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.

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 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.

Multifrequency backscattering properties of Atlantic herring (Clupea harengus) and Norway pout (Trisopterus esmarkii)

2007 ◽  
Vol 64 (2) ◽  
pp. 362-374 ◽  
Author(s):  
Sascha M.M. Fässler ◽  
Rita Santos ◽  
Norma García-Núñez ◽  
Paul G Fernandes
Keyword(s):  
North Sea ◽  
Empirical Data ◽  
Ambient Pressure ◽  
Clupea Harengus ◽  
Atlantic Herring ◽  
The North ◽  
Fish Flesh ◽  
Fishing Vessels ◽  
The North Sea ◽  
Acoustic Surveys

The multifrequency backscattering characteristics of echotraces of Atlantic herring (Clupea harengus) and Norway pout (Trisopterus esmarkii) are described. These fish cohabit similar areas of the North Sea in summer and echotraces of their schools are difficult to distinguish. Mean volume backscattering strengths at 18, 38, 120, and 200 kHz were taken from the International North Sea Herring Acoustic Surveys along with coincident pelagic trawl samples. The results indicate that echotraces of these fish species cannot be distinguished on the basis of differences in backscattering at discrete frequencies typically used in fish surveys and on fishing vessels. However, some discrimination between herring size-classes was evident. The empirical data for herring were then compared with a backscattering model for herring combining fish flesh, the swimbladder, and the effect of increased pressure at depth. Both the empirical data and model data indicate that, compared with large herring, progressively smaller herring generally have higher backscattering at the lowest frequency (18 kHz), although variability was high. According to the model, this frequency-specific signature is due to the progressively more significant contribution made by the fish body compared with the swimbladder, as the latter diminishes owing to an increase in ambient pressure in deeper water.

Fishing During the Great War

2019 ◽  
pp. 116-139
Author(s):  
Robb Robinson
Keyword(s):  
North Sea ◽  
Great War ◽  
Fishing Industry ◽  
Front Line ◽  
Previous Night ◽  
The North ◽  
Fishing Vessels ◽  
The North Sea ◽  
The Great War

This chapter reflects on the British fishing industry that boomed in 1913 and in the years preceding the outbreak of the Great War. It refers to the Grimsby steam trawler Zenobia that was detained for several hours in Heligoland after being stopped by a German gunboat on 4 August 1914, but then was eventually allowed to proceed. It also recalls the German trawler Else Kunkel and fishing smack Hammil Warden that were detained after sailing into Aberdeen, unaware that war had been declared the previous night. The chapter mentions the Admiralty that had been keen to get fishing vessels off the North Sea as the waters were likely to be on the front line of the maritime war, providing no place for civilian fishing vessels. It elaborates how substantial numbers of fishermen and fishing vessels became required for wartime naval security duties.

scholarly journals ‘The want of sufficient men’: Labour recruitment and training in the British North Sea fisheries, 1850–1950

2015 ◽  
Vol 27 (4) ◽  
pp. 723-742 ◽  
Author(s):  
Martin Wilcox
Keyword(s):  
North Sea ◽  
Technological Development ◽  
World War ◽  
The North ◽  
Fishing Vessels ◽  
The First World War ◽  
The North Sea ◽  
The Impact ◽  
First World ◽  
And Training

Between 1815 and 1950 the British fishing industry underwent fundamental and far-reaching changes. The industry expanded rapidly in the half-century prior to the First World War, before entering a period of stagnation thereafter. The technology of fishing was transformed by the spread of trawling, and the application of steam, and later motor power to the catching sector. All of this was driven by an expansion of demand for fish, consequent upon improvements in overland transport, which saw distribution and marketing arrangements transformed. This had major implications for labour in the industry. Fishermen became more numerous, and in many cases more specialised, as technological development introduced specialists such as the engineer and wireless operator into fishing vessels’ crews. The period also saw the rise of tied labour in the industry, in the form of thousands of teenaged apprentices brought in to man the North Sea trawling fleets, before apprenticeship declined in favour of more informal training arrangements. The impact of all of this was highly uneven. Some sectors of the industry were rapidly transformed, whereas others developed more slowly. The rapid growth and evolution of trawling promoted the widespread use of apprenticeship, for example, whereas concomitant developments in the herring fisheries had no such ramifications. This article seeks to provide an overview of labour recruitment and training in the British fisheries between 1815 and 1950, highlighting the scale and scope of the most important developments, and setting the best known facet of the subject, the apprenticeship system, in context.

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