Bait-bucket introductions" related to the fishing bait industry are the suspected primary cause of alien (non-indigenous) crayfish introductions that have damaged North American aquatic ecosystems. Our 2008 survey of U.S. and Canadian fisheries agencies revealed that 49% of respondents reported aquatic resource problems that were believed to have been caused by bait-bucket introductions of alien crayfishes. Most respondents reported existing regulations designed to address those problems; however, only 4% prohibited the use of live crayfish bait. Our 2002-2007 examination of Missouri bait shops revealed sales of illegal and invasive alien crayfishes by bait shop proprietors who could not identify the species they were selling. Fisheries agencies should consider more effective bait regulations and education to prevent negative impacts to aquatic biodiversity, habitat, and fisheries that can result from alien crayfish introductions. La industria de la carnada como potencial vector de introduccion de langostino: reconocimiento del problema por agencias de pesquerias y una evaluacion en Missouri RESUMEN:Se sospecha que la introduccion de especies exoticas a traves de cubetas con carnada, ha impactado negativamente los ecosistemas acuaticos de Norteamerica. Un muestreo que realizamos en el 2008 a agencias de pesquerias en Canada y Estados Unidos de Norteamerica, revelo que el 49% de los corresponsales reportaron problemas relacionados a recursos acuaticos que se cree fueron causados por introduccion de langostinos exoticos en cubetas con carnada. La mayor parte de los corresponsales reportaron la existencia de regulaciones para abordar el problema; sin embargo, solo el 4% de estas prohibe el uso de langostinos vivos como carnada. Nuestro examen realizado a tiendas de carnada en Missouri durante el periodo 2007-2007, revelo venta de langostinos ilegales e invasivos por parte de los propietarios de las tiendas, quienes no pudieron identificar las especies que vendian. Las agencias de pesquerias debieran contemplar regulaciones y programas de educacion mas efectiva en cuanto al uso de carnada para prevenir los impactos negativos que la introduccion de langostinos exoticos tiene sobre la biodiversidad acuatica, los habitats y las pesquerias.

Recent radiations are important to evolutionary biologists, because they provide an opportunity to study the mechanisms that link micro-and macroevolution. The role of ecological speciation during adaptive radiation has been intensively studied, but radiations can arise from a diversity of evolutionary processes; in particular, on large continental landmasses where allopatric speciation might frequently precede ecological differentiation. It is therefore important to establish a phylogenetic and ecological framework for recent continental-scale radiations that are species-rich and ecologically diverse. Here, we use a genomic (approx. 1 200 loci, exon capture) approach to fit branch lengths on a summary-coalescent species tree and generate a time-calibrated phylogeny for a recent and ecologically diverse radiation of Australian scincid lizards; the genus Cryptoblepharus. We then combine the phylogeny with a comprehensive phenotypic dataset for over 800 individuals across the 26 species, and use comparative methods to test whether habitat specialization can explain current patterns of phenotypic variation in ecologically relevant traits. We find significant differences in morphology between species that occur in distinct environments and convergence in ecomorphology with repeated habitat shifts across the continent. These results suggest that isolated analogous habitats have provided parallel ecological opportunity and have repeatedly promoted adaptive diversification. By contrast, speciation processes within the same habitat have resulted in distinct lineages with relatively limited morphological variation. Overall, our study illustrates how alternative diversification processes might have jointly stimulated species proliferation across the continent and generated a remarkably diverse group of Australian lizards.

Summary We synthesized wild and stocked pallid sturgeon Scaphirhynchus albus capture data collected in four recovery areas of the Missouri River during 1998–2007, providing the first basin‐wide analysis of size structure, growth, and condition. Proportional size distribution (PSD) values ranged from 20 to 33 and were indicative of past stockings given the continued lack of natural recruitment. A new weight‐length regression derived from 2268 captured wild (8%), hatchery‐stocked (75%), and unknown origin (16%) pallid sturgeon had a significantly lower slope and intercept from a previously published model that used only 214 wild fish and a truncated size range. Relative condition (Kn) declined after stocking throughout the basin but stabilized at 0.94 within 3 years. Spatially, Kn of juvenile pallid sturgeon (330–629 mm) was generally highest in the reaches of the Missouri River with large tributaries. In accordance with the latitudinal counter gradient growth hypothesis, similar absolute growth increments (both length and weight) of tagged age‐1 pallid sturgeon in the Upper and Lower Missouri River indicated upstream fish grew at faster rates given the 1.3 fold difference in growing season length. From North to South, von Bertalanffy growth coefficients (k) showed a latitudinal increase while L∞ decreased, providing additional support of the latitudinal counter gradient growth hypothesis. However, growth rates of tagged juvenile pallid sturgeon aged 2–6 years were highest at the two most downstream reaches showing an increased influence of growing season length. In the Missouri River, pallid sturgeon (≤ ages 1–9 or 10 years) exhibited linear growth in the two most upstream reaches (Montana and North Dakota), exhibited logistic growth in the inter‐reservoir reach in South Dakota/Nebraska while a power function best described growth downstream of the lowermost dam (Nebraska, Iowa, Kansas, and Missouri). Differing growth models among reaches highlights the confounding affect of habitat fragmentation by dams in the Missouri River on growth as well as potential latitudinal affects on sexual maturation. Relative condition and growth of pallid sturgeon appears adequate throughout the Missouri River indicating success of past stocking efforts to forestall extirpation.

We assessed hooking mortality of saugers Stizostedion canadense in two Tennessee reservoirs by holding fish overnight in a net‐pen. We also attached radio tags equipped with a mortality switch to 19 saugers to document survival. Rates of gas bladder overinflation and foul‐hooking using common terminal gear were estimated. The mortality rate for saugers observed in the net‐pen was only 4% (3 of 74). Seventeen of 19 radio‐tagged saugers were located and 15 were alive 12 d later (12% mortality). Although we could not detect a statistical relation between mortality and gas bladder overinflation, depth of capture was weakly related to the occurrence of gas bladder overinflation. When we caught saugers using the terminal gear most common in these fisheries (a bucktail jig tipped with a minnow and equipped with a trailing treble hook), equal numbers of fish were caught by the jig hook and stinger hook. Despite the fact that 42% of all the saugers we caught were foul‐hooked, blood flowed from the primary hook wound in only 21% of all the fish we caught. Concerns that using a stinger hook increases rates of foul‐hooking and mortality were unfounded; most (70%) saugers were hooked “fairly” (i.e., in the jaws or mouth) when the stinger hook was responsible for the hook‐up, and the jig hook was responsible for twice as many foul‐hookings as the stinger hook. Based on these findings, we recommend that the minimum length limit remain in effect for saugers in Tennessee waters. We also conclude that prohibiting the use of stinger hooks is unwarranted.

Forty‐four species of terrestrial reptiles and eight species of frogs were recorded from 60 continental islands of the Wessel and English Company groups off northeastern Arnhem Land, Northern Territory. Two gecko species, Oedura rhombifer and Heteronotia binoei, were present on the most islands (34 and 31, respectively), and occurred on islands < 5 ha. In contrast, agamids, pygopodids and varanids were absent from islands < 18 ha, and snakes and frogs were not reported from islands < 240 ha. Island size explained 82% of the variation in species richness for terrestrial reptiles, and 84% of that for lizards. The relationship was less good for (i) groups with generally uncommon species (notably snakes), for which sampling effort explained more variation, and (ii) groups with species which had relatively specific habitat requirements (notably frogs), for which island size and isolation factors were not especially relevant. For most taxonomic groups considered, isolation factors added little to the relationship between species richness and island size. Across all reptiles, larger species were found on fewer islands, and had larger island size thresholds. This relationship broke down with analysis restricted to the single most species‐rich family, Scincidae. Only 6 of the 20 most frequently recorded species showed significant variation in abundance among 8 vegetation types sampled by 226 quadrats across 40 islands. The number of species (alpha‐diversity) and total abundance of herpetofauna within quadrats was generally unrelated to island size; however, (with analysis restricted to islands on which they occurred) six individual species were significantly more abundant on smaller islands than on larger islands, with no species showing the opposite pattern. The islands’ herpetofauna is largely a relatively depauperate subset of that of the far more complex sandstone massif and escarpment of western Arnhem Land, especially missing species associated with rugged sandstone gorges, riparian areas, open forests, swamps and clay soils. Patterns in species richness and composition are explained by greater range of environments on larger islands allowing better retention of species since isolation and/or richer tallies at the time of isolation. The evidence suggests that there has been relatively little colonization, although at least two gecko species and one varanid may have moved reasonably frequently.

The Australian dragon lizard genus Diporiphora currently comprises 21 species based on genetic and morphological evidence, with 11 of these species occurring in the monsoonal tropics of northern Australia. Diporiphora are climbing lizards that are found on either trees, grasses or rocks, with usually only subtle morphological differences to distinguish between species. Since the last taxonomic treatment of this genus in northern Australia over 40 years ago, species delimitation using genetic techniques has clarified the number of lineages and increased collections from recent surveys have significantly broadened the distributions of these taxa. However, no formal taxonomic assessments have been undertaken to redefine species, including the many lineages that represent undescribed species. Currently, there are seven species of Diporiphora with vast distributions across northern Australia and a broad and variable set of morphological characteristics that make species identification challenging, even for experienced field workers. Here, we provide a comprehensive taxonomic treatment of Diporiphora species across northern Australia based on previously published genetic data and morphological examination of voucher specimens. Our analyses demonstrate that these broadly distributed taxa actually comprise multiple, often allopatric, species, with especially high diversity in the Kimberley region of Western Australia. We redescribe nine previously described species and describe five new species of Diporiphora based on historical types, newly collected material and older museum vouchers. In the D. australis species group, we resurrect D. jugularis Macleay from synonomy. In the D. bennettii species group, we synonomise D. arnhemica Storr with D. albilabris Storr, and raise to full species the latter and D. sobria Storr. In addition, we describe as new a wide-ranging saxicoline species previously attributed to D. bennettii Gray. In the D. bilineata species group, we resurrect D. margaretae Storr from synonomy with D. magna Storr and describe three new species. Lastly, we describe a species from the northwest Kimberley that is more closely related to an arid zone radiation. The revision of the northern Diporiphora dragons here stabilises the taxonomy, redefines many species distributions and reveals many new species. Further work on Diporiphora includes further surveys to better understand distributions and habitat preferences and continue to refine their evolutionary history and biogeography in northern Australia.

No abstract

Trawling is commonly used to assess abundance, distribution, and diversity of fish assemblages as well as to commercially harvest various species of fish. We compared fish community structure and total catch of a 4.9-m otter trawl (OT16; 19-mm bar mesh body with a 6-mm mesh cod end) with a smaller mesh trawl of similar physical dimensions (OT01; composed entirely of 4-mm bar mesh). Total catch from both trawls revealed a trend toward the capture of smaller-sized individuals in the OTOl and larger individuals in the OT16; however, both trawls provided a high degree of overlap in species richness and diversity. Shannon's index values (H') were 2.47 and 2.40 for the OT16 and the OTO1, respectively, signifying that both of these trawls caught a diverse assortment of fishes, regardless of mesh size. An analysis of similarity test resulted in strong similarities in fish assemblage composition between both trawls, corroborating diversity indices. Our results indicate that 19-mm and 4-mm bar mesh are both effective mesh sizes to collect a variety of benthic fish species of various size classes in the Missouri River.