Abstract Alien species are organisms introduced into an area outside of their natural range and are considered a major cause of biodiversity loss in the marine environment. The aim of this work is to report on the alien crustacean species observed in Ecuador. A bibliographic review was conducted using a digital search in the scientific literature. A total of ten alien species of crustaceans, representing eight genera in seven families, were encountered in Ecuador. The only crab, Cardisoma crassum Smith, 1870, was observed in the Galapagos Islands. The other species include barnacles, crayfishes, and freshwater prawns. Native ranges of the alien crustaceans include the Indo-Pacific region, North America, Asia, and Australia. Major introduction pathways are aquaculture and transport by ship. Procambarus alleni (Faxon, 1884) was reported recently as an aquarium species, but its presence in the natural environmental is currently unknown. One alien species has been introduced each decade since the 1960s. Some species (the barnacles Amphibalanus improvisus (Darwin, 1854), Amphibalanus reticulatus (Utinomi, 1967), and the copepod Lernaea cyprinacea Linnaeus, 1758) were reported as alien species for Ecuador but need verification regarding their current status. Additionally, the barnacle Dosima fascicularis (Ellis and Solander, 1786) presented an occasional record in the Galapagos Islands, but due to its dispersal ability and open ocean habitat it is not possible to conclude that this really is an alien species. The list of alien crustacean species recorded in Ecuador is considered incomplete due to both scarce published work regarding this topic and taxonomic problems. Therefore, it is necessary to carry out more research to establish a complete list of the alien species present in Ecuador and assess their impact on aquatic ecosystems.

Abstract Relative growth can help to identify dimorphism between individuals, and it is also used to determine changes in ontogeny related to sexual maturity. The morphometric variables recorded were width, length and height in carapace and chelae. The abdomen width was taken only in females. Data analysis was made separating males and females. Exploratory analysis used maximum, minimum and mean values and compared these values between sexes using MANOVA, ANOVA and LSD-Fisher methods. A weight-size relationship was also determined. Relative growth was estimated using a multi-model approach. Six models were applied, and the best was selected using Akaike and Bayesian information criteria. Residual versus predicted graphics were also produced based on the selected models. The mean sizes were similar between sexes, but the maximum values were observed in males. The weight-size relationships showed a negative allometry. The best model varied by morphometric variables and sex, but the type of relative growth was principally isometric and negative allometry. Biometric characteristics in Menippe frontalis A. Milne-Edwards, 1879 did not show abrupt changes in the relative growth. The threshold was not assumed as an indicator of morphometric sexual maturity however, they may be used for establishing legal minimum size in M. frontalis.

Scientific information on Ucides occidentalis is scarce, and part of these studies have not adequate diffusion, this situation restricts the availability of knowledge about this commercial species. In this work, on the one hand, diverse studies on U. occidentalis are reviewed, and on the other, information obtained from direct observations made since 2011 to 2014 in the Gulf of Guayaquil mangroves, is presented. Notes on changes in the taxonomy of U. occidentalis, its biology, ecological and fishery characteristics are presented. Characteristics to fishing interest such as density data and reproduction periods are discussed. By last, it is discussed the management of fisheries of U. occidentalis in the Gulf of Guayaquil, because in recent decades, U. occidentalis has evidenced a decrease in the landing levels and at the same time, an increase in the average commercial size; this suggest that both factors should be considered in the evaluation of stock, and thereby to have a better approximation on the population status of the resource.

La información científica sobre Ucides occidentalis es escasa y parte de estos estudios no han logrado una difusión adecuada, lo cual restringe la disponibilidad de conocimiento sobre esta especie comercial. En este trabajo se revisan diversos estudios sobre U. occidentalis y se presenta información obtenida de observaciones directas realizadas entre 2011-2014 en los manglares del Golfo de Guayaquil, Ecuador. Se muestran notas sobre cambios en la taxonomía de U. occidentalis, sus características biológicas, ecológicas y pesqueras. Se discuten características del interés pesquero como la densidad poblacional y períodos de reproducción. Finalmente, se discute el manejo de las pesquerías de U. occidentalis en el Golfo de Guayaquil debido a que, en los últimos años, se ha evidenciado una disminución en los niveles de desembarques y a la vez, un aumento en la talla media comercial; aquello sugiere que se deben considerar ambos factores en la evaluación del stock, para tener una mejor aproximación sobre el estado poblacional del recurso y sus niveles de explotación.