scholarly journals Large-Scale Examination of Spatio-Temporal Patterns of Drifting Fish Aggregating Devices (dFADs) from Tropical Tuna Fisheries of the Indian and Atlantic Oceans

PLoS ONE ◽  
2015 ◽  
Vol 10 (5) ◽  
pp. e0128023 ◽  
Author(s):  
Alexandra Maufroy ◽  
Emmanuel Chassot ◽  
Rocío Joo ◽  
David Michael Kaplan
2014 ◽  
Vol 71 (7) ◽  
pp. 1728-1749 ◽  
Author(s):  
David M. Kaplan ◽  
Emmanuel Chassot ◽  
Justin M. Amandé ◽  
Sibylle Dueri ◽  
Hervé Demarcq ◽  
...  

Abstract Effective use of spatial management in the pelagic realm presents special challenges due to high fish and fisher mobility, limited knowledge and significant governance challenges. The tropical Indian Ocean provides an ideal case study for testing our ability to apply existing data sources to assessing impacts of spatial management on tuna fisheries because of several recent controversial spatial closures. We review the scientific underpinnings of pelagic MPA effects, spatio-temporal patterns of Indian Ocean tuna catch, bycatch and fish movements, and the consequences of these for the efficacy of spatial management for Indian Ocean tropical tuna fisheries. The tropical Indian Ocean is characterized by strong environmental fluctuations, regular seasonal variability in catch, large observed tuna displacement distances, relatively uniform catch-per-unit-effort and bycatch rates over space, and high fisher mobility, all of which suggest significant variability and movement in tropical tuna fisheries that are simply not well adapted to static spatial closures. One possible exception to this overall conclusion would be a large time/area closure east of Somalia. If closed for a significant fraction of the year it could reduce purse-seine bycatch and juvenile tuna catch. Dynamic closures following fish migratory patterns are possible, but more focused information on fish movements will be needed for effective implementation. Fortunately, several recent improvements in conventional fishery management and reporting will likely enhance our ability to evaluate spatial and non-spatial management options in the near future, particularly as pertaining to bycatch species.


2013 ◽  
Vol 5 (2) ◽  
pp. 97
Author(s):  
Duto Nugroho ◽  
Suherman Banon Atmaja

<p>Penggunaan rumpon laut-dalam telah mengubah taktik dan strategi perikanan pukat cincin pelagis kecil yang beroperasi di perairan dangkal untuk bergeser pada perikanan tuna neritik tropis. Rumponisasi perikanan pukat cincin yang dirancang untuk meningkatkan produktivitas telah menjadi masalah serius pada perikanan neritik tuna. Hal ini terjadi karena tertangkapnya ikan berukuran kecil dalam jumlah yang dominan sehingga dalam jangka panjang akan berpotensi konflik dengan perikanan lainnya. Para ilmuwan yang tergabung dalam pengelolaan perikanan regional merekomendasikan bahwa pengembangan terkendali terhadap penggunaan rumpon di daerah asuhan juvenile tuna tropis. Pengendalian dalam jangka panjang dapat meminimalkan ancaman bagi kelangsungan hidup kelompok jenis tuna. Hal ini terkait dengan pentingnya memperbesar peluang masuknya sediaan kelompok jenis ini pada tingkat yang layak untuk dimanfaatkan. Di Indonesia, pilihan kebijakan perikanan tangkap baik melalui peralihan sasaran kelompok spesies maupun diversifikasi usaha penangkapan akan selalu bertumpu pada pertimbangan sosial. Bagaimanapun juga, proses mengubah pemahaman nelayan nelalui pengendalian jumlah dan teknologi kapal penangkap ikan serta penutupan sementara daerah penangkapan yang akan melalui proses panjang harus tetap dijalankan untuk mencegah runtuhnya perikanan yang saat ini sedang berjalan.</p><p>The use of Fish Aggregating Devices (FADs) has radically changing the tactic and strategy shallow waters small pelagic purse seiner into high seas tropical neritics tuna fisheries. Applying FADs on purse seine fishery which initiated to increase its productivity became a serious problem to neritics<br />tuna fishery. This indicated by the negative impact on neritics and tropical tuna populations due to large number of small size of tunas being caught and uncertain of number and of FADS position in the high seas. In the long run it will generate a potential conflict to other existing fisheries. The member scientists of regional fisheries management organization (RFMO) recommends that the development of the use of FADs, especially in the area which dominated of juvenile of tropical tuna, should be strongly regulated. FADs management through control system should be applied to minimize impact on recruitment process that associated with the importance of long term availability of its fisheries. Management option through shifting target species and diversification of the fishing activities in<br />Indonesia would always be rely on social dimension. Nevertheles, reorientation on fishers understanding on controllable number of fishing vessels and its technological creeps should strongly be implemented to avoid collapse their existing fisheries.</p>


2013 ◽  
Vol 41 (3) ◽  
pp. 253-264 ◽  
Author(s):  
SADIA E. AHMED ◽  
ROBERT M. EWERS ◽  
MATTHEW J. SMITH

SUMMARYThere is burgeoning interest in predicting road development because of the wide ranging important socioeconomic and environmental issues that roads present, including the close links between road development, deforestation and biodiversity loss. This is especially the case in developing nations, which are high in natural resources, where road development is rapid and often not centrally managed. Characterization of large scale spatio-temporal patterns in road network development has been greatly overlooked to date. This paper examines the spatio-temporal dynamics of road density across the Brazilian Amazon and assesses the relative contributions of local versus neighbourhood effects for temporal changes in road density at regional scales. To achieve this, a combination of statistical analyses and model-data fusion techniques inspired by studies of spatio-temporal dynamics of populations in ecology and epidemiology were used. The emergent development may be approximated by local growth that is logistic through time and directional dispersal. The current rates and dominant direction of development may be inferred, by assuming that roads develop at a rate of 55 km per year. Large areas of the Amazon will be subject to extensive anthropogenic change should the observed patterns of road development continue.


2017 ◽  
Vol 7 (1) ◽  
Author(s):  
Xi Jiang ◽  
Isaac Shamie ◽  
Werner K. Doyle ◽  
Daniel Friedman ◽  
Patricia Dugan ◽  
...  

2008 ◽  
Vol 65 (6) ◽  
pp. 1193-1205 ◽  
Author(s):  
Mathieu Doray ◽  
Pierre Petitgas ◽  
Erwan Josse

Universal kriging was used to model the spatio-temporal variability in the acoustic density of tuna aggregations recorded during star echosounding surveys around moored fish aggregating devices (FADs) in Martinique (Lesser Antilles). The large-scale deterministic drift in the tuna spatial distribution was modeled using an advection–diffusion equation applied to animal grouping. Residuals from the drift were modeled as a random component with small-scale spatial correlation. An estimation variance formula was derived from this deterministic–statistical mixed model to assess the mean precision of density estimates of daytime tuna aggregation. The mean relative error obtained with our star design for daytime surveys was 24%. The methodology was applied to estimate daily maxima of tuna biomass around moored FADs during four monthly sea cruises. The daily peak of tuna biomass aggregated around moored FADs was 9 t on average (standard deviation = 4). Estimation variances for different survey designs were compared for optimizing sampling strategy.


2014 ◽  
Vol 94 (7) ◽  
pp. 1401-1408 ◽  
Author(s):  
Stephen K. Pikesley ◽  
Brendan J. Godley ◽  
Sue Ranger ◽  
Peter B. Richardson ◽  
Matthew J. Witt

Concern has been expressed over future biogeographical expansion and habitat capitalization by species of the phylum Cnidaria, as this may have negative implications on human activities and ecosystems. There is, however, a paucity of knowledge and understanding of jellyfish ecology, in particular species distribution and seasonality. Recent studies in the UK have principally focused on the Celtic, Irish and North Seas, but all in isolation. In this study we analyse data from a publicly-driven sightings scheme across UK coastal waters (2003–2011; 9 years), with the aim of increasing knowledge on spatial and temporal patterns and trends. We describe inter-annual variability, seasonality and patterns of spatial distribution, and compare these with existing historic literature. Although incidentally-collected data lack quantification of effort, we suggest that with appropriate data management and interpretation, publicly-driven, citizen-science-based, recording schemes can provide for large-scale (spatial and temporal) coverage that would otherwise be logistically and financially unattainable. These schemes may also contribute to baseline data from which future changes in patterns or trends might be identified. We further suggest that findings from such schemes may be strengthened by the inclusion of some element of effort-corrected data collection.


Author(s):  
Soumyajit Sarkar ◽  
Abhijit Mukherjee ◽  
Srimanti Duttagupta ◽  
Soumendra Nath Bhanja ◽  
Animesh Bhattacharya ◽  
...  

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