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Piura es una región del norte de Perú que destaca por su pesca artesanal, su industria procesadora y exportadora de productos para consumo humano directo (CHD) y su gastronomía marina. Usando información primaria y secundaria, se caracterizó la cadena de valor de la actividad pesquera regional durante el 2014 y se estimaron indicadores de producción, valor agregado (VA) y empleo. El desembarque de Piura fue de 732.000 t y generó U$D 1.771 millones en ingresos, U$D 700 millones de valor agregado y 49.000 empleos. Las capturas fueron destinadas principalmente a: (1) la elaboración industrial y exportación de productos de CHD, preferentemente suministrados por la pesca artesanal (82% del desembarque, 59% del VA y 46% del empleo), y (2) el suministro de recursos frescos para el consumo doméstico (13% del desembarque, 37% del VA y 52% del empleo). Esta región no sigue el patrón nacional, caracterizado por una gran extracción industrial de anchoveta para la producción y exportación de harina y aceite de pescado (CHI). Finalmente, dado que está extensamente documentado que la pesca artesanal aún tiene una amplia agenda de pendientes para lograr la sostenibilidad y que hay que prever escenarios climáticos futuros que puedan impactar la productividad pesquera, se recomienda desarrollar una gobernanza más sólida y participativa que ayude a prevenir posibles colapsos y fomente la competitividad de las actividades económicas aquí descritas.

Sustainably managed wild fisheries support food and nutritional security, livelihoods, and cultures (1). Harmful fisheries subsidies—government payments that incentivize overcapacity and lead to overfishing—undermine these benefits yet are increasing globally (2). World Trade Organization (WTO) members have a unique opportunity at their ministerial meeting in November to reach an agreement that eliminates harmful subsidies (3). We—a group of scientists spanning 46 countries and 6 continents—urge the WTO to make this commitment...

The Humboldt Current Large Marine Ecosystem (HCLME) is a salient feature of the southeastern Pacific, along the South American coast of Chile and Peru. It is associated with coastal upwelling which generates a very productive ecosystem. However, due to a variety of interconnected biophysical processes at diverse temporal and spatial scales, production varies greatly in time and space. The interplay of the biophysical environment, biological processes involving valuable resources on international markets, the socio-political context, and some management decisions, has shaped the daily life of the HCLME fisheries, marked by booms and busts, offering wealth for short periods of time, followed by collapses. These collapses are generally interpreted as the consequence of a lack of appropriate management, so that a variety of increasingly stricter regulations have been implemented. Nevertheless, this has not significantly reduced the temporal variability of the fisheries landings, which is broadly characterized by a peaks and troughs pattern. While the HCLME is one of the most productive marine ecosystems on Earth, along with a great biophysical and biological variability, it is also a huge but fragile exploited social-ecological system. Modelers can help to understand how to continuously adapt in order to deal with recurrent fisheries “crises,” which, as we are beginning to learn, may simply be an expression of the variability inherent in this complex system. Furthermore, it is essential to increase our capacity to adapt to the expected consequences of climate change.

The scallop Argopecten purpuratus is a heavily exploited resource along the coasts of Peru and north-central Chile, especially after El Niño events, when the species undergoes high increases in abundance. Little is known about its genetic structure or demographic history, two important factors to ensure sustainable exploitation. We sequenced the cytochrome oxidase I and cytochrome b genes of 116 individuals from six localities (between 05°44′S 80°53′W and 23°31′S 70°33′W). We found high levels of genetic diversity in the analyzed populations. No geographical structuring was observed in the haplotype network, which consisted of a few central, widely distributed haplotypes, and many derived population-specific haplotypes separated by few mutations. This pattern suggests a recent population expansion and moderate to low current gene flow among populations. Mismatch analysis, neutrality tests, and a Bayesian skyline analysis confirmed the occurrence of a past event of population expansion approximately 5,000 years ago, which coincides with increasingly stronger and more frequent El Niño events. Fil: Acosta Jofré, Maria Soledad. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Diversidad y Ecología Animal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto de Diversidad y Ecología Animal; Argentina Fil: Sahade, Ricardo Jose. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Diversidad y Ecología Animal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto de Diversidad y Ecología Animal; Argentina Fil: Mendo, Jaime. Universidad Nacional Agraria La Molina ; Perú Fil: González Ittig, Raúl Enrique. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Diversidad y Ecología Animal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto de Diversidad y Ecología Animal; Argentina Fil: Laudien, Jürgen. Alfred-Wegener-Institut. Helmholtz-Zentrum für Polar und Meeresforschung; Alemania Fil: Chiappero, Marina Beatriz. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Diversidad y Ecología Animal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto de Diversidad y Ecología Animal; Argentina

The South Pacific bay scallop Argopecten purpuratus represents a high-value species harvested along the Peruvian and Chilean coastline for more than 60 years. Following the strong El Nino event of 1983/84, both countries experienced a boom in scallop fisheries, but catches dropped as soon as environmental conditions normalized. Aquaculture production began in Chile, which dominated the Latin American scallop market in the 1990s. Peruvian production remained small until the early 2000s, but has increased dramatically ever since, with a single location in northern Peru, Sechura Bay, contributing most (50%) to the Latin American scallop production. We review the historical trends of this species’ production and analyse the ecological and socio-economic factors that have favoured Sechura Bay's progress, and largely displaced Chilean production through dominance of the market. Advantageous environmental conditions in Sechura Bay (e.g. low water depths, higher temperatures, high natural seed supply) result in improved scallop growth and production, and the socio-economic factors, causing lower operational costs than those of the Chilean production favoured this development. The bottom-up initiation of aquaculture operations by small-scale producers likely created a personal incentive for the long-term sustainable use, which differs from the more industrialized aquaculture activities in Chile.

The Peruvian scallop (Argopecten purpuratus) is the second main contributor to the total catch of mollusks in Peru, after jumbo squid. There are two main scallop banks populations in northern Peru: Lobos de Tierra Island (LTI) and Sechura Bay (SB). Despite a continuous, intense relocation of seeds from LTI, the natural bank population still persists there. To understand this, we studied larval connectivity between LTI and SB using the first invertebrate larval transport biophysical model developed in the region. Larval local retention were 2.4% and 1.57% on average at LTI and SB respectively, while larval transport from SB to LTI was 0.02% on average and 0.07% in the opposite direction. Both larval retention and larval transport increased with spawning depth and were highest in austral summer. Two main larval transport paths from SB to LTI were identified, resulting from a combination of horizontal mesoscale circulation patterns and vertical flows. Potential management implications for these natural banks are discussed.

International audience; We investigated the rhythm of micro-striae formation in the shell of Argopecten purpuratus and environmental influence on micro-growth increments by monitoring growth over a 98-day period between April and July 2007 under bottom and suspended culture (2m above the bottom) rearing conditions. The transfer of individuals to the study site induced the formation of a notable growth mark that allowed us to count the number of micro-striae formed between transfer and sampling dates. Micro-striae counts showed a deposition rate of one stria per day independent of rearing condition. This result allowed us to analyse the relationships between growth increments and environmental conditions. We therefore examined the deviations between observed growth rates and growth rates predicted from a Von Bertalanffy growth function. Cross-correlation analysis revealed significant correlations, without time-lag, between these deviations and both particulate organic carbon and nitrogen concentrations in the bottom treatment. Additionally, we observed negative correlations with temperature and current speed at this depth with time-lags of 1 and 10 days respectively. In the suspended treatment, we observed a significant negative correlation with temperature, only with a 12-day lag-time. Our results show that growth response to environmental variability is not always instantaneous. This delay can be explained by the time delay over which metabolic processes need to be performed (e.g. digestion, use/movements of reserves, growth, reproduction). Further modeling studies could help to better understand these processes.

International audience; The response of Argopecten purpuratus (Peruvian scallop) to environmental conditions was studied in the upwelling-influenced Bay of Paracas (Peru). Scallops growth and reproduction were monitored weekly over a 7-month period under two conditions (culture depths): on the bottom and 2 m above (suspended culture). At the same time, a high-frequency environmental monitoring was realized at the aforementioned depths. The results indicate that environmental conditions in the Bay are highly variable, especially during the summer: temperature fluctuations up to 8∘C were recorded in less than one day while oxic conditions ranged from oversaturation to anoxia. Milky-turquoise waters discoloration events (sulphide presence suspected) were simultaneously observed together with anoxic conditions and sudden temperature drops. Increased stratification and upwelling favorable winds during the summer might be partly responsible for the observed environmental variability. Higher somatic and gonadal growth were observed in scallops growing in suspended culture compare with bottom culture. This pattern might be related to different environmental conditions at culture depth: turbidity was lower in suspended culture and hypoxic conditions occurred only 18% of the whole study period versus 48% on the bottom. The Gonadosomatic index varied according to an approx. 30-day cycle between winter and late spring and it was synchronous between the different scallop size groups. During summer, when milky waters and anoxic events occurred frequently, cessation of reproduction, somatic weight losses and increased scallop mortality were observed. Exposure to severe hypoxia and related environmental conditions clearly affected scallop bioenergetics and subsequently growth and reproduction. In addition, the occurrence of milky waters harmed the survival of the Peruvian scallop in culture. These results are discussed in terms of management strategies for sustainable scallop aquaculture in the Bay.

This chapter discusses the biology, ecology and aquaculture of the scallop, Argopecten purpuratus, in Peru. Of several scallop species, this is the only one exploited and cultured in Peru. During the last three decades, this resource has become one of the most important molluscs in Peru in terms of export value with volume greatly fluctuating since the onset of the export business in the early 1980s. The impact of El Nino on the population of A. purpuratus is discussed by regions in Peru, being favourable in central and southern Peru and detrimental in northern Peru. Conversely, the scallop production in northern Peru is augmented during cold years. Since most of the scallop production is dependent on seed extraction from natural banks, the use of artificial collectors and the production of larvae in hatcheries is proposed and discussed.

Macrobenthic soft bottom community assemblages were studied from December 2006 to December 2007 at Paracas Bay (Atenas Beach, 13°45' S, 76°17' W, Peru), including the period of the tsunami of 15 August 2007, providing a unique opportunity to assess the effects of this type of natural disturbance in soft bottom marine ecosystems. The results show that the tsunami affected the soft bottom community assemblage by changing the sediment granulometry, the biomass and abundance of epifaunal species, and by increasing the silt proportion. The event affected all functional groups, resulting in an increased numbers and biomass of filter feeder and grazers that were followed soon after by predators during the post-tsunami period. A similar pattern was observed for biomass and the abundance of infaunal species without changing the functional groups. The slow recovery observed after four months was likely related to the loss of sediment stability. In summary, there were differences in the structure and composition of soft bottom macrofaunal assemblages before and after the earthquake and posterior tsunami disturbance, forcing benthic communities to initiate re-colonisation processes. Fil: Lomovasky, Betina Judith. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Departamento de Biología. Laboratorio de Ecología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata; Argentina Fil: Firstater, Fausto Nahuel. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Departamento de Biología. Laboratorio de Ecología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata; Argentina Fil: Salazar, Alex Gamarra. Universidad Nacional Mayor de San Marcos; Perú Fil: Mendo, Jaime. Universidad Nacional Agraria La Molina; Perú Fil: Iribarne, Oscar Osvaldo. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Departamento de Biología. Laboratorio de Ecología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata; Argentina

Peru experiences recurrent ENSO (El Nino Southern Oscillation) events during which the Peruvian bay scallop (Argopecten purpuratus) undergoes substantial changes in its stock size. In the North of the country strong warm ENSO events are synonymous with floods and river discharges that negatively affect scallop biomass, while in the South increased sea surface temperatures lead to an increase in stock size. This paper explores how formal institutions respond to climate variability and resource fluctuations in the scallop fishery, and what role they play in the maintenance or erosion of resilience. The research shows that formal institutions are slow to learn, self-reorganize and respond to climate variability while fishermen’s responses are spontaneous, ensuring a rapid process of individual adaptation. Institutional responses are mostly ex-post, and are not strongly shaped by past experience, thus eroding the resilience of the system. However, fishermen’s responses sometimes lead to negative outcomes such as local stock overexploitation or ‘invasion’ of natural scallop habitats for scallop grow-out, and formal institutions play an important role in resilience building through the control of effort and entry in the fishery. In this paper causal loop diagrams are used to conceptualize the fishery system to highlight key variables and processes. The study thus provides the opportunity to explore the usefulness of causal loop diagrams and conceptual models combined with participatory approaches in the exploration of the resilience of a system. The case study also illustrates that individual adaptation, a feature of resilience, is occurring and will occur spontaneously, changing property right regimes and responding not only to climate variability but also market forces. In order to maintain and build resilience and engender positive management outcomes, formal institutions not only need to shape fishermen decision-making, they must also contribute to knowledge building as well as the adoption of innovative approaches.

During the strong warm El Nino (EN) that occurred in 1997/98, Independence Bay (14°S, Peru) showed a ca. 10 °C increase in surface temperatures, higher oxygen concentrations, and clearer water due to decreased phytoplankton concentrations. Under these quasi-tropical conditions, many benthic species suffered (e.g. macroalgae, portunid crabs, and polychaetes) while others benefited (e.g. scallop, sea stars, and sea urchins). The most obvious change was the strong recruitment success and subsequent proliferation of the scallop Argopecten purpuratus , whose biomass increased fiftyfold. To understand these changes, steady-state models of the bay ecosystem trophic structure were constructed and compared for a normal upwelling year (1996) and during an EN (1998), and longer-term dynamics (1996–2003) were explored based on time series of catch and biomass using Ecopath with Ecosim (EwE) software. Model inputs were based on surveys and landings data collected by the Instituto del Mar del Peru (IMARPE). Results indicate that while ecosystem size (total throughput) is reduced by 18% during EN, mainly as a result of decreased total primary production, benthic biomass remains largely unchanged despite considerable shifts in the dominant benthic taxa (e.g. scallops replace polychaetes as secondary consumers). Under normal upwelling conditions, predation by snails and crabs utilize the production of their prey almost completely, resulting in more efficient energy flow to higher trophic levels than occurs during EN. However during EN, the proliferation of the scallop A . purpuratus combined with decreased phytoplankton increased the proportion of directly utilized primary production, while exports and flows to detritus are reduced. The simulations suggest that the main cause for the scallop outburst and for the reduction in crab and macroalgae biomass was a direct temperature effect, whereas other changes are partially explained by trophic interactions. The simulations suggest that bottom-up effects largely control the system.

La acuicultura marina se perfila como una actividad muy prometedora en respuesta a la creciente presión mundial por recursos alimenticios. Debido a las limitaciones de espacio y menor calidad ambiental en las zonas costeras, las aguas mar afuera se proyectan como el área natural de expansión de la acuicultura marina o maricultura oceánica. Ecuador, un país con vocación pesquera y acuícola, pretende impulsar esta actividad. No obstante, a la luz de los problemas ambientales observados en otros países, su desarrollo puede entrar en conflicto con los principios de sostenibilidad y la visión ambiental del gobierno. A pesar de los avances tecnológicos y la existencia de un marco jurídico para el desarrollo de la actividad, se han autorizado pocas concesiones. En tal sentido, el objetivo de este trabajo es estructurar un modelo de investigación que, teniendo como base la Evaluación Ambiental de última generación, es decir la Evaluación de la Sostenibilidad (ES),conduzca a la realización de una microzonificación del mar ecuatoriano para una maricultura sostenible de la especies locales: pargo (Lutjanusguttatus) y huayaipe (Seriolarivoliana). El estudio plantea que la actividad pudiera impulsarse con un estudio que analice la sostenibilidad en sus dimensiones ambiental, social, económica y de gobernanza, estableciendo las áreas más apropiadas para implementar proyectos en Ecuador. Palabras claves: Maricultura, sostenibilidad, evaluación ambiental, Seriolarivoliana, Lutjanusguttatus. ABSTRACT Marine aquaculture is emerging as a promising activity in response to the growing global pressure of food resources. Offshore waters are projected as the natural area of expansion of marine aquaculture in open water due to space constraints and lower environmental quality in coastal areas. Ecuador has important fishery and aquaculture industries. Since last few years, several governmental initiatives point to promote the marine aquaculture. However, considering the environmental problems observed in other countries, the development of the marine aquaculture may conflict with the principles of sustainability and environmental vision of the Ecuadorian government. Despite technological advances and the existence of a legal framework for the development of the activity, few concessions for offshore marine fish aquaculture has been authorized. In this sense, the goal of this work is to structure a research model, based on the Environmental Assessment of last generation, i. e. Sustainability Assessment (ES), leading to the realization of a micro-zoning of the Ecuadorian sea for a sustainable mariculture of local species snapper (Lutjanusguttatus) and huayaipe (Seriolarivoliana). This work suggests that the activity could be promoted if a study is done by analyzing sustainability of oceanic mariculture in its environmental, social, economic and governance dimensions, establishing the most appropriate areas to implement projects in Ecuador. Keywords: Marine aquaculture, sustainability, environmental assessment, Seriolarivoliana, Lutjanusguttatus. El presente trabajo constituye un ensayo introductorio de la investigación para optar el grado de Doctoris Philosophiae en Ingeniería y Ciencias Ambientales con el tema “Análisis de la sostenibilidad ambiental del desarrollo de la maricultura oceánica de pargo (Lutjanusguttatus) y huayaipe (Seriolarivoliana) en Ecuador” Recibido: octubre de 2014Aprobado: febrero de 2015

1.This study is the first attempt using Levins's Theory (loop analysis) in order to develop a sustainable management for the scallop, Argopecten purpuratus, fishery in Peru during El Nino-Southern Oscillation events (ENSO) and upwelling conditions. Based on this theoretical framework, it was possible to estimate the local stability for each of these model systems and to follow the qualitative changes of the variables in response to external factors. 2.Based on our results, we suggest the following management policies to be implemented: (1) during ENSO events the size at the first capture of the scallops should be >70 mm and (2) the increase in the number of fishermen during ENSO events must be prevented. Both measures increase the sustainability of fishery under ENSO and upwelling conditions. The ecological models predict that during ENSO and upwelling events, any management strategy to increase the recruitment of the scallop would not have a positive impact on the adult stock. 3.Finally, we suggest that more efforts must be focused on the development of extended eco-social models, which incorporate further social and economic variables, increasing realism of the abstractions for this fishery activity. Copyright © 2002 John Wiley & Sons, Ltd.

Este estudio compara el crecimiento y supervivencia de Argopecten purpuratus (Lamarck, 1819) “concha de abanico” sembradas con diferentes densidades de Ulva spp., Linnaeus, 1753 en la bahía Paracas (Ica-Perú) durante el 7 agosto al 16 de octubre del 2011. Para ello se instalaron tres corrales cada uno con tres unidades experimentales de 1m2 y en cada unidad se sembraron conchas de abanico de 40-50mm de altura a una densidad de 60 individuos/m2. En dos de los corrales se sembró Ulva spp., con 10 (T2) y 20 (T3) kg/m2 y el tercer corral fue considerado como testigo (T1), es decir, sin Ulva spp. Para evaluar el crecimiento, cada dos semanas se extrajeron al azar 10 individuos por cada repetición (30 por tratamiento) y se registró la altura y el peso seco del soma y la gónada. La supervivencia se evaluó contando los individuos muertos en periodos variables. Adicionalmente cada 30 minutos durante todo el experimento se registró la temperatura y oxígeno del fondo y diariamente el pH, conductividad y corrientes se registraron en una zona media a los tratamientos. La clorofila a se registró diariamente, para cada tratamiento. Los resultados indican que la supervivencia, el crecimiento en altura y peso se vieron afectados por la presencia de Ulva spp. La concentración de oxígeno y clorofila a, mostraron mayores valores en los tratamiento con presencia de Ulva spp. Se concluyó que densidades mayores a 20 kg de Ulva spp./m2, afectan el crecimiento y supervivencia de Argopecten purpuratus, por lo que se recomienda su extracción. This study compares the growth and survival of juvenile Argopecten purpuratus (Lamarck, 1819) seeded with different densities of Ulva spp., in the bay of Paracas (Ica-Peru) between August 7 and October 16, 2011. For this purpose, three pens were installed each with three experimental units of 1m2 and each experimental unit had a density of 60 scallops /m2, with an average height of 40-50mm. In two of the pens Ulva spp., was introduced with 10 (T2) and 20 (T3) kg/m2 and the third was considered witness (T1), ie without Ulva spp. To assess growth, every two weeks 10 scallops for each repetition (30 in each treatment) were randomly extracted their individual height was recorded and dry weight and gonad somatic tissue were sampled. Survival was assessed by counting the dead individuals in varying periods. During the entire experiment temperature and bottom oxygen were assessed every 30 minutes while pH, conductivity and currents were daily assessed at noon in the treatments middle zone. Chlorophyll a was measured daily, for each treatment. The results indicate that survival, height and weight were affected by the presence of Ulva spp. Oxygen concentration and chlorophyll a, showed higher concentration in the presence of Ulva spp. It was concluded that higher than 20 kg spp./m2 densities of Ulva affect growth and survival of A. purpuratus, so a removal is recommended.

In order to understand the effect of different culture systems on Cd and Pb accumulation, suspended long-line and bottom cultures of Argopecten purpuratus were conducted during January until April 2010 (120 days). The Cd tissue levels were the highest at the middle of the experiment (30-d till 70-d) for suspended-cultured individuals, while bottom-cultured individuals showed an increasing trend. Gonad Pb levels were also higher during the same period for all cultures, while adductor muscle exhibited no considerable variations. Cd and Pb tissue concentrations were mainly greater in deeper cultures. There were no significant differences in Cd and Pb accumulation between individual sizes. The Cd and Pb levels in edible tissue (gonad+adductor muscle) did not exceed the EU and FDA maximum levels. Based on the target hazard quotient (THQ) and the provisional tolerance weekly intake (PTWI), no risk (THQ1 and %PTWI30) was found for human consumption.

1. This paper sets out to: (1) review previous ecological studies and analyse recent trends of the Peruvian bay scallop fishery in order to better understand and to model the species’ temporal and spatial (meta) population dynamics along the South Pacific coast; (2) develop a fisheries model to protect the stock from overexploitation and optimize the annual yield of the pulse fishery in Independence Bay, the centre of the scallop diving fishery in Peru. 2. Natural stock fluctuations are very pronounced in this species and are positively correlated with the El Nino–Southern Oscillation (ENSO). During such an event, habitat conditions for the Peruvian bay scallop are improved either regionally or locally, such that populations proliferate and larval production and dispersal are greatly increased. Extinct beds and new habitats are recolonized during these periods (producing a strong pulse of metapopulation biomass), although most become extinct very shortly thereafter. 3. For management purposes, two considerations are fundamental: (1) heavy overfishing or extinction of the main scallop source populations would endanger the metapopulation as a whole; (2) rates of growth and survival greatly increase (and with them the potential yield of the scallop stock) locally over an El Nino cycle in a way that can be roughly estimated from past experience, including the most recent El Nino event (1997–1998). 4. We suggest a fisheries management regime capable of adapting to natural changes and propose a procedure for calculating both the optimal yield and the respective fishing effort under normal upwelling and El Nino scenarios, considering changes in the size at first capture (Lc) and fishery mortality (F). Copyright © 2000 John Wiley & Sons, Ltd.

Growth parameters, instantaneous mortality rates ( Z , F and M ), yield per recruit and biomass per recruit of the oyster Crassostrea rhizophorae were estimated using the FiSAT package, based on shell length frequency data of 2551 individuals. Von Bertalanffy growth parameters and total mortality were estimated using the ELEFAN I program and the catch curve method, respectively. Pauly's and M = 2 K empirical equations were used to estimate natural mortality. Values found are L ∞ = 149 mm, K = 0.9 year −1 , φ′ = 4.3 and t 0 = −0.05 year −1 , respectively. Age at entry is too low because of the harvest of small oysters attached to the adults shells. Total, natural and fishing mortalities were estimated at 5.16, 2.0 and 3.16 year −1 , respectively. The exploitation rate (0.6) and fishing mortality indicate that oyster is slightly overexploited due mainly to the harvest method used by fishermen rather than to the increase of effort itself. Yield per recruit could be substantially improved by returning shells to the environment.

Durante muchos años los desembarques de la pesquería pelágica en la costa peruana se han caracterizado por la presencia de un alto porcentaje de individuos juveniles, especialmente en el caso de la anchoveta ( Engraulis ringens ) durante el año 2002 con consecuencias poco conocidas y estudiadas. En este trabajo se analizan las pérdidas en biomasa y económicas que la pesca de juveniles ocasiona basado en proyecciones de la composición por tallas de los desembarques de los puertos de Paita, Chimbote, Callao y Pisco. Las proyecciones de biomasa, se realizaron mediante el modelo predictivo de Thompson y Bell utilizando parámetros de crecimiento de von Bertalanffy estimados para cada puerto mediante el programa ELEFAN I y de la tasa de mortalidad natural proporcionado por el Instituto del Mar del Perú ( IMARPE ) . Las biomasas fueron proyectadas hasta que la fracción de individuos

El lenguado Paralichthys adspersus ( Steindachner ) es una especie de gran importancia para Chile y el Perú por su abundancia y alto valor comercial, sin embargo muy poco se conoce sobre su potencial de cultivo en el Perú. Este estudio determina el crecimiento y la fecundidad del lenguado y realiza un análisis de caracteres externos que permita su separación por sexos, tres aspectos importantes del cultivo de organismos acuáticos. Se analizaron 5 caracteres merísticos y 10 morfométricos de 150 ejemplares utilizados para determinar diferencias entre machos y hembras. La edad fue determinada en base a la lectura de anillos en los otolitos, estimando los parámetros de crecimiento de von Bertalanffy mediante el ploteo de Ford-Walford, en tanto la fecundidad se calculó mediante el conteo de ovocitos de gónadas en estadio IV de madurez. Los caracteres merísticos y morfométricos analizados no permiten separar individuos por sexo, sin embargo, la diferencia observada en cuanto a los orificios anal, urinario y genital presentes en hembras ( presenta los 3 separadamente ) y machos ( sólo 2, anal y urogenital ) , si permiten realizar dicha separación en forma rápida y confiable. Las hembras del lenguado presentaron mayor crecimiento que los machos, así la ecuación de von Bertalanffy tiene la forma de: Lt= 101.17 ( 1-e -0.140 ( t+ 0.584 ))en hembras y Lt= 60.53 ( 1-e -0.253 ( t+ 0.310 ) ) en machos. El lenguado es un desovador parcial asincrónico con ovocitos maduros de un diámetro entre 0.665 y 0.805 mm, con una fecundidad total de 2 125 000 huevos por individuo y una relativa de 1 500 huevos por gramo de pez. Se discute el potencial de esta especie para su cultivo comparando el crecimiento y la fecundidad con otras especies de lenguados de ambiente natural y que se cultivan en el mundo. The fine flounder Paralichthys adspersus ( Steindachner ) is a species of great importance for Chile and Peru by its abundance and high commercial value, however little is known about its potential for culture in Peru. This study determine growth and fecundity and analyzes external characters, which permit the sex differentiation in order to know about its potential for culture. Meristic ( 5 ) and morphometric ( 10 ) characters from 150 individuals were measured and analyzed using linear regressions in order to find differences between sex. Age was determined counting annual rings in otoliths and von Bertalanffy growth parameters were estimated using the Ford- Walford plot, meanwhile fecundity of females was estimated counting the number of ovocites of mature gonads ( stage IV ) . The morphometric and meristic characters used in the determination of sexual differentiation, did not show significant differences that can be used in the separation of males from females in a easily and confidentially way. However, it was observed differences in relation to the genital, urinary and anal orifices; females show the 3 orifices separately but males show only two, anal and urogenital orifices. It was found that P. adspersus females growth faster than males. The von Bertalanffy equation for females was Lt= 101.17 ( 1-e -0.140 ( t+ 0.584 ) ) , and Lt= 60.53 ( 1-e -0.253 ( t+ 0.310 ) ) for males. P. adspersus is a partial asynchronic spawner, with mature ovocites between 0.665-0.805mm. The total fecundity was estimated in 2 125 000 eggs per individual and the relative fecundity was 1500 eggs per gram of fish. The potential for culture of this species is discussed comparing growth and fecundity with other flatfish species from natural and cultured stocks.

La Bahía Independencia puede ser considerada a nivel mundial como una de las zonas mas productivas en invertebrados bentónicos, cuyas capturas están sujetas a fluctuaciones fuertes originadas por la ocurrencia del fenómeno El Niño y La Niña y por la falta de medidas de manejo adecuadas. Durante períodos con calentamientos fuertes los desembarques anuales alcanzan las 50000 t en un área de aproximadamente 150 km² y durante años fríos estas se mantienen alrededor de 500 a 1000 t. El presente estudio analiza los cambios de los desembarques en la Bahía Independencia observados durante las dos últimas décadas y discute los principales factores que afectan los "booms" de concha de abanico. En este sentido se usa información sobre capturas, temperatura y aquella relacionada con el crecimiento, reproducción, prelación, densidad media y condiciones de oxígeno procedente de trabajos publicados y no publicados. La relación entre la captura anual y la temperatura promedio durante el periodo reproductivo de la concha de abanico durante los últimos 20 años, muestra que la producción es afectada positivamente solo con la ocurrencia de El Niño fuertes como en 1983 y 1998. Los resultados muestran que los "booms" de concha de abanico durante estos El Niño se debe al efecto combinado de (1) incremento en la actividad reproductiva a través de una aceleración de la maduración y un incremento de la frecuencia de desove; (2) acortamiento del periodo larval e incremento en la supervivencia larval; (3) incremento en el rendimiento en crecimiento individual; (4) incremento en la supervivencia de juveniles y adultos debido a la reducción de la biomasa de predadores; (5) incremento en la capacidad de carga de los bancos de conchas debido a elevados niveles de oxígeno. En el marco de discusión sobre los factores que contribuyen al desarrollo de la población de concha de abanico durante el evento El Niño, no podemos dejar de considerar en detalle el impacto de la pesquería. Considerando que el volumen de captura no solo depende de la abundancia relativa de la especie, la estrategia de pesca aplicada fue analizada con el fin de explicar los diferentes niveles de producción de concha de abanico durante El Niño 1983 y 1998. Independencia Bay can be considered as one of the most productive invertebrate fishing grounds worldwide. One of the most important exploited species is the scallop (Argopecten purpuratus) with strong catching fluctuations related to El Niño and La Niña events and to inadequate management strategies. During strong warming periods annual landings reach up to 50 000t in an area of about 150 km2 and during cold years they remain around 500 to 1000 t. This study analyses the changes in scallop landings at Independencia Bay observed during the last two decades and discusses the main factors affecting the scallop proliferations during the El Niño events. In this way data on landings, sea surface temperature and those related to growth, reproduction, predation, mean density and oxygen concentration from published and unpublished papers are used. The relationship between annual catches and average water temperature over the preceding reproductive period of the scallop over the past 20 year’s period, showed that scallop production is affected positively only with strong El Niño such as those of 1983 and 1998. Our review showed that the scallop stock proliferation can be traced to the combined effect of (1) an increase in reproductive output through an acceleration of gonad maturation and a higher spawning frequency; (2) a shortening of the larval period and an increase in larval survival; (3) an increase in the individual growth performance; (4) an increase in the juvenile and adult survival through reduction of predator biomass; (5) an increase in carrying capacity of the scallop banks due to elevated oxygen levels. When discussing the factors that contribute to the development of the scallop population during an El Niño event, the fishery must be considered in detail. Since the volume of the catch not only depends on the relative abundance of the species, fishing efforts and strategies were analyzed in order to explain different levels of scallop production during El Niño 1983 and 1998.

Merluccius gayi peruanus es la especie demersal más importante de la pesquería industrial de la costa norte del Perú y juega un rol ecológico importante en el ecosistema. Con la finalidad de conocer el comportamiento dietario de esta especie se analizaron los contenidos estomacales de 2 836 individuos capturados a bordo de embarcaciones arrastreras industriales en la zona norte del Perú durante 1995 a 1997. La longitud total de la merluza fluctuó entre 24 y 73 cm y mayormente en un rango de 34 y 46 cm. El porcentaje de estómagos con alimento en las diferentes clases de longitud fluctuaron entre 39,5 y 100 %. Los peces teleósteos contribuyeron con el 87% de la masa de alimento ingerido, 10.4% fueron moluscos cefalópodos y sólo el 2.6% fueron crustáceos. Entre los peces ingeridos, la misma merluza es el principal ítem alimenticio (40.6%) evidenciando un alto grado de canibalismo, siguiéndole en importancia la familia Engraulidae (24.1%) donde predomina claramente la anchoveta. Para el año 1997 se produce una modificación en la dieta ampliándose el espectro de la estructura alimenticia de la merluza. Basados en el IRI los grupos predominantes en la dieta correspondieron a la familia Eufausidae, la especies Engraulis ringens, Merluccius gayi y P. stephanophrys. La Plenitud total media (TFI) presenta una tendencia ascendente principalmente hasta fines de 1996, pero a inicios del año 1997 manifiesta un franco descenso. Para los años 1995 y 1996 el análisis cluster organizó a las clases de longitud de la merluza en 3 grupos compuesto por ejemplares de 30-34 cm, 34-50 cm y un último con merluzas grandes de 50-66 cm. Para 1997, se observan solo 2 grupos principales compuestos básicamente por merluzas de 30-46 cm y 50-66 cm, resultado que demuestra el efecto del fenómeno El Niño en el comportamiento alimentario de la merluza y su adaptación a los cambios en la oferta alimenticia. Merluccius gayi is the most important demersal species exploited by the fishery industry in the northern coast of Peru and plays an important ecological function in the ecosystem. In order to know its predatory behavior stomach content of 2836 individuals were analyzed. The individuals were caught on board of industrial trawlers in the north of Peru during 1995 to 1997. The total lengths ranged between 24 and 73 cm and mainly in a range of 34 and 46 cm. The percentage of stomachs with food in different length classes ranged between 39.5 and 100%. Fishes were the largest item in the diet with 87% followed by the mollusks cephalopods with 10.4% and crustaceans with 2.6%. The euphausiids were the most abundant crustacean and among the fishes ingested the hake was the main food item (40.6%) showing a high degree of cannibalism, followed by the Engraulidae (24.1%) clearly dominated by the anchovy. For 1997 the diet showed a wider spectrum. Based on IRI values, the predominant groups in the diet corresponded to Eufausidae, the species Engraulis ringens, Merluccius gayi and P. stephanophrys. According to the total fullness (TFI) showed a positive trend mainly until the end of 1996, however after started to decline. The cluster analysis applied to the stomachs contents sampled in 1995 and 1996 by length classes organized the individuals in 3 groups: of 30-34 cm, 34-50 cm and 50-66 cm. For 1997, the cluster analysis grouped the stomachs of hake into two groups of 30-46 cm and 50-66 cm, which demonstrates the effect of El Niño on the foraging behavior and the adaptation of hake to changes in the food supply.

Trachurus murphyi es una de las especies más importantes de la red trófica del ecosistema pelágico-oceánico y representa una de las pesquerías industriales de mayor significancia de la costa del Perú. Con la finalidad de conocer el comportamiento dietario de esta especie se analizaron los contenidos estomacales de 3 175 ejemplares capturados a bordo de embarcaciones industriales arrastreras semi-pelágicas y cerqueras en la zona norte y centro del Perú respectivamente desde 1995 hasta 1997. La longitud total del jurel fluctuó entre 22 y 59 cm y mayormente en un rango de 26 y 46 cm. Estadísticamente se comprueba que la variación observada de los contenidos estomacales es significativa para todo el periodo de estudio como también para los diferentes grupos de tallas. El porcentaje de estómagos con alimento en las diferentes clases de longitud fluctuaron entre 42.3 y 100%. Los crustáceos contribuyeron con el 60.4% de la masa de alimento ingerido, seguido por los peces con 39.3%, mientras que los moluscos sólo representaron el 0.36%. Dentro de estos grupos la especie más representativa es Euphausia mucronata (54.3%) y peces (35.5%) pero sin poder identificar la especie predominante por el estado de descomposición en los contenidos estomacales. En el año 1997 (El Niño) se produce un aumento considerable en el número de especies como presas llegando a 23 especies. Aunque con pequeñas variantes en cada año se destaca la preferencia de eufausidos para los ejemplares más pequeños (< 38 cm) y de peces (>42 cm). Basados en el IRI y el Indice de Jerarquización se destaca la notable preferencia de los eufausidos como presa, esencialmente la E. mucronata en los años 1995 y 1996 pero diversificándose en 1997 con otras especies de eufausidos y de peces en su dieta, manifestándose su carácter de predador oportunista. El análisis cluster para los datos de contenido estomacal para el año 1995 organizó las 8 clases de longitud en 2 grupos principales de tallas de 58 cm. Trachurus murphyi is one of the most relevant species in the food chains of the pelagic-oceanic system and represents one of the most important industrial fisheries in the Peruvian coast. In order to know its predatory behavior, stomach contents of 3175 individuals were analyzed. The individuals were caught on board in industrial semi-pelagic trawlers and purse seine vessels in the north and central coast of Peru from 1995 to 1997. Individuals´ total lengths ranged from 22 to 58 cm, the main range being from 26 to 46 cm. Percentage of stomachs with food of different length classes ranged from 42.3 to 100%. Crustaceans were the largest item in the diet with 60.4% followed by fishes with 39.3% and mollusks with only 0.36%. Euphausia. mucronata was the most representative species in the diet with 54.3% followed by a 35.5% of fishes which could not be identified due to decomposition processes. Based on IRI values, the predominant groups in the diet corresponded to the Eufausidae family. Cluster analysis applied to the stomachs contents sampled in 1995 by length classes organized the individuals into 2 groups: 58 cm.

Von Bertalanffy growth parameters of the Peruvian scallop ( Argopecten purpuratus ) from Peru were derived from (1) a growth experiment with suspended scallops near Independence Island (September 1987 – September 1988); (2) monthly length frequencies from a natural scallops bank at Tunga, Independence Bay (September 1987 – March 1988); (3) length frequencies data from scallops collected in Atenas (Paracas Bay) during the El Nino event 1982–1983. The growth parameters obtained using a Gulland and Holt plot for the suspended scallops were K =2.25 year −1 and L ∞ =94.3 mm. The analysis of the length frequencies data yielded K and L ∞ of 0.565 year −1 and 110 mm for the Tunga data and 2.9 year −1 and 112.0 mm for the Atenas data, respectively. The growth performance index ƒ ′ ( ƒ ′ = log K + 2 log L ∞ was highest for scallops from Atenas (4.56) followed by those from Independence Island (4.30) and Tunga (3.83). Our results indicate that the suspended scallops from Independence Island (1987–1988) grew to a similar length to those on the bottom in Atenas during the 1982–1983 El Nino phenomenon, whereas the growth of the scallops on the bottom at Tunga was significantly inferior.

To a certain degree, Eastern Boundary Current (EBC) ecosystems are similar: Cold bottom water from moderate depths, rich in nutrients, is transported to the euphotic zone by a combination of trade winds, Coriolis force and Ekman transport. The resultant high primary production fuels a rich secondary production in the upper pelagic and nearshore zones, but where O2 exchange is restricted, it creates oxygen minimum zones (OMZs) at shelf and upper slope (Humboldt and Benguela Current) or slope depths (California Current). These hypoxic zones host a specifically adapted, small macro- and meiofauna together with giant sulphur bacteria that use nitrate to oxydise H2S. In all EBC, small polychaetes, large nematodes and other opportunistic benthic species have adapted to the hypoxic conditions and co-exist with sulphur bacteria, which seem to be particularly dominant off Peru and Chile. However, a massive reduction of macrobenthos occurs in the core of the OMZ. In the Humboldt Current area the OMZ ranges between The properties described are valid for very cold and cold (La Niña and "normal") ENSO conditions with effective upwelling of nutrient-rich bottom water. During warm (El Niño) episodes, warm water masses of low oxygen concentration from oceanic and equatorial regions enter the upwelling zones, bringing a variety of (sub)tropical immigrants. The autochthonous benthic fauna emigrates to deeper water or poleward, or suffers mortality. However, some local macrofaunal species experience important population proliferations, presumably due to improved oxygenation (in the southern hemisphere), higher temperature tolerance, reduced competition or the capability to use different food. Both these negative and positive effects of El Niño influence local artisanal fisheries and the livelihood of coastal populations. In the Humboldt Current system the hypoxic seafloor at outer shelf depths receives important flushing from the equatorial zone, causing havoc on the sulphur bacteria mats and immediate recolonisation of the sediments by mega- and macrofauna. Conversely, off California, the intruding equatorial water masses appear to have lower oxygen than ambient waters, and may cause oxygen deficiency at upper slope depths. Effects of this change have not been studied in detail, although shrimp and other taxa appear to alter their distribution on the continental margin. Other properties and reactions of the two Pacific EBC benthic ecosystems to El Niño seem to differ, too, as does the overall impact of major episodes (e.g., 1982/1983(1984) vs. 1997/1998). The relation of the "Benguela Niño" to ENSO seems unclear although many Pacific-Atlantic ocean and atmosphere teleconnections have been described. Warm, low-oxygen equatorial water seems to be transported into the upwelling area by similar mechanisms as in the Pacific, but most major impacts on the eukaryotic biota obviously come from other, independent perturbations such as an extreme eutrophication of the sediments ensuing in sulphidic eruptions and toxic algal blooms. Similarities and differences of the Humboldt and California Current benthic ecosystems are discussed with particular reference to ENSO impacts since 1972/73. Where there are data available, the authors include the Benguela Current ecosystem as another important, non-Pacific EBC, which also suffers from the effects of hypoxia.

El presente estudio se efectuó en el área de El Queso, Bahía Independencia (Pisco, Perú), de febrero de 1992 a marzo de 1993. Se usaron colectores de netlón para determinar la distribución vertical del asentamiento larval y se hizo un seguimiento de la captación de semillas en colectores comerciales para determinar el patrón temporal de asentamiento larval de concha de abanico (Argopecten purpuratus). Con el fin de relacionar este patrón con las condiciones ambientales, se registró la temperatura, oxígeno disuelto y transparencia del agua. La distribución vertical de larvas e individuos asentados en los colectores de prueba indicó que la intensidad del asentamiento larval aumenta hasta 45 veces entre los niveles superficial y de fondo, concentrándose entre 11 y 16 m en una columna de agua de 20 m de profundidad. La ocurrencia de un período de desove intenso en otoño, fue deducida por máximos de captación en colectores comerciales entre mayo y julio. Se obtuvieron cosechas en colectores comerciales superiores a 500 semillas/bolsa en abril, mayo, junio, julio y octubre en 3 long-lines, lo cual indica importantes períodos de asentamiento ocurridos en la segunda mitad del verano, al inicio y mediados de otoño y a fines de invierno de 1992. Se observó que la captación varía en forma directa al tiempo de exposición de los colectores y se discute la relación entre la variación de los parámetros ambientales y la captación

Este estudio compara el crecimiento y supervivencia de juveniles de Argopecten purpuratus "concha de abanico" cultivados en sistema de fondo y suspendido en la zona de Casma, Ancash- Perú. Del 29 de Julio y 21 de Octubre del 2006 se instaló un experimento usando "pearl nets" y corrales con individuos de 10mm (0.067g de parte blanda) a densidades de 816, 2450 y 4080 individuos/m2. Cada 2 semanas se colectaron 20 individuos y se registro la altura (mm) y peso de partes blandas (gramos) y mensualmente el número de muertos. Adicionalmente se registró información sobre los costos de producción para comparar la rentabilidad en ambos sistemas. Al final del experimento las tallas y pesos en el cultivo suspendido fueron mayores que en fondo y se relacionaron inversamente con la densidad. Las tasas de crecimiento en talla y peso en el sistema suspendido oscilaron entre 0.07 y 0.43 mm/día y entre 0.009 y 0.100 g/día y en el cultivo de fondo variaron entre 0.11 y 0.26 mm/día y entre 0.007 y 0.045 g/día, respectivamente. Una mayor supervivencia en promedio se registró en el sistema suspendido (96.8%) que en fondo (84.8%). Los resultados del ANOVA mostraron que la densidad y el sistema de cultivo afecta significativamente al crecimiento y supervivencia de juveniles de concha de abanico (P < 0.01). El análisis costo-beneficio realizado demuestra que es mas rentable cultivar juveniles en sistemas de fondo que en suspendido y que la densidad de 4080 ind/m2 permite obtener los más altos beneficios en el cultivo suspendido y la densidad de 816 ind/m2 en el de fondo. Se discute la factibilidad de la adopción del cultivo de fondo de juveniles de concha de abanico por parte de empresas y pescadores artesanales con el fin de obtener mejores beneficios. This study analyzes and compares the growth and survival of juvenile Argopecten purpuratus cultivated in suspended and bottom systems in Casma, Ancash-Peru. From July 29th to October 21th, 2006 an experiment was installed using pearl nets and yards with individuals of 10mm (0.067g of soft tissue) at densities of 816, 2450, and 4080 indiv/m2. Every two weeks individuals were measured (mm, shell height) and weighted (g, total and tissue weight) and dead scallops counted. Additionally information on production costs was recorded in order to compare profits in both systems. At the end of the experiment height and weight were higher in suspended than in bottom system and showed an inverse relation with density. Growth rates in height and weight in suspended system ranged from 0.07 to 0.43 mm/day and from 0.009 and 0.100 g/day and in bottom system varied between 0.11 and 0.26 mm/day and between 0.007 and 0.045 g/day, respectively. Survival was higher in suspended (96.8%) than in bottom systems (84.8%). The ANOVA showed a significant effect of density and culture system on growth and survival of juvenile scallops (P

Se estimaron los parámetros de crecimiento y producción de la población de D. obesulus de la playa arenosa expuesta de Sarapampa, 100 km al sur de Lima. Para ello se realizaron muestreos mensuales durante 11 meses (Octubre 2005-Agosto 2006) en 6 estaciones distribuidas a lo largo de la playa. Se elaboraron frecuencias de tallas y se determinaron los parámetros de crecimiento de la ecuación de Von Bertalanffy (ECVB) mediante ELEFAN I. La tasa de mortalidad total (Z) se estimó por el método de la curva de captura linealizada. Los parámetros de crecimiento fueron K= 0.991 y L∞= 33.70 mm y la tasa de mortalidad total Z= 3.28. La biomasa promedio fue estimada utilizando la relación talla-peso húmedo libre de valvas (PHLV = 0.0003 L3.061) en 54.10 g PHLV m-2. La producción de esta especie en términos de peso seco libre de ceniza (PSLC) se calculó en 3.76 g PSLC.m-2.año-1 en promedio. Los individuos de 22 y 23 mm de talla aportaron mayormente a la producción anual (10.3%). La tasa de renovación anual (P/ B) fue estimada en 1.20. Se discute el crecimiento y la productividad de esta especie en relación a otras del mismo género. Growth parameters and production of the population of D. obesulus at the exposed sandy beach of Sarapampa (100 km south of Lima) were estimated. Monthly samplings were carried out during a year (October 2005-August 2006) in 6 stations distributed throughout the beach. Lengthfrequency distributions were elaborated and the growth parameters of the Von Bertalanffy growth equation (VBGE) determined by ELEFAN I. Total mortality rate (Z) was estimated by the lengthbased catch curve method and production of somatic and shell components were estimated by the mass specific growth rate method. Growth parameters were estimated as K= 0.991 and L∞= 33.70 mm and total mortality as Z= 3.28. Mean biomass was calculated using the relation length-shell and free wet mass (SFWM = 0.0003 L3.061) as 54.10 g SFWM.m-2. The average production of this species was calculated in terms of ash free dry weight in 3.76 g AFDW.m-2.year-1. Individuals ranging from 22 to 23 mm contributed most to the total production (10.3%). Mean annual turnover rate (P/ B) was 1.20. Growth and production of this species is compared with other species of the same genus.