Biological traits and growth patterns of pejerreyOdontesthes argentinensis

Abstract

This study assesses for the first time the relationship between annual cycles of different biological indices with growth patterns of a marine pejerrey Odontesthes argentinensis population near its southern-distribution boundary in North Patagonia. The reproductive period is between September and November evidenced by an increase in the gonado-somatic index with a peak in October corresponding to spawning. The reproductive cycle was also coupled with metabolic processes related to energy allocation as shown by changes in the hepato-somatic index and body condition. Total length (L(T) ) at maturity was 270 for females and 282 mm for males, whereas fecundity was estimated at mean ±s.d. = 9380 ± 1797 mature oocytes. Based on the marginal increment analysis, most of the scales showed a maximum value during summer, with a sharp decline thereafter during autumn and winter, indicating that scale rings are formed during the latter period and only once a year. Growth fitted by the von Bertalanffy model for both males and females did not show significant differences and showed a rapid growth during the first 2 years. The shorter reproductive period compared with that of the northern O. argentinensis populations inhabiting tropical and subtropical areas was interpreted as an adjustment to temperate environmental conditions. The larger maximum L(T) and L(T) at first maturity are in agreement with the counter-gradient hypothesis and could be related to the selective effects of low temperature and a shorter growing season. This latitude dependency argues strongly against the application of the same fishing regulations for different O. argentinensis populations as a whole and reinforces the need to assess basic biological features at a population scale to promote local sustainable fisheries management.

Natural growth, otolith shape and diet analyses of Odontesthes nigricans Richardson (Atherinopsidae) from southern Patagonia

“…It was assumed that O. nigricans from Varela Bay has the same periodicity of band formation. These results agreed with previous growth studies in O. nigricans from lower latitudes (L opez, 2009) and in other atherinopsids where an annual periodicity in mark formation was also identified (Sverlij and Mestre Arceredillo, 1991;Becker et al, 2003;Llompart et al, 2013). The count of annual marks allowed identifying 7 year classes (0þ to 6þ) in Varela Bay and 6 year classes (0þ to 5þ) in Punta María, extending the previously estimated life span of the species in lower latitudes, which was from 4 to 6 years (L opez, 2009).…”

“…The count of annual marks allowed identifying 7 year classes (0þ to 6þ) in Varela Bay and 6 year classes (0þ to 5þ) in Punta María, extending the previously estimated life span of the species in lower latitudes, which was from 4 to 6 years (L opez, 2009). Nevertheless, these age ranges fell within the values registered for other atherinopsid species from South America (Sverlij and Mestre Arceredillo, 1991;Becker et al, 2003;Llompart et al, 2013). The von Bertalanffy growth model explained more than 95% of the growth pattern observed in O. nigricans.…”

Life history traits of the Chinese minnow Rhynchocypris oxycephalus in the upper branch of Yangtze River, China

“…This provides a possible explanation to why the winter in Laohegou Stream drainage began in November, but the forming of the second discontinuity on otolith began in September. The monthly variations of K N , a useful index for assessing the condition of fish independent of fish size (Baigun et al 2009;Llompart et al 2013), coincided with our speculation. The K N of R. oxycephalus showed two peak values in March and August, just when the two opaque bands were forming; when the two translucent bands were forming, the value of K N was low.…”

Inter-estuarine and temporal patterns of the fish assemblage of subtropical subestuaries along the Río de la Plata coast (Uruguay)

“…In this subestuary dominated Odontesthes argentinensis, a shallow-water pelagic fish known by its marine affinities and inhabits both estuarine and inshore waters (MORESCO; BEMVENUTI, 2006). The large phenotypic plasticity of this species allows it to adapt to a wide range of salinities (LLOMPART et al, 2013). We need to highlight the high abundance and diversity of species in the P subestuary probably related to the proximity to reproduction and breeding areas located in the inner RdlP estuary (ACHA; MACCHI, 2000;ACHA et al, 2008) such Micropogonias furnieri and Brevoortia aurea species.…”