Abstract
The Brazilian sardine, Sardinella brasiliensis, is small pelagic clupeid fish distributed primarily between 22°S and 29°S, where it forms large schools. The species is an important fishery resource and is targeted by purse seine vessels operating in the area. Although an extensive literature addresses various characteristics of the species, studies of its morphometry and relative growth are scarce. The aim of the present study was to analyze the relative growth based on body and otolith morphometry to identify the patterns characterizing the population. Monthly samples were obtained during 1985 and 1987, and data on total length, total weight and otolith length, height and weight were analyzed. The allometric model of Huxley (y = ax ) was fitted seasonally and by year, and regressions were compared among seasons and between years. The regression coefficient b was tested (t-test) to identify isometry and allometry. A total of 603 sardines, with total lengths ranging from 120 mm to 229 mm, were analyzed. The length-weight relationships tended to show positive allometry, whereas the total length-otolith measurement relationships tended to show negative allometry. The relative growth rates decreased during the year and showed the lowest values during spring in association with the peak of the spawning period. In contrast, the condition factor (coefficient a of the allometric regression) increased gradually during the year until spring as consequence of the increasing weight of the fish due to gonad maturation. Comparisons between the years analyzed also show that the fish grew faster during the collapse of the stock, in 1987. The methodology used in this study allowed the detection of this effect. This study established the historical pattern of relative growth and showed that morphometry and relative growth offer efficient tools for monitoring the sardine in the study area.
Highlights
The Brazilian sardine, Sardinella brasilien‐ sis (Steindachner, 1879) (Teleostei: Clupeidae), is a species endemic to the Southeastern Brazilian Bight (SEBB), the region between the Cape of São Tomé, Rio de Janeiro, and the Cape of Santa Marta Grande, in Santa Catarina, sporadic occurrences are2
According to Matsuura (1986) and Castro et al (2006), the Southeastern Brazilian Bight is characterized by the presence of the Coastal Water (CW), a mixture of continental and neritic waters with low salinities (< 33.5S); the Tropical Water (TW, > 20°C, > 36.4S) predominating in the neritic region; the Subtropical Shelf Water (SSW) which is a mixture of CW and TW; and the South Atlantic Central Water (SACW, 6°C < 20°C, 34S < 36S) closely related to the continental slope
Contrary to Vaz-dos-Santos et al (2010) that showed a reduction in relative growth of Sardinella brasiliensis during January-February, the results of the present study showed a decrease in relative growth of the species during spring (October to December) in all variables investigated
Summary
& Vaz-dos-Santos, A.M.: Morphometry and relative growth of Sardinella brasiliensis known from Argentinian waters (Figueiredo & Menezes, 1978; Rossi-Wongtschowski et al, 2009). This small pelagic fish forms schools in the neritic region to a depth of 100 m (Cergole & Dias Neto, 2011). It presents a short life cycle, high rates of growth and high fecundity. Its life cycle is influenced by environmental conditions (oceanographic and meteorology), food availability and fisheries (Saccardo & Isaac-Nahum, 1985; Isaac-Nahum et al, 1988; Rossi-Wongtschowski et al, 1991; Checkley Jr. et al, 2009; Dallagnolo et al, 2010)
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.
