Peruvian Amazon Region Research Articles

CONCIENCIA FONOLÓGICA Y APRENDIZAJE INICIAL DE LA LECTOESCRITURA EN NIÑAS Y NIÑOS SHIPIBOS

Esta investigación tuvo la finalidad de demostrar que la conciencia fonológica tiene una relación significativa con la lectura inicial en niños y niñas shipibos de la región Ucayali en la Amazonía peruana. Se aplicó un modelo descriptivo de tipo correlacional a una muestra de 31 alumnos del Primer Grado de Primaria. A la muestra se le evaluó el nivel de conciencia fonológica a través de una prueba que midió la dimensión silábica, intrasilábica y fonémica. Al relacionar los puntajes obtenidos se demuestra el grado de asociación de la dimensión conciencia fonológica silábica e intrasilábica con el aprendizaje inicial de la lectura. También se confirmó que no existe relación significativa con la conciencia fonémica en niñas y niños shipibos del 1er Grado de Educación Primaria. Los resultados confirman que el modelo teórico cognitivo y psicolingüístico es un soporte significativo del aprendizaje lector. PALABRAS CLAVE: conciencia fonológica, aprendizaje de la lectura, habilidades metalingüísticas.

Mineral characterisation of the non-sulphide Zn mineralisation of the Florida Canyon deposit, Bongará District, Northern Peru

ABSTRACTThe Florida Canyon deposit hosted by a carbonate-evaporite sequence of the Pucará Group, Peru, has both Zn–Pb sulphide and Zn non-sulphide mineralisations. The mineralogical characterisation of samples from the deposit enables the definition of a supergene assemblage dominated by smithsonite, in addition to hemimorphite, cerussite, and goethite. The main oxidation in the study area involved the direct replacement of primary MVT stratabound sulphide ore. In comparison with other non-sulphide deposits of the Bongará District, the Florida Canyon deposit can be correlated with the Cristal deposit by means of the original sulphides preserved in the supergene textures, the similar hosting dolostone layer, lack of hydrozincite, and depth of emplacement, which are characteristics that contrast with those of the Mina Grande deposit, also inserted in the Pucará Group. The Florida Canyon supergene mineral assemblage is a paleoclimatic indicator suggesting a humid tropical climate during the late Miocene in the Peruvian Amazon region.

Population numbers of Amazon river dolphins Inia geoffrensis and Sotalia fluviatilis (Mammalia: Cetaceae: Delphinidae) in the lower Río Tigre region, Loreto, Perú

We conducted a study to assess the populations of the two potentially endangered river dolphin species Inia geoffrensis and Sotalia fluviatilis in the river systems of the Río Tigre and the Río Marañon in the Peruvian Amazon region. Various observation methods were used and evaluated along ca. 353 kilometres of river and 134 to a maximum of 173 dolphins were recorded from 125 sightings and about 2000 photographs. Only about 10% of these dolphins could not be determined to species level, at least 57 individuals were identified as S. fluviatilis, and 89 individuals as I. geoffrensis. The abundance of dolphins along the entire stretch was 0.13 individuals per km for S. fluviatilis and 0.25 individuals per km for I. geoffrensis. Each participant spent an average of 82 working hours on observation. Evaluation of methods used revealed that observation supported by photographic documentation (PSO) increases observation accuracy by 19%. PSO is thus regarded as an ideal method for future population assessments. Perspectives and potential financial costs for conservation of Amazonian dolphin populations are discussed.

Impact on the transmission of malaria with different treatment schemes in the peruvian coast and amazon region within the framework of a policy on antimalarial medications, 1994-2017

At the end of the 90s in Peru, after determining the resistance to antimalarial drugs, a change in antimalarial treatment schemes was decided; this change included the combined therapy for P. falciparum, mefloquine/artesunate in the Amazon region, and sulfadoxine pyrimethamine/artesunate in the North coast. After two decades, and aimed at assessing the impact of these schemes on the malaria endemic, a review was conducted of malaria reports in three departments accounting for more than 70% of cases reported in the country. The major impact of the sulfadoxine-pyrimethamine/ artesunate scheme in the North coast was evident since it reduced the number of cases of P. falciparum to virtually zero four years after implementation of the combined therapy. The single dose and the ability to limit the development of sporozoites were crucial in order to achieve this goal. The mefloquine/artesunate scheme had a limited impact because it was not possible to ensure supervised treatment in the health service facilities and the need for three doses. It is important to select an effective and easy-to-administer scheme when choosing the first line of treatment for malaria. This experience is significant for the malaria eradication goals in Peru.

Proteomic profile, biological activities and antigenic analysis of the venom from Bothriopsis bilineata smaragdina (“loro machaco”), a pitviper snake from Peru

In order to determine Bothriopsis bilineata smaragdina venom (BbsV) composition, proteomic approaches were performed. Venom components were analyzed by RP-HPLC, SDS- PAGE and nano LC on line with LTQ Orbitrap XL. Results showed a total of 189 identified proteins, grouped into 11 different subgroups, which include snake venom metalloproteinases (SVMPs, 54.67%), snake C-type lectins (Snaclecs, 15.78%), snake venom serine proteinases (SVSPs, 14.69%), cystein-rich secretory proteins (CRISP, 2.61%), phospholipases A2 (PLA2, 1.14%), phosphodiesterase (PDE, 1.17%), venom endothelial growth factor (VEGF, 1.06%) 5’nucleotidases (0.33%), L-amino acid oxidases (LAAOs, 0.28%) and other proteins. In vitro enzymatic activities (SVMP, SVSP, LAAO, Hyal and PLA2) of BbsV were also analyzed. BbsV showed high SVSP activity but low PLA2 activity, when compared to other Bothrops venoms. In vivo, BbsV induced hemorrhage and edema in mice and showed intraperitoneal median lethal dose (LD50) of 92.74 (± 0.15) μg/20 g of mice. Furthermore, BbsV reduced cell viability when incubated with VERO cells. Peruvian and Brazilian bothropic antivenoms recognize BbsV proteins, as detected by ELISA and Western Blotting. Both antivenoms were able to neutralize in vivo edema and hemorrhage. SignificanceIn Peru, snakebite is a public health problem, especially in the rain forest, as a result of progressive colonization of this geographical area. This country is the second in Latin America, after Brazil, to exhibit the largest variety of venomous snakes. B. atrox and B. b. smaragdina snakes are sympatric species in Peruvian Amazon region and are responsible for approximately 95% of the envenomings reported in this region. B. b. smaragdina may cause a smaller share (3 to 38%) of those accidents, due to its arboreal habits, that make human encounters with these snakes less likely to happen. Despite B. b. smaragdina recognized medical importance, its venom composition and biological activities have been poorly studied. Furthermore, BbsV is not a component of the antigenic pool used to produce the corresponding Peruvian bothropic antivenom (P-BAV). Our results not only provide new insights on BbsV composition and biological activity, but also demonstrate that both P-BAV and B-BAV polyvalent antivenoms have a considerable recognition of proteins from BbsV and, more importantly, neutralized hemorrhage and edema, the main local effects of bothropic envenomation.

Delays in seeking and receiving health care services for pneumonia in children under five in the Peruvian Amazon: a mixed-methods study on caregivers\u2019 perceptions

BackgroundDelays in receiving adequate care for children suffering from pneumonia can be life threatening and have been described associated with parents’ limited education and their difficulties in recognizing the severity of the illness. The “three delays” was a model originally proposed to describe the most common determinants of maternal mortality, but has been adapted to describe delays in the health seeking process for caregivers of children under five. This study aims to explore the caregivers’ perceived barriers for seeking and receiving health care services in children under five years old admitted to a referral hospital for community-acquired pneumonia in the Peruvian Amazon Region using the three-delays model framework.MethodsThere were two parts to this mixed-method, cross-sectional, hospital-based study. First, medical charts of 61 children (1 to 60 months old) admitted for pneumonia were reviewed, and clinical characteristics were noted. Second, to examine health care-seeking decisions and actions, as well as associated delays in the process of obtaining health care services, we interviewed 10 of the children’s caregivers.ResultsHalf of the children in our study were 9 months old or less. Main reasons for seeking care at the hospital were cough (93%) and fever (92%). Difficulty breathing and fast breathing were also reported in more than 60% of cases. In the interviews, caregivers reported delays of 1 to 14 days to go to the closest health facility. Factors perceived as causes for delays in deciding to seek care were apparent lack of skills to recognize signs and symptoms and of confidence in the health system, and practicing self-medication. No delays in reaching a health facility were reported. Once the caregivers reached a health facility, they perceived lack of competence of medical staff and inadequate treatment provided by the primary care physicians.ConclusionAccording to caregivers, the main delays to get health care services for pneumonia among young children were identified in the initial decision of caregivers to seek healthcare and in the health system to provide it. Specific interventions targeted to main barriers may be useful for reducing delays in providing appropriate health care for children with pneumonia.

The effects of rural development policy on land rights distribution and land use scenarios: The case of oil palm in the Peruvian Amazon

Decades of development history show that rural agricultural policies and government support for specific en vogue crops can seriously alter land rights, land tenure regimes and land use strategies for local people in tropical forests. Today, oil palm is such a crop, and it is an emergent commodity that is proliferating in the Peruvian Amazon. This paper asks: How is government interest in promoting oil palm development affecting property rights formalization for smallholders in the Peruvian Amazon region of Ucayali, and what are the socio-ecological implications? While there are strong theoretical reasons that expect these phenomena to be related, the precise nature of their interaction has not been rigorously examined in Peru. The study analyses data from a large household survey, and three years of participant observation work in those villages to unpack how these factors interact. The paper presents descriptive results comparing smallholder claims to their formal rights, and finds a large discrepancy between de facto and de jure land ownership scenarios – especially with relation to old-growth forest fragments. Furthermore, whilst our statistical model testing qualifies our hypothesis about the link between oil palm and land right in the region at both the household and village levels, it is not a direct causal relationship. The empirical results suggest a more complex nuanced picture of how migration, oil palm expansion and development are more broadly linked to land use change in the region. We conclude with policy recommendations that could facilitate improved forest conservation in the area, and a more equitable distribution of land rights to smallholders.

Conservation assessment of the Peruvian Andes and Amazon based on mapped forest functional diversity

Ongoing tropical deforestation and forest degradation, combined with climate change, call for improved forest functional and biological diversity mapping to support increasingly tactical decision-making for conservation action. We combine a new map of forest canopy functional and biological composition with extensive protected area and indigenous land allocation data to quantify current protections and opportunities for new protections throughout the Peruvian Andes and Amazon region, a global biodiversity hotspot. The analysis is based on a map of 36 distinct Forest Functional Classes (FFC) covering >76millionha of forest at 1-ha spatial resolution. We find that while 42.6% of forests are under some form of protection, the percentage of protections applied to any particular FFC ranges from 20% to 69%. Under-represented FFCs are in the submontane and montane Andes, and in the northwestern Amazonian lowlands. Nationally-administered protections are uneven across the 36 FFCs, and regionally- and locally-administered protections are biased to relatively few mapped forest classes. Indigenous lands contain a relatively even distribution of FFC protections, providing the most FFC protection per unit forest area in Peru. Without the current portfolio of indigenous lands, the network of nationally-, regionally-, and locally-administered protected areas would greatly under-represent multiple functionally and biologically distinct FFCs throughout Peru. Mapping canopy functional diversity can support tactical approaches to protect a wider variety of forest types in a time of rapid environmental change.

Spatio-temporal analysis of malaria incidence in the Peruvian Amazon Region between 2002 and 2013

Malaria remains a major public health problem in the Peruvian Amazon where the persistence of high-risk transmission areas (hotspots) challenges the current malaria control strategies. This study aimed at identifying significant space-time clusters of malaria incidence in Loreto region 2002–2013 and to determine significant changes across years in relation to the control measures applied. Poisson regression and purely temporal, spatial, and space-time analyses were conducted. Three significantly different periods in terms of annual incidence rates (AIR) were identified, overlapping respectively with the pre-, during, and post- implementation control activities supported by PAMAFRO project. The most likely space-time clusters of malaria incidence for P. vivax and P. falciparum corresponded to the pre- and first two years of the PAMAFRO project and were situated in the northern districts of Loreto, while secondary clusters were identified in eastern and southern districts with the latest onset and the shortest duration of PAMAFRO interventions. Malaria in Loreto was highly heterogeneous at geographical level and over time. Importantly, the excellent achievements obtained during 5 years of intensified control efforts totally vanished in only 2 to 3 years after the end of the program, calling for sustained political and financial commitment for the success of malaria elimination as ultimate goal.

La Educación Superior Intercultural en la Amazonía Peruana: Balance y desafíos

In the last decades, an important discussion has been developed in Latin America about the access of indigenous students to higher-education institutions and about the creation of intercultural universities. This article specifically revises the different types of experiences of higher-education offered to the indigenous youth of the Peruvian Amazon region, and it builds on information gathered throughout the last decade of following and studying these experiences. The article begins with a discussion of the programs for bilingual teachers, which has been the prioritized form of access to higher education offered to the indigenous peoples. Then it analyzes different cases of affirmative action programs promoted by the Peruvian State and Peruvian universities, such as quotas and special scholarship programs. Finally, it presents the case of the intercultural universities, most of which have been created only a few years ago, and it discusses their real possibilities of becoming an alternative form of engaging with intercultural education.

Desnutrición crónica y anemia en niños menores de 5 años de hogares indígenas del Perú – Análisis de la Encuesta Demográfica y de Salud Familiar 2013.

Introducción: La desnutrición crónica y anemia infantil son un problema importante de salud pública, cuyas consecuencias se manifiestan a lo largo de todo el ciclo vital. El Estado peruano se caracteriza por albergar una de las mayores riquezas etnoculturales del continente americano, siendo la Amazonía Peruana la región que posee la mayor diversidad de grupos indígenas del país. Objetivo: Determinar la prevalencia de desnutrición crónica y anemia en niños menores de 5 años de hogares indígenas del Perú. Diseño: análisis secundario de los datos de la Encuesta Demográfica y de Salud Familiar (ENDES) 2013, del Instituto Nacional de Estadística e Informática (INEI). Institución: Segunda Especialidad en Nutrición Pública, Facultad de Medicina, Universidad Nacional Mayor de San Marco. Lima, Perú. Participantes: Niños menores de 5 años de hogares de la región natural selva en los cuales el idioma principal es una lengua indígena. Principales medidas de resultados: Desnutrición crónica (<-2 DE para valores Z de talla para la edad) y anemia (<11 g/dL de hemoglobina ajustado por altitud). Resultados: La desnutrición crónica afectó al 43,0%y la anemia al 43,5% de los niños menores de 5 años de hogares indígenas. No existió una asociación estadísticamente significativa entre desnutrición crónica con el sexo ni edad del niño, ni entre la anemia y sexo del niño. Sin embargo, sí se encontró asociación entre la edad del menor y la anemia (p <0,001). Conclusiones: La desnutrición crónica y anemia resultaron elevadas en niños menores de 5 años de hogares indígenas en la selva del Perú, siendo evidentes las grandes desigualdades en la situación de pobreza, servicios básicos y salud de los niños indígenas.

An unidentified cluster of infection in the Peruvian Amazon region.

Bartonella bacilliformis is the etiological agent of Carrion's disease, which is a neglected disease linked to people in low-socioeconomic populations in Andean valleys. An outbreak of B. bacilliformis was reported in a rural area of the Peruvian Amazon region. The aim of this study was to characterize this outbreak using molecular techniques. Fifty-three blood samples from patients diagnosed with Carrion's disease were analyzed by molecular tools, using both a Bartonella-specific polymerase chain reaction (PCR) and an universal PCR, both based on 16S rRNA gene amplification. Additional water samples from the area were also analyzed. Unexpectedly, the samples were positive only when the universal PCR was used. Although environmental contamination cannot be ruled out, the results showed that Sphingomonas faeni was the possible causative agent of this outbreak, and that water was the most feasible infection source. Diagnosis by clinical criteria or microscopy may lead to misdiagnosis. There is a need to include molecular tools in the routine diagnosis of febrile syndromes, including Carrion's disease.

Modelling the potential of focal screening and treatment as elimination strategy for Plasmodium falciparum malaria in the Peruvian Amazon Region.

BackgroundFocal screening and treatment (FSAT) of malaria infections has recently been introduced in Peru to overcome the inherent limitations of passive case detection (PCD) and further decrease the malaria burden. Here, we used a relatively straightforward mathematical model to assess the potential of FSAT as elimination strategy for Plasmodium falciparum malaria in the Peruvian Amazon Region.MethodsA baseline model was developed to simulate a scenario with seasonal malaria transmission and the effect of PCD and treatment of symptomatic infections on the P. falciparum malaria transmission in a low endemic area of the Peruvian Amazon. The model was then adjusted to simulate intervention scenarios for predicting the long term additional impact of FSAT on P. falciparum malaria prevalence and incidence. Model parameterization was done using data from a cohort study in a rural Amazonian community as well as published transmission parameters from previous studies in similar areas. The effect of FSAT timing and frequency, using either microscopy or a supposed field PCR, was assessed on both predicted incidence and prevalence rates.ResultsThe intervention model indicated that the addition of FSAT to PCD significantly reduced the predicted P. falciparum incidence and prevalence. The strongest reduction was observed when three consecutive FSAT were implemented at the beginning of the low transmission season, and if malaria diagnosis was done with PCR. Repeated interventions for consecutive years (10 years with microscopy or 5 years with PCR), would allow reaching near to zero incidence and prevalence rates.ConclusionsThe addition of FSAT interventions to PCD may enable to reach P. falciparum elimination levels in low endemic areas of the Amazon Region, yet the progression rates to those levels may vary substantially according to the operational criteria used for the intervention.Electronic supplementary materialThe online version of this article (doi:10.1186/s13071-015-0868-4) contains supplementary material, which is available to authorized users.

Infection of Laboratory-Colonized Anopheles darlingi Mosquitoes by Plasmodium vivax

Anopheles darlingi Root is the most important malaria vector in the Amazonia region of South America. However, continuous propagation of An. darlingi in the laboratory has been elusive, limiting entomological, genetic/genomic, and vector–pathogen interaction studies of this mosquito species. Here, we report the establishment of an An. darlingi colony derived from wild-caught mosquitoes obtained in the northeastern Peruvian Amazon region of Iquitos in the Loreto Department. We show that the numbers of eggs, larvae, pupae, and adults continue to rise at least to the F6 generation. Comparison of feeding Plasmodium vivax ex vivo of F4 and F5 to F1 generation mosquitoes showed the comparable presence of oocysts and sporozoites, with numbers that corresponded to blood-stage asexual parasitemia and gametocytemia, confirming P. vivax vectorial capacity in the colonized mosquitoes. These results provide new avenues for research on An. darlingi biology and study of An. darlingi–Plasmodium interactions.

First Report of Meloidogyne javanica on Sacha Inchi (Plukenetia volubilis) in China.

Sacha inchi (Plukenetia volubilis L.) is a plant native to the rain forest of the Peruvian Amazon region. Because of its high protein and oil content as well as general nutritional quality, it is regarded as a promising new crop. Successfully introduced from South America in 2006, Sacha inchi has been cultivated in Xishuangbanna, in the southwestern region of Yunnan Province, China. During an investigation from August to October of 2012, severely stunted and withered Sacha inchi plants with rotted and galled root were observed in fields. Dissection of galled root tissue revealed mature root-knot nematode (Meloidogyne sp) females with body cavity filled with red color contents. The population was extracted and quantified from soil and root samples and identified to species by morphology, esterase (EST) isozyme phenotypes, and molecular characterization (3). Mean populations of 774 ± 251 Meloidogyne second stage juveniles (J2) per 100 cm3 of soil were extracted from the rhizosphere of symptomatic plants. These juveniles (n = 20) were characterized by length (410 to 480 μm) and hyaline tail terminus length (11 to 17 μm). Females (n = 20) were characterized by stylet length (14.1 to 17.3 μm) and the perineal pattern (rounded with fine striae, low to moderately high dorsal arch, and a distinct lateral field clearly demarcated from striae by parallel lines). The distinct lateral lines of the perineal pattern are diagnostic for this species (3). Gravid females were used for esterase (Est) isoenzyme analysis, and showed the J3 phenotype (relative migration rate [Rm] = 1.0, 1.25, and 1.4), typical of M. javanica, a species-specific phenotype used to differentiate this species from other members of Meloidogyne (1). Additionally, three single egg masses associated with red body females were extracted from the field-collected Sacha inchi roots and inoculated onto three potted tomato plants (Solanum lycopersicum 'Rutgers') and maintained in the greenhouse for 8 weeks until root galls and egg masses were visible. The observation of root-knot nematodes from tomato roots showed that all females' bodies were normal white, and the nematode species was also identified as M. javanica based on the esterase phenotype and the perineal pattern. It is suggested that the red body contents associated with females on Sacha inchi is the result of an unknown chemical compound acquired from that host. Although undetermined to species, Meloidogyne has been reported on Sacha inchi in Peru (2). To our knowledge, this is the first detection of M. javanica on this plant. Since M. javanica is widely distributed throughout the tropics, this root-knot nematode could be an important threat to the commercial cultivation of Sacha inchi.

To Be Shipibo Nowadays: The Shipibo‐Konibo Youth Organizations as a Strategy for Dealing with Cultural Change in the Peruvian Amazon Region

ResumenMuchas sociedades indigenas están preocupadas por su futuro. Las personas mayores no saben cómo las nuevas generaciones van a continuar viviendo y transmitiendo su herencia y se critica a la juventud por cambiar u olvidar las tradiciones. En el caso Shipibo‐Konibo, los mayores creen que a los jóvenes solo les interesa vivir en la ciudad y olvidar sus raíces. Sin embargo, no todos piensan así necesariamente. Hay muchas formas de ser Shipibo y de expresar la identidad shipiba. Este artículo discute cómo los valores culturales y morales ayudan a la juventud shipiba a enfrentar los nuevos desafíos de esta época. Asimismo, cómo las organizaciones juveniles shipibas constituyen una forma de lidiar con los dilemas que los y las jóvenes shipibas enfrentan. La pregunta central no es “ser o no ser Shipibo”, sino qué significa ser joven shipibo ahora, en nuevos contextos sociales y culturales.

Síndrome pulmonar por Hantavirus (Virus Río Mamoré) en la Amazonía Peruana

Hantavirus infection is a viral zoonotic infection borne by rodents which most letal form clinical is the Hantavirus Pulmonary Syndrome (SPH, Spanish abbreviation). The Mamore River variant originates in South America and was found in rodents without any association to human diseases. Two cases of SPH were identified in the Peruvian Amazon region in November 2011. In both cases, a molecular diagnostic testing was conducted by the Instituto Nacional de Salud from Peru. A phylogenetic analysis of a viral genome fragment and a histopathological evaluation were conducted. Both patients developed adult respiratory distress syndrome and refractory shock. A patient died and another one recovered 12 days later.

High Degree of Plasmodium vivax Diversity in the Peruvian Amazon Demonstrated by Tandem Repeat Polymorphism Analysis

Molecular tools to distinguish strains of Plasmodium vivax are important for studying the epidemiology of malaria transmission. Two sets of markers-tandem repeat (TR) polymorphisms and MSP3α-were used to study Plasmodium vivax in patients in the Peruvian Amazon region of Iquitos. Of 110 patients, 90 distinct haplotypes were distinguished using 9 TR markers. An MSP3α polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) using HhaI and AluI revealed 8 and 9 profiles, respectively, and 36 profiles when analyzed in combination. Combining TR and PCR-RFLP markers, 101 distinct molecular profiles were distinguished among these 110 patients. Nine TR markers arrayed along a 100 kB stretch of a P. vivax chromosome containing the gene for circumsporozoite protein showed non-linear linkage disequilibrium (I(SA) = 0.03, P = 0.001). These findings demonstrate the potential use of TR markers for molecular epidemiology studies.

Reproductive biology of the wild red brocket deer ( Mazama americana) female in the Peruvian Amazon

Knowledge of the reproductive biology is critical for the development of management strategies of the species both in captivity and in the wild, and to address conservation concerns regarding the sustainable use of a species. The present report characterizes some aspects of the reproductive biology of the wild red brocket deer inhabiting the North-eastern Peruvian Amazon region, based on the anatomical and histological examination of the female reproductive organs of 89 wild adult females in different reproductive states. The red brocket deer female presented ovarian follicular waves involving the synchronous growth of a cohort of an average 25 follicles but only one follicle generally survived and continued development, reaching maturity at 4 mm. Mean ovulation rate was 1.14 and litter size was 1 fetus. Females presented a low rate of reproductive wastage of 14.3% of embryos. Among the 89 adult females studied, 41 (46.1%) were pregnant and 48 (53.9%) were non-pregnant females. In the Northeastern Peruvian Amazon, conceptions occurred year-round in the red brocket deer but there were peaks in the rate of conception. Estimated yearly reproductive production was 0.76–0.82 young per adult female. Most pregnant females in advanced stage of pregnancy had at least one active CL, suggesting the persistence of CL throughout gestation.

Modelling production of migratory catfish larvae (Pimelodidae) on the basis of regional hydro‐ climatology features of the Madre de Dios Basin in southeastern Peru

AbstractA simple stochastic model is presented to describe the influence of the natural flow regime of the Madre de Dios River (southeastern Peru) on the presence and downstream transportation of catfish larvae (Siluriformes: Pimelodidae), an important migratory species in commercial fisheries in the Peruvian Amazon region. One year of daily river stage records were related to weekly larval catches to determine the association between floods and spawning events, and based on the hydro‐climatologic characteristics of Andean‐Amazon regions, available long‐term historical rainfall records were used to determine the inter‐annual variability of floods within the Madre de Dios Basin. Major larval drift occurred during the high water season, specifically in association with stages of over 5 m, which served as an indicator triggering spawning responses of these species, termed a ‘biologically significant event’ (BSE). Timing of these BSEs, estimated from the historical rainfall records, described a uniform distribution during the wet season, and their inter‐arrival times were exponentially distributed. These observations provided the basis of the stochastic model describing the likelihood of larvae releases from this headwater region to the lowland Amazon. Copyright © 2011 John Wiley & Sons, Ltd.