Abstract
AbstractSamples 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 batch‐spawning 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).
Highlights
The interaction between reproduction and growth is one of the most important trade-offs in fish (Stearns 1992) because most reproductive traits and growth are a function of body size (Wootton 1998)
Most clupeiform fishes have indeterminate fecundity and are characterized by a small size, high growth rates, a relatively short life span, and late maturity occurring at a large size relative to adult size such that energy is first allocated to growth and to reproduction
The linear models (LMs) showed that the ovary weight and Wgutted exhibited a significant linear relationship (R2 = 0.81, F = 568.3, P < 0.01; Figure 1A), and the slopes for the two ovary groups did not differ significantly from 1.0 (Student’s t-test, ovaries with unyolked oocyte stages: t = 1.3474, n = 204, P = 0.16; ovaries with yolked oocyte stages: t = −1.0119, n = 209, P = 0.24), indicating that gonadosomatic index (GSI) is independent of fish somatic weight and that ovarian development is isometric for the oocyte stages considered
Summary
The interaction between reproduction and growth is one of the most important trade-offs in fish (Stearns 1992) because most reproductive traits (especially female fecundity) and growth are a function of body size (Wootton 1998). Similar to most other clupeid fishes, it is a fast-growing species with a relatively short life span (Sinovcic 1986; Alemany and Alvarez 1993; Voulgaridou and Stergiou 2003; Silva et al 2008) and early maturation (up to the second year of life; Silva et al 2006) These characteristics, in addition to important interannual fluctuations in population biomass and recruitment, make Atlantic sardine stocks especially difficult to manage (Cole and McGlade 1998; Schwartzlose et al 1999; Borges et al 2003; Carrera and Porteiro 2003; Silva et al 2009). There has not yet been a comprehensive study to assess the interactions between reproductive activity and somatic growth, changes in condition, and feeding during an annual cycle for Atlantic sardine off the Portuguese coast
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
