ABSTRACT Background: The exploitation of aquaculture resources, such as the freshwather crayfish C. montezumae (Mexican endemic crustacean), is related with fertility of females due to the available number of postlarvae that can be cultivated. Goals: To evaluate the impact on reproductive aspects of the sex ratio C. montezumae in relation to obtained postlarvae. Methods: The impact of three sex ratio of males and females in the number of ovigerous females, fertility, fecundity, hatching time and the relation between these variables was determinate under laboratory conditions. Results: The analysis of variance shows that sex ratio 1:1 produced the highest number of ovigerous females (61) and a higher number of postlarvae (2451). When comparing the average fecundity (37 eggs per female) and the mean hatching percentage (97.96%), no significant differences between treatments were obtained. Females of first reproduction influenced the absence of linear relationships between size (weight and length) and reproductive aspects evaluated (fecundity and fertility). Conclusions: The sex ratio 1:1 is set as the optimum to get the highest number of postlarvae. The absence of linear relationship between size and studied variables provides the opportunity to study the influence of second breeding females to determine the technical conditions of higher postlarvae production in this specie.

RESUMEN Antecedentes: El aprovechamiento de los recursos acuícolas como el acocil de río C. montezumae (crustáceo endémico mexicano) se relaciona con la fertilidad de las hembras por el número disponible de postlarvas que se puedan cultivar. Objetivo: Evaluar el impacto de la proporción de sexos en aspectos reproductivos del acocil C. montezumae en relación a la obtención de postlarvas. Métodos: En condiciones de laboratorio se determinó el impacto de tres proporciones de machos y hembras en el número de hembras ovígeras, fertilidad, fecundidad, tiempo de eclosión y la relación entre dichos aspectos. Resultados: El análisis de varianza de la proporción de sexos 1:1 produjo el mayor número de hembras ovígeras (61) y por tanto, una cantidad más elevada de postlarvas (2451). Al comparar la fecundidad promedio (37 huevos por hembra) y la eclosión media porcentual (97.96 %) no se registraron diferencias significativas entre tratamientos debido a que se utilizaron hembras de primera reproducción con tallas similares, lo cual es sustentado con la ausencia de relaciones lineales entre la talla (peso y longitud), y los aspectos reproductivos valorados (fecundidad y fertilidad). Conclusiones: La proporción 1:1 se establece como la óptima para obtener el mayor número de postlarvas. La ausencia de una relación lineal entre la talla y los aspectos valorados proporcionan la oportunidad de estudiar la influencia de hembras de segunda reproducción para determinar las condiciones técnicas de mayor producción de postlarvas en la especie estudiada.

The objective of this research was to determine the effect of the type of food -a line one represented by Daphnia pulex and a one commercial Camaronina 35 by Purina with 35% protein- and water quality -presence and absence of microorganisms and suspended solids- on growth and survival of postlarvae of the crustacean Cambarellus montezumae. Four treatments were evaluated for 14 weeks conducting observations and periodic measurements as a follow-up of the development of the organisms. The obtained data showed significant differences between treatments (p< 0.05), where the best results in growth and survival were obtained in the organisms fed on animal feed (M2 and M4) regardless of the water quality. In addition, values of up to 45% protein were obtained and the lipid fraction identified as the fatty acids 20:4 n6 (ARA), 20:5 n3 (EPA) and 22:6 n3 (DHA) when considering the total body of the organisms. Our results increase the interest in the sustainable culture of C. montezumae to be used in the food industry through its addition to food products for human consumption due to its content of biomolecules of biological importance.

El objetivo de esta investigación es determinar el efecto del tipo de alimento -uno vivo, representado por Daphnia pulex y uno balanceado de la marca Purina Camaronina 35 con 35% de proteínas- y la calidad del agua -presencia y ausencia de microorganismos, y sólidos suspendidos- en el crecimiento y sobrevivencia de postlarvas del crustáceo Cambarellus montezumae. Para lo cual, se formaron 4 tratamientos que se evaluaron durante 14 semanas, mediante la realización de observaciones y biometrías periódicas como seguimiento del desarrollo en los organismos. Los datos obtenidos registraron diferencias significativas entre tratamientos (p< 0.05), en donde los mejores resultados de crecimiento y sobrevivencia se obtuvieron en los organismos alimentados con el alimento balanceado (M2 y M4), independientemente de la calidad del agua. Además, se obtuvieron valores de proteínas de hasta 45% y en la fracción lipídica se identificaron los ácidos grasos 20:4 n6 (ARA), 20:5 n3 (EPA) y 22:6 n3 (DHA) al considerar el cuerpo total del organismo. Lo antes mencionado incrementa el interés por el cultivo sustentable de C. montezumae para ser utilizado en la industria alimentaria a través de su adición en productos alimentarios de consumo humano debido a su contenido de biomoléculas de importancia biológica.

O objetivo do estudo foi descrever a magnitude e a distribuição da mortalidade por homicídios nas Américas e analisar suas tendências. Foram analisados óbitos por homicídios (X85 a Y09 e Y35) de 32 países das Américas, período 1999-2009, registrados no Sistema de Informações de Mortalidade/Organização Pan Americana da Saúde. Utilizou-se modelo binomial negativo para estudar as tendências. Cerca de 121.297 mortes por homicídios (89% homens e 11% mulheres) ocorreram anualmente nas Américas, predominando as idades de 15 a 24 e de 25 a 39 anos. Em 2009, a taxa padronizada de homicídios da região foi 15,5/100.000. Os países com taxas/100.000 baixas foram Canadá (1,8), Argentina (4,4), Cuba (4,8), Chile (5,2) e Estados Unidos (5,8); e com taxas/100.000 altas foram El Salvador (62,9), Guatemala (51,2), Colômbia (42,5), Venezuela (33,2) e Porto Rico (25,8). Entre 1999-2009 as taxas da região permaneceram estáveis; aumentaram em nove países, como Venezuela (p < 0,001), Panamá (p < 0,001), El Salvador (p < 0,001) e Porto Rico (p < 0,001); diminuíram em quatro países, especialmente na Colômbia (p < 0,001); e permaneceram estáveis no Brasil, Estados Unidos, Equador e Chile. O aumento no México ocorreu no período mais recente. Apesar dos esforços empreendidos, diversos países têm taxas altas de homicídios e crescimento nas mesmas.

The scope of this study was to describe the magnitude and distribution of deaths by homicide in the Americas and to analyze the prevailing trends. Deaths by homicide (X85 to Y09 and Y35) were analyzed in 32 countries of the Americas Region from 1999 to 2009, recorded in the Mortality Information System/Pan American Health Organization. A negative binomial model was used to study the trends. There were around 121,297 homicides (89% men and 11% women) in the Americas, annually, predominantly in the 15 to 24 and 25 to 39 year age brackets. In 2009 the homicide age-adjusted mortality rate was 15.5/100,000 in the region. Countries with lower rates/100,000 were Canada (1.8), Argentina (4.4), Cuba (4.8), Chile (5.2), and the United States (5.8), whereas the highest rates/100,000 were in El Salvador (62.9), Guatemala (51.2), Colombia (42.5), Venezuela (33.2), and Puerto Rico (25.8). From 1999-2009, the homicide trend in the region was stable. They increased in nine countries: Venezuela (p<0.001), Panama (p<0.001), El Salvador (p<0.001), Puerto Rico (p<0.001); decreased in four countries, particularly in Colombia (p<0.001); and were stable in Brazil, the United States, Ecuador and Chile. The increase in Mexico occurred in recent years. Despite all efforts, various countries have high homicide rates and they are on the increase.

O objetivo do estudo foi descrever a magnitude e a distribuição da mortalidade por homicídios nas Américas e analisar suas tendências. Foram analisados óbitos por homicídios (X85 a Y09 e Y35) de 32 países das Américas, período 1999-2009, registrados no Sistema de Informações de Mortalidade/Organização Pan Americana da Saúde. Utilizou-se modelo binomial negativo para estudar as tendências. Cerca de 121.297 mortes por homicídios (89% homens e 11% mulheres) ocorreram anualmente nas Américas, predominando as idades de 15 a 24 e de 25 a 39 anos. Em 2009, a taxa padronizada de homicídios da região foi 15,5/100.000. Os países com taxas/100.000 baixas foram Canadá (1,8), Argentina (4,4), Cuba (4,8), Chile (5,2) e Estados Unidos (5,8); e com taxas/100.000 altas foram El Salvador (62,9), Guatemala (51,2), Colômbia (42,5), Venezuela (33,2) e Porto Rico (25,8). Entre 1999-2009 as taxas da região permaneceram estáveis; aumentaram em nove países, como Venezuela (p < 0,001), Panamá (p < 0,001), El Salvador (p < 0,001) e Porto Rico (p < 0,001); diminuíram em quatro países, especialmente na Colômbia (p < 0,001); e permaneceram estáveis no Brasil, Estados Unidos, Equador e Chile. O aumento no México ocorreu no período mais recente. Apesar dos esforços empreendidos, diversos países têm taxas altas de homicídios e crescimento nas mesmas.

The scope of this study was to describe the magnitude and distribution of deaths by homicide in the Americas and to analyze the prevailing trends. Deaths by homicide (X85 to Y09 and Y35) were analyzed in 32 countries of the Americas Region from 1999 to 2009, recorded in the Mortality Information System/Pan American Health Organization. A negative binomial model was used to study the trends. There were around 121,297 homicides (89% men and 11% women) in the Americas, annually, predominantly in the 15 to 24 and 25 to 39 year age brackets. In 2009 the homicide age-adjusted mortality rate was 15.5/100,000 in the region. Countries with lower rates/100,000 were Canada (1.8), Argentina (4.4), Cuba (4.8), Chile (5.2), and the United States (5.8), whereas the highest rates/100,000 were in El Salvador (62.9), Guatemala (51.2), Colombia (42.5), Venezuela (33.2), and Puerto Rico (25.8). From 1999-2009, the homicide trend in the region was stable. They increased in nine countries: Venezuela (p<0.001), Panama (p<0.001), El Salvador (p<0.001), Puerto Rico (p<0.001); decreased in four countries, particularly in Colombia (p<0.001); and were stable in Brazil, the United States, Ecuador and Chile. The increase in Mexico occurred in recent years. Despite all efforts, various countries have high homicide rates and they are on the increase.