Age, growth and reproduction of the barrelfish Hyperoglyphe perciformis (Mitchill) in the western North Atlantic

Otoliths ( n = 847) and gonads ( n = 817) were collected from barrelfish Hyperoglyphe perciformis that were captured by commercial fishermen in the waters off South Carolina and Georgia in 1995, 1997 and 2001–2006. Of the otoliths collected, 97% were aged successfully, and specimens sampled ranged from 5 to 85 years, with a median age of 12 years. The von Bertalanffy growth parameters yielded the equation: L_t = 857·8{1 − e^{−0·0985[ t −(−8·95)]}}, where L_t is fork length ( L _F) at time t . Through histological examination, 94% of the gonads assessed were assigned to a sex and reproductive class. Females spawned from September to May with a peak from November to January. Males spawned year round, but had a peak from September to April. The sex ratio (M:F) for this population was 1:1·34. The smallest mature female was 605 mm L _F and the youngest immature female was 697 mm L _F. Estimates of L _F and age at 50% maturity ( L ₅₀ and A ₅₀) for females were 660 mm L _F (95% CI = 633–667 mm L _F) and 6·08 years (95% CI = 3·50–7·27 years), respectively. The youngest mature male was 575 mm L _F and the oldest immature male was 762 mm L _F, and no estimates of L ₅₀ or A ₅₀ were made for males. It was determined that barrelfish exhibit the typical characteristics of long life span, slow growth and high age at maturity seen in other deepwater fishes, and that care should be taken to manage this species accordingly.     

Comparison of growth rate and formation of otolith increments in age-0 red snapper

For wild red snapper Lutjanus campechanus , mean otolith increment deposition rate after marking with oxytetracycline dihydrate (OTC) was daily (0.97 increments day⁻¹) when growth rates were fast (0.63 mm fork length, L _F day⁻¹), but were not daily (0.82 increments day⁻¹) when somatic growth was slow (0.2 mm L _F day⁻¹). For reared larvae ( n =8), increment deposition rates were daily (0.99–1.03 increments day⁻¹), and growth rates ranged from 0.6 to 0.9 mm L _F day⁻¹. Growth rate affected increment deposition rate as a threshold function, i.e. when growth rate was <0.3 mm L _F day⁻¹, deposition was less than daily, but above this level increment deposition did not exceed a daily rate. As growth rates increased increment widths increased. Examination of a sub-sample ( n =8) of the otoliths from the slowest growing wild fish by scanning electron microscopy did not increase increment counts. Because L. campechanus are late spring-early summer spawners, young fish can expect maximum growth due to warm summer temperatures. Thus, daily ageing methods should be well suited to this species.     

Comparison of otolith growth and morphology with somatic growth and age in young-of-the-year bluefin tuna

Otolith morphological characteristics were studied using image analysis techniques and the relationships between otolith growth and somatic growth and age, as estimated from counting daily otolith increments, were examined in young-of-the-year (YOY) bluefin tuna Thunnus thynnus ranging in fork length ( L _F) from 8·5 to 55·5 cm. Whole otolith length, width, area and perimeter, and three shape indexes, circularity, E value and rectangularity, were extracted for each pair of sagittae. Since no statistical significant differences between left and right otolith morphometrics were found, only one otolith from each fish was used for correlations. Statistically significant relationships were observed between otoliths measurements and fish somatic growth when a linear regression was applied after logarithmic transformation of all variables tested. Among the variables, otolith length was the one that showed the highest correlation with L _F, followed by otolith area and perimeter, whereas otolith rectangularity exhibited the lowest correlation. Statistically significant relationships were also observed between the otolith variables tested and the age of the fish, which ranged from 20 to 129 days. The ages estimated using otolith mass were very close to those assessed using daily increment counts (bias ranged from 1 to 24 days). Therefore, otolith mass could represent a valuable criterion for age estimation in YOY bluefin tuna that is objective, economic and easy to perform compared to daily increment counting method.     

Growth rates of juvenile smalltooth sawfish Pristis pectinata Latham in the western Atlantic

The growth rates of juvenile smalltooth sawfish Pristis pectinata collected in Florida waters between 1999 and 2006 were investigated using length-frequency and tag-recapture data. Stretched total length ( L _ST) data from 144 smalltooth sawfish (690–4960 mm) and 28 recaptures (775–2150 mm) were used for the analyses. Both methods indicated that growth was rapid during the first 2 years after birth. The L _ST increased by 650–850 mm in the first year, and by 480–680 mm in the second year. Data for animals >2200 mm were limited, so growth beyond 2 years of age was uncertain. The von Bertalanffy growth parameters estimated from L _ST frequency data were L _∞= 6000 mm, K = 0·140 year⁻¹ and t ₀=−0·863 years. Growth rates over the size range for which tag-recapture data were available were similar to that from L _ST frequency data. The growth rates reported are substantially faster than those previously assumed for this species and may have important implications for the recovery of this endangered species. There are conflicting data regarding the growth rates of older P. pectinata which need to be resolved with more data from the wild population before a complete understanding of the conservation implications can be obtained.     

Growth of North Alboran Sea sardine larvae estimated by otolith microstructure, nucleic acids and protein content

Wet mass and DNA, RNA and protein content increased significantly with standard length ( L _S) of sardine Sardina pilchardus larvae, collected in January 1995, in the Bay of Málaga, North Alboran Sea. L _S, 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 L _S and larval growth.     

Comparison between micro- and macro-structure readings in the age estimations of Cape hake

By counting otolith daily increments juvenile Cape hake Merluccius capensis were found to grow faster than European hake Merluccius merluccius . The mean frequency of translucent zones in juveniles 130–240 mm L _T were higher (×3·2) than the annual frequency, although their mean duration was shorter (1 month) than a season. Comparison between micro- and macro-structure readings showed that the latter tended to overestimate the age of juvenile hake, with 1 year old hake being overestimated by 18% in individuals of 160 and 210 mm L _T.     

Age and growth of the dusky grouper Epinephelus marginatus (Lowe 1834) in an exploited population of the western Mediterranean Sea

The age and growth of the dusky grouper, Epinephelus marginatus , in the Balearic Islands (western Mediterranean) were studied by otolith analysis from a sample of 358 specimens ranging in total length ( L _T) from 6·6 to 105·6 cm. The specimens came from commercial artisanal and recreational spear fisheries between 1999 and 2003. Otoliths grew asymmetrically throughout the range of L _T studied, showing a clear pattern of alternating translucent and opaque bands. Marginal increment analysis of specimens up to 8 years-old indicated that a single opaque band was formed each year during spring and summer. Whole otoliths allowed ageing specimens up to 10 years old, but above that age whole otoliths yielded lower age estimates than sectioned otoliths. The maximum estimated age was 61 years, which significantly extends the estimated life span of the species from a maximum of 36 years in a previous study. The von Bertalanffy growth parameters were estimated as L _∞= 95·5 cm L _T, K = 0·087 and T _O=−1·12. The study revealed differences in mean L _T at age and age structure between the shallow- and deep-water samples which may be attributed to different fishing pressure and environmental conditions.     

Feeding and growth of early juvenile Japanese sardines in the Pacific waters off central Japan

Larval and early juvenile growth was backcalculated for individual Japanese sardines Sardinops melanostictus using the biological intercept method based on the allometric relationship between otolith radii and fish lengths. Sardines grew at 0·81 mm day⁻¹ during the larval stage. In the early juvenile stage, they grew from 32·3 to 45·4 mm fork length ( L ) over a 20-day period (0·64mm day⁻¹). Using the observed relationship between L and wet body weight ( W ), W = 0·00942 L ^2.99, W of the sardine juveniles was calculated to increase from 306 to 832 mg during the 20-day period. The carbon (C) requirement to achieve this growth in weight was estimated to increase from 5·7 to 9·6 mg day⁻¹. Stomach contents of the sardines were composed mostly of copepods (73%) and larvaceans (25%). Wet stomach content weight ( W_s ) was expressed by a power function of the W , W_s=0·731 W ^0·658. Carbon and nitrogen constituted 41·7 ± 1·5 and 10·0 ± 0·4% of the dry W_s , respectively. Stomach C content increased from 2·0 to 3·9 mg during the 20-day period. Three to four cycles of the daily turnover of stomach contents during the 16 h of daytime, corresponding to a gastric evacuation rate of 0·2–0·3 h⁻¹ under continuous feeding, met the C requirement to achieve the backcalculated growth in early juvenile sardines. The Kuroshio frontal waters seem to provide Japanese sardine juveniles with favourable growth conditions.     

The effect of temperature and somatic growth on otolith growth: the discrepancy between two clupeid species from a similar environment

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, L _S), 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 L _S relationship was affected by temperature and somatic growth in both species, but the variance of otolith size at L _S 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.     

Growth, diet and metabolism of common wolf–fish in the North Sea, a fast–growing population

The von Bertalanffy growth parameters for common wolf–fish Anarhichas lupus in the North Sea were: male: L ∞=111·2 cm, t ₀=–0·43 and K =0·12; and female: L ∞=115·1 cm, t ₀=–0·39 and K =0·11, making this the fastest growing stock reported. Resting metabolic rates (RMR±S.E.) and maximum metabolic rates (MMR±S.E.) for six adult common wolf–fish (mean weight, 1·39 kg) at 5° C were 12·18±1·6 mg O₂ kg^–1 h^–1 and 70·65±7·63 mg O₂ kg^–1 h^–1 respectively, and at 10° C were 25·43±1·31 mg O₂ kg^–1 h^–1 and 113·84±16·26 mg O₂ kg^–1 h^–1. Absolute metabolic scope was 53% greater at 10° C than at 5° C. The diet was dominated by Decapoda (39% overall by relative occurrence), Bivalvia (20%) and Gastropoda (12%). Sea urchins, typically of low energy value, occupied only 7% of the diet. The fast growth probably resulted from summer temperatures approximating to the optimum for food processing and growth, but may have been influenced by diet, and reduced competition following high fishing intensity.     

Modelling the growth of Weissella cibaria as a function of fermentation conditions

Aims:  To investigate the effect of pH, water activity ( a _w) and temperature on the growth of Weissella cibaria DBPZ1006, a lactic acid bacterium isolated from sourdoughs.
Methods and Results:  The kinetics of growth of W. cibaria DBPZ1006 was investigated during batch fermentations as a function of pH (4·0–8·0), a _w (0·935–0·994) and temperature (10–45°C) in a rich medium. The growth curve parameters (lag time, growth rate and asymptote) were estimated using the dynamic model of Baranyi and Roberts (1994. A dynamic approach to predicting bacterial growth in food. Int J Food Microbiol 23, 277–294). The effect of pH, a _w and temperature on maximum specific growth rate (μ_max) were estimated by fitting a cardinal model. μ_max under optimal conditions (pH = 6·6, a _w = 0·994, T  = 36·3°C) was estimated to be 0·93 h⁻¹. Minimum and maximum estimated pH and temperature for growth were 3·6 and 8·15, and 9·0°C and 47·8°C, respectively, while minimum a _w was 0·918 (equivalent to 12·2% w/v NaCl).
Conclusions:  Weissella cibaria DBPZ1006 is a fast-growing heterofermentative strain, which could be used in a mixed starter culture for making bread.
Significance and Impact of the Study:  This is the first study reporting the modelling of the growth of W. cibaria , a species that is increasingly being used as a starter in sourdough and vegetable fermentations.     

Growth and mortality of the introduced Lake Tanganyika clupeid, Limnothrissa miodon, in Lake Kariba

The growth and mortality of the small clupeid fish Limnothrissa miodon were studied in Lake Kariba, a large, man-made lake in central Africa. Growth could be described by the von Bertalanffy equation l_t = 74.2 (1—e^{−0.254( t +0.07)}) where length ( l ) is expressed in millimetres and time ( t ) in months. The monthly rates of mortality were high and increasing under intensive fishing; in 1983 the total mortality rate Z =1.15 and natural mortality M =0.7. Limnothrissa appears to be stunted in the man-made lakes where it occurs (Kariba and Cahora Bassa) where it grows at a faster rate but to a smaller size than it does in natural lakes (Kivu and Tanganyika). Various hypotheses to account for this are discussed and it was concluded that this is an adaptation to the relatively unstable conditions found in the man-made lakes.     

Influence of water temperature and feeding regime on otolith growth in Anguilla japonica glass eels and elvers: does otolith growth cease at low temperatures?

The influences of water temperature and feeding regime on otolith growth in Anguilla japonica glass eels and elvers were investigated using individuals reared at 5, 10, 15, 20, 25 and 30° C and in fed or unfed conditions at salinity 32 after their otoliths were marked with alizarin complexone (ALC). To eliminate the difficulty of observing the edges of otoliths with optical (OM) or scanning electron (SEM) microscopes, three to 10 individuals were sampled from each tank at 10, 20 and 30 days during the experiment and reared for an additional 10 days at 25° C after their otoliths were marked a second time. Otolith growth and the number of increments were measured using both OM and SEM. Most A. japonica commenced feeding after 10 days at 20–30° C or after 20 days at 15° C, but no feeding occurred at 5 and 10° C. No otolith growth occurred at 5 and 10° C except in two individuals with minimal increment deposition at 10° C. Otolith growth was proportional to water temperature within 15–25° C and not different between 25 and 30° C. At 15, 25 and 30° C, the mean otolith growth rate in fed conditions was higher than in unfed conditions. The number of increments per day was significantly different among water temperatures (0·00–0·01 day⁻¹ at 5 and 10° C, 0·43–0·48 day⁻¹ at 15° C and 0·94–1·07 day⁻¹ at 20–30° C). These results indicated that otolith growth in A. japonica glass eels and elvers was affected by temperature and ceased at ≤10° C under experimental conditions. Hence, future studies analysing the otoliths of wild-caught A. japonica glass eels and elvers need to carefully consider the water temperatures potentially experienced by the juveniles in the wild.     

Growth of young-of-the-year mackerel in the Bay of Biscay

The first growth season of young-of-the-year (0+ year) mackerel Scomber scombrus , sampled in the Bay of Biscay, was parameterized to determine growth patterns. Daily increments were identified on sagittae otoliths, for calculation of age and growth of 92 larvae and 54 juveniles over the range 3·6–215·0 mm standard length ( L _S). A Gompertz curve was fitted to the length-at-age data. At the end of the first year of growth L _S was 194·2 mm, with a maximum growth increment of c . 2 mm day⁻¹, observed 62 days after hatching. Backcalculated growth increments for mackerel juveniles, during their larval stage, were higher than those observed for sampled larvae; only 10·9% of sampled larvae were estimated to survive. Growth for north-eastern Atlantic mackerel was slower than that published for north-western Atlantic mackerel. Backcalculated hatching dates for mackerel were consistent with the typical temporal distribution of mackerel spawning in the Bay of Biscay.     

Differences in temperature conditions and somatic growth rate of larval and early juvenile spring-spawned herring from the Vistula Lagoon, Baltic Sea manifested in the otolith to fish size relationship

Larval and juvenile herring Clupea harengus collected in the Polish part of the Vistula Lagoon in May-July 1997 had hatched between 17 April and 9 June and originated from three cohorts. The spawning season began on 1 March at 3·8° C and was completed on 3 June at 12·7° C. Mortality among larvae was high in the first 2 weeks of April, probably associated with significant temperature decrease at the beginning of the spawning season. The growth of 10–48 mm L _S herring was linear, highest for larvae and juveniles from the first cohort (0·58 mm mm^-1 day^-1), slower for the second cohort (0·55 mm mm^-1 day^-1) and the slowest for the third cohort (0·45 mm mm day^-1). Temperature effects on the growth were inconclusive and potentially unfavourable feeding conditions in June might have been responsible for the relatively slow growth of third cohort larvae and juveniles.
Relationships between otolith size (perimeter, length, width, area, and weight) and fish size ( L _S) differed among the three cohorts, related mostly to the positive temperature effect on otolith growth, individuals growing in warmer water had larger otoliths. Although a negative growth rate effect was observed as well, it was less significant.     

Seasonal differences in muscle fibre recruitment of pilchard larvae in the north‐western Mediterranean

The recruitment of slow and fast myotomal muscle fibres with respect to growth in body length in European pilchard larvae Sardina pilchardus [(3·5–13·5 mm standard length ( L _S)] was significantly higher in November 1998 than February 1999. This resulted in a significant seasonal difference in the relationship between fibre number and L _S, particularly for the fast muscle. Mean sea surface temperature was c . 6° C higher in November than February, whereas the mean abundance of potential prey items (copepod nauplii) was comparable between cruises. Laboratory and field data obtained from other clupeid species have indicated the importance of early thermal experience on muscle fibre recruitment patterns. Differences in average sea temperature therefore provide a plausible mechanism for the observed seasonal differences in muscle growth characteristics.     

Gastric evacuation in horse mackerel. I. The effects of meal size, temperature and predator weight

Gastric evacuation experiments were performed on horse mackerel Trachurus trachurus. A nearly full matrix experimental design with respect to the variables predator weight (<10–400 g) meal size (up to 7·8% body weight) and temperature (10–20°) was covered with 0-group smelt Osmerus eperlanus as prey. A general evacuation model without meal size as a variable was fitted to the data on wet weights as well as on dry weights by means of non-linear regression technique. Two methods of data transformation, relative data and square root transformation, were applied to improve variance homogeneity. The most reliable model fit was achieved on dry weight data applying the square root transformation technique: where S_t=stomach content (g wet weight) at time t after ingestion, S₀=the initial meal size, W =predator (g wet weight), and T =temperature. The estimated coefficient of the exponential temperature function, δ=00·032, corresponds to a Q ₁₀ value of 1·4 which is outstandingly low in comparison with results on other species. However additional experiments to determine maximum daily food rations indicated that appetite in contrast to gastric evacuation is strongly temperature dependent.     

Lacustrine growth of juvenile pink salmon and a comparison with sympatric sockeye salmon

The growth rates of naturally sympatric juvenile pink Oncorhynchus gorbuscha and sockeye Oncorhynchus nerka salmon were compared in a common lacustrine environment in south‐west Alsaka, an unusual opportunity given the normal disparity in freshwater residence time of these two species. Fork length ( L _F) frequency distributions of juvenile pink salmon caught in the lake during the summer in 1991 and 1999–2003 indicated a growth rate of 0·54 mm day⁻¹, 54% greater than the estimated growth rate of juvenile sockeye salmon sampled from 1958 to 2003 (0·35 mm day⁻¹). Examination of daily growth rings on otoliths indicated that pink salmon in Lake Aleknagik grew an average of 1·34 mm day⁻¹ in 2003 but sockeye salmon grew only 0·63 mm day⁻¹(average specific growth rates were 3·0 and 1·8% day⁻¹, respectively). Pink salmon increased from c . 32 mm L _F and 0·2 g at emergence to 78 mm L _F and 3·0 g within 3–4 weeks. After experiencing these rapid growth rates, the pink salmon appeared to leave the lake by late July in most years. The diets of pink and sockeye salmon in the littoral zone of the lake were very similar; >80% of the stomach contents consisted of adult and pupal insects and the remainder was zooplankton. This high degree of diet overlap suggested that the observed differences in growth rate were not attributable to variation in prey composition.     

Relationships between otolith microstructure, otolith growth, somatic growth and ontogenetic transitions in two cohorts of windowpane

Otolith increments in larval and juvenile windowpane Scophthalmus aquosus can provide an estimate of daily age for spring-spawned individuals held under summer conditions. Otolith increments for spring- and autumn-spawned individuals occurred at intervals >1 day under winter conditions. A significant decrease in the slope of the linear relationship between otolith size and somatic size at 40 mm L_S coincided with significant habitat, morphological and behavioural transitions. In smaller, field-captured windowpane belonging to spring- and autumn-spawned cohorts, the formation of accessory growth centres coincided with a transitional settlement period and the completion of eye migration (c. 8–20 mm L_S). Back-calculated growth rate estimates for spring-spawned windowpane were significantly faster than those for autumn-spawned windowpane and these differences could produce differential rates of survival for the two cohorts during the first year of life.     

Comparison of field-based and indirect estimates of daily food consumption in larval perch and zander

Since bioenergetics models for 0+ fish have seldom been validated by field consumption estimates, field-based and indirectly estimated daily food rations were compared in larval perch Perca fluviatilis and zander Stizostedion lucioperca. Field-based estimates were calculated with linear and exponential evacuation rates based on gut fullness data during a 24-h cycle, with hourly field samplings instead of the normally recommended 3-h intervals. Indirect calculations used bioenergetics modelling with variable activity multipliers ( A ). Field-based estimates of daily rations ranged between 0·21 and 0·27 g g⁻¹ day⁻¹ in perch (mean L _T 13·1 mm) and 0·31–0·40 g g⁻¹ day⁻¹ in zander (mean L _T 10·6 mm). The higher values were calculated by using the exponential model. Daily rations calculated by bioenergetics modelling with A = 1 were only slightly higher than direct estimates in both species. However, if A values >1 were used, calculated daily rations were substantially higher than direct estimates. Estimates of daily ration based only on every third value ranged between 41 and 72% compared with 1-h intervals, mainly because of lower estimates of evacuation rate.