scholarly journals Impact of a large-scale area closure on patterns of fishing disturbance and the consequences for benthic communities

2003 ◽  
Vol 60 (2) ◽  
pp. 371-380 ◽  
Author(s):  
T.A Dinmore ◽  
D.E Duplisea ◽  
B.D Rackham ◽  
D.L Maxwell ◽  
S Jennings
Keyword(s):  
North Sea ◽  
Large Scale ◽  
Fishery Management ◽  
Benthic Communities ◽  
Benthic Invertebrate ◽  
Homogeneous Distribution ◽  
Cumulative Impacts ◽  
Management Actions ◽  
Fishing Vessels ◽  
Fishing Disturbance

Abstract Seasonal area closures of fisheries are primarily used to reduce fishing mortality on target species. In the absence of effort controls, fishing vessels displaced from a closed area will impact fish populations and the environment elsewhere. Based on the observed response of the North Sea beam trawl fleet to the closure of the “cod box” and an existing size-based model of the impacts of beam trawling, we predict the effects of seasonal area closures on benthic communities in the central North Sea. We suggest that repeated seasonal area closures would lead to a slightly more homogeneous distribution of annual trawling activity, although the distribution would remain patchy rather than random. The increased homogeneity, coupled with the displacement of trawling activity to previously unfished areas, is predicted to have slightly greater cumulative impacts on total benthic invertebrate production and lead to localized reductions in benthic biomass for several years. To ensure the effective integration of fisheries and environmental management, the wider consequences of fishery management actions should be considered a priori. Thus, when seasonal closures increase the homogeneity of overall disturbance or lead to the redistribution of trawling activity to environmentally sensitive or previously unfished areas, then effort reductions or permanent area closures should be considered as a management option. The latter would lead to a single but permanent redistribution of fishing disturbance, with lower cumulative impacts on benthic communities in the long run.

scholarly journals Predicting the effects of area closures and fishing effort restrictions on the production, biomass, and species richness of benthic invertebrate communities

2006 ◽  
Vol 63 (5) ◽  
pp. 822-830 ◽  
Author(s):  
J.G. Hiddink ◽  
T. Hutton ◽  
S. Jennings ◽  
M.J. Kaiser
Keyword(s):  
Species Richness ◽  
North Sea ◽  
Fishery Management ◽  
Benthic Communities ◽  
Fishing Effort ◽  
Management Actions ◽  
The North ◽  
The North Sea ◽  
Effort Reduction ◽  
Positive Effect

AbstractTo effectively implement an Ecosystem Approach to Fisheries (EAF), managers need to consider the effects of management actions on the fishery and the ecosystem. Methods for assessing the effects on target stocks are generally well developed, but methods for assessing the effects on other components and attributes of the ecosystem are not. Area closures and effort controls are widely used fishery management tools that affect the distribution of fishing effort and may therefore have consequences for a range of species and habitats. An approach is developed to predict the effects of area closures and effort control on the biomass, production, and species richness of benthic communities in the North Sea. The redistribution of beam trawling effort as a result of management action was modelled with a random utility model, assuming that fishers selected fishing grounds on the basis of their knowledge of past catch rates. The effects of trawling on benthic invertebrates were predicted using a size-based model that accounted for differences in habitat among fishing grounds. Our simulations demonstrated that closures of different sizes and in different locations could have positive or negative effects on benthic communities. These predicted effects resulted from the trade-off between recovery in the closed areas and additional trawling effects in the open areas that arose from displaced fishing activity. In the absence of effort controls, closure of lightly fished areas had the strongest positive effect on benthic communities. Effort reduction also had a positive effect. Therefore, area closures in lightly fished areas, coupled with effort reduction, are expected to minimize the effects of fishing on benthic communities. As it was not possible to access full international data for the North Sea beam trawl fleet, the results of the analyses are illustrative rather than complete. Nevertheless, what is demonstrated is an effective approach for assessing the environmental consequences of fishery management action that can be used to inform management decision-making as part of an EAF.

scholarly journals Favorites and leftovers on the menu of scavenging seabirds: modelling spatiotemporal variation in discard consumption

2016 ◽  
Vol 73 (9) ◽  
pp. 1446-1459 ◽  
Author(s):  
Jochen Depestele ◽  
Marie-Joëlle Rochet ◽  
Ghislain Dorémus ◽  
Pascal Laffargue ◽  
Eric Willem Maria Stienen
Keyword(s):  
Large Scale ◽  
Benthic Communities ◽  
Mitigation Measures ◽  
Spatial And Temporal Variation ◽  
Bay Of Biscay ◽  
Modelling Framework ◽  
Fishing Vessels ◽  
Fisheries Policy ◽  
Seabird Ecology ◽  
Fishery Discards

Fishery discards subsidise the food supply of a large community of scavenging seabirds, thus substantially influencing seabird ecology. Seabird preference for certain types of discards determines the number and composition of discards available for non-avian marine scavengers. To quantify both portions of discards temporally as well as spatially, we have used a modelling framework that integrates the spatial and temporal variation in seabird distribution, seabird attraction to fishing vessels, and discard distribution. The framework was applied to a case study in the Bay of Biscay, where a wide variation in discard consumption was observed across seabird foraging guilds, discard types, periods, and locations. Seabirds removed about one-quarter of the Bay of Biscay discards. The remaining sinking discards have limited potential to subsidize scavenging benthic communities on a large scale, but they may contribute substantially to scavenger diets on a local scale. Changes in food subsidies caused by discard mitigation measures, such as the “landing obligation” in the European Common Fisheries Policy, are likely to have ecosystem effects on both scavenging seabirds and non-avian marine scavengers.

scholarly journals A proposed method for assessing the extent of the seabed significantly affected by demersal fishing in the Greater North Sea

2013 ◽  
Vol 70 (6) ◽  
pp. 1085-1096 ◽  
Author(s):  
Markus Diesing ◽  
David Stephens ◽  
John Aldridge
Keyword(s):  
North Sea ◽  
Large Scale ◽  
Spatial Scales ◽  
Grid Cell ◽  
Natural Disturbance ◽  
Sea Floor ◽  
Natural Processes ◽  
Environmental Status ◽  
Waves And Currents ◽  
Fishing Disturbance

Abstract Diesing, M., Stephens, D., and Aldridge, J. 2013. A proposed method for assessing the extent of the seabed significantly affected by demersal fishing in the Greater North Sea. – ICES Journal of Marine Science, 70: 1085–1096. The widespread impact of bottom towed fishing gear on benthic species and communities has long been recognized. The responses to a given intensity of fishing disturbance can be influenced by the extent to which these species and communities are preconditioned to disturbance by natural processes, in particular waves and currents. The advent of vessel monitoring system (VMS) and models of natural disturbance enable high-resolution and large-scale comparisons of fishing and natural disturbance. VMS data were employed to estimate the trawled area per 12 km by 12 km grid cell. We then quantified natural disturbance by estimating the number of days in a year the seabed was disturbed by tides and waves. As natural disturbance acts on large spatial scales, we assumed that each natural disturbance event affects whole grid cells. Frequencies could thus be translated into an area of impact, allowing us to compare fishing with natural disturbance. We show how such comparisons can be used to estimate the extent of different seabed substrate types significantly affected by demersal fishing. A measure of the probability that fishing disturbance exceeds natural disturbance provides one metric for identifying areas of significant trawling impact on seabed habitats and might be used to measure progress towards achieving good environmental status for sea-floor integrity within the context of the European Union's Marine Strategy Framework Directive. For more than half the seabed in the English sector of the Greater North Sea, the results suggest that disturbance attributable to demersal fishing exceeds natural disturbance based on data from the years 2006 to 2008. The imbalance between natural and fishing disturbance is greatest in muddy substrates and deep circalittoral habitats.

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 Genotyping of Two Mediterranean Trout Populations in Central-Southern Italy for Conservation Purposes Using a Rainbow-Trout-Derived SNP Array

Animals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 1803
Author(s):  
Valentino Palombo ◽  
Elena De Zio ◽  
Giovanna Salvatore ◽  
Stefano Esposito ◽  
Nicolaia Iaffaldano ◽  
...  
Keyword(s):  
Rainbow Trout ◽  
Genetic Structure ◽  
Fishery Management ◽  
Snp Array ◽  
Fine Scale ◽  
Principal Coordinates Analysis ◽  
Data Set ◽  
Management Actions ◽  
Principal Coordinates ◽  
Mediterranean Trout

Mediterranean trout is a freshwater fish of particular interest with economic significance for fishery management, aquaculture and conservation biology. Unfortunately, native trout populations’ abundance is significantly threatened by anthropogenic disturbance. The introduction of commercial hatchery strains for recreation activities has compromised the genetic integrity status of native populations. This work assessed the fine-scale genetic structure of Mediterranean trout in the two main rivers of Molise region (Italy) to support conservation actions. In total, 288 specimens were caught in 28 different sites (14 per basins) and genotyped using the Affymetrix 57 K rainbow-trout-derived SNP array. Population differentiation was analyzed using pairwise weighted FST and overall F-statistic estimated by locus-by-locus analysis of molecular variance. Furthermore, an SNP data set was processed through principal coordinates analysis, discriminant analysis of principal components and admixture Bayesian clustering analysis. Firstly, our results demonstrated that rainbow trout SNP array can be successfully used for Mediterranean trout genotyping. In fact, despite an overwhelming number of loci that resulted as monomorphic in our populations, it must be emphasized that the resulted number of polymorphic loci (i.e., ~900 SNPs) has been sufficient to reveal a fine-scale genetic structure in the investigated populations, which is useful in supporting conservation and management actions. In particular, our findings allowed us to select candidate sites for the collection of adults, needed for the production of genetically pure juvenile trout, and sites to carry out the eradication of alien trout and successive re-introduction of native trout.

Offshore Claims and Problems in the North Sea

1965 ◽  
Vol 59 (3) ◽  
pp. 505-522 ◽  
Author(s):  
Richard Young
Keyword(s):  
North Sea ◽  
Large Scale ◽  
Geneva Convention ◽  
Legal Principles ◽  
The North ◽  
Legal Problems ◽  
The North Sea ◽  
The Subject ◽  
First Time ◽  
Economic Considerations

The possible presence of very large petroleum and natural gas reserves in the area beneath the North Sea is currently the subject of intense investigation. If confirmed, as seems likely in at least some localities, this occurrence will raise legal problems of considerable interest and complexity. For the North Sea is not merely an oilfield covered by water: for centuries it has been one of the world's major fishery regions and the avenue to and from the world's busiest seaports. Thus all three of the present principal uses of the sea—fishing, navigation, and the exploitation of submarine resources—promise to meet for the first time on a large scale in an area where all are of major importance. The process of reconciling the various interests at stake will provide the first thoroughgoing test of the adequacy and acceptability of the general principles laid down in the 1958 Geneva Convention on the Continental Shelf and should add greatly to the practice and precedents available in this developing branch of the law. In the present article an attempt is made to review some of the geographical and economic considerations involved in the North Sea situation, to note some of the technical and legal developments that have already taken place, and to consider these elements in the light of the various interests and legal principles concerned.

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.

Fishing catch shares in the face of global change: a framework for integrating cumulative impacts and single species management

2010 ◽  
Vol 67 (12) ◽  
pp. 1968-1982 ◽  
Author(s):  
Isaac C. Kaplan ◽  
Phillip S. Levin ◽  
Merrick Burden ◽  
Elizabeth A. Fulton
Keyword(s):  
Global Change ◽  
Ocean Acidification ◽  
Fishery Management ◽  
Single Species ◽  
Ecosystem Model ◽  
Careful Consideration ◽  
Reference Points ◽  
Cumulative Impacts ◽  
English Sole ◽  
Modeling Tools

Any fishery management scheme, such as individual fishing quotas (IFQs) or marine protected areas, should be designed to be robust to potential shifts in the biophysical system. Here we couple possible catch scenarios under an IFQ scheme with ocean acidification impacts on shelled benthos and plankton, using an Atlantis ecosystem model for the US West Coast. IFQ harvest scenarios alone, in most cases, did not have strong impacts on the food web, beyond the direct effects on harvested species. However, when we added the impacts of ocean acidification, the abundance of commercially important groundfish such as English sole ( Pleuronectes vetulus ), arrowtooth flounder ( Atheresthes stomias ), and yellowtail rockfish ( Sebastes flavidus ) declined up to 20%–80%, owing to the loss of shelled prey items from their diet. English sole exhibited a 10-fold decline in potential catch and economic yield when confronted with strong acidification impacts on shelled benthos. Therefore, it seems prudent to complement IFQs with careful consideration of potential global change effects such as acidification. Our analysis provides an example of how new ecosystem modeling tools that evaluate cumulative impacts can be integrated with established management reference points and decision mechanisms.

scholarly journals Inferring the location and scale of mixing between habitat areas of lesser sandeel through information from the fishery

2010 ◽  
Vol 68 (1) ◽  
pp. 43-51 ◽  
Author(s):  
Henrik Jensen ◽  
Anna Rindorf ◽  
Peter J. Wright ◽  
Henrik Mosegaard
Keyword(s):  
North Sea ◽  
Large Scale ◽  
Pelagic Fish ◽  
Fishing Ground ◽  
Marine Science ◽  
Foraging Habitat ◽  
Small Pelagic Fish ◽  
The North ◽  
The North Sea

Abstract Jensen, H., Rindorf, A., Wright, P. J., and Mosegaard, H. 2011. Inferring the location and scale of mixing between habitat areas of lesser sandeel through information from the fishery. – ICES Journal of Marine Science, 68: 43–51. Sandeels are small pelagic fish that play an important role in the diet of a range of natural predators. Because of their limited capture by traditional survey gear, little is known about their large-scale distribution or the degree of mixing between habitat areas. Detailed information collected directly from the fishery was used to map fishing grounds, which were then assumed to reflect the foraging habitat of the species. Length distributions from individual hauls were used to assess differences in the distributions as a function of distance between samples. Sandeel foraging habitat covered some 5% of the total area of the North Sea. Mixing between neighbouring fishing grounds was too low to eliminate differences in length distributions at distances between grounds down to 5 km. Within fishing grounds, mixing was sufficient to eliminate differences in length distributions at scales <28 km but insufficient at greater distances. The lack of mixing between grounds may result in large differences in sandeel abundance among adjacent fishing grounds. Further, notable abundance at one end of an extensive fishing ground is not necessarily indicative of similar abundance at its other end.

A Synthesis of Knowns, Unknowns, and Policy Recommendations from the Sea Lamprey International Symposium

1980 ◽  
Vol 37 (11) ◽  
pp. 2202-2208 ◽  
Author(s):  
Carl J. Walters ◽  
George Spangler ◽  
W. J. Christie ◽  
Patrick J. Manion ◽  
James F. Kitchell
Keyword(s):  
International Symposium ◽  
Large Scale ◽  
Fishery Management ◽  
Field Experiments ◽  
Lake Trout ◽  
Sea Lamprey ◽  
Future Research ◽  
Fish Stock ◽  
Total Production ◽  
Pilot Studies

The Sea Lamprey International Symposium (SLIS) has provided a broad spectrum of facts and speculations for consideration in future research and management programs. Many aspects of the laboratory biology and field life history of the sea lamprey (Petromyzon marinus) are now well understood. There is little question that it can now be controlled by chemical larvicides, and perhaps in the future by more efficient integrated control programs. There is correlative evidence (wounds, scars, catch curves) that lamprey caused major mortalities in some fish species, and that control in conjunction with stocking has lead to remarkable recoveries of salmonid stocks in the Great Lakes. However, there are great gaps in understanding about just what the lamprey does under field conditions, and it is not yet possible to reject several hypotheses that assign lamprey a minimum or transient role in fish stock changes. Further studies on details of lamprey biology are, in themselves, unlikely to fill the gaps; one alternative is to conduct a large-scale field experiment involving cessation of lamprey control while holding other factors (fishing, stocking) as steady as possible. If it is decided to proceed with management on the assumption that lamprey are important, without the major field experiments to confirm it, then at least the following steps should be taken: (1) the chemical treatment program should be reviewed in detail, with a view to finding treatment schedules that will minimize frequency and dose rates for lampricide applications; (2) pilot studies on alternative control schemes (sterile male, attractants, barriers) should only be funded if they are statistically well designed (several replicate and control streams), and involve quantitative monitoring of lamprey spawning success and subsequent total production of transforming larvae; (3) the lake trout (Salvelinus namaycush) stocking program should be maintained at its present level, and should involve diverse genotypes rather than a few hatchery strains; (4) growth in the sport fisheries for lake trout should be curtailed, and commercial fisheries should not yet be permitted; (5) a multispecies harvesting policy should be designed that takes into account the buffering effect of each species on lamprey mortality suffered by others (i.e. should some species not be harvested at all, and viewed instead as buffers for more valuable species?); and (6) a program should be developed for restoring, by culture if necessary, native forage species in case the introduced smelt and alewife should collapse under pressure from fishing and prédation by the growing salmonid community.Key words: sea lamprey, proposed research, fishery management, mathematical models, population dynamics

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