Search

Changes in fish length-at-age can be modeled by adding the age, year-class, and year effects together, or tracking cohort-specific growth with time-dependent parameters. We implemented both approaches to better understand lake trout (Salvelinus namaycush) length-at-age variations in US waters of Lake Huron, 1977–2019. We directly compared length-at-age over time using our linear-mixed model, where the expected length-at-age on logscale was represented by the sum of a fixed age effect, a fixed year-class effect (same for all ages of a cohort), and a random year effect (same for all ages within a year). The age, year-class, and year effects together indicated a general decline in length-at-age between the two time-periods of 1977–1997 and 1998–2019. The random year effect had local temporal trends that differed between the two time-periods, while the pattern of decreases in the fixed year-class effect appeared to reflect changes in growth conditions that were represented eventually by the largest prey-biomass decline during 1995–1996 and the final alewife collapse in 2003. We also predicted annual averages of length-at-age by tracking cohort-specific growth histories. We modified the Ford-Walford plot to illustrate how the growth processes are both cohort-specific and time-dependent. The estimates of year-specific asymptotic length indicated the decline in lake trout growth potential between the two time-periods specified above. Our two models differed fundamentally in their statistical assumptions, but they both fitted the data well and explained the growth decline between the two time-periods, which was also consistent with our understanding of the trophic shift in the ecosystem. [ABSTRACT FROM AUTHOR]

Age and growth of European eel (Anguilla anguilla) from a coastal lagoon in southwestern Europe were investigated using a sample of 871 eels. Fish were caught with fyke nets in two fishing seasons, 2011/12 and 2015/16. Age was determined by reading sagittal otoliths and age estimates were validated through semi-direct methods. The yellow and silver eels ranged in length from 174 to 904 mm corresponding to an age range of 2–9 years for females and 2–6 years for males. Length-at-age was estimated through back-calculation using the measurements taken in otoliths and a common biological intercept. The von Bertalanffy growth equation fitted to the back-calculated lengths is L t (mm) = 673.5 1 - e - 0.45 t - 0.17 for females, and L t (mm) = 338.1 [ 1 - e - 1.23 t - 0.15 ] for males. The growth rate of the eel population in Santo André lagoon is high and the males show an early onset of maturity. The mean length of males at silvering is almost half the size of silvering females. Comparison with eel somatic growth from 17 other geographical locations revealed that the eel growth in Santo André lagoon is among the fastest reported for the species. A principal component analysis showed a gradient in somatic growth ranging from fast-growing eels in coastal lagoons (larger K, early maturity, smaller asymptotic size Linf) to slow-growing eels in freshwaters (smaller K, late maturity, larger Linf). [ABSTRACT FROM AUTHOR]

This study was conducted to evaluate four hybrid poplar comparison tests along a groundwater availability gradient in Western Slovakia. The weather fluctuation during the 3-year study period was described with indices, such as the Forestry Aridity Index (FAI) or the hydrothermal coefficient (HTC). The soil chemical and physical parameters were determined from soil samples from the two upper horizons. The nutrient status and supply of the trees were categorized based on leaf elemental analysis. Altogether, 21 different clones from 6 genomic groups were compared. The survival (SRV), diameter at breast height (DBH), and height of the trees (H) had been measured annually since the plantations were established, and from these measurements, mean annual height increment (MAHI) values were derived. These weather, edaphic, and clonal factors were evaluated and compared. Significant effects of the site (edaphic factors) were found as the primary source of variance and clonal differences as secondary sources of variance among the growth of trees. The interaction of site × clone effects was not significant. The results showed that for short rotation forestry (SRF), the site parameters—especially groundwater availability—are key factors. [ABSTRACT FROM AUTHOR]

Paulownia is a fast-growing woody tree, native to the forests of China. It belongs to the family Scrophulariaceae and is mainly used as a source of wood for furniture and musical instruments. Due to its fast-growing nature and high-quality of wood, there has been growing interest in cultivation and research of Paulownia in Nepal. Growth comparison was performed by measuring shoot length in in vitro condition. Among two species of Paulownia - Paulownia tomentosa (Thunb.) Steud and Paulownia fortuneii (Seem.) Hemsl., the growth rate of P. tomentosa was found to be 0.355 cm/week while that of P. fortuneii was found to be 0.637 cm/week in in-vitro conditions in MS medium supplemented with 0.1 mg/l NAA and 1mg/l BAP. Optimization of rooting methods was also performed, in which, sand rooting was found to be easier and more effective than in-vitro rooting. Dipping the plantlets in 1 mg/l of NAA was found to produce longer and denser roots than lower or higher concentrations during sand rooting.

Paulownia is a fast-growing woody tree, native to the forests of China. It belongs to the family Scrophulariaceae and is mainly used as a source of wood for furniture and musical instruments. Due to its fast-growing nature and high-quality of wood, there has been growing interest in cultivation and research of Paulownia in Nepal. Growth comparison was performed by measuring shoot length in in vitro condition. Among two species of Paulownia - Paulownia tomentosa (Thunb.) Steud and Paulownia fortuneii (Seem.) Hemsl., the growth rate of P. tomentosa was found to be 0.355 cm/week while that of P. fortuneii was found to be 0.637 cm/week in in-vitro conditions in MS medium supplemented with 0.1 mg/l NAA and 1mg/l BAP. Optimization of rooting methods was also performed, in which, sand rooting was found to be easier and more effective than in-vitro rooting. Dipping the plantlets in 1 mg/l of NAA was found to produce longer and denser roots than lower or higher concentrations during sand rooting. [ABSTRACT FROM AUTHOR]

Growth is one of the most important characteristics of cultured species. Growth curve provide a visual assessment of growth as a function of time and prediction of body weight at a specific age. Therefore, this study was conducted to develop growth curve for Clarias magur and to evaluate the growth curve parameters. 160 numbers of fingerlings were collected from river Godavari, Hooghly and Mahanadi and the no of individuals from each river are 74, 46 and 40 respectively. The collected individuals were stocked in 5 cemented tanks for 45 day and thereafter a total of 100 animals transferred to a cemented pond with soil based bottom. Sampling was performed and data recorded for body weight, total length and body depth in every 10 days for three months culture period. The data obtained was analyzed using SAS software (Ver. 9.2). Models were tested for goodness of fit for determining growth curves. The model was evaluated according to determine coefficient (R2) and Error sum of square (ESS). The R2 values for the three stocks for body weight, total length and body depth was measured. When considering R2 value for body weight Mahanadi stock showed highest R2value i.e. 68, whereas for total length and for body depth Hooghly stock showed highest R2 value i.e. 78 and 83 respectively. Multiple regression models showed R2 values ranged between 54 to 91. The linear model registered low ESS value (204.1)for body weight of Godavari stock, for body depth the values recorded was (1.3) in case of Hooghly stock and for total length the value recorded was (11.6) with Hooghly stock being the least. Multiple regression model showed lowest ESS value for Mahanadi stock. These growth comparisons can be considered as a baseline study for selective breeding programme in C. batrachus. [ABSTRACT FROM AUTHOR]

Marsh shoreline, an important habitat for juvenile penaeid shrimps, was extensively oiled in coastal Louisiana by the Deepwater Horizon oil spill of 2010. The effect of this spill on growth was examined for brown shrimp Farfantepenaeus aztecus and white shrimp Litopenaeus setiferus held for 7 days in field mesocosms in Barataria Bay during May and August 2011, respectively. The experiments each had 10 treatment combinations, five apparent oil levels, each one with and without added food. Mesocosms were placed in northern Barataria Bay along shorelines that varied in oiling (designated as heavy, moderate, light, very light, or none based on NOAA surveys), and shrimp in half the mesocosms received additional food. Polycyclic aromatic hydrocarbon (PAH) concentrations determined from sediment cores collected at each mesocosm were significantly higher at heavy and moderate than very light shorelines and also higher at moderate than light and none shorelines. Brown shrimp grew more slowly at heavy than very light or none shorelines, and a statistically significant negative relationship was detected between brown shrimp growth rates and sediment PAH concentrations. In August, PAH sediment concentrations had decreased significantly from the values measured in May, no significant difference in white shrimp growth rates was detected among oiling levels, and no relationship was detected between white shrimp growth and sediment PAH concentrations. Both brown shrimp and white shrimp grew more rapidly in mesocosms where food was added. Our study shows that exposure to nonlethal concentrations of petroleum hydrocarbons can reduce growth rates of juvenile penaeid shrimps. [ABSTRACT FROM AUTHOR]

Comparative growth observations (13 months) of European (Anguilla anguilla L.) and American (Anguilla rostrata Le Sueur) glass eels were undertaken. Plastic containers (60 x 30 x 35 cm, volume of 30 L) were combined with a sedimentation tank and submerged, gravel, biological filter to form a recirculation system. Feeding commenced on the second day after arrival of the fish and proceeded as follows : days 1 to 50, krill hydrolysate ; days 51 to 58, krill hydrolysate mixed with a salmon starter feed ; day 59 onwards, standard salmon feed. Feed was provided at 2-hourly intervals via automatic feeders for the first 161 days of rearing, and thereafter by hand 5 times a day at a feeding rate of 5 % of the fish biomass. The average individual weight of the European eels on rrival (x = 0.266 ± 0.005 g), was significantly higher than that of the American eels (x = 0.167 ± 0.006 g). After 45 days of rearing, the weight differences between the species became insignificant. Except for the different transportation mortalities on arrival, the European and the American eels demonstrated similar mortality rates during the experiment ( 1 2 . 5 % ) , food conversion rate (2.3) and specific growth rate (0.90 and 0.99 respectively). No parasites or diseases were detected. No differences were observed in general behaviour and feeding between the two species.

Oreochromis niloticus ( O), the sixth generation of Genetic Improvement of Farmed Tilapia, shows rapid growth but poor salt tolerance, while Sarotherodon galilaeus ( S) exhibits opposite traits. To combine the traits, F1 progeny was obtained through artificial fertilization. Fertile F1 produced F2 by natural spawning. The mean survival times, the median survival time (ST50) or the survival rate of hybrids was greater than O. niloticus in a gradual or an acute salinity change. Plasma osmolarity, [Na+] and [Cl−] of the hybrids fluctuated in 32 g L−1 water during a 24-h period, but eventually reached levels similar to fish in freshwater. O. niloticus♀× S. galilaeus♂ ( OS F2) or S. galilaeus♀× O. niloticus♂ ( SO F2) showed the fastest growth at 22.5 g L−1, equal to about 78.2% or 69.7% of O. niloticus at 0 and 3.87 or 3.45 times that of S. galilaeus at their individual optimum growth. Growth in OS F2 was 12% faster than SO F2. Microsatellite analysis showed that F2 had more alleles, a higher polymorphism information content and greater observed and expected heterozygosity than O. or S. Population differentiation was not detected between F1 and F2. All the results indicated that F2 could be exploited for commercial production under saline conditions. [ABSTRACT FROM AUTHOR]

Abstract: Lyme borreliosis is a tick-borne disease caused by genetically diverse Borrelia strains including B. afzelii, B. garinii, and B. burgdorferi sensu stricto (s.s.). The aim of the present study was to assess and compare the growth of one strain per species of B. afzelii, B. garinii, and B. burgdorferi s.s. in modified Kelly–Pettenkofer (MKP) and Barbour–Stonner–Kelly-II (BSK-II) medium, and to check for the presence of the overgrowth after inoculating the media with a mixture of two different Borrelia species. All three Borrelia strains grew well in both media. In the majority of the experiments the number of B. afzelii cells was higher in MKP than in BSK-II medium while for B. garinii and B. burgdorferi s.s. a tendency for better growth in BSK-II than MKP was established. In a mixture of equivalent amounts of two species, B. burgdorferi s.s. as a rule overgrew the other two species while in the mixture of B. afzelii and B. garinii the latter was a “dominant” strain. Comparing the performance of the two media, B. burgdorferi s.s. usually overgrew either B. afzelii or B. garinii in MKP as well as in BSK-II medium, however, the results were found to be statistically significant only for MKP medium. In the mixture of B. afzelii and B. garinii the latter was the predominant species but significant differences were established only for BSK-II medium. It seems that the overgrowth is predominantly the result of the characteristics of the individual Borrelia species and most probably not a consequence of growth differences in the two culture media. Further work with a larger number of strains is needed to confirm these findings. [Copyright &y& Elsevier]

Dietary protein and energy utilization were compared in three Pangasiid species of high economical interest for fish farming in South-East Asia. Feeding experiments were performed during 4 weeks onPangasius bocourti,P. djambalandP. hypophthalmusfingerlings, 6.68, 7.69 and 6.41 g mean mass, respectively. A high-protein diet containing mostly fishmeal was designed to provide proteins without energy limitation. Growth response, variation in body composition and nutrient utilization were compared for fish receiving variable amounts of diet corresponding to increasing protein supply, 0, 5, 15, 25, 35 and 45 g kg−1 day−1. The highest specific growth rate was observed forP. bocourti(6.0% day−1), followed byP. djambal(5.6) andP. hypothalamus(4.1).Pangasius djambalexhibited the highest protein deposition rate, whereasP. bocourtiwas characterized by a high fat deposition rate even with a low feeding rate. Lower performance was obtained withP. hypophthalmus. [ABSTRACT FROM AUTHOR]

Growth was studied from skeletal growth markers in the cosmopolitan abyssal brittle star Ophiocten hastatm. Samples for analysis were taken at five sites located in the southern (2900 m) and central (2000 m) Rockall Trough, at ca. 3000 and 4000 m in the Porcupine Seabight, and at 4850 m on the Porcupine Abyssal Plain. Growth bands were assumed to reflect an annual cycle in skeletal growth. Band measurements on arm vertebrae, standardised to disc diameter, were used to provide size-at-age data and size-increment data that took into account overgrowth of early bands in older individuals. The Richards growth function marginally provides best fit to pooled size-at-age data, although the asymptote-less Tanaka function and the Gompertz growth function also provided good fit to size-at-age data which showed a rather linear growth pattern with little indication of a growth asymptote. Loge transformed size-increment data were linearised by applying the Ford–Walford method to approximate Gompertz growth so that growth could be compared at the five sites. Grouped linear regression and analysis of covariance showed no significant differences between growth at the sites and a common fitted regression. However, pairwise comparisons suggest growth differences with increasing bathymetric separation. Oocyte size frequencies measured from histological preparations of the gonad of specimens from the Porcupine Abyssal Plain indicate marked reproductive periodicity, with spawn-out in late winter that is likely followed by planktotrophic early development in spring with benthic settlement in summer. Although usually rare in the trawl and epibenthic sled samples, several years of successful recruitment followed by a period when recruitment was low or absent might explain size structure observed in a single unusually large sample from the Rockall Trough. This is consistent with previous observations during the late 1990s of a large population increase on the Porcupine Abyssal Plain. Analysis of growth bands of these specimens sampled in 1997 suggest the population increase derives from a single or small number of year classes recruited during the early 1990s. [Copyright &y& Elsevier]

Shrimp (Penaeus semisulcatus) length-frequency data collected from the coastal waters of Kuwait, Saudi Arabia, Bahrain, and Qatar during a 23-month study from 1999 to 2001 were analyzed to estimate parameters of von Bertalanffy growth equation. All growth curves show a strong seasonal oscillation and a difference in size between males and females. The estimates of l∞ exhibit a southward decreasing trend with increasing temperature and salinity. A single variable of annual mean temperature explains 94 and 81% of the variations in l∞ for males and females, respectively. Likelihood ratio tests compared growth parameters among survey areas. A significant difference in growth was found between Kuwait and Kufji, and between Manifa and Dareen. Based on these results, we conclude that three separate populations of P. semisulcatus are present in the western Arabian Gulf: one in Kuwait, one in Kufji and Manifa, Saudi Arabia, and a third occupying Dareen, Saudi Arabia, Bahrain, and Qatar waters. Countries sharing unit stocks should implement a cooperative approach to the management of each. [Copyright &y& Elsevier]

Acanthamoeba astronyxis strains, isolated from intertidal belts of Sagar Island (21°30′ to 21°50′ N and 88°04′ to 88°08′ E) facing Bay of Bengal, were cultured in saline distilled water agar medium supplemented with Escherichia coli as food bacterium. Population growth in bay water agar, cerophyl bay water agar and soil extract distilled water agar were compared with special reference to devised saline distilled water agar medium. The overall growth showed little variation over ranges of media salinity (5-30‰). However, greater values were encountered in media of intermediate range. Isolate from mangrove litter-soil of highest high tide belt (strains) grew more efficiently in cerophyl bay water agar and soil extract distilled water agar media while mid-littoral and lowest low tide isolates preferred bay water agar and saline distilled water agar media more. [ABSTRACT FROM AUTHOR]