Estimating global numbers of fishes caught from the wild annually from 2000 to 2019.

Finfishes are caught from the wild for food, feed (often in the form of fishmeal and oil) and bait. According to the Food and Agriculture Organisation of the United Nations (FAO), between 74 and 83 million tonnes (averaging 77 million tonnes) were caught annually in 2000-2019. Although fishes are now widely recognised as sentient beings, capture is still quantified as biomass rather than number of individuals (in contrast to wild-caught marine mammals and crocodiles; and farmed mammals and birds). Here, we estimate global numbers of wild-caught finfishes using FAO capture production (landing) tonnages (2000-2019 data) and estimates of mean individual weight at capture, based on internet-sourced capture and market weights. We estimate that between 1,100 and 2,200 billion (1.1-2.2 × 1012), or 1.1-2.2 trillion, wild finfishes were caught annually, on average, during 2000-2019. Anchoveta (Engraulis ringens) comprised 28%, by estimate midpoint. Estimated numbers in 2019, totalling 980-1,900 billion, were lower due to reduced anchoveta landings, but still represented 87.5% of vertebrate numbers killed for food or feed, as obtained or estimated from FAO data. These figures exclude unrecorded capture such as illegal fishing, discards and ghost fishing. Estimated finfish numbers used for reduction to fishmeal and oil represented 56% of the total 2010 estimate (1,000-1,900 billion), by midpoint. It is recommended that the FAO reports fish capture numbers. The welfare of wild-caught fishes, which is generally very poor during and after capture, should be addressed as part of sustainable utilisation of aquatic resources.

Intertwined realities - hybrid institutions in the Peruvian fisheries and aquaculture sectors.

Following pro-market policies, the Peruvian state has aimed to regulate profitable fisheries and aquaculture activities in order to increase their production. However, informal and illegal activities not only persist but are also interlinked with formal practices and frameworks, creating intertwined realities in fostering processes of institutional hybridization. This article analyses the (re)production of informal and illegal activities by explaining the formation of hybrid institutional entanglements in the Peruvian anchoveta (Engraulis ringens) fishery in Pisco and the Peruvian bay scallop (Argopecten purpuratus) aquaculture industry in Sechura. It argues that state policies to promote industrial fisheries and entrepreneurial aquaculture for the global market coupled with limited interest in supporting small-scale fisheries and aquaculture activities have resulted in processes of institutional hybridization. Within these processes, social actors resist and accommodate formal regulatory frameworks to suit their respective needs, while intertwining formal and informal practices and institutional arrangements, based on their political leverage or ability to produce hybrid institutional entanglements in a context where regulation is limited and state authority is negotiated. Under these forms of hybrid governance, the article shows that interactions between state and non-state actors do not lead to collaborations for solving problems but to the persistence of sustainability problems.

Establishing company level fishing revenue and profit losses from fisheries: A bottom-up approach.

A third of global fish stocks are overexploited and many are economically underperforming, resulting in potential unrealized net economic benefits of USD 51 to 83 billion annually. However, this aggregate view, while useful for global policy discussion, may obscure the view for those actors who engage at a regional level. Therefore, we develop a method to associate large companies with their fishing operations and evaluate the biological sustainability of these operations. We link current fish biomass levels and landings to the revenue streams of the companies under study to compute potentially unrealized fisheries revenues and profits at the level of individual firms. We illustrate our method using two case studies: anchoveta (Engraulis ringens; Engraulidae) in Peru and menhaden in the USA (Brevoortia patronus and B. tyrannus; Clupeidae). We demonstrate that both these fisheries could potentially increase their revenues compared to the current levels of exploitation. We estimate the net but unrealized fishery benefits for the companies under question. This information could be useful to investors and business owners who might want to be aware of the actual fisheries performance options of the companies they invest in.

Daily growth patterns and age-at-recruitment of the anchoveta Engraulis ringens as indicated by a multi-annual analysis of otolith microstructure across developmental stages.

The anchoveta (Engraulis ringens) plays a key role in the ecology of the Humboldt Current System and is of major economic importance; however, many aspects of its early life history are still poorly understood. In this study, an analysis of daily age and length patterns was carried out using the sagittal otoliths from wild larvae (0-0.2 cm standard length, LS ), pre-recruits (3-6 cm total length, LT ), recruits (7-12 cm LT ) and young adults (12-15 cm LT ). Additionally, variability in growth and age at recruitment (AR ) were evaluated for recruits caught in northern Chile in 1973, 1982, 2009, 2010, 2012, 2013, 2014 and 2015. The age-length relationship showed four allometric patterns that were well described by Laird-Gompertz models. The absolute growth rates at the inflexion point (GAR ) were 0.56, 0.75, 1.22 and 1.16 mm d-1 for larvae, pre-recruits, recruits and young adults, respectively. At the interannual scale, GAR values were always >1 mm d-1 (mean ± S.D. 1.37 ± 0.21 mm d-1 ; range 1.12-1.64 mm d-1 ), irrespective of the season of hatching (i.e. winter v. spring); additionally, in most cases, GAR values were reached before the second month of life (mean ± S.D. 50.47 ± 9.73 days) at c. 4 cm LT (mean ± S.D. 4.22 ± 0.29 cm). Mean AR was < 150 days (112 ± 29 days; range 75-149 days); in contrast, estimates of AR were higher and growth rates were lower in 1973, 1983 and 2000. These results demonstrate very fast growth and early AR of anchoveta in northern Chile, suggesting most fish are removed by the fisheries at very early ages. An evaluation of the implications of these results on stock assessment and management of this species is highly recommended.

The impact of kraft pulping effluent on egg survival and hatching success in two species of Clupeiformes (Teleostei).

The anchoveta (Engraulis ringens) and sardine (Strangomera bentincki) are coastal pelagic species with important spawning areas off the coast of Chile. The discharge of secondary-treated effluents from a kraft pulp plant near one of these spawning areas has raised environmental concerns. Therefore, effluent effects on the development of anchoveta and sardine eggs were assessed by in vitro exposure. Eggs were sampled between 2007 and 2010 off Talcahuano, Chile. Subsequent toxicity tests (96 h duration, 12 °C) were performed using increasing effluent concentrations, a filtered seawater control, and two potassium dichromate concentrations (to verify consistent embryonic sensitivity). Egg mortality and hatching success were evaluated. For anchoveta, mortality (9.9 ± 7.1%) did not significantly differ among groups in five toxicity tests except the final toxicity test that showed significant differences in mortality (5.6% control vs 27.8% in 100% effluent). For sardines, no differences in mortality existed between the effluent dilutions (2.6 ± 3.6%) and control (6.3 ± 3.9%). Notably, anchoveta egg survival and hatching success rates were inconsistent, i.e., the highest rates of hatching failure occurred on the same sampling date with the highest rates of survival for the 100% effluent group (72%). In conclusion, the obtained results indicate that (i) anchoveta egg mortality and hatching failure increase only under 100% effluent exposure, coinciding with decreased egg quality near the end of spawning season and (ii) high effluent dilutions not significantly increase sardine and anchoveta egg mortalities. Nevertheless, the recorded adverse effects to the hatching process should be studied in greater detail, particularly considering interspecific variability and the complexity of reproductive processes, especially during early development.

High quality diet improves lipid metabolic profile and breeding performance in the blue-footed booby, a long-lived seabird.

Understanding the role of diet in the physiological condition of adults during reproduction and hence its effect on reproductive performance is fundamental to understand reproductive strategies in long-lived animals. In birds, little is known about the influence of the quality of food consumed at the beginning of the reproductive period and its short-term effects on reproductive performance. To assess the role of diet in the physiological condition of female blue-footed booby, Sula nebouxii (BFBO), during reproduction we evaluated whether individual differences in diet (assessed by using δ13C and δ15N values of whole blood from female birds and muscle tissue of the principal prey species) prior to egg laying and during incubation influenced their lipid metabolic profile (measured as triglyceride levels and C:N ratio) and their reproductive performance (defined by laying date, clutch size and hatching success). Females with higher δ15N values in their blood during the courtship and incubation periods had a higher lipid metabolic profile, earlier laying date, greater clutch size (2-3 eggs) and higher hatching success. Females that laid earlier and more eggs (2-3 eggs) consumed more Pacific anchoveta (Cetengraulis mysticetus) and Pacific thread herring (Opisthonema libertate) than did other females. These two prey species also had high amounts of lipids (C:N ratio) and caloric content (Kcal/g fresh weight). The quality of food consumed by females at the beginning of reproduction affected their physiological condition, as well as their short-term reproductive performance. Our work emphasizes the importance of determining the influence of food quality during reproduction to understand the reproductive decisions and consequences in long-lived animals.

An estimate of the percentage of non-predatory dead variability in coastal zooplankton of the southern Humboldt Current System.

Non-predatory dead variability in zooplankton remains poorly quantified worldwide. Here, we make the first estimation of the percentage of dead organisms in coastal zooplankton communities in the Humboldt Current System (HCS) under in situ conditions. The study was conducted in four coastal sites of the southern HCS (between 36 and 37°S) over a period of one year. Percentages of dead organisms were based on the classification as live or dead of 158,220 holoplankton and 17,591 meroplankton individuals using neutral red staining technique. The percentage of dead organisms in total-zooplankton was between 4.3% in Coronel Bay (summer) and 76.9% in Llico (autumn). The percentage of dead total-holoplankton varied from 4.2% (Itata River Mouth; autumn) to 77.6% (Llico; autumn), while the percentage of dead total-meroplankton ranged from 1.5% to 56.8% in Coronel Bay and Coliumo Bay, respectively. The most abundant taxa analyzed were the copepods Acartia sp., Paracalanus sp., Calanoides sp., Cladocera, Polychaeta, and the eggs of anchoveta Engraulis ringens. Among these taxa, there was a high degree of interspecific variability in the estimation of the dead organisms. The Pearson correlation shows significant relationships between maximum temperature, and minimum salinity, with the percentage of dead individuals of Acartia sp. and Paracalanus sp. Environmental factors explaining those relationships were: the El Niño 2015-2016 event, and freshwater river runoff. The use of vital staining to estimate non-predatory death for total-zooplankton and selected sentinel species is a promising tool to establish baselines to evaluate natural perturbations (e.g. ENSO), and anthropogenic alterations in coastal pelagic ecosystems.

Spatial patterns of Anchoveta (Engraulis ringens) eggs and larvae in relation to pCO2 in the Peruvian upwelling system.

Large and productive fisheries occur in regions experiencing or projected to experience ocean acidification. Anchoveta (Engraulis ringens) constitute the world's largest single-species fishery and live in one of the ocean's highest pCO2 regions. We investigated the relationship of the distribution and abundance of Anchoveta eggs and larvae to natural gradients in pCO2 in the Peruvian upwelling system. Eggs and larvae, zooplankton, and data on temperature, salinity, chlorophyll a and pCO2 were collected during a cruise off Peru in 2013. pCO2 ranged from 167-1392 µatm and explained variability in egg presence, an index of spawning habitat. Zooplankton abundance explained variability in the abundance of small larvae. Within the main spawning and larva habitats (6-10°S), eggs were found in cool, low-salinity, and both extremely low (less than 200 µatm) and high (more than 900 µatm) pCO2 waters, and larvae were collected in warmer, higher salinity, and moderate (400-600 µatm) pCO2 waters. Our data support the hypothesis that Anchoveta preferentially spawned at high pCO2 and these eggs had lower survival. Enhanced understanding of the influence of pCO2 on Anchoveta spawning and larva mortality, together with pCO2 measurements, may enable predictions of ocean acidification effects on Anchoveta and inform adaptive fisheries management.

Tamaño óptimo de muestra para estimar la distribución de tallas y proporción de juveniles de anchoveta por lance a bordo de la flota de cerco peruana

La distribución de tallas de las capturas es una fuente de información esencial para la estimación del crecimiento y la dinámica espacio-temporal de las cohortes. La distribución de tallas de las capturas se estima a partir de muestras de individuos capturados en los lances. Este trabajo estudia la cantidad óptima de individuos a muestrear en cada lance para obtener una muestra representativa de las tallas del lance, y de la proporción de juveniles en el lance. Para ello, se utilizan datos de tallas de diferentes lances en la pesca de anchoveta peruana (Engraulis ringens) registrados por observadores a bordo del Programa Bitácoras de Pesca del Instituto del Mar del Perú, y remuestreos a partir de esos datos. Finalmente proponemos un tamaño de muestra óptimo que permite obtener estimaciones robustas de tallas y proporción de juveniles. Aunque este trabajo se aplicó a la pesca de anchoveta, el procedimiento es aplicable a cualquier pesquería, para muestreos bio-métricos a bordo o en tierra

The length distribution of catches represents a fundamental source of information for estimating growth and spatiotemporal dynamics of cohorts. The length distribution of caught is estimated based on samples of catched individuals. This work studies the optimum sample size of individuals at each fishing set in order to obtain a representative sample of the length and the proportion of juveniles in the fishing set. For that matter, we use anchovy (Engraulis ringens) length data from different fishing sets recorded by observers at-sea from the On-board Observers Program from the Peruvian Marine Research Institute. Finally, we propose an optimum sample size for obtaining robust size and juvenile estimations. Though the application of this work corresponds to the anchovy fishery, the procedure can be applied to any fishery, either for on board or inland biometric measurements

Tamaño óptimo de muestra del programa de observadores a bordo de la flota dirigida a la explotación de la anchoveta peruana (Engraulis ringens) / Optimum sample size for a program of observers on board fishing vessels targetting Peruvian anchovy (Engraulis ringens)

El monitoreo de la pesquería de anchoveta en el Perú es de suma importancia para la sostenibilidad del ecosistema de Humboldt. El Programa de observadores a bordo Bitácoras de Pesca constituye una rica plataforma de recolección de datos de las embarcaciones durante sus viajes de pesca, y donde se recopila información acerca de las capturas en cada lance, distribuciones de tallas, descartes, captura incidental, captura por unidad de esfuerzo, entre otros. Para que los indicadores obtenidos a partir de esta información tengan robustez es preciso contar con un método de solidez estadística para el cálculo del número necesario de viajes a muestrear. Este trabajo presenta un método con estas características, para calcular el número óptimo de viajes de manera independiente para cada una de las variables y a diferentes escalas de tiempo. Se muestra que, dependiendo del objetivo y de la escala temporal, la cantidad óptima de viajes a muestrear varía. A partir de estos resultados, se proporcionan recomendaciones prácticas sobre el tamaño de muestra para el Programa Bitácoras de Pesca. También se discute la aplicabilidad de esta metodología para otros recursos pelágicos.

Monitoring the anchovy fishery is of great importance for assuring the sustainability of the Humboldt ecosystem. The on-board observers program constitutes a rich platform for data collection for monitoring, as it consists of the collection of data from vessels during their fishing trips, regarding catches, size distribution, discards, catch per unit of effort, among others. To get robust indicators from these data, it is necessary to use a solid statistical procedure for computing the number of fishing trips to sample. This work presents a method with those characteristics, for computing each indicator independently and at different time scales. We show that the optimum size varies depending on the objective (indicator) and the time scale. Based on these results, practical recommendations for fixing the sample size are given. We finally discuss the aplicability of this methodology for other pelagic resources.

Estimación del descarte por exceso de captura en la pesquería industrial de cerco del stock Norte-Centro de la anchoveta peruana Engraulis ringens a partir de un programa de observación a bordo / Estimating discard excess catch in the industrial purse seine fisheries of the North-Center stock of the Peruvian anchoveta (Engraulis ringens) from an on-board observer program

En este trabajo se presenta la estimación del descarte por exceso de captura en la pesquería industrial de cerco del stock Norte-Centro de anchoveta peruana. Se define el descarte por exceso de captura, como la porción de captura que se arroja al mar cuando se ha capturado más de lo que la capacidad de bodega de la embarcación puede almacenar. El análisis de estimación para el periodo 2005 - 2014, se realizó a partir del "Programa de observadores a bordo de la flota de cerco" que ejecuta el Instituto del Mar del Perú (IMARPE), en donde 5 837 viajes, que representan el 1.6% de los viajes totales, fueron muestreados. Las metodologías utilizadas en la estimación fueron: Modelo Lineal Generalizado (GLM) y el Modelo Delta. Las estimaciones por el Modelo Delta y el GLM fueron diferentes en magnitudes pero similares en tendencias, sin embargo la evaluación del funcionamiento del Modelo Delta, indica que este modelo se ajusta mejor a los datos. El Modelo Delta estimó que la pesquería descarta por exceso de captura entre 2 954 y 199 164 toneladas, con un promedio de 121 312 toneladas para el periodo de estudio, el cual representó una tasa del 2.6% en relación a los desembarques. Se sugiere la incorporación de variables espaciales (p. ej. distancia a la costa, latitud, longitud), físicas (TSM) y del comportamiento del cardumen (p.e. agregación), para mejorar el análisis y comprender mejor el comportamiento de este tipo de descarte.

This paper presents estimates of the discard excess catch in the industrial purse seine fisheries of the North-Center stock of the Peruvian anchoveta (Engraulis ringens). Discard excess catch is defined as the portion of the catch that is thrown into the sea when has captured more than the hold capacity can store. The analysis is based on the "On-board observer of the purse seine vessels program" led by the Instituto del Mar del Peru (IMARPE), and in the period 2005 - 2014, 5837 trips were sampled, corresponding to 1.6% of the total trips. The methodologies used in the discard excess catch estimation were: Generalized Linear Model (GLM) and Delta Model. The estimations showed difference in magnitudes but similar trends, although the delta model appears to be a better alternative procedure for estimating the discard excess catch. The Delta Model estimated the purse seine fisheries discarded a range from 2954 to 199 164 tons, an average estimated 121 312 tons, which represent 2.6% of the landings in the period 2005 - 2014. Spatial variables (e.g. distance from the shore, latitude, longitude), physical (SST), and school behavior (e.g. fish aggregation) should be included to improve the analysis and a better understanding of the discard excess catch behavior.

Predictive modelling of habitat selection by marine predators with respect to the abundance and depth distribution of pelagic prey.

Understanding the ecological processes that underpin species distribution patterns is a fundamental goal in spatial ecology. However, developing predictive models of habitat use is challenging for species that forage in marine environments, as both predators and prey are often highly mobile and difficult to monitor. Consequently, few studies have developed resource selection functions for marine predators based directly on the abundance and distribution of their prey. We analysed contemporaneous data on the diving locations of two seabird species, the shallow-diving Peruvian Booby (Sula variegata) and deeper diving Guanay Cormorant (Phalacrocorax bougainvilliorum), and the abundance and depth distribution of their main prey, Peruvian anchoveta (Engraulis ringens). Based on this unique data set, we developed resource selection functions to test the hypothesis that the probability of seabird diving behaviour at a given location is a function of the relative abundance of prey in the upper water column. For both species, we show that the probability of diving behaviour is mostly explained by the distribution of prey at shallow depths. While the probability of diving behaviour increases sharply with prey abundance at relatively low levels of abundance, support for including abundance in addition to the depth distribution of prey is weak, suggesting that prey abundance was not a major factor determining the location of diving behaviour during the study period. The study thus highlights the importance of the depth distribution of prey for two species of seabird with different diving capabilities. The results complement previous research that points towards the importance of oceanographic processes that enhance the accessibility of prey to seabirds. The implications are that locations where prey is predictably found at accessible depths may be more important for surface foragers, such as seabirds, than locations where prey is predictably abundant. Analysis of the relative importance of abundance and accessibility is essential for the design and evaluation of effective management responses to reduced prey availability for seabirds and other top predators in marine systems.

Reproductive biology of Cetengraulis edentulus (Cuvier, 1829), the major fishery resource in Guanabara Bay, Brazil

Cetengraulis edentulus is a broadely distributed engraulid in Southwest Atlantic, currently accounting for the main fish species commercially exploited at Guanabara Bay, Brazil. This study aimed to extend the knowledge on reproduction of C. edentulus at Guanabara Bay and to test whether some descriptors of reproductive activity, especially the gonadosomatic index (GSI), and the index of reproductive activity (IRA) changed among seasons. A total of 978 C. edentulus specimens were retrieved from purse seine commercial landings at Conservas Rubi S.A. company, in São Gonçalo city, RJ. Subsamples of 90-120 individuals were collected from bimonthly yields between July 2010 (winter) and June 2011 (autumn). Most fish were adults (120-170 mm TL), in response to the high selectivity of commercial fisheries. All descriptors indicated a broad spawning period (late winter to spring), peaking in November, suggesting this is the critical period to protect C. edentulus stocks from overfishing at Guanabara Bay. Fecundity averaged 12,720 oocytes and was positively related to fish size, GSI and fullness index, indicating that preserving larger individuals (TL > 160 mm) could contribute significantly to the reproductive success of C. edentulus, since they produce more oocytes. Cetengraulis edentulus é um engraulídeo amplamente distribuído no Atlântico Sudoeste, sendo um importante recurso comercialmente explorado na baía de Guanabara, Brasil. O presente estudo teve como objetivo ampliar o conhecimento sobre a reprodução de C. edentulus na baía de Guanabara e testar quais descritores da atividade reprodutiva, especialmente o índice gonadossomático (IGS) e o índice de atividade reprodutiva (IAR) se modificaram ao longo das estações do ano. Um total de 978 indivíduos de C. edentulus foram capturados pelo método de rede de cerco da frota comercial no cais da empresa Conservas Rubi S.A., na cidade de São Gonçalo, RJ. Subamostras de 90-120 indivíduos de C. edentulus foram coletados bimestralmente durante o período de julho de 2010 (inverno) e junho de 2011 (outono). A maioria dos indivíduos foram adultos (120-170 mm CT), em resposta a alta seletividade das capturas comerciais. Todos os índices indicaram um amplo período reprodutivo (final do inverno e primavera), com pico em novembro, sugerindo que este seria um período crítico para preservar os estoques de C. edentulus da sobrepesca na baía de Guanabara. A fecundidade média foi de 12720 ovócitos e foi positivamente relacionada com tamanho do peixe, IGS e índice de repleção, indicando que preservar maiores indivíduos (CT > 160 mm) poderia contribuir significativamente para o sucesso reprodutivo de C. edentulus na área, visto que esses indivíduos produzem um maior número de ovócitos.

Coupled ecosystem/supply chain modelling of fish products from sea to shelf: the Peruvian anchoveta case.

Sustainability assessment of food supply chains is relevant for global sustainable development. A framework is proposed for analysing fishfood (fish products for direct human consumption) supply chains with local or international scopes. It combines a material flow model (including an ecosystem dimension) of the supply chains, calculation of sustainability indicators (environmental, socio-economic, nutritional), and finally multi-criteria comparison of alternative supply chains (e.g. fates of landed fish) and future exploitation scenarios. The Peruvian anchoveta fishery is the starting point for various local and global supply chains, especially via reduction of anchoveta into fishmeal and oil, used worldwide as a key input in livestock and fish feeds. The Peruvian anchoveta supply chains are described, and the proposed methodology is used to model them. Three scenarios were explored: status quo of fish exploitation (Scenario 1), increase in anchoveta landings for food (Scenario 2), and radical decrease in total anchoveta landings to allow other fish stocks to prosper (Scenario 3). It was found that Scenario 2 provided the best balance of sustainability improvements among the three scenarios, but further refinement of the assessment is recommended. In the long term, the best opportunities for improving the environmental and socio-economic performance of Peruvian fisheries are related to sustainability-improving management and policy changes affecting the reduction industry. Our approach provides the tools and quantitative results to identify these best improvement opportunities.

A rapid method for differentiating four species of the Engraulidae (anchovy) family.

The four species of the Engraulidae family: European anchovy (Engraulis encrasicolus), Californian anchovy (Engraulis mordax), Peruvian anchoveta (Engraulis ringens), and Japanese anchovy (Engraulis japonicus) studied in this work are very similar morphologically, and it is very difficult to distinguish between them, especially when frozen or processed. We have used the 5S rDNA as a molecular marker to discriminate these four species and used specific primers designed for each species in the nontranscribed spacers (NTS) of these genes. Multiplex PCR was performed with three pairs of primers, and three different sizes were obtained: 597 bp E. encrasicolus, 598 bp E. japonicus, 380 bp E. mordax, and 250 bp E. ringens. For the species E. encrasicolus and E. japonicus, PCR-RFLP was used as an additional technique to distinguish between them because their NTS sequences showed considerable similarity.

Ontogenetic and spatiotemporal variability in anchoveta Engraulis ringens diet off Peru.

In this study, historical data available since 1954 were used to get new insight to ontogenetic and spatiotemporal variability in Peruvian anchovy or anchoveta Engraulis ringens diet. Whatever the period, E. ringens foraged mainly on macrozooplankton and the importance of euphausiids in E. ringens diet appears directly related to euphausiids abundance. This bottom-up effect is also observed at smaller scale because the euphausiids fraction increased with E. ringens total length and euphausiids accessibility. Selecting the largest prey, the euphausiids, provides an energetic advantage for E. ringens in its ecosystem where oxygen depletion imposes strong metabolic constraints on pelagic fishes. This study illustrates the plasticity of E. ringens that allows it to cope with its highly variable environment.

Eating up the world's food web and the human trophic level.

Trophic levels are critical for synthesizing species' diets, depicting energy pathways, understanding food web dynamics and ecosystem functioning, and monitoring ecosystem health. Specifically, trophic levels describe the position of species in a food web, from primary producers to apex predators (range, 1-5). Small differences in trophic level can reflect large differences in diet. Although trophic levels are among the most basic information collected for animals in ecosystems, a human trophic level (HTL) has never been defined. Here, we find a global HTL of 2.21, i.e., the trophic level of anchoveta. This value has increased with time, consistent with the global trend toward diets higher in meat. National HTLs ranging between 2.04 and 2.57 reflect a broad diversity of diet, although cluster analysis of countries with similar dietary trends reveals only five major groups. We find significant links between socio-economic and environmental indicators and global dietary trends. We demonstrate that the HTL is a synthetic index to monitor human diets and provides a baseline to compare diets between countries.

Efecto ahorrativo de la proteína usando niveles altos de energía y obtención de la relación optima energía digestible/proteína digestible en dietas para el crecimiento de Oreochromis niloticus (L)

Se evaluó el efecto ahorrativo de la proteína usando dietas altas en energía. Se utilizó un diseño factorial para medir la interacción de dos niveles de proteína (30% y 35%) y dos niveles de energía digestible (3.3 y 3.7 kcal/g de alimento) sobre la ganancia (GP), conversión alimenticia (CA), proteína retenida (PR), energía retenida (ER) y la relación de eficiencia proteica (REP) en la tilapia del Nilo todos machos (Oreochromis niloticus). En la composición de las dietas se emplearon harina de anchoveta y harina de torta de soya como fuentes de proteína y maíz amarillo duro y subproducto de trigo como fuentes de energía. El aceite de pescado fue añadido para ajustar los niveles de energía requeridos en las dietas experimentales. Se encontraron interacciones altamente significativas (P<0.01) entre la proteína y la energía digestible. Cuando se utilizaron las dietas con 30% de proteína, el incremento del nivel de energía digestible afectó significativamente la GP, CA, PR, ER y la REP, donde el nivel de 3.3 kcal/g tuvo el mejor comportamiento. Con 35% de proteína, el nivel de energía digestible no influyó significativamente sobre la GP, CA, PR, ER y la REP, sin embargo el nivel de 3.0 kcal/g tuvo el mayor rendimiento. Cuando se compararon las dos dietas no se observaron diferencias estadísticamente significativas. Considerando el costo de la proteína dietaría se concluyó que la mejor respuesta fue obtenida con la dieta de 30% de proteína y 3.7 kcal/g de energía digestible y una relación optima energía digestible/proteína digestible de 13.75 kcal/g de proteína.

The sparing effect of the dietary protein using diets with high energy levels was evaluated. A factorial design was used to examine the interaction of two levels of protein (30 and 35%) and two levels of digestible energy (3.3 and 3.7 kcal/g) on the weight gain (WG), food conversion FC), retained protein (PR), retained energy (ER) and protein efficiency ratio (PER) in “sex reversal Nile tilapia” ( Oreochromis niloticus). Diets contained anchovy and soybean meal as protein sources and yellow corn and wheat bran as energy sources. The fish oil was used to adjust the energy levels. There were highly significant interactions (P<0.01) between the experimental diets. In diets with 30% proteins, the increase of digestible energy significantly enhances WG, FC, PR, ER and PER, where the level of 3.7 kcal/g had the best performance. With 35% protein, the increase of digestible energy had not significant influence on the GP, CA, PR, ER and PER, however the growth of sex reversal Nile Tilapia was improved with the level of 3.3 kcal/g. When were compared both diets, were not find significant differences. Considering the protein cost, it can be concluded that best response was obtained with a diet containing 30 % of protein and 3.7 kcal/g of digestible energy and optimum digestible energy/digestible protein ratio of 13.75 kcal/g protein.

Ecología trófica del jurel Trachurus murphyi en el Perú entre 1977 - 2011

Se analizó la variabilidad espacio-temporal de la dieta de jurel Trachurus murphyi frente a Perú de 1977 a 2011. Un total de 21058 estómagos fueron analizados utilizando métodos bivariados y el Modelo de Árbol de Regresión Multivariado (ARM). Se utilizó como variable respuesta la composición gravimétrica de la dieta, con respecto a diferentes variables pre dictivas como años, profundidad de la isoterma de 15 °C, Índice de Oscilación del Sur (IOS), Índice de Oscilación Decadal del Pacífico (PDO), anomalía de la temperatura superficial del mar, zona (norte, centro y sur) y distancia de la costa. Nuestros resultados nos permitieron identificar dos escenarios diferentes, uno desde el año 1977 al 2000, donde la dieta del jurel T. murphyi estuvo fuertemente dominada por Euphausiidae, y otro escenario después del 2000, donde el jurel T. murphyi consumió mayor diversidad de presas, principalmente Euphausiidae, camaroncito rojo Pleuroncodes monodon y Zoeas. Se destaca que el primer escenario corresponde a condiciones cálidas y el segundo a condiciones frías, ambas coincidentes con los periodos multidecadales. A diferencia de estudios anteriores que muestran que la anchoveta Engraulis ringens es una presa abundante, en este estudio no fue significativamente importante. Espacialmente, los Euphausiidae dominaron la dieta en el norte-centro de Perú, mientras que al sur, la composición de las presas fue más diversa. La dieta también varió significativamente según la distancia a la costa, con mayor proporción de P. monodon cerca a la costa y con respecto a su etapas de desarrollo ontogenético.

We analyzed the spatiotemporal variability of Jack mackerel Trachurus murphyi diet off Peru from 1977 to 2011. A total of 21058 stomachs were analyzed using bivariate methods and the Multivariate Regression Tree Model (MRT). The gravimetric composition of the diet was used as response variable with respect to different predictor variables such as years, depth of the 15°C isotherm, Southern Oscillation Index (SOI), Index of the Pacific Decadal Oscillation (PDO), sea surface temperature anomaly, zone (north, center and south) and distance to the coast. Our results allowed us to identify two different scenarios. From 1977 to 2000 the Jack mackerel T. murphy diet was strongly dominated by Euphausiidae, and since 2000 when T. murphyi consumed a greater diversity of prey, mainly Euphausiidae, squat lobster Pleuroncodes monodon and Zoea. It is noted that the first scenario corresponds to warm conditions and the second to cold conditions, both coincident with observed multidecadal periods. In contrast to previous studies showing that the anchovy Engraulis ringens is an abundant prey, in this study anchovy was not significantly important. Spatially, the Euphausiidae dominated the diet in central-northern Peru, while further south the prey composition was more diverse. The diet also varied significantly according to the distance from the coast (higher proportion of P. monodon closer to the coast) and the ontogenic stages.

Biomasa acústica y distribución del jurel Trachurus murphyi en el Perú

Se analizan los resultados de las evaluaciones hidroacústicas del recurso jurel Trachurus murphyi Nichols 1920 realizadas en aguas peruanas entre 1983 - 2012. Desde 1983 se incluyó al T. murphyi como especie de estudio durante los cruceros de evaluación de recursos pelágicos ejecutados por el Instituto del Mar del Perú. Debido al énfasis en la estimación de biomasa de la anchoveta Engraulis ringens y de la sardina Sardinops sagax cuando esta última es más abundante, los cruceros se llevan a cabo durante el verano austral y las áreas de evaluación están circunscritas a las zonas más costeras hasta 100 mn, con sólo algunas exploraciones en otras estaciones y hasta 200 millas. El máximo valor de biomasa de 8.51 millones de toneladas de T. murphyi en aguas peruanas estimado con las evaluaciones hidroacústicas fue encontrado durante el crucero realizado en otoño (marzo-mayo) de 1983. En los años siguientes los estimados de biomasa acústica fluctuaron entre 180 mil toneladas en 1985 y otro máximo de 8.47 millones de toneladas en 1993, para luego disminuir gradualmente hasta un mínimo de 1239 t en 2010, con una ligera recuperación en los años 2011 y 2012. El área de distribución de T. murphyi fue muy fluctuante en todo el periodo observado.

This paper analyzes the results of acoustic stock assessment surveys for Jack mackerel Trachurus murphy Nichols 1920 conducted in Peruvian waters between 1983 and 2012. Since 1983 Jack mackerel T. murphyi was included as a target species to be assessed during the pelagic stock assessment surveys executed by the Peruvian Institute of Marine Research. Due to the emphasis on the assessment of anchovy Engraulis ringens and sardine Sardinops sagax when this species was abundant, these surveys usually took place during the austral summer and only covered the first 100 nautical miles from the coast, and only occasional surveys were conducted in other seasons or surveyed as far as 200 nm offshore. A maximum biomass of 8.51 million t of T. murphyi in Peruvian waters estimated through acoustics during a survey carried out in autumn (March-May) 1983. In the following years acoustic biomass estimates ranged between 180 thousand t in 1985 and another maximum of 8.47 million t in 1993, to then decreased gradually to a minimum of 1239 t in 2010, with a slight recovery in 2011 and 2012. The areas of ​​distribution of T. murphyi have been fluctuating markedly throughout the observed period.