This is the third compilation of imperiled (i.e., endangered, threatened, vulnerable) plus extinct freshwater and diadromous fishes of North America prepared by the American Fisheries Society'S Endangered Species Committee. Since the last revision in 1989, imperilment of inland fishes has increased substantially. This list includes 700 extant taxa representing 133 genera and 36 families, a 92% increase over the 364 listed in 1989. The increase reflects the addition of distinct populations, previously non-imperiled fishes, and recently described or discovered taxa. Approximately 39% of described fish species of the continent are imperiled. There are 230 vulnerable, 190 thretened, and 280 endangered extant taxa, and 61 taxa presumed extinct or extirpated from nature. Of those that were imperiled in 1989, most (89%) are the same or worse in conservation status; only 6% have improved in status, and 5% were delisted for various reasons. Habitat degradation and nonindigenous species are the main threats to at-risk fishes, many of which are restricted to small ranges. Documenting the diversity and status of rare fishes is a critical step in identifying and implementing appropriate actions necessary for their protection and management.

Building trust in science and evidence-based decision-making depends heavily on the credibility of studies and their findings. Researchers employ many different study designs that vary in their risk of bias to evaluate the true effect of interventions or impacts. Here, we empirically quantify, on a large scale, the prevalence of different study designs and the magnitude of bias in their estimates. Randomised designs and controlled observational designs with pre-intervention sampling were used by just 23% of intervention studies in biodiversity conservation, and 36% of intervention studies in social science. We demonstrate, through pairwise within-study comparisons across 49 environmental datasets, that these types of designs usually give less biased estimates than simpler observational designs. We propose a model-based approach to combine study estimates that may suffer from different levels of study design bias, discuss the implications for evidence synthesis, and how to facilitate the use of more credible study designs.

The cichlid genus Archocentrus has been considered one of the most promising (i.e., possibly natural) genera resurrected to receive some of the species formerly included in Cichlasoma. Evidence is presented to justify generic recognition of Archocentrus, as well as eight other closely related genera (Caquetaia, Hypsophrys, Parachromis, Amphilophus, Archocentrus, Cryptoheros, Amatitlania, and Rocio). Of these, Amatitlania (type species, A. nigrofasciata) and Rocio (type species, R. octofasciata) are described as new. The present revision treats all nominal species ever assigned to Archocentrus, as well as species that have been included in or near the same clade as Archocentrus centrarchus (type species of the genus) in available phylogenetic analyses. Geographical variation in morphology of the more widespread species was examined, which has resulted in the description of six new species (Cryptoheros chetumalensis, Amatitlania coatepeque, A. kanna, A. siquia, Rocio gemmata, and R. ocotal) with a seventh resurrected from synonymy (Cryptoheros cutteri). Archocentrus includes the type species (Ar. centrarchus), plus Ar. spinosissimus and Ar. multispinosus. Cryptoheros is restricted to the species complexes of Cr. spilurus (= subgenus Cryptoheros, including also Cr. chetumalensis and Cr. cutteri) and Cr. septemfasciatus (= Bussingius n. subgen., including also Cryptoheros altoflavus, Cr. nanoluteus, Cr. myrnae, and Cr. sajica); Cryptoheros panamensis is placed in Panamius n. subgen. Herotilapia is synonymized with Archocentrus, and Neetroplus is synonymized with Hypsophrys, which now includes the type species H. nicaraguensis and H. nematopus. Lectotypes are designated for Amatitlania nigrofasciata, Archocentrus spinosissimus, Cryptoheros septemfasciatus, Cr. spilurus, and Rocio octofasciata. Cichlasoma immaculatum is considered to be a synonym of Archocentrus spilurus, not of Ar. spinosissimus.

México is the southernmost country in North America, and extends into Central America, south of the Isthmus of Tehuantepec. The northern half of México is located on the Temperate belt and is arid in character (Nearctic), while the rest is within the Tropical belt (Neotropical). Climate varies from extremely temperate desert in the north, to tropical humid in the south. México has more than 500 freshwater fish species, about 271 of them country endemics, and approximately 48 endemics from binational basins. There are still some 30–40 fish species not yet described. There are 563 fish species colonizing coastal flood plain species. In addition to the numbers of colonizing fishes, the burden of introduced exotics has also been growing. In 1904, only 4 species were recognized as exotics; by 1997 the number had increased to 94, and by 2008 to 115. The main fish collections in Mexico are at IPN, UNAM, and UANL and are the most representative, being national in scope, although concentrated in the tropics, central region, and general in coverage, respectively. The decline of the native fish fauna has been in focus in recent years, usually as trend-in-time comparisons, where the loss of native forms and increase of exotics and/or colonizer species is evident in many basins, mainly in Río Balsas, Río Grande, and Río Lerma-Santiago. As a result, the numbers of species reported at some degree of risk have been increasing also, from 17 in 1963 to 192 in 2005. The trends in colonizers, exotics, and species at risk among Mexican fishes are parallel. The Index of Biological Integrity (IBI), in either its geographical, or historical form (IBIh), has been applied to the Rio Grande/Río Bravo basin, USA and México. IBIh values go between 0–91 (average 31). Alien species are regarded as detrimental. Overall, the IBI trends have been similar in all regions, starting from 70–95% in upper reaches, decreasing to less than 0–35% in the lower reaches of West central basins, and then down to 15% or less near the Lower Rio Grande delta. Several alien species of plecos have been recognized in the rivers Balsas, Grijalva-Río Usumacinta complex, and, also, one in the Rio Grande. Mexican rivers are notoriously dewatered in the northern half of the country. Until 1962, the Rio Grande had an average runoff of 12,000+ millions of cubic meters/year; however by 2002 it was less than 2% of that value. The river went nearly dry along the Big Bend region and was dry for months in the delta region, both in 2002 and 2004. The Rio Grande is mostly dry north of the Río Conchos junction, its main Mexican tributary, and other tributaries provide now between 1% (Río San Juan) and 20% (Río Conchos) of pre-1960 runoff. A modified Index of Biological Integrity for Rio Grande resulted in grades from 70 to 95% of the baseline in upper reaches, less than 35% in lower reaches, to less than 15% near the coast. The Texan version of the IBI was not representative as it suppresses data on euryhaline fishes. The reports of total toxics were masked, since the sum should have included both organics and heavy metals exceeding USA regulations to the total count, but only one of the two was included.