽  
pp. 1511-1523 ◽  
Author(s):  
Dan Kosloff ◽  
John Sherwood ◽  
Zvi Koren ◽  
Elana Machet ◽  
Yael Falkovitz
Keyword(s):  
North Sea ◽  
Determination Method ◽  
Prestack Migration ◽  
Traveltime Tomography ◽  
The North ◽  
Depth Determination ◽  
The North Sea ◽  
Set Up

A method for velocity and interface depth determination based on tomography of migrated common reflecting point (CRP) gathers is presented. The method is derived from the tomographic principle that relates traveltime change along a given ray to perturbations in slowness and layer depths. The tomographic principle is used to convert depth errors in migrated CRP gathers to time errors along a CRP ray pair and thus enable use of conventional traveltime tomography. It is also used to affect a very fast prestack migration and set up the tomography matrix. The velocity‐depth determination method uses the available offsets of all CRPs and inverts for the parameters of all layers simultaneously. Hand picking of depth errors on CRP gathers is avoided by a method where the tomography matrix operates directly on the migrated gathers. The velocity‐depth determination method is demonstrated on a synthetic example and on a field example from the North Sea.

scholarly journals A Healthy Metaphor? The North Sea Consultation and the Power of Words

2021 ◽  
Vol 13 (22) ◽  
pp. 12905
Author(s):  
Haye Geukes ◽  
Udo Pesch ◽  
Aad Correljé ◽  
Behnam Taebi
Keyword(s):  
North Sea ◽  
Reflective Equilibrium ◽  
Decisive Role ◽  
Conservation Areas ◽  
Consultation Process ◽  
The North ◽  
Fishing Sector ◽  
The North Sea ◽  
Set Up ◽  
Power Of Words

The North Sea Consultation was set up to resolve conflicting claims for space in the North Sea. In 2020, this consultation process resulted in the North Sea Agreement, which was supported by the Dutch Parliament and cabinet as a long-term policy; however, the fishing sector felt excluded, left the consultation process, and does not support the agreement. Using semi-constructed interviews and the method of wide reflective equilibrium, this research found that in this conflict the metaphor of ‘health’ has played a decisive role. While all stakeholders want to keep the sea ‘healthy’, they disagree on what a healthy sea actually means, leading to contrastive positions on the desirability of trawler fishing, wind parks, and conservation areas—the North Sea Agreement’s main foci of interest. To prevent the unproductive escalation of such a conflict, it is inevitable to acknowledge the moral connotations of such metaphors, as this allows a decision-making process that can be considered more just.

I: The English Flood of 1953

1957 ◽  
Vol 16 (2) ◽  
pp. 3-5 ◽  
Author(s):  
John Spiegel
Keyword(s):  
Comparative Study ◽  
North Sea ◽  
The North ◽  
Disaster Studies ◽  
The North Sea ◽  
Set Up

The National Research Council's Committee on Disaster Studies sent us to England about two weeks after the North Sea flood of February 1, 1953, to set up a rather extensive comparative study of the flood's effects in several communities. Unfortunately, the larger study did not materialize and we were compelled to learn what we could by ourselves in about two weeks. The following report, therefore, must be regarded as very tentative. It deals with Kimbark1, one of the two flooded communities we were able to study.

scholarly journals Maritime Vessel Classification to Monitor Fisheries with SAR: Demonstration in the North Sea

2019 ◽  
Vol 11 (3) ◽  
pp. 353 ◽  
Author(s):  
Boris Snapir ◽  
Toby Waine ◽  
Lauren Biermann
Keyword(s):  
North Sea ◽  
Automatic Identification ◽  
Identification System ◽  
Fishing Vessel ◽  
Fishing Activity ◽  
The North ◽  
Fishing Vessels ◽  
Monitoring Strategies ◽  
The North Sea ◽  
Sar Imagery

Integration of methods based on satellite remote sensing into current maritime monitoring strategies could help tackle the problem of global overfishing. Operational software is now available to perform vessel detection on satellite imagery, but research on vessel classification has mainly focused on bulk carriers, container ships, and oil tankers, using high-resolution commercial Synthetic Aperture Radar (SAR) imagery. Here, we present a method based on Random Forest (RF) to distinguish fishing and non-fishing vessels, and apply it to an area in the North Sea. The RF classifier takes as input the vessel’s length, longitude, and latitude, its distance to the nearest shore, and the time of the measurement (am or pm). The classifier is trained and tested on data from the Automatic Identification System (AIS). The overall classification accuracy is 91%, but the precision for the fishing class is only 58% because of specific regions in the study area where activities of fishing and non-fishing vessels overlap. We then apply the classifier to a collection of vessel detections obtained by applying the Search for Unidentified Maritime Objects (SUMO) vessel detector to the 2017 Sentinel-1 SAR images of the North Sea. The trend in our monthly fishing-vessel count agrees with data from Global Fishing Watch on fishing-vessel presence. These initial results suggest that our approach could help monitor intensification or reduction of fishing activity, which is critical in the context of the global overfishing problem.

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