Samples of Atlantic sardineSardina pilchardus (also known as European pilchard) were collected bimonthly from 2004 to 2008 off the central west coast of Portugal to describe the reproductive activity of this indeterminate batchspawning species; compare the seasonality of somatic growth, condition, and feeding; and evaluate differences between sexes. Monthly assessments of individual biological information for both males and females were complemented by histological analysis of ovaries during 1 year and liver tissues (both sexes) at different times of the reproductive cycle. The temporal patterns of the gonadosomatic index and various histological indices (most advanced oocyte stage, atresia incidence and prevalence, and spawning activity) indicated that Atlantic sardine were reproductively active mainly from October to March and that residual activity occurred in the remaining months. For both sexes, condition indices (hepatosomatic index, relative weight, and amount of fat stored) increased mainly during spring, reached a maximum at the end of summer just before the subsequent spawning season began, and then decreased during autumn and winter, declining to minimum levels at the beginning of spring coincident with a significant reduction in reproductive activity. Somatic growth took place mainly during spring and early summer for both sexes. The observed seasonal patterns in these biological properties suggest a seasonal transition from a period in which energy resources are allocated to reproduction (autumn and winter) to a period in which resources are allocated to growth and fat deposition (spring and summer). The only exception was the distinct hepatosomatic index pattern and the histological differences in hepatocytes between males and females during the spawning season, which may be related to the dual function of the liver in females (lipid metabolism and yolk precursor synthesis).Fish reproductive investment is the result of essential life history trade-offs in resource allocation (Stearns 1992). Energy that is surplus to the essential standard metabolic requirements (i.e., maintenance, locomotion, predation avoidance, and feeding activity) is allocated to somatic growth, energy storage, or reproduction after the fish reaches sexual maturation. The priority with which this surplus energy is allocated

Following the classic lines of evidence of Hunter et al. (Hunter, J. R., Macewicz, B., Lo, N. C. H., and Kimbrell, A. 1992. Fecundity, spawning, and maturity of female Dover sole Microstomus pacificus, with an evaluation of assumptions and precision. Fishery Bulletin US, 90: 101–128.) on the fecundity type of fishes (determinate vs. indeterminate), the stock of horse mackerel (Trachurus trachurus) in Atlantic Iberian waters (ICES Division IXa) was shown to exhibit a mixed picture. Total fecundity, the total number of secondary growth (SG) oocytes dropped during the spawning season and there were reproductively active individuals with a distinct size hiatus between primary growth (PG) oocytes and SG oocytes, while no massive atresia was observed in late-season spawners. All of these characteristics matched with evidence for determinate fecundity. However, daily decrease rate of total fecundity was lower than daily specific fecundity (i.e. the number of eggs produced daily per unit weight) by orders of magnitude which suggested that the stock of SG oocytes was replenished during the spawning period through de novo oocyte recruitment. In addition, the maximum number of batches in reproductively active females was lower than the predicted annual number of spawnings, while total fecundity in recent spawners—those containing post-ovulatory follicles—was not lower than the fecundity of the remaining reproductively active females. All of these results suggest that, despite the aforementioned mixed lines of evidence, the fecundity of horse mackerel is clearly indeterminate. We attribute these mixed characteristics to the fact that, unlike most typical indeterminate spawners, horse mackerel ceases to recruit new SG oocytes during the latter part of its spawning season.

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We present a method for estimating the interspawning interval (ISI) in batch‐spawning teleosts with indeterminate fecundity based on the rate of oocyte growth and the size of oocytes at the beginning and end of the spawning cycle. The method is accompanied by a number of prerequisites, which are tested and subsequently applied to wild collections of Atlantic sardine Sardina pilchardus (also known as European pilchard). The rate of oocyte growth and oocyte size at the end of vitellogenesis were shown to exhibit rather constant values in Atlantic sardine; thus, the ISI could be simply estimated as a factor of oocyte size at the beginning of the spawning cycle (Ob). Given that vitellogenesis in Atlantic sardine ceases at final oocyte maturation, Ob was estimated by measuring the size of oocytes of the subsequent batch in females with hydrated oocytes. The resulting average ISI was very close to inverse values of the spawning fraction estimated through the postovulatory follicle method, which indicated the validity of the ISI method. Applications of the ISI method require fewer samples of adult females compared with the postovulatory follicle method, are histology independent, and could be combined with oocyte counts to provide batch fecundity measurements. These modifications in spawning frequency and batch fecundity estimation could help to decrease both cost and labor in daily egg production method surveys.

SUMMARY: Long-term changes in sardine maturation were described using samples collected from landings off the western Portuguese coast since 1947. Estimates of the length at 50% maturity (L 50 ) were calculated in 44 years of the study period and proved to be good proxies of the maturation length of first-year spawners (Lp 50 of age 0-1 fish). Sardine probability of maturing at a given length declined from the early 1950s to the late 1960s, corresponding to an increase of ca. 2 cm in both L 50 and Lp 50 . This trend reversed in the early 1970s and halted in the early to mid-1990s. The tendency for sardine to mature at a lower length was positively correlated with improved body condition in the growing season preceding maturation. Long-term trends in sardine maturation and body condition were parallel to trends in sea surface temperature reported in the literature. The results suggest that maturation at a lower size is directly influenced by increased temperature, and that higher temperatures improve body condition through increased feeding efficiency or a combination of both. We found no evidence that fishing intensity has contributed to long-term changes in sardine maturation.Keywords: maturation, condition, sardine, Portuguese waters. RESUMEN: Cambios a largo plazo de la madurez de la sardina, Sardina pilcharduS, en aguas portuguesas. -Se describen los cambios a largo plazo de la madurez de la sardina utilizando muestras recogidas desde 1947 en los desembarcos en la costa oeste de Portugal. Las estimas de la talla de primera madurez al 50% (L 50 ) fueron calculadas en 44 años del periodo de estudio y se mostraron como una buena aproximación de la talla de madurez de los individuos desovantes de primer año de vida (Lp 50 peces de edad 0-1). La probabilidad de madurar de la sardina a una talla determinada disminuye desde principios de los años 50 hasta finales de los años 60, correspondiendo a un aumento de 2 cm en ambas tallas, L 50 y Lp 50 . Esta tendencia cambió a principio de los años 70 y se detuvieron a mediados de los años 90. La tendencia de la sardina a madurar a tallas inferiores se correlacionó positivamente con la mejora de la condición corporal en la estación de crecimiento que precedía a la madurez. Las tendencias a largo plazo de la madurez y la condición corporal eran paralelas a las tendencias en la temperatura superficial del mar reportadas en la literatura. Los resultados sugieren que la madurez a tallas pequeñas está influida directamente por el aumento de la temperatura, que temperaturas más elevadas mejoran la condición mediante un aumento de la eficiencia en la alimentación o a una combinación de ambas. Por otra parte, no encontramos evidencias de que la presión de la pesca haya contribuido a los cambios a largo plazo en la madurez de la sardina.Palabras clave: madurez, condición, sardina, aguas portuguesas.