|
|
|
| Registros recuperados: 13 | |
|
|
| Floch, Laurent; Depetris, Mathieu; Dewals, Patrice; Duparc, Antoine; Kaplan, David; Lebranchu, Julien; Marsac, Francis; Pernak, Marianne; Bach, Pascal. |
| In 2018, a total of 14 French vessels operated in the eastern Indian Ocean including 12 purse seiners and 2 supplies. The total capacity weighted by the months of activity for each vessel is 11686t. The total nominal effort in 2018 was of 2885 fishing days and 2723 sets with 2463 sets on floating objects and 260 on free schools. In 2018, the percentage of sets on FOB was 90% and the catches reached 91%. The total catch of the French component of the EU purse seine fleet of the Indian Ocean was 84,729 t, being composed of 36%, 58%, and 6% of yellowfin tuna, skipjack tuna, and bigeye tuna respectively. Thus, the most noticeable change in 2018 is the shift of catches from the free school sets, dominated by yellowfin, to the associated school sets, dominated... |
| Tipo: Text |
Palavras-chave: Tropical tuna fisheries; French purse seining; Free swimming school; Fish aggregating devices; Katsuwonus pelamis; Thunnus albacares; Thunnus obesus. |
| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00590/70259/68318.pdf |
| |
|
|
| Cuif, Marion; Kaplan, David; Lefevre, Jerome; Faure, Vincent Martin; Caillaud, Matthieu; Verley, Philippe; Vigliola, Laurent; Lett, Christophe. |
| In the present work, a biophysical dispersal model is used to understand the role of the physical environment in determining reef fish larval dispersal patterns in the South-West Lagoon of New Caledonia. We focus on a reef fish species, the humbug damselfish Dascyllus aruanus, to investigate seasonal variability of simulated larval retention at the scale of a reef patch and at the scale of the lagoon, and to explore links between larval retention and wind variability. The model shows that retention exhibits considerable temporal variability and periodically reaches values much larger than anticipated. Non-zero larval settlement occurs over a large part of the lagoon. Nevertheless, settlement values decrease quickly away from the natal reef and mean... |
| Tipo: Text |
|
| Ano: 2014 |
URL: http://archimer.ifremer.fr/doc/00170/28115/26326.pdf |
| |
|
|
| Lett, Christophe; Tri Nguyen-huu,; Cuif, Marion; Saenz-agudelo, Pablo; Kaplan, David. |
| Three indices of larval retention have been used in the literature to assess the tendency for self-maintenance of local marine populations: local retention (LR), self-recruitment (SR), and relative local retention (RLR). Only one of these, LR, defined as the ratio of locally produced settlement to local egg production, has a clear relationship to self-persistence of individual sites. However, SR, the ratio of locally produced settlement to settlement of all origins at a site, is generally easier to measure experimentally. We use theoretical, simulation, and empirical approaches to bridge the gap between these different indices, and demonstrate that there is a proportional relationship between SR and LR for metapopulations close to a stable state and with... |
| Tipo: Text |
Palavras-chave: Connectivity; Larval dispersal; Lifetime egg production; Local retention; Marine reserve; Metapopulation; Network persistence; Population persistence; Self-persistence; Self-recruitment. |
| Ano: 2015 |
URL: https://archimer.ifremer.fr/doc/00275/38628/81243.pdf |
| |
|
|
| Meynard, Christine N.; Kaplan, David; Leroy, Boris. |
| Liu et al. (2018) used a virtual species approach to test the effects of outliers on species distribution models. In their simulations, they applied a threshold value over the simulated suitabilities to generate the species distributions, suggesting that using a probabilistic simulation approach would have been more complex and yield the same results. Here, we argue that using a probabilistic approach is not necessarily more complex and may significantly change results. Although the threshold approach may be justified under limited circumstances, the probabilistic approach has multiple advantages. First, it is in line with ecological theory, which largely assumes non‐threshold responses. Second, it is more general, as it includes the threshold as a... |
| Tipo: Text |
Palavras-chave: ENM; Observation errors; Outliers; Prevalence; Probabilistic approach; Sample bias; Simulations; Species distribution models; Virtual ecology; Virtual species. |
| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00501/61309/64868.pdf |
| |
|
|
| Bonhommeau, Sylvain; Dubroca, Laurent; Le Pape, Olivier; Barde, Julien; Kaplan, David; Chassot, Emmanuel; Nieblas, Anne-elise. |
| Trophic levels are critical for synthesizing species' diets, depicting energy pathways, understanding food web dynamics and ecosystem functioning, and monitoring ecosystem health. Specifically, trophic levels describe the position of species in a food web, from primary producers to apex predators (range, 1-5). Small differences in trophic level can reflect large differences in diet. Although trophic levels are among the most basic information collected for animals in ecosystems, a human trophic level (HTL) has never been defined. Here, we find a global HTL of 2.21, i.e., the trophic level of anchoveta. This value has increased with time, consistent with the global trend toward diets higher in meat. National HTLs ranging between 2.04 and 2.57 reflect a... |
| Tipo: Text |
Palavras-chave: Human ecology; Nutrition transition; Trophic ecology. |
| Ano: 2013 |
URL: http://archimer.ifremer.fr/doc/00171/28190/26609.pdf |
| |
|
|
| Imzilen, Taha; Lett, Christophe; Chassot, Emmanuel; Kaplan, David. |
| Debris from fisheries pose significant threats to coastal marine ecosystems worldwide. Tropical tuna purse seine fisheries contribute to this problem via the construction and deployment of thousands of human-made drifting fish aggregating devices (dFADs) annually, many of which end up beaching in coastal areas. Here, we analyzed approximately 40,000 dFAD trajectories in the Indian Ocean and 12,000 dFAD trajectories in the Atlantic Ocean deployed over the decade 2008–2017 to identify where and when beachings occur. We find that there is tremendous promise for reducing beaching events by prohibiting deployments in areas most likely to lead to a beaching. For example, our results indicate that 21% to 40% (depending on effort redistribution after closure) of... |
| Tipo: Text |
Palavras-chave: Marine pollution; Fishing debris; Coral reefs; Fish aggregating device (FAD); Ocean currents. |
| Ano: 2021 |
URL: https://archimer.ifremer.fr/doc/00669/78060/80807.pdf |
| |
|
|
| Boudin, Elyse; Santos, Bianca; Carcaillet, Frédérique; Kaplan, David. |
| Sea turtles around the world are threatened with extinction, largely due to human activities. To better protect sea turtles, we need to improve our understanding of the activities that threaten them. However, we often do not know the cause of sea turtle deaths, making it difficult to help protect them. This is the case in the Chesapeake Bay, USA, where hundreds of dead sea turtles are found washed up on beaches each year. In this study, researchers investigated these events, known as sea turtle strandings, to better understand why sea turtles in this region are dying. First, they carried out experiments to predict when and where sea turtles died at sea. This information was then used to identify potential causes of sea turtle mortality. The results of the... |
| Tipo: Text |
|
| Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00654/76600/77750.pdf |
| |
|
|
| Currie, J. C.; Lengaigne, M.; Vialard, Jerome; Kaplan, David; Aumont, Olivier; Naqvi, S. W. A.; Maury, Olivier. |
| The Indian Ocean Dipole (IOD) and the El Nino/Southern Oscillation (ENSO) are independent climate modes, which frequently co-occur, driving significant interannual changes within the Indian Ocean. We use a four-decade hindcast from a coupled biophysical ocean general circulation model, to disentangle patterns of chlorophyll anomalies driven by these two climate modes. Comparisons with remotely sensed records show that the simulation competently reproduces the chlorophyll seasonal cycle, as well as open-ocean anomalies during the 1997/1998 ENSO and IOD event. Results suggest that anomalous surface and euphotic-layer chlorophyll blooms in the eastern equatorial Indian Ocean in fall, and southern Bay of Bengal in winter, are primarily related to IOD forcing.... |
| Tipo: Text |
|
| Ano: 2013 |
URL: http://archimer.ifremer.fr/doc/00166/27749/25945.pdf |
| |
|
|
| Kaplan, David; Bach, Pascal; Bonhommeau, Sylvain; Chassot, Emmanuel; Chavance, Pierre; Dagorn, Laurent; Davies, Tim; Dueri, Sibylle; Fletcher, Rick; Fonteneau, Alain; Fromentin, Jean-marc; Gaertner, Daniel; Hampton, John; Hilborn, Ray; Hobday, Alistair; Kearney, Robert; Kleiber, Pierre; Lehodey, Patrick; Marsac, Francis; Maury, Olivier; Mees, Chris; Menard, Frederic; Pearce, John; Sibert, John. |
| Tipo: Text |
|
| Ano: 2013 |
URL: http://archimer.ifremer.fr/doc/00139/25068/23186.pdf |
| |
|
|
| Maufroy, Alexandra; Chassot, Emmanuel; Joo, Rocio; Kaplan, David. |
| Since the 1990s, massive use of drifting Fish Aggregating Devices (dFADs) to aggregate tropical tunas has strongly modified global purse-seine fisheries. For the first time, a large data set of GPS positions from buoys deployed by French purse-seiners to monitor dFADs is analysed to provide information on spatio-temporal patterns of dFAD use in the Atlantic and Indian Oceans during 2007-2011. First, we select among four classification methods the model that best separates "at sea" from "on board" buoy positions. A random forest model had the best performance, both in terms of the rate of false "at sea" predictions and the amount of over-segmentation of "at sea" trajectories (i.e., artificial division of trajectories into multiple, shorter pieces due to... |
| Tipo: Text |
|
| Ano: 2015 |
URL: https://archimer.ifremer.fr/doc/00271/38256/73660.pdf |
| |
|
|
| Mannocci, Laura; Forget, Fabien; Travassos Tolotti, Mariana; Bach, Pascal; Bez, Nicolas; Demarcq, Herve; Kaplan, David; Sabarros, Philippe; Simier, Monique; Capello, Manuela; Dagorn, Laurent. |
| Fisheries observer programs represent the most reliable way to collect data on fisheries bycatch. However, their limited coverage leads to important data gaps that preclude bycatch mitigation at the basin scale. Habitat models developed from available fisheries observer programs offer a potential solution to fill these data gaps. We focus on tropical tuna purse seine fisheries (TTPSF) that span across the tropics and extensively rely on floating objects (FOBs) for catching tuna schools, leading to the bycatch of other species associated with these objects. Bycatch under floating objects is dominated by five species, including the vulnerable silky shark Carcharhinus falciformis and four bony fishes (oceanic triggerfish Canthidermis maculata, rainbow runner... |
| Tipo: Text |
Palavras-chave: Bycatch; Habitat modelling; Hotspots; Fisheries observer programs; Geographical extrapolation; Tropical oceans. |
| Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00662/77385/78986.pdf |
| |
|
|
| Beckensteiner, Jennifer; Kaplan, David; Scheld, Andrew M.. |
| The eastern oyster once provided major societal and ecosystem benefits, but these benefits have been threatened in recent decades by large declines in oyster harvests. In many areas, recovery of oyster aquaculture faces significant societal opposition and spatial constraints limiting its ability to meet expectations regarding future food needs and provision of ecosystem services. In Virginia, oyster aquaculture has begun to expand, concurrent with an increase in subaqueous leased areas (over 130,000 acres of grounds are currently leased). Though private leases must in theory be used for oyster production, in practice, they can be held for other reasons, such as speculation or intentional exclusion of others. These factors have led to large variation over... |
| Tipo: Text |
Palavras-chave: Crassostrea virginica; Oyster aquaculture; Chesapeake Bay; Spatial management; User conflicts. |
| Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00611/72337/71162.pdf |
| |
|
|
| Meynard, Christine N.; Leroy, Boris; Kaplan, David. |
| Species distribution models (SDMs) have become one of the major predictive tools in ecology. However, multiple methodological choices are required during the modelling process, some of which may have a large impact on forecasting results. In this context, virtual species, i.e., the use of simulations involving a fictitious species for which we have perfect knowledge of its occurrence‐environment relationships and other relevant characteristics, have become increasingly popular to test SDMs. This approach provides for a simple virtual ecologist framework under which to test model properties, as well as the effects of the different methodological choices, and allows teasing out the effects of targeted factors with great certainty. This simplification is... |
| Tipo: Text |
Palavras-chave: Artificial species; Environmental niche models; Niche; Simulations; Species distribution modelling; Virtual ecologist. |
| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00501/61308/64864.pdf |
| |
| Registros recuperados: 13 | |
|
|
|
