In fluctuating environments, matching breeding timing to periods of high resource availability is crucial for the fitness of many vertebrate species, and may have major consequences on population health. Yet, our understanding of the proximate environmental cues driving seasonal breeding is limited. This is particularly the case in marine ecosystems, where key environmental factors and prey abundance and availability are seldom quantified. The Northern Humboldt Current System (NHCS) is a highly productive, low-latitude ecosystem of moderate seasonality. In this ecosystem, three tropical seabird species (the Guanay Cormorant Phalacrocorax bougainvillii, the Peruvian Booby Sula variegata, and the Peruvian Pelican Pelecanus thagus) live in sympatry and prey almost exclusively on anchovy, Engraulis ringens. From January 2003 to December 2012, we monitored 31 breeding sites along the Peruvian coast to investigate the breeding cycle of these species. We tested for relationships between breeding timing, oceanographic conditions, and prey availability using occupancy models. We found that all three seabird species exhibited seasonal breeding patterns, with marked interspecific differences. Whereas breeding mainly started during the austral winter/early spring and ended in summer/early fall, this pattern was stronger in boobies and pelicans than in cormorants. Breeding onset mainly occurred when upwelling was intense but ecosystem productivity was below its annual maxima, and when anchovy were less available and in poor physiological condition. Conversely, the abundance and availability of anchovy improved during chick rearing and peaked around the time of fledging. These results suggest that breeding timing is adjusted so that fledging may occur under optimal environmental conditions, rather than being constrained by nutritional requirements during egg laying. Adjusting breeding time so that fledglings meet optimal conditions at independence is unique compared with other upwelling ecosystems and could be explained by the relatively high abundances of anchovy occurring throughout the year in the NHCS.

Recruitment success of commercially important marine resources, such as the Peruvian anchovy Engraulis ringens, is based on continuous assessment and fisheries management. Potential egg production (PEP) is a valuable tool that, unlike the reproductive indices, quantifies spawning activity and increases the likelihood of a better prediction of recruitment. From 2000 to 2008, spawning females >14.0 cm total length contributed largely to the annual PEP (more than 60%), while females ranging from 12.0 to 14.0 cm TL had a significant participation during peak spawning periods. During the main spawning periods, 68% of the total PEP was obtained, with each length group contributing 50% of this production, whereas during the period of low activity, females >14.0 cm were those that kept spawning, contributing 81% of PEP. The breeding-related closed fishing seasons protected 57% of PEP, 22% in summer and 35% in winter-spring; fishery closure is an effective management measure to protect the main reproductive activity. This protection and quantitative knowledge of the spawning of E. ringens, such as that provided by PEP, will help us to better understand the recruitment process and predict recruitment.

In this paper we analyze the standardized monthly anomalies of time series of the gonadosomatic index (

The time series of monthly gonadosomatic index (GSI) and biannual size at first maturity of Jack mackerel Trachurus murphyiNichols 1920 in Peru between 1967 and 2012 is analyzed and discussed. The annual and interannual variation of the reproductive cycle was determined. It is shown that in Peru T. murphyihas a single relatively extended spawning period with a maximum in November each year. It is also shown that for more than four decades T. murphyi has spawned regularly every year in Peruvian waters. The reproductive activity of T. murphyi has a greater variability off Peru and the spawning period has peaks of lesser magnitude but extend longer than observed in the spawning occurring off Chile. The analyses of the sizes at first maturity of Jack mackerel in Peruvian waters did not show significant changes throughout the entire period observed.

Los índices reproductivos fracción desovante o índice de actividad de desove (FD o IAD) e índice gonadosomático (IGS) permiten evaluar la condición reproductiva de un recurso y brindar un mayor alcance en el conocimiento de su estrategia reproductiva ante diversos cambios, como los producidos en el ambiente ante un evento como El Niño Costero. Con el objetivo de conocer el impacto de El Niño Costero 2017 sobre el proceso reproductivo del stock norte-centro de la anchoveta peruana Engraulis ringens (Jenyns, 1842), se analizó el comportamiento de las anomalías IGS (2010 - 2018) y de la FD (2010 - 2018) o IAD (2010 - 2018), relacionadas a las anomalías de temperatura superficial del mar (ATSM). Se determinaron las anomalías mensuales en base a la comparación del valor del índice correspondiente para cada mes con el patrón respectivo (2010-2017). Se observa que, respecto al periodo de El Niño Costero, en el mes de enero se produjo una anomalía positiva de efecto moderado de FD; mientras que en los meses de febrero y marzo se presentaron anomalías negativas de efecto fuerte. Los meses posteriores (abril – junio) se registraron anomalías sin efecto en la FD. Por otro lado, el IGS mostró anomalías positivas de efecto moderado en los meses de enero y febrero. En los siguientes meses (marzo – junio), se observaron anomalías negativas con efecto moderado en la maduración del recurso. Finalmente, la anchoveta peruana desovó masivamente en el mes de enero, adelantando su desove de verano (el cual se produce, generalmente, en el mes de febrero) como parte de su estrategia reproductiva, asegurándose así, un periodo de desove que permita la renovación de su población.