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Otolith Growth (otolith + growth)
Selected AbstractsValidation of daily increment formation and the effects of different temperatures and feeding regimes on short-term otolith growth in Australian smelt Retropinna semoniECOLOGY OF FRESHWATER FISH, Issue 2 2008Z. Tonkin Abstract,,, To aid otolith interpretation of wild fish, we conducted a laboratory study using metalarval Australian smelt (Retropinna semoni) collected from the Murray River, to examine daily increment deposition and the effects of different temperatures and feeding regimes on otolith growth. Daily increment deposition was confirmed by comparing the number of increments from an oxytetracycline mark with the known number of days from marking. After holding fish at two temperature levels and three feeding rates, both food density and temperature were found to have a significant effect on otolith growth, with food density having the greatest influence. Overall trends in final lengths and condition of fish were well represented by recent otolith growth. The results of the experiment have implications for estimating growth histories and its relationship to various environmental conditions. [source] Linking growth to environmental histories in central Baltic young-of-the-year sprat, Sprattus sprattus: an approach based on otolith microstructure analysis and hydrodynamic modellingFISHERIES OCEANOGRAPHY, Issue 6 2006HANNES BAUMANN Abstract Otolith microstructure analysis and hydrodynamic modelling were combined to study growth patterns in young-of-the-year (YoY) sprat, Sprattus sprattus, which were sampled in October 2002 in the central Baltic Sea. The observed ,window of survival', approximated by the distribution of back-calculated days of first feeding (DFF), was narrow compared to the extended spawning season of sprat in the Baltic Sea (mean± SD = 22 June ± 14.1 days) and indicated that only individuals born in summer survived until October 2002. Within the group of survivors, individuals born later in the season exhibited faster larval, but more rapidly decreasing juvenile growth rates than earlier born conspecifics. Back-calculated larval growth rates of survivors (0.48,0.69 mm day,1) were notably higher than those previously reported for average larval sprat populations, suggesting that the YoY population was predominantly comprised of individuals which grew faster during the larval stage. Daily mean temperatures, experienced across the entire YoY population, were derived from Lagrangian particle simulations and correlated with (1) detrended otolith growth and (2) back-calculated, daily somatic growth rates of survivors. The results showed that abrupt changes in ambient temperature can be detected in the seasonal pattern of otolith growth, and that higher temperatures led to significantly faster growth throughout the entire age range of YoY sprat. [source] The effect of temperature and somatic growth on otolith growth: the discrepancy between two clupeid species from a similar environmentJOURNAL OF FISH BIOLOGY, Issue 3 2006D. P. Fey Otolith growth rates of the early life stages of herring Clupea harengus (n= 472) and smelt Osmerus eperlanus (n= 348) collected in the Vistula Lagoon (Baltic Sea) during 1997,1999 were analysed. The larvae and early juveniles were not only collected in the same geographical area they were also of the same size (range 15,43 mm standard length, LS), similar ages and were collected during the same seasons (May to July). Although the two clupeid species experienced very similar environmental conditions, there were significant discrepancies in the analysed relationships. The otolith growth of larval and juvenile smelt was very strongly related to somatic growth while temperature had a minor effect. In herring, the effect of somatic growth, although clearly visible and statistically highly significant, was of less importance than temperature. Furthermore, variation in the otolith size and LS relationship was affected by temperature and somatic growth in both species, but the variance of otolith size at LS was higher for herring than for smelt. Although growth backcalculation from otoliths can presently be recommended as an appropriate method for use with both smelt and herring (despite possibly lower precision and accuracy with the latter), other methods referring directly to short-term increment width changes (e.g. marginal increment analysis) are recommended for smelt but not for herring. [source] Effects of different food restrictions on somatic and otolith growth in Nile tilapia reared under controlled conditionsJOURNAL OF FISH BIOLOGY, Issue 5 2002A. M. Massou .Nile tilapia Oreochromis niloticus, initial age 12 days, were given an unrestricted (NR) or restricted (R) ration over 93 days which resulted in fish of very different sizes although the body condition factor (K) and the viscero-somatic index (IV) remained almost unchanged. In a second stage (64 days) each group (NR & R) was divided into three subgroups that were subjected to 0 (NR0, R0), 15 (NR15, R15) and 30 (NR30, R30) days of food restriction, respectively. The impact of the different treatments on the somatic growth during the second stage of the experiment had an effect, with a highly significant difference between the mean ± S.D. masses (MT) in the different subgroups (NR0= 115.0 ± 26.6 g; NR15 = 94.8 ± 24.9 g; NR30 = 56.3 ± 28 g; R0 = 76.4 ± 20.1 g; R15 = 72.l ± 17.6 g; R30 = 43.6 ± 17.2 g). Similarly, K and IV decreased. Irrespective of the initial feeding condition, the width of the otolith microincrements started to decrease at the end of the first or second day of restricted feeding. In the subgroups given a restricted food ration for 30 days (NR30 and R30), this decrease reached a plateau at about day 30, which was maintained even when the restriction had ended. This slowed growth did not lead to any marked halt in microincrement formation, since there were no significant differences (ANOVA; P>0.05) in the numbers of increments counted in the various subgroups. The results show that in 153 day old fish, a period of severe food restriction, even if prolonged (15 to 30 days), had no influence on the timing of the laying down of microincrements but only affected their growth. [source] Growth of North Alboran Sea sardine larvae estimated by otolith microstructure, nucleic acids and protein contentJOURNAL OF FISH BIOLOGY, Issue 2 2001T. Ramírez Wet mass and DNA, RNA and protein content increased significantly with standard length (LS) of sardine Sardina pilchardus larvae, collected in January 1995, in the Bay of Málaga, North Alboran Sea. LS, wet mass and DNA, RNA and protein content were closely related allometrically to otolith radius (R). Larval daily length increments decreased but DNA, protein and wet mass daily increments increased with larval age. Daily length increments showed a negative and poor relationship with long-term otolith growth. In contrast, DNA, protein and wet mass daily increments were positively correlated. Differences between observed and back-calculated otolith radius-at-age indicated that larvae with slow otolith growth were under represented in older age groups, suggesting the existence of growth-selective mortality. Recent otolith growth, estimated from the mean widths of the last six increments, increased with age and R. Individual RNA: DNA and protein: DNA ratios were correlated significantly, although weakly, with LS and larval growth. [source] | ||||||||||