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Most fishery regulations aim to control angler harvest. Yet, we lack a basic understanding of what actually determines the angler's decision to harvest or release fish caught. We used XGBoost, a machine learning algorithm, to develop a predictive angler harvest-release model by taking advantage of an extensive recreational fishery data set (24 water bodies, 9 years, and 193 523 fish). We were able to successfully predict the harvest-release outcome for 99% of fish caught in the training data set and 96% of fish caught in the test data set. Unsuccessful predictions were mostly attributed to predicting harvest of fish that were released. Fish length was the most essential feature examined for predicting angler harvest. Other important predictive harvest-release features included the number of individuals of the same species caught, geographic location of an angler's residence, distance traveled, and time spent fishing. The XGBoost algorithm was able to effectively predict the harvest-release decision and revealed hidden and intricate relationships that are often unaccounted for with classical analysis techniques. Exposing and accounting for these angler-fish intricacies is critical for fisheries conservation and management. La plupart des reglements relatifs a la peche visent a controler les prises des pecheurs a la ligne. Une comprehension de base de ce qui determine reellement la decision d'un pecheur de conserver ou de relacher un poisson peche manque toutefois. Nous avons utilise XGBoost, un logarithme d'apprentissage automatique, pour elaborer un modele predictif de decisions de pecheurs de conserver ou relacher un poisson en tirant parti d'un vaste ensemble de donnees de peche sportive (24 plans d'eau, 9 annees, 193 523 poissons). Nous avons ete en mesure de predire avec succes le resultat (conserver ou relacher) pour 99 % des poissons peches dans l'ensemble de donnees d'entrainement et 96 % des poissons peches dans l'ensemble de donnees experimental. Les predictions inexactes etaient pour la plupart de poissons conserves qui avaient en fait ete relaches. La longueur du poisson est l'aspect examine le plus important pour la prediction de la conservation par les pecheurs. D'autres aspects importants pour predire la conservation ou le lacher comprennent le nombre de specimens de la meme espece peches, l'emplacement geographique de la residence du pecheur, la distance parcourue et le temps passe a pecher. L'algorithme XGBoost est arrive a predire efficacement les decisions de conserver ou de relacher et a fait ressortir des relations cachees et complexes dont les methodes d'analyse classiques ne tiennent souvent pas compte. La reconnaissance et la prise en consideration de ces facteurs complexes associes aux pecheurs et aux poissons sont d'importance cle pour la conservation et la gestion des ressources halieutiques. [Traduit par la Redaction], Introduction Once a fish is caught by an angler, will it be harvested or released? Currently, we lack a basic understanding of this very important decision process. Fish harvest by [...]

Networks used to study interactions could provide insights to fisheries. We compiled data from 27 297 interviews of anglers across waterbodies that ranged in size from 1 to 12 113 ha. Catch rates of fish species among anglers grouped by species targeted generally differed between angling methods (bank or boat). We constructed angler-catch bipartite networks (angling method specific) between anglers and fish and measured several network metrics. There was considerable variation in networks among waterbodies, with multiple metrics influenced by waterbody size. Number of species-targeting angler groups and number of fish species caught increased with increasing waterbody size. Mean number of links for species-targeting angler groups and fish species caught also increased with waterbody size. Connectance (realized proportion of possible links) of angler-catch interaction networks decreased slower for boat anglers than for bank anglers with increasing waterbody size. Network specialization (deviation of number of interactions from expected) was not significantly related to waterbody size or angling methods. Application of bipartite networks in fishery science requires careful interpretation of outputs, especially considering the numerous confounding factors prevalent in recreational fisheries. Les reseaux utilises pour etudier les interactions pourraient fournir de l'information utile sur les peches. Nous avons compile des donnees de 27 297 entrevues de pecheurs a la ligne dans differents plans d'eau allant de 1 ha a 12 113 ha. Les taux de prise de differentes especes de poisson de pecheurs regroupes selon l'espece ciblee varient generalement selon la methode de peche (de la rive ou d'une embarcation). Nous avons construit des reseaux bipartites pecheur-prises (selon la methode de peche) entre les pecheurs et les poissons et mesure plusieurs parametres de ces reseaux. Il y a des variations considerables des reseaux entre plans d'eau, plusieurs parametres etant influences par la taille de ces derniers. Le nombre de groupes de pecheurs ciblant des especes precises et le nombre d'especes de poissons pechees augmentent avec la taille du plan d'eau. Le nombre moyen de liens pour les groupes de pecheurs ciblant des especes et les especes pechees augmente egalement avec la taille du plan d'eau. La connectance (proportion de liens possibles realises) des reseaux d'interactions pecheur-prises diminue plus lentement pour les pecheurs en embarcation que pour les pecheurs de la rive pour des plans d'eau de plus en plus grands. La specialisation des reseaux (ecart entre le nombre d'interactions observees et prevues) n'est pas significativement reliee a la taille du plan d'eau ou a la methode de peche. L'application de reseaux bipartites aux sciences halieutiques necessite une interpretation soigneuse des donnees de sortie, etant donne, notamment, les nombreux facteurs de confusion qui caracterisent les peches recreatives. [Traduit par la Redaction], Introduction In recreational fisheries, anglers' influence extends beyond the species that they target (Cooke and Cowx 2004, 2006; Lewin et al. 2006). The influence of recreational angling on targeted species [...]

The history of maize (Zea mays L.) is one of the most debated topics in New World archaeology. Molecular and genetic studies indicate that maize domestication took place in tropical southwest Mexico. Although archaeological evidence for the evolution of maize from its wild ancestor teosinte has yet to be found in that poorly studied region, other research combining paleoecology and archaeology is documenting the nature and timing of maize domestication and dispersals. Here we report a phytolith analysis of sediments from San AndrOs, Tabasco, that confirms the spread of maize cultivation to the tropical Mexican Gulf Coast >7,000 years ago ([approximately equal to] 7,300 calendar years before present). We review the different methods used in sampling, identifying, and dating fossil maize remains and compare their strengths and weaknesses. Finally, we examine how San Andres amplifies the present evidence for widespread maize dispersals into Central and South America. Multiple data sets from many sites indicate that maize was brought under cultivation and domesticated and had spread rapidly out of its domestication cradle in tropical southwest Mexico by the eighth millennium before the present. phytoliths | pollen | paleoecology | radiocarbon

Abstract. -- Catch data are summarized for common snook, (Centropomus undecimalis) from 1975 through 2004 from the lower Laguna Madre, the only area along the Texas coast where common snook [...]

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.icarus.2006.01.012 Byline: Kevin O. Pope (a), Susan W. Kieffer (b), Doreen E. Ames (c) Keywords: Impact processes; Cratering; Mars; Exobiology Abstract: Hydrothermal deposits are a prime exobiological research target on Mars and impact craters are potentially a significant source for these deposits. Key factors in the longevity of terrestrial impact crater hydrothermal systems are the volume of shock melt produced and the degree to which this melt is quenched by mixing with un-melted clasts. Mixing occurs when the shock melt is smeared along the crater floor, and the degree of mixing is inversely proportional to the thickness of this smeared layer. To investigate the potential development of thick melt sheets on Mars, we apply an analytical impact model to asteroid and long-period (LP) comet impacts that produces martian craters with final diameters of 30-640 km. We combine our model shock melt volumes with estimates of the surface area of the transient cavity to estimate initial shock melt thickness, which we use as a proxy measure of the amount of mixing between shock melt and un-melted clasts. We calculate this shock melt thickness parameter for a range terrestrial craters with and without thick melt sheets, from which we infer the melt sheet characteristics for the model Mars craters. The results demonstrate that most asteroid impacts on Mars do not produce thick, clast-free melt sheets. Only asteroid impact craters [greater than or equal to]580 km in diameter on Mars produce shock melt thicknesses comparable to Earth's 200-km-diameter Sudbury crater, and martian craters a[c]1/265 km in diameter produce shock melt thicknesses comparable to terrestrial craters that lack melts sheets entirely. LP comet impacts on Mars are more likely to produce thick melt sheets. LP comet impact craters [greater than or equal to]280 km in diameter on Mars produce shock melt thicknesses comparable to that of the Sudbury crater. Given that LP comet impacts on Mars are rare compared to asteroid impacts, we conclude that large, long-lived impact hydrothermal systems are likewise rare on Mars. Comparisons of the Mars asteroid impact rate with the potential longevity of impact hydrothermal systems indicate that such systems were active Author Affiliation: (a) Geo Eco Arc Research, 16305 St. Mary's Church Road, Aquasco, MD 20608, USA (b) Department of Geology, University of Illinois, Urbana, IL 61801, USA (c) Geological Survey of Canada, 601 Booth Street, Ottawa, ON K1A 0E8, Canada Article History: Received 8 July 2005; Revised 19 December 2005

Hydrothermal deposits are a prime exobiological research target on Mars and impact craters are potentially a significant source for these deposits. Key factors in the longevity of terrestrial impact crater hydrothermal systems are the volume of shock melt produced and the degree to which this melt is quenched by mixing with un-melted clasts. Mixing occurs when the shock melt is smeared along the crater floor, and the degree of mixing is inversely proportional to the thickness of this smeared layer. To investigate the potential development of thick melt sheets on Mars, we apply an analytical impact model to asteroid and long-period (LP) comet impacts that produces martian craters with final diameters of 30-640 km. We combine our model shock melt volumes with estimates of the surface area of the transient cavity to estimate initial shock melt thickness, which we use as a proxy measure of the amount of mixing between shock melt and un-melted clasts. We calculate this shock melt thickness parameter for a range terrestrial craters with and without thick melt sheets, from which we infer the melt sheet characteristics for the model Mars craters. The results demonstrate that most asteroid impacts on Mars do not produce thick, clast-free melt sheets. Only asteroid impact craters [more than or equal to] 580 km in diameter on Mars produce shock melt thickness comparable to Earth's 200-km-diameter Sudbury crater, and martian craters [less than or equal to] 65 km in diameter produce shock melt thickness comparable to terrestrial craters that lack melts sheets entirely. LP comet impacts on Mars are more likely to produce thick melt sheets. LP comet impact craters [more than or equal to] 280 km in diameter on Mars produce shock melt thickness comparable to that of the Sudbury crater. Given that LP comet impacts on Mars are rare compared to asteroid impacts, we conclude that large, long-lived impact hydrothermal systems are likewise rare on Mars. Comparisons of the Mars asteroid impact rate with the potential longevity of impact hydrothermal systems indicate that such systems were active Keywords: Impact processes; Cratering; Mars: Exobiology

Abstract.--A randomized design was used to test the difference in growth rates of juvenile green sunfish (Lepomis cyanellus) subjected to three treatments (food ration, temperature and salinity). Food ration and [...]

Abstract.--Total length and mass were measured on 883 spotted gar, Lepisosteus oculatus, collected between 1984 and 1996 from 49 Texas reservoirs. Spotted gar mass was positively related to length ([r.sup.2] [...]

A cylinder seal and carved greenstone plaque bearing glyphs dating to ~650 B.C. have been uncovered near the Olmec center of La Venta in Tabasco, Mexico. These artifacts, which predate others containing writing, reveal that the key aspects of the Mesoamerican scripts were present in Olmec writing: the combination of pictographic and glyphic elements to represent speech; the use of the sacred 260-day calendar; and the connection between writing, the calendar, and kingship. They imply that Mesoamerican writing originated in the La Venta polity., Our excavations at San Andres, located 5 km northeast of the Olmec center of La Venta, produced a cylinder seal and a greenstone plaque with glyphs dating to ~650 B.C., [...]

Most of the 3-mm-thick globally distributed Chicxulub ejecta layer found at the Cretaceous-Tertiary (K-T) boundary was deposited as condensation droplets from the impact vapor plume. A small fraction of this layer ( Keywords: Cretaceous-Tertiary boundary, mass extinctions, Chicxulub crater, impact crater, ejecta.

Analyses of spaceborne imaging radar-C (SIR-C) data and field data from the northwestern Yucatan Peninsula, Mexico, demonstrate that spaceborne multifrequency polarimetric radars are excellent tools for characterizing patterns of wetland flooding. Seasonal flooding can be detected in most types of forest and marsh in the radar backscatter magnitude and phase data of both L and C band. Field observations made in the wet and dry seasons concurrent with the space missions and chemical analyses of floodwaters confirm that flooding is the product of discharge from the Yucatan aquifer, which consists of a fresh-water lens floating on seawater. This discharge controls the distribution of wetlands. Therefore, vegetation and flooding patterns, mapped with SIR-C imagery, provide valuable information on the hydrogeology of the region. Radar-image maps of wetlands and flooding indicate that there are three major zones of groundwater discharge that correlate with structures of the buried Chicxulub crater--zone 1 with the peak ring, zone 2 with the crater rim, and zone 3 with the exterior ring. Zone 1 has sulfate-poor discharge, unlike the sulfate-rich discharge in zones 2 and 3. The highest discharge is in zone 3, where the buried crater is closest to the surface. This groundwater-discharge pattern can be explained by tidal pumping of fresh water to the surface through high permeability zones developed in the Tertiary carbonates overlying crater faults and escarpments. Keywords: Chicxulub crater, coastal environment, groundwater, radar, remote sensing, wetlands.

A new species of carcineretid crab, Carcineretes planetarius, is described from the Upper Cretaceous (lower Maastrichtian) Barton Creek Dolomite at Albion Island, Belize. The age is based on the stratigraphic range of associated nerineid gastropods and correlation with nannoplankton, benthic foraminifera, and the other known congeneric species of crab found in Jamaica. Confirmation of this age aids in constraining the timing of ejecta deposits of the Chicxulub impact found at the top of Barton Creek Dolomite exposed on Albion Island. Paleoenvironmental and paleoecological analyses suggest that these crabs were swimmers in lagoonal settings, capable of burrowing a few centimeters into the mud for protection.

Analyses of geomorphic, soil, and topographic data from the northern Yucatan Peninsula, Mexico, confirm that the buried Chicxulub impact crater has a distinct surface expression and that carbonate sedimentation throughout the Cenozoic has been influenced by the crater. Late Tertiary sedimentation was mostly restricted to the region within the buried crater, and a semicircular moat existed until at least Pliocene time. The topographic expression of the crater is a series of features concentric with the crater. The most prominent is an [approximately]83-km-radius trough or moat containing sinkholes (the Cenote ring). Early Tertiary surfaces rise abruptly outside the moat and form a stepped topography with an outer trough and ridge crest at radii of [approximately]103 and [approximately]129 km, respectively. Two discontinuous troughs lie within the moat at radii of [approximately]41 and [approximately]62 km. The low ridge between the inner troughs corresponds to the buried peak ring. The moat corresponds to the outer edge of the crater floor demarcated by a major ring fault. The outer trough and the [approximately]62-km-radius inner trough also mark buried ring faults. The ridge crest corresponds to the topographic rim of the crater as modified by postimpact processes. These interpretations support previous findings that the principal impact basin has a diameter of [approximately]180 km, but concentric, low-relief slumping extends well beyond this diameter and the eroded crater rim may extend to a diameter of [approximately]260 km.

Archaeological research in the Gulf Coast of Tabasco reveals the earliest record of maize cultivation in Mexico. The first farmers settled along beach ridges and lagoons of the Grijalva River [...]