Abstract. The Peruvian moonfish (Selene peruviana) is an important fisheries resource that is landed in the main fishing harbors of Ecuador. At the local level, little information is available regarding the biology of this species, which hinders the development of management plans. The present study evaluates the reproductive characteristics of S. peruviana such as the size at sexual maturity and reproductive cycle. Specimens were obtained from artisanal and industrial catches from January 2017 to December 2018. The morphometric characteristics, sex, and maturity stage of 886 specimens were determined, and the gonadosomatic index (GSI), hepatosomatic index (HSI), and relative condition factor (Kn) were estimated. The length-weight relationship and length at sexual maturity (L50) were evaluated with an allometry equation and multi-model analyses, respectively. The mean capture size (total length, TL) was 23.62 cm for males and 22.97 cm for females. A sex ratio (M:F) of 0.70:1.00 (χ 2 = 26.28, P < 0.05) was obtained. The allometric factor of the length-weight relationship for both sexes (b) was 2.63 (t = 12.16, P < 0.05), and the coefficient of determination (r 2) was 0.89, which suggests that negative allometric growth was present. The L50 (TL) was estimated to be 22.61, 23.86, and 23.27 cm for males, females, and sexes combined, respectively. The monthly GSI, HSI, and Kn values were significantly different (K-W, P < 0.05) among study months. The maximum GSI values were observed in February and March, which constituted the period of highest reproductive activity. The HSI and Kn values exhibited similar trends. The size at sexual maturity was similar to the average catch size, which could indicate that S. peruviana is currently at the limit of its optimal catch size.

Resumen. El pez luna peruano, Selene peruviana, es un importante recurso desembarcado en las principales caletas pesqueras del Ecuador. A nivel local, existe poca información sobre la biología de esta especie, lo cual dificulta el desarrollo de planes de manejo. El presente estudio evalúa aspectos reproductivos de S. peruviana como la talla de madurez sexual y el ciclo reproductivo. Se obtuvieron muestras de capturas artesanales e industriales desde enero de 2017 hasta diciembre de 2018. Las características morfométricas, el sexo y la etapa de madurez de 886 especímenes fueron registrados y se estimó el índice gonadosomático (IGS), el índice hepatosomático (IHS) y el factor de condición relativo (Kn). La relación talla-peso y la talla de madurez sexual (L50) se evaluaron mediante la ecuación de alometría y análisis multimodelos, respectivamente. La talla media de captura (longitud total, LT) fue de 23.62 cm para los machos y 22.97 cm para las hembras. Se obtuvo una proporción de sexos (M:H) de 0.70:1.00 (χ2 = 26.28, P < 0.05). El factor alométrico de la relación longitud-peso para sexos combinados (b) fue 2.63 (t = 12.16, P < 0.05) y el coeficiente de determinación (r 2) fue 0.89, lo que sugiere una relación alométrica negativa. La L50 (LT) se estimó en 22.61, 23.86 y 23.27 cm para machos, hembras y sexos combinados, respectivamente. Los valores mensuales de IGS, IHS y Kn mostraron diferencias significativas (K-W, P < 0.05) entre los meses de estudio. Los valores máximos de IGS se observaron durante febrero y marzo, siendo el periodo de mayor actividad reproductiva. Los índices de IHS y Kn mostraron tendencias similares. La talla de madurez sexual fue similar a la talla media de captura, lo que podría indicar que S. peruviana se encuentra en el límite de su talla óptima de captura.

ABSTRACT. In Ecuador, Peprilus medius is an important fishery resource whose destination is for local consumption and export. There are few local studies on its reproductive biology, and its capture is not regulated. Therefore, this study evaluates the most relevant aspects of its reproductive activity. Samples were obtained monthly from January to December 2017 from the capture of the purse seine fleet and the artisanal gillnet fleet landing near Manta. The morphometric analysis included the length-weight relationship, estimated using the allometry equation. The size at sexual maturity is based on the L50 criterion; the reproductive cycle was determined according to the monthly analyses of the gonadosomatic index (GSI), hepatosomatic index (HSI), and relative condition factor (Kn). A total of 334 specimens were analyzed, with average sizes of 22.0, 21.87, and 21.91 cm of total length (TL), for males, females, and combined sexes, respectively. Sex ratio was 1.17M: 1F (P > 0.05), while the length-weight relationship showed negative allometric growth for both males and females (b = 2.58; CI95% 2.48-2.72). Size at sexual maturity L50 was estimated at 21.84 and 21.23 cm TL for males and females, respectively. The GSI and HSI values and Kn showed significant differences among months (P < 0.05), with a marked seasonality during the single reproductive period. Mean size at first capture of 21 cm TL is recommended.

ABSTRACT The feeding habits of Makaira nigricans, Kajikia audax, Istiophorus platypterus (Istiophoridae), and Xiphias gladius (Xiphiidae) in the southeast Pacific Ocean were examined in Manta and Santa Rosa, Ecuador. This study describes the diets of these billfish species, evaluates dietary differences between species, and assesses seasonal differences in diet. A total of 274 M. nigricans, 321 K. audax, 267 I. platypterus, and 252 X. gladius were collected between February 2014 and April 2015. The scombrid Auxis spp. was the most important prey for M. nigricans, K. audax and I. platypterus, while the squid Dosidicus gigas was the most important prey for X. gladius. The results of the ANOSIM confirmed significant differences in feeding habits between the members of the family Istiophoridae and X. gladius. Seasonal differences for I. platypterus also were observed. Billfishes are specialist consumers with a narrow niche breadth (B a: M. nigricans and K. audax=0.1, I. platypterus=0.05, and X. gladius=0.04).

RESUMEN Los hábitos alimentarios de Makaira nigricans, Kajikia audax, Istiophorus platypterus (Istiophoridae) y Xiphias gladius (Xiphiidae) en el Océano Pacífico sudeste se examinaron en Manta y Santa Rosa, Ecuador. Este estudio describe las dietas de estas especies de peces de pico, evalúa las diferencias de la dieta entre especies y las diferencias estacionales en la dieta. Se obtuvo un total de 274 M. nigricans, 321 K. audax, 267 I. platypterus y 252 X. gladius entre febrero 2014 y abril 2015. El escómbrido Auxis spp. fue la presa más importante para M. nigricans, K. audax y I. platypterus, mientras que el calamar Dosidicus gigas fue la presa más importante para X. gladius. Los resultados de ANOSIM confirmaron diferencias significativas en los hábitos alimentarios entre los miembros de la familia Istiophoridae y X. gladius. También se observaron diferencias estacionales para I. platypterus. Los peces de pico son consumidores especialistas con una amplitud de nicho estrecha (B a: M. nigricans y K. audax=0.1, I. platypterus=0.05 y X.gladius=0.04).