Mapping diversity indices: not a trivial issue

Mapping diversity indices, that is estimating values in all locations of a given area from some sampled locations, is central to numerous research and applied fields in ecology. Two approaches are used to map diversity indices without including abiotic or biotic variables: (i) the indirect approach, which consists in estimating each individual species distribution over the area, then stacking the distributions of all species to estimate and map a posteriori the diversity index, (ii) the direct approach, which relies on computing a diversity index in each sampled locations and then to interpolate these values to all locations of the studied area for mapping. For both approaches, we document drawbacks from theoretical and practical viewpoints and argue about the need for adequate interpolation methods. First, we point out that the indirect approach is problematic because of the high proportion of rare species in natural communities. This leads to zero-inflated distributions, which cannot be interpolated using standard statistical approaches. Secondly, the direct approach is inaccurate because diversity indices are not spatially additive, that is the diversity of a studied area (e.g. region) is not the sum of the local diversities. Therefore, the arithmetic variance and some of its derivatives, such as the variogram, are not appropriate to ecologically measure variation in diversity indices. For the direct approach, we propose to consider the -diversity, which quantifies diversity variations between locations, by the mean of a -gram within the interpolation procedure. We applied this method, as well as the traditional interpolation methods for comparison purposes on different faunistic and floristic data sets collected from scientific surveys. We considered two common diversity indices, the species richness and the Rao\u27s quadratic entropy, knowing that the above issues are true for complementary species diversity indices as well as those dealing with other biodiversity levels such as genetic diversity. We conclude that none of the approaches provided an accurate mapping of diversity indices and that further methodological developments are still needed. We finally discuss lines of research that may resolve this key issue, dealing with conditional simulations and models taking into account biotic and abiotic explanatory variables

A participatory scenario method to explore the future of marine social‐ecological systems

Source at https://doi.org/10.1111/faf.12356.Anticipating future changes in marine social‐ecological systems (MSES) several decades into the future is essential in the context of accelerating global change. This is challenging in situations where actors do not share common understandings, practices, or visions about the future. We introduce a dedicated scenario method for the development of MSES scenarios in a participatory context. The objective is to allow different actors to jointly develop scenarios which contain their multiple visions of the future. The method starts from four perspectives: “fisheries management,” “ecosystem,” “ocean climate,” and “global context and governance” for which current status and recent trends are summarized. Contrasted scenarios about possible futures are elaborated for each of the four single perspectives before being integrated into multiple‐perspective scenarios. Selected scenarios are then developed into storylines. Focusing on individual perspectives until near the end allows actors with diverse cultures, interests and horizons to confront their own notions of the future. We illustrate the method with the exploration of the futures of the Barents Sea MSES by 2050. We emphasize the following lessons learned: first, many actors are not familiar with scenario building and attention must be paid to explaining the purpose, methodology, and benefits of scenarios exercises. Second, although the Barents Sea MSES is relatively well understood, uncertainties about its future are significant. Third, it is important to focus on unlikely events. Fourth, all perspectives should be treated equally. Fifth, as MSES are continuously changing, we can only be prepared for future changes if we collectively keep preparing

Status, challenges and pathways to the sustainable use of wild species

DATA AVAILABILITY : Data will be made available on request.The use of wild species is extensive in both high- and low-income countries. At least 50,000 wild species are used by billions of people around the world for food, energy, medicine, material, education or recreation, contributing significantly to efforts to achieve the United Nations Sustainable Development Goals. However, overexploitation remains a major threat to many wild species. Ensuring and enhancing the sustainability of use of wild species is thus essential for human well-being and biodiversity conservation. Globally, the use of wild species is increasing due to growing human demand and efficiency, but its sustainability varies and depends on the social-ecological contexts in which the use occurs. Multiple environmental and social (including economic) drivers affect the sustainability of use of wild species, posing major current and future challenges. In particular, climate change has already increased the vulnerability of many uses and is expected to increase it further in the coming decades, while global and illegal trades are, in many cases, key drivers of unsustainability. There is no single “silver bullet” policy to address these and other major challenges in the sustainable use of wild species. Rather, effective policies need to integrate inclusive actions at multiple scales that adopt right-based approaches, pay attention to equitable distribution of access and costs and benefits, employ participatory processes, strengthen monitoring programs, build robust customary or government institutions and support context-specific policies, as well as adaptive management.http://www.elsevier.com/locate/gloenvchahj2023Plant Production and Soil Scienc

The 2002 size composition of bluefin tuna catches of the French purse seine compared to those of the early 1990s and 2001

In 2002, about 40% of the yield of the French purse seine fleet targeting bluefin tuna came from the Gulf of Lions, 38% from the Balearic Islands and about 22% from the Malta-Lybia area (a new area for this fleet). The fleet caught, in the Gulf of Lions, mostly juvenile bluefin (mainly 2 and 3 years old), whereas both juveniles and adults were targeted and caught in the Balearic and Maltese areas. As in 2001, the 2002 size composition of bluefin catches have been estimated from the EU log-books and both years looked very similar. Calculating Kolmogorov-Smirnov two sample tests between the yearly size compositions of 1990-1995 and those of 2001 and 2002, indicated significant differences between these two pools of data. Finally, we confirm that if the information provided by the EU log-books allows calculation of a rough estimate of the size composition of the catches, it remains too imprecise and lacks validation to allow the computation of a size frequency table that would fulfil the ICCAT requirements for Task II.Près de 40% des captures des senneurs français visant le thon rouge atlantique provenait du golfe du lion, 38% de la zone Baléares et environ 22% de la zone sud-Malte (une nouvelle aire de pêche pour cette flottille). Une grande majorité de juvéniles (principalement des poissons d’âge 2 et 3) est capturée lors de la campagne dans le golfe du lion, alors que juvéniles et adultes se retrouvent dans les captures des zones Baléares et Malte. Comme en 2001, la composition en taille des captures 2002 des senneurs français a été estimée à partir des données des livres de bord européens et les distributions de ces 2 années sont apparues très similaires. En utilisant des tests à deux échantillons de Kolmogorov-Smirnov entre les distributions des taille de captures des années 1990-1995 et 2001-2002, nous avons dégagé des fortes différences entre ces deux pools d’années. Finalement nous confirmons que si les informations issues des livres de bord européens permettent d’établir une composition en taille des captures approximative, elles restent cependant trop imprécises et manquent de validation pour permettre de calculer une composition en taille des captures qui répondrait au cahier des charges de la CICTA pour la tâche II.En 2002, cerca del 40% de las capturas de los cerqueros franceses que se dirigen al atún rojo procedía del Golfo de León, el 38% de las Islas Baleares y cerca del 22% de la zona de Libia-Malta (una nueva zona para esta flota). En el Golfo de León la flota capturó fundamentalmente atunes rojos juveniles (principalmente de 2 a 3 años de edad), mientras que en las zonas de Baleares y Malta capturó y se dirigió principalmente a juveniles y adultos. Como en 2001, la composición por tallas de 2002 de las capturas de atún rojo se ha estimado a partir de cuadernos de pesca de la CE y ambos años parecen muy similares. Utilizando un test Kolmogorov-Smirnov de dos muestras entre las distribuciones de talla de las capturas de los años 1990-1995 y 2001-2002, hemos advertido que existen grandes diferencias entre estos dos grupos de datos. Por último, confirmamos que aunque la información facilitada por los cuadernos de pesca de la CE permite el cálculo de una estimación aproximativa de la composición por tallas de las capturas, sigue siendo muy imprecisa y falta de validación para permitir el cálculo de una tabla de frecuencia de tallas que cumpla los requisitos de la Tarea II de ICCAT

Descriptive analysis of the ICCAT bluefin tuna tagging database

The present paper proposes a simple descriptive analysis of the ICCAT bluefin tuna tagging database. Since 1954, about 91.2% of the tags were released in the West Atlantic and 8.8% in the East Atlantic. The great majority of tags was recaptured in their area of release, i.e., 95.7% and 97.25% for the East and the West Atlantic, respectively. The number of tags released in the West and recaptured in the East (102) was about 5 times higher than the reverse (19), but the percentage of transatlantic migrations from East-to-West (4.3%) was about 2 times higher than the one from West-to-East (2.25%). The percentage of transatlantic migrations varies over time, especially from West-to-East. It was much higher during the 90’s (7.6%) than in the three previous decades (0.8% to 2.3%). The probability to get a recapture in another area than the one of release seems further to depend on two factors: (i) the time at liberty and (ii) the age (or size) of the fish; higher the time at liberty and/or older the fish, higher the probability to get a transatlantic migration.Cet article propose une simple analyse descriptive de la base de données marquage de thon rouge du CICTA. Depuis 1954, environ 91.2% des marques ont réalisées dans l’Atlantique Ouest et 8.8% dans l’Atlantique Est. La grande majorité des marques a été recapturée dans leur zone de marquage, i.e., 95.7% et 97.25% pour l’Est et l’Ouest. Le nombre de marques réalisé dans l’Ouest et recapturé dans l’Est (102) était environ 5 fois plus important que l’opposé (19), mais le pourcentage de migrations trans-atlantiques d’Est en Ouest (4.3%) était environ 2 fois plus important que celui d’Ouest en Est (2.25%). Le pourcentage de migrations trans-atlantiques varie dans le temps, en particulier d’Ouest en Est, où il fut bien plus fort dans les années 1990 (7.6%) que durant les 3 décades précédentes (0.8% à 2.3%). La probabilité d’obtenir une recapture dans une autre zone que celle du marquage semble de plus dépendre de 2 facteurs : (i) le temps de liberté et (ii) l’âge (ou la taille) du poisson ; plus long est le temps de liberté et/ou plus âgé est le poisson, plus importante est la probabilité d’obtenir une migration trans-atlantique.El presente documento propone un simple análisis descriptivo de la base de datos de marcado del atún rojo de ICCAT. Desde 1954, se han colocado el 94,2% de las marcas en el Atlántico oeste y el 8,8% en el este. La gran mayoría de las marcas se recuperaron en la zona en que fueron colocadas, es decir, 95,7% y 97,25% para el Atlántico este y oeste, respectivamente. El número de marcas colocadas en el Oeste y recuperadas en el Este (102) fue el quíntuple que la inversa (19), pero el porcentaje de migraciones trasatlánticas de Este a Oeste (4,3%) duplicó al porcentaje de las del Oeste al Este (2,25%). El porcentaje de migraciones trasatlánticas varía en el tiempo, especialmente del Oeste al Este, donde fue mucho más elevado en los 90 (7,6%) que en las tres décadas anteriores (0,8% a 2,3%). La probabilidad de recuperar una marca en una zona que no sea aquella en que se realizó el marcado parece depender de dos factores: (i) el tiempo de libertad y (ii) la edad (o la talla) de los peces; cuando el pez pasa más tiempo en libertad o alcanza una edad más avanzada, mayor es la probabilidad de que se detecte una migración trasatlántica

Tagging bluefin tuna in the Mediterranean sea: challenge or mission: impossible?

Since 2007, Ifremer together with the French Federation of Sport fishermen (FFPM) and Big Game Fishing Club France (BGFCF) have been carrying out a program of conventional and electronic tagging on bluefin tuna in the western Mediterranean Sea. 479 and 95 ICCAT “spaghetti” tags have been deployed by the FFPM recreational and sportive fishermen along the Mediterranean French coasts in 2007 and 2008, respectively. To date, not a single recapture has been registered. Ifremer together with BGFCF has deployed 11, 6 and 8 pop-up archival tags (PAT) offshore of Marseille in 2007, 2008 and 2009, respectively. Outputs were impaired by two main technical difficulties: premature detachment and low transmission rates in the Argos band over the Mediterranean. While the first difficulty can be partially solved, the second remains a key limitation when using pop-up archival tags in this area. Preliminary results are, however, of interest and indicate that (i) most tagged fish remained in the western Mediterranean Sea and did not migrate in the Atlantic but (ii), migration to the central Mediterranean Sea (Sicily or Gulf of Syrta) occurred during the spawning period, and (iii) a possible foraging ground has been detected South of the Gulf of Lions in both 2007 and 2008.Depuis 2007, l’Ifremer, la Fédération française des pêcheurs en mer (FFPM) et le Big Game Fishing Club France (BGFCF) joignent leur effort pour mener une campagne de marquage conventionnel et électronique sur le thon rouge de la Méditerranée occidentale. Les pêcheurs récréatifs et sportifs de la FFPM ont apposé respectivement 479 et 95 marques « spaghetti » ICCAT le long des côtes méditerranéennes françaises en 2007 et 2008. Aucune recapture n’a été répertoriée pour l’instant. L’Ifremer et le BGFCF ont déployé 11, 6 et 8 marques archives pop-up (PAT) au large de Marseille en 2007, 2008 et 2009 respectivement. Deux difficultés techniques entachent cependant les résultats : la prématurité des détachements et la médiocre performance du système Argos sur la Méditerranée. Si la première de ces difficultés peut être en partie résolue, la seconde reste une limitation clé pour l’utilisation des PAT en Méditerranée. Les résultats préliminaires sont cependant intéressants et montrent que : (i) la plupart des poissons marqués sont restés en Méditerranée occidentale et n’ont pas migré en Atlantique, mais (ii) une migration en Méditerranée centrale (Sicile et golfe de Syrte) s’est produite lors de la période de reproduction et (iii) une aire potentielle de nutrition a été identifiée au sud du Golfe du Lion en 2007 et 2008.Desde 2007, el Ifremer, la Federación francesa de Pesca marina (FFPM) y el Big Game Fishing Club Francia (BGFCF) ha estado llevando a cabo un programa de marcado convencional y electrónico de atún rojo en el Mediterráneo occidental. Los pescadores recreativos y deportivos del FFPM han colocado 479 y 95 marcas “espagueti” de ICCAT a lo largo de las costas mediterráneas francesas en 2007 y 2008, respectivamente. Hasta la fecha no se ha producido ninguna recaptura. Ifremer, junto con BGFCF, ha colocado 11, 6 y 8 marcas archivo pop-up (PAT) en aguas de Marsella en 2007, 2008 y 2009 respectivamente. Sin embargo, los resultados se han visto afectados por dos dificultades técnicas: suelta prematura y bajas tasas de transmisión en la banda Argos a lo largo del Mediterráneo. Aunque la primera dificultad puede ser parcialmente resuelta, la segunda sigue siendo una limitación importante al usar marcas archivo pop-up en esta zona. No obstante, los resultados preliminares son interesantes e indican que (i) la mayoría de los peces marcados permaneció en el Mediterráneo occidental y no emigró al Atlántico pero (ii) la migración al Mediterráneo central (Sicilia y golfo de Syrta) se produjo durante la temporada de puesta, y (iii) se ha detectado una posible zona de alimentación al Sur del Golfo de León tanto en 2007 como en 2008