Technological trends in capture fisheries

Valdemarsen, John Willy

doi:10.1016/s0964-5691(01)00073-4

Cited by 81 publications

(29 citation statements)

References 4 publications

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“…Gillnet fisheries are a relatively low cost and efficient method of fishing and are widely used among small scale fisheries throughout the world (Valdemarsen 2001). The ubiquitous nature of these fisheries, their associated societal benefits and known wider ecological effects raise important questions on how to balance food security, employment, economic activity and equitability against environmental concerns.…”

Section: Discussionmentioning

confidence: 99%

Disentangling the causes of protected‐species bycatch in gillnet fisheries

Northridge

Coram

Kingston

et al. 2017

Conservation Biology

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Gillnet fisheries are widely thought to pose a conservation threat to many populations of marine mammals, seabirds and turtles. Gillnet fisheries also support a significant proportion of small-scale fishing communities worldwide. Despite a large number of studies on protected species bycatch in recent decades, relatively few have examined the underlying causes of bycatch, and fewer still have looked at the issue from a multi-taxon perspective. We used three bibliographic databases and one search engine to identify studies by year of publication and taxon. The majority of studies on the mechanisms of gillnet bycatch are not This article is protected by copyright. All rights reserved. 2 accessible through mainstream published literature sources. Many are reported in technical papers, government reports and University theses. We reviewed over 600 published and unpublished studies of bycatch where causal or correlative factors were considered, and identified therein 28 environmental, operational, technical and behavioral factors that might plausibly be associated with higher or lower bycatch rates of the three taxa. Of the factors considered, 11 were found to have been associated with potential bycatch reduction in two out of the three taxa, while three factors (water depth, mesh size and net height) were associated with trends in bycatch rate for all three taxa. These findings provide a basis to guide further experimental work to test hypotheses about which factors most influence bycatch rates, and to explore ways of managing fishing activities and/or improving gear design to minimize the incidental capture of species of conservation concern, whilst ensuring the viability of the fisheries concerned.

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Section: Discussionmentioning

confidence: 99%

Disentangling the causes of protected‐species bycatch in gillnet fisheries

Northridge

Coram

Kingston

et al. 2017

Conservation Biology

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“…Fishers have developed a variety of trawl gears to maximize catch efficiency and their ability to operate on the different types of seabed habitats (Eigaard et al, 2014). As a result, bottom trawls differ in their design and dimensions, in particular in groundrope design and the methods used to spread the trawl horizontally (beam trawl, otter trawl, seine) (Valdemarsen, 2001). We distinguish between the physical effects of the gear on the seabed and the effects of the gear on marine organisms and the functioning of the benthic ecosystem (Figure 1).…”

Section: Trawling Impactmentioning

confidence: 99%

Towards a framework for the quantitative assessment of trawling impact on the seabed and benthic ecosystem

Rijnsdorp

Bastardie

Bolam

et al. 2015

ICES Journal of Marine Science

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A framework to assess the impact of mobile fishing gear on the seabed and benthic ecosystem is presented. The framework that can be used at regional and local scales provides indicators for both trawling pressure and ecological impact. It builds on high-resolution maps of trawling intensity and considers the physical effects of trawl gears on the seabed, on marine taxa, and on the functioning of the benthic ecosystem. Within the framework, a reductionist approach is applied that breaks down a fishing gear into its components, and a number of biological traits are chosen to determine either the vulnerability of the benthos to the impact of that gear component, or to provide a proxy for their ecological role. The approach considers gear elements, such as otter boards, twin trawl clump, and groundrope, and sweeps that herd the fish. The physical impact of these elements on the seabed, comprising scraping of the seabed, sediment mobilization, and penetration, is a function of the mass, size, and speed of the individual component. The impact of the elements on the benthic community is quantified using a biological-trait approach that considers the vulnerability of the benthic community to trawl impact (e.g. sediment position, morphology), the recovery rate (e.g. longevity, maturation age, reproductive characteristics, dispersal), and their ecological role. The framework is explored to compare the indicators for pressure and ecological impact of bottom trawling in three main seabed habitat types in the North Sea. Preliminary results show that the Sublittoral mud (EUNIS A5.3) is affected the most due to the combined effect of intensive fishing and large proportions of long-lived taxa.

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“…Technological improvements include the increase of the size and performance of the fishing vessels, the increasing efficiency of the fishing gears, increasing performances of electronic devices such as bird radar, sonar and remote sensing tools and the deployment of increasingly sophisticated fish aggregating devices (FADs) (Valdemarsen 2001). The term…”

Section: Modelling Fishing Mortality and The Redistribution Of Fishinmentioning

confidence: 99%

Modelling the effect of marine protected areas on the population of skipjack tuna in the Indian Ocean

Dueri

Maury

2012

Aquat. Living Resour.

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-The benefits of implementing no-take Marine Protected Areas (MPAs) for the conservation of highly migratory species are not easy to assess. They depend on several factors, such as the fish mobility, fisher behaviour and the area covered by the MPA with respect to the distribution area of the species to protect. In this study, we explore the simultaneous effects of MPAs and fishing scenarios on skipjack tuna population dynamics, using the spatially-explicit APECOSM-E model. The model represents the size-structured population dynamics of skipjack tuna in the Indian Ocean and their dependence on climatic variability and exploitation by fisheries. Numerical experiments were run from the beginning of industrial fisheries in the early 1980s to the year 2030, considering different scenarios for the future development of fisheries. These scenarios combined different trends in fishing effort and technological development, either assuming a continuous increase following historical trends or a stabilization of these factors at present values. The simulations were designed to explore the effects of two MPAs of different size and location: the recently established Chagos MPA, and a hypothetical MPA covering a large part of the Western Indian Ocean, where most of the skipjack catches are presently made. We modelled the redistribution of fishing effort around the MPAs assuming that the fishers had partial knowledge of the spatial distribution of the skipjack population. The effects of the two MPAs on the population dynamics, catch and fishing mortality are shown. Our results revealed a very minor effect of the Chagos MPA on the skipjack tuna population, while the Western Indian Ocean MPA had an important impact on the fishing mortality and succeeded in stabilizing the spawning population. The simulations also showed that the effect of an MPA depends on the evolution of fisheries and it is therefore important to explore different fishery scenarios to assess the future benefits of an MPA.

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Technological trends in capture fisheries

Cited by 81 publications

References 4 publications

Disentangling the causes of protected‐species bycatch in gillnet fisheries

Disentangling the causes of protected‐species bycatch in gillnet fisheries

Towards a framework for the quantitative assessment of trawling impact on the seabed and benthic ecosystem

Modelling the effect of marine protected areas on the population of skipjack tuna in the Indian Ocean

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