scholarly journals Contrasting fishing effort reduction and habitat connectivity as management strategies to promote alewife ( Alosa pseudoharengus ) recovery using an ecosystem model

2021 ◽  
Author(s):  
Beatriz S. Dias ◽  
Michael G. Frisk ◽  
Adrian Jordaan
Keyword(s):  
Management Strategies ◽  
Ecosystem Model ◽  
Fishing Effort ◽  
Habitat Connectivity ◽  
Alosa Pseudoharengus ◽  
Effort Reduction

scholarly journals The MINOUWApp: a web-based tool in support of by-catch and discards management

2020 ◽  
Vol 192 (12) ◽  
Author(s):  
Lorenzo D’Andrea ◽  
Aida Campos ◽  
Karim Erzini ◽  
Paulo Fonseca ◽  
Simone Franceschini ◽  
...  
Keyword(s):  
Management Strategies ◽  
Fishing Effort ◽  
Negative Effects ◽  
Web Based ◽  
Management Plans ◽  
By Catch ◽  
Selection Of Species ◽  
Areas Of Interest ◽  
Ecosystem Based Fisheries Management ◽  
Selection Of

AbstractCurrent fishing practices often do not allow adequate selection of species or sizes of fish, resulting in unwanted catches, subsequently discarded, with the consequent negative effects on both marine communities and fisheries profitability. The cross-analysis of density patches of potential unwanted catches and distribution of fishing effort can support the identification of spatial-temporal hot-spots in which the fishing pressure should be reduced to limit the amount of discards. The MinouwApp represents a technological and methodological framework to bring different, and structurally complex, sources of georeferenced data together into a simple visual interface aiming to interactively explore temporal ranges and areas of interest. The objective is to improve the understanding of fisheries dynamics, including discards, thus contributing to the implementation of discard management plans in a context of participative, ecosystem-based fisheries management strategies.

scholarly journals Modelling Reef Fish Population Responses to Fisheries Restrictions in Marine Protected Areas in the Coral Triangle

2012 ◽  
Vol 2012 ◽  
pp. 1-18 ◽  
Author(s):  
Divya Varkey ◽  
Cameron H. Ainsworth ◽  
Tony J. Pitcher
Keyword(s):  
Reef Fish ◽  
Marine Protected Area ◽  
Marine Ecosystem ◽  
Ecosystem Model ◽  
Fish Population ◽  
Fishing Effort ◽  
Coral Triangle ◽  
Trade Offs ◽  
Coral Reef Ecosystems ◽  
Marine Ecosystem Models

Marine ecosystem models are used to investigate marine protected area (MPA) benefits for coral reef ecosystems located in Raja Ampat, in the heart of the Coral Triangle. Field data from an integrated and diverse research project is used to develop a spatial ecosystem model using Ecopath, Ecosim, and Ecospace modelling software. The ecological and fisheries responses of a reef ecosystem to different levels of fishing effort restrictions inside MPAs are explored. The trade-offs of allowing some fisheries to operate inside the MPAs versus designating the MPAs as no-take zones are highlighted. The results show that rapid rebuilding of reef fish populations, especially the large charismatic species, requires no-take areas. Distinct trade-offs in spillover benefits are observed between partially fished and no-take MPAs.

Managing growth overfishing with multiannual compromise strategies

1997 ◽  
Vol 54 (10) ◽  
pp. 2255-2276 ◽  
Author(s):  
P Marchal
Keyword(s):  
Management Strategies ◽  
Fishing Effort ◽  
Reference Points ◽  
Long Term Outcomes ◽  
Northeast Atlantic ◽  
Factors Influencing ◽  
Optimal Balance ◽  
Short And Long Term ◽  
Mobile Target

Most of the Northeast Atlantic stocks are currently fished above the biological reference points (e.g., Fmax). In attempting to achieve such targets, advisers and managers have faced two main problems. First, it is impractical to (i) simultaneously maximize yields, stabilize fisheries, and safeguard stocks and (ii) optimize both short- and long-term outcomes for the industry. Second is the lack of predictability, several years ahead, in factors influencing decisions. This study addresses these twin issues by exploring the relative performances of various multiannual and compromise (or composite) management strategies. Multiannual fishing efforts are set in advance for a ``resolution'' period of several years, at the end of which they are updated. They are calculated to satisfy a prior weighted compromise amongst three criteria: (i) minimizing fishing effort variability, (ii) minimizing catch variability, and (iii) reaching a ``mobile target:'' the latter is defined with a second weighted compromise between the long-term target and the fishing effort at the beginning of the resolution period. A safe and optimal balance between all the short- and long-term fishery outcomes is found with a 5-year resolution period, during which the mobile target is split into 40-60% of the long-term target, and 60-40% of the fishing effort at the start of the resolution period, while criteria i, ii, and iii are weighted equally.

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 The effects of seasonal processes on size spectrum dynamics

2016 ◽  
Vol 73 (4) ◽  
pp. 598-610 ◽  
Author(s):  
Samik Datta ◽  
Julia L. Blanchard
Keyword(s):  
Environmental Variability ◽  
Management Strategies ◽  
Growth Curves ◽  
Fishing Effort ◽  
Size Spectrum ◽  
Interspecies Interactions ◽  
Community Size ◽  
Modelling Framework ◽  
Batch Spawning ◽  
Similar Growth

The recent advent of dynamic size spectrum models has allowed the analysis of life processes in marine ecosystems to be carried out without the high complexity arising from interspecies interactions within dense food webs. In this paper, we use “mizer”, a size spectrum modelling framework, to investigate the consequences of including the seasonal processes of plankton blooms and batch spawning in the model dynamics. A multispecies size spectrum model is constructed using 12 common North Sea fish species, with growth, predation, and mortality explicitly modelled, before simulating both seasonal plankton blooms and batch spawning of fish (using empirical data on the spawning patterns of each species). The effect of seasonality on the community size spectrum is investigated; it is found that with seasonal processes included, the species spectra are more varied over time, while the aggregated community spectrum remains fairly similar. Growth of seasonally spawning mature individuals drops significantly during peak reproduction, although lifetime growth curves follow nonseasonal ones closely. On analysing properties of the community spectrum under different fishing scenarios, seasonality generally causes more varied spectrum slopes and lower yields. Under seasonal conditions, increasing fishing effort also results in greater temporal variability of fisheries yields due to truncation of the community spectrum towards smaller sizes. Further work is needed to evaluate robustness of management strategies in the context of a wider range of seasonal processes and behavioural strategies, as well as longer term environmental variability and change.

Biological reference points for sea scallops (Placopecten magellanicus): the benefits and costs of being nearly sessile

2004 ◽  
Vol 61 (8) ◽  
pp. 1338-1354 ◽  
Author(s):  
Stephen J Smith ◽  
Paul Rago
Keyword(s):  
Management Strategies ◽  
Fishing Effort ◽  
Reference Points ◽  
Placopecten Magellanicus ◽  
Nonlinear Mixed Effects Models ◽  
Lower Productivity ◽  
Boom And Bust ◽  
Sea Scallops ◽  
Habitat Damage ◽  
Definition Of

In this paper, we concentrate on spatial aspects of growth and reproduction for sea scallops (Placopecten magellanicus) to advance the general theory for development of reference points for sessile animals and to illustrate the general points with several specific examples. Nonlinear mixed effects models can be used to define the spatial distribution of growth rates and their implications for the definition of growth overfishing. We develop a basin model to illustrate that the typical "boom and bust" effects, often attributed to environmental factors, are explained equally well by spatial variations in habitat quality, spatial concentration of fisheries, and dispersal of larvae among areas. Results suggest that incentives to concentrate fishing effort in lower productivity areas may be an effective tool for reducing recruitment variation and improving yields. Reductions in fishing mortality might be possible with closed areas as they can be used to reduce the concentration of effort on high scallop densities. Further, rotational area management strategies can offer the promise of balancing demands for increased yield, prevention of recruitment overfishing, maintaining spawning reserves, and reducing habitat damage and bycatch.

scholarly journals Integrating Economic dynamics into Ecological Networks: The case of fishery sustainability

2019 ◽  
Author(s):  
Paul Glaum ◽  
Valentin Cocco ◽  
Fernanda S. Valdovinos
Keyword(s):  
Network Theory ◽  
Management Strategies ◽  
Single Species ◽  
Fishing Effort ◽  
Ecological Networks ◽  
Ecological Network ◽  
Ecological Dynamics ◽  
Natural Systems ◽  
Insight Into

Summary/AbstractUnderstanding and sustainably managing anthropogenic impact on ecosystems requires studying the integrated economic -ecological dynamics driving coupled human-natural systems. Here, we expand ecological network theory to study fishery sustainability by incorporating economic drivers into food-web models to evaluate the dynamics of thousands of single-species fisheries across hundreds of generated food-webs and two management strategies. Analysis reveals harvesting high population biomass species can initially support fishery persistence, but threatens long term economic and ecological sustainability by indirectly inducing extinction cascades in non-harvested species. This dynamic is exacerbated in open access fisheries where profit driven growth in fishing effort increases perturbation strength. Results demonstrate the unique insight into both ecological dynamics and sustainability garnered from considering economically dynamic fishing effort in the network.One Sentence SummaryIntegrating economic drivers into ecological networks reveal non-linear drivers of sustainability in fisheries.

scholarly journals VARIABILITY OF CARAPACE WIDTH SIZE AND ABUNDANCE OF BLUE SWIMMING CRABS (Portunus pelagicus Linnaeus) IN PATI WATERS

2016 ◽  
Vol 7 (2) ◽  
Author(s):  
Dyah Ika Nugraheni ◽  
Achmad Fahrudin ◽  
. Yonvitner
Keyword(s):  
Coastal Waters ◽  
Accretion Rate ◽  
Carapace Width ◽  
Management Strategies ◽  
Fishing Effort ◽  
Swimming Crab ◽  
Nearshore Zone ◽  
Portunus Pelagicus ◽  
Males And Females ◽  
Swimming Crabs

<p><em>Fishing effort enhancement would put pressure on blue swimming crab resources and its ecosystem. The objective of this study was to determine the spatial distribution based on the size of the carapace width (CW), abundance, temperature, salinity, depth, and fishing intensity in Pati waters which was divided into two zones (zones 1=nearshore, zone 2=offshore). The result showed that the average of carapace width in zone 1 to zone 2 was significantly different (p &lt;0.05), as well as between males and females. Average number of individual (abundance) was significantly different according to fishing areas and sex (p &lt;0.05). The average of water temperature in zone 1 was higher than in zone 2, salinity in zone 1 was smaller than in zone 2, and the water depth in zone 1 was shallower than in zone 2. The higher the crab catch intensity leaded to the smaller the abundance and size of carapace width. Alternative management strategies were proposed such as to divert fishing grounds from coastal waters to offshore during low productivity season, to uphold rules on minimum legal size for catching (Lm = 107 mm),  to release of berried females catch, and to reduce accretion rate of gear and fishing fleet mainly in the coastal zone waters.</em></p><p><em><strong><em>Keywords:  </em></strong><em>blue swimming crab, carapace widht (CW), abundance, intensity of fishing</em></em></p>

A management strategy evaluation of the commercial sockeye salmon fishery in Bristol Bay, Alaska

2019 ◽  
Vol 76 (9) ◽  
pp. 1669-1683 ◽  
Author(s):  
Curry J. Cunningham ◽  
Christopher M. Anderson ◽  
Jocelyn Yun-Ling Wang ◽  
Michael Link ◽  
Ray Hilborn
Keyword(s):  
Management Strategy ◽  
Sockeye Salmon ◽  
Estimation Error ◽  
Management Strategies ◽  
Fishing Effort ◽  
Time Varying ◽  
Bristol Bay ◽  
Traditional Methods ◽  
Management Strategy Evaluation ◽  
Strategy Evaluation

Bristol Bay, Alaska, is home to the largest sockeye salmon (Oncorhynchus nerka) fishery in the world, harvesting an average of 25 million fish with an ex-vessel value exceeding US$100 million annually. Daily fishing effort is adaptively managed to achieve stock-specific escapement goals. Traditional methods for defining these goals relied on stock–recruitment analysis; however, this approach often ignores three fundamental sources of uncertainty: estimation error, implementation uncertainty, and time-varying recruitment dynamics. To compare escapement goal alternatives, we conducted a management strategy evaluation that simulated time-varying recruitment across production regimes and replicated the daily in-season management process. Results indicate (i) implementation uncertainty can be reasonably approximated with simple rules reflecting fishery managers’ daily decision process; (ii) despite implementation uncertainty, escapement goals are likely to be realized or exceeded, on average; and (iii) management strategies targeting escapement levels estimated by traditional methods to produce maximum sustainable yield may result in lower catch and greater variability in fishing opportunity compared with a strategy with defining high and low escapement goals that are targeted depending on assessed run size, which may maximize future catch while reducing the frequency of extremely low harvests.

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