predominantemente de adultos, como resultado de una aparente distribución diferencial por talla/edad de la especie. La proporción sexual fue 1:1. Las hembras presentaron un crecimiento alométrico y los machos, isométrico. De acuerdo con el análisis morfocromático de las gónadas, la época de reproducción es en abril-mayo y octubre-noviembre, aunque los machos presentan madurez durante periodos más amplios. El IGS sí es un buen indicador de la época de reproducción de S. annulatus, mientras que el Kn muestra una tendencia a disminuir durante el periodo de reproducción.

The reproduction of any fish species may be influenced by environmental factors, knowledge of which is required for an adequate control of the reproductive process to improve culture practices. Thus, the reproduction of a wild population of bullseye puffer, Sphoeroides annulatus (Jenyns, 1842), and the influence of temperature, photoperiod, lunar cycle and tide level were analyzed. Ovarian ripeness is asynchronous, and the ovary may ripen again at least once following spawning. Testes also display an asynchronous ripeness, but once sexual maturity is attained, spermatozoa are continually produced and released. The reproduction is highly seasonal, with an intense spawning period during the spring-summer, when the sea surface temperature is 22.5-30.9°C and a 11-14 h photoperiod. The observations suggest that the timing of spawning is synchronized by a semi-lunar cycle together with the rise of the average tide level. Size at first maturation was similar for females (28.2 cm TL) and males (28.6 cm TL). However, some specimens may start their gonad maturation when are as small as 19 cm TL.

ABSTRACT. The puffer fish Sphoeroides annulatus is an important target species for the artisanal fishing fleets of NW Mexico. To obtain information on population structure of the local stock, we determined the total length and total weight (TL and TW) ranges, sex ratio and reproductive stages of 745 specimens of this species, landed from May 2010 to April 2011 in Teacapán, Sinaloa, NW Mexico. TL ranged from 15 to 40 cm and TW from 100 to 1600 g. There were no differences between mean TL (27.41 ± 4.14 cm) and TW (534.5 ± 226.0 g) of males and females respectively. Sex ratio was not significantly different (χ² = 0.03, P > 0.05) from 1F:1M. The length-weight relationship for both sexes was TW = 0.044TL 2.815 , R 2 = 0.895. The value of the slope b was significantly lower than 3 (P < 0.05), and indicated negative allometric growth. The distribution of maturity stages indicated one main reproductive period from June to September and one less intense, from November to December for females, and in December for males. Size at first maturity (L 50% ) of females was 26.52 cm and that of males was 27.41 cm. Keywords: puffer fish, Sphoeroides annulatus, size distribution, weight distribution, sexual maturity, reproduction, northeastern Pacific.Estructura poblacional y aspectos reproductivos del botete diana Sphoeroides annulatus (Jenyns, 1842) (Osteichthyes: Tetraodontidae), capturado en Teacapán, Sinaloa, México RESUMEN. El botete diana Sphoeroides annulatus es un importante recurso pesquero para las flotas pesqueras artesanales del NW de Mexico. Para obtener información sobre la estructura poblacional del stock local, se determinó el rango de longitud total y peso total (TL y TW), proporción sexual y estadios reproductivos de 745 especímenes, desembarcados entre mayo 2010 y abril 2011, en Teacapán, Sinaloa, noroeste de México. No hubo diferencias entre LT promedio (27,41 ± 4,14 cm) y TW promedio (534,5 ± 226,0 g) entre machos y hembras. La proporción entre sexos no resultó significativamente diferente de 1H:1M (χ² = 0,03; P > 0,05). El modelo de la relación longitud-peso fue TW = 0,044 LT 2,815 ; R2 = 0,895 para ambos sexos. El valor del parámetro b fue significativamente menor que 3, indicando que el tipo de crecimiento es alométrico (b ≠ 3, P < 0,05). La distribución de los estadios de madurez indica un periodo reproductivo principal de junio a septiembre y otro menos intenso de noviembre a diciembre en hembras y en diciembre para machos. La talla de primera madurez (L 50% ) fue de 26,52 cm en hembras y 27,41 cm en machos.Palabras clave: botete diana, Sphoeroides annulatus, distribución de tamaño, peso, madurez, biología reproductiva, Pacífico nororiental.

ABSTRACT. The feeding habits of the sharpnose shark Rhizoprionodon longurio of the SE Gulf of California are described using the stomach contents of 250 specimens (135 males and 115 females) obtained weekly from December 2007 to March 2008 in the two main landing sites of the artisanal fishing fleet of Mazatlan. The mean total length (TL) was 77.7 ± 12.8 cm and the respective ranges for males and females were 60-120 cm and 52-120 cm. Size distribution showed two modal groups (juveniles: 52-80 cm, mode 72.5 cm, and adults: 85-140 cm, mode 92.5 cm). Out of the 395 preys identified in 235 stomachs with identifiable contents, the most important were cephalopods (Index of Relative Importance, IRI = 93.1%), mainly Argonauta spp. (IRI = 92.9%). The total IRI value for fish was 5.9%, mostly represented by Oligoplites refulgens and Oligoplites sp. (joint IRI value = 4.8%). The diversity of the stomach contents of males and females was not significantly different, and although the values of diversity, equitability and dietary breadth indexes were lower in juveniles than in adults, ANOSIM analysis did not show differences in dietary habits related to age and sex. The results indicate a specialized feeding behaviour, with Argonauta spp. as preferred prey. This behaviour does not agree with all previous information on R. longurio, and is probably due to local availability of this prey during the sampling period.

To estimate the weight-length relationship, determine age, and describe growth of the finescale triggerfish, Balistes polylepis Steindachner, 1876, 552 specimens were measured and weighed, and 318 first dorsal spines were collected from the artisanal catch in Mazatlán, Sinaloa, Mexico, between October 2000 and October 2001. Fish ranged between 16 and 53 cm in total length (TL), and distribution was biased toward small sizes. Age was assigned according to the number of opaque-hyaline bands in spines, identifying seven age groups (1-7), with age groups 2, 3, and 4 jointly representing over 80% of the collection. The von Bertalanffy model was adequately fitted to the age-TL data and accounted for 91% of the variation in TL. Parameters were estimated as TL y ¼ 55:8 cm; K ¼ 0.17 yr À1 , and t 0 ¼ À1:7 yr. The total weight (TW ) of the finescale triggerfish ranged between 75 and 2,200 g, and the TW-TL relationship showed a negative allometric growth ðb ¼ 2:7Þ. These results are the first reported for age and growth of this species.