Age structure and biological parameters of southern blue whiting (<i>Micromesistius australis</i>) in its main concentration area in the southwestern Atlantic Ocean in 2019

American Shad Alosa sapidissima is an anadromous species with populations ranging along the U.S. Atlantic coast. Past American Shad stock assessments have been data limited and estimating system‐specific growth parameters or instantaneous natural mortality (M) was not possible. This precluded system‐specific stock assessment and management due to reliance on these parameters for estimating other population dynamics (such as yield per recruit). Furthermore, climate‐informed biological reference points remain a largely unaddressed need in American Shad stock assessment. Population abundance estimates of American Shad and other species often rely heavily on M derived from von Bertalanffy growth function (VBGF) parameters. Therefore, we developed Bayesian hierarchical models to estimate coastwide, regional, and system‐specific VBGF parameters and M using data collected from 1982 to 2017. We tested predictive performance of models that included effects of various climate variables on VBGF parameters within these models. System‐specific models were better supported than regional or coast‐wide models. Mean asymptotic length (L∞) decreased with increasing mean annual sea surface temperature (SST) and degree days (DD) experienced by fish during their lifetime. Although uncertain, K (Brody growth coefficient) decreased over the same range of lifetime SST and DD. Assuming no adaptation, we projected changes in VBGF parameters and M through 2099 using modeled SST from two climate projection scenarios (Representative Concentration Pathways 4.5 and 8.5). We predicted reduced growth under both scenarios, and M was projected to increase by about 0.10. It is unclear how reduced growth and increased mortality may influence population productivity or life history adaptation in the future, but our results may inform stock assessment models to assess those trade‐offs.

Investigating spatial heterogeneity of von Bertalanffy growth parameters to inform the stock structuration of common sole, Solea solea, in the Eastern English Channel

Based on the re-interpretation of published data, the von Bertalanffy growth function parameters of the coelacanth, Latimeria chalumnae, are estimated as L∞=218 cm total length, s.e. 23; K=0.059 (year−1), s.e. 0.012; t0=−3.3 (year), s.e. 0.5, corresponding to a life span of 48 years. The length–weight relationship of the form W=a*TL∧b, with wet weight (W) in g and total length (TL) in cm, is estimated as a=0.0278, b=2.89, r2=0.893, n=87, range=42.5–183 cm TL. Using extreme value theory, the maximum length for female coelacanths is estimated as 199 cm TL (95% confidence interval=175–223 cm TL) and for males as 168 cm TL (95% confidence interval 155–180 cm TL). Based on data from seven females with embryos or mature eggs, the length-at-first-maturity for females is estimated to be about 150 cm TL, corresponding to an age of about 16 years. Based on the value of t0=−3.3 years and on the presence of three scale rings found in a newborn coelacanth, the period of embryogenesis lasts for about three years, the longest known in vertebrates. The natural mortality rate is estimated at M=0.12. Population food consumption is found to be 1.4 times the existing biomass per year, and gross food conversion efficiency indicates that only 10% of the consumed food is utilized for somatic growth.

We investigated the effect of combining organic and inorganic fertilizers on the growth and yield of hybrid rice (Palethwe-1) in the dry and wet seasons of 2015. Four quantities of inorganic fertilizer were used in the main plot [0%, 50%, 75%, and 100% nitrogen, phosphorus, and potassium (NPK)] based on the recommended amounts of 150 kg N ha-1, 70 kg P2O5 ha-1, and 120 kg K2O ha-1, while different organic manures were applied to subplots [no organic manure (O0), cow manure (Oc), poultry manure (Op), and vermicompost (Ov); all at 5 t·ha-1] as part of a split-plot experimental design with three replicates. In both seasons, significant differences in growth parameters including number of tillers hill-1, soil-plant analysis development (SPAD) values, total dry matter, yield, and yield components were observed in plants supplied with different inorganic fertilizers. The 100% NPK (I100) fertilizer produced the maximum yield but similar yields were achieved in plots supplied with 50% NPK (I50) and 75% NPK (I75). Significant differences in growth and yield parameters were also found in crops supplied with organic manures. Although identical quantities were supplied, Op produced the best growth parameters in both seasons including total dry matter, yield, and yield components. Oc also performed well. Combining inorganic and organic fertilizers demonstrated that I50 together with Op (5 t·ha-1) provided similar growth, total dry matter, and yield parameters to I100 in both seasons. Oc (5 t·ha-1) plus I75 also achieved similar yields to I100. This study demonstrates that the combined application of inorganic fertilizers and organic manures has the potential to reduce chemical fertilizer usage without decreasing the yield of hybrid rice, and can enhance the growth, yield, and yield components of Palethwe-1.

The Caspian Kutum , Rutilus frisii , is one of the endemic and most important commercial cyprinid species in the southern Caspian Sea. A detailed study on growth and mortality parameters of this species was conducted based on 700 samples collected from commercial catches of beach seining in Guilan and Mazanderan provinces during fishing season 2017-2018. Females were dominated in both studied populations. Size frequency distributions showed significant variation among same sexes and between different sexes. The different WLRs were observed, positive allometric in Mazanderan, and negative allometric in Guilan. There were significant differences in growth parameters between sexes, females were of much greater asymptotic length than males, while the male fish had a higher growth rate and attained a smaller theoretical L ∞ size than females. The theoretical maximum length ( L ∞ ) was larger than the maximum one recorded during sampling. Based on the Bhattacharya method, the Caspian kutum from Guilan fishing grounds was more diverse, and included nine cohorts, while the population from Mazanderan Province showed only six cohorts. The linearized catch curve based on age composition data showed that total mortality rates ( Z ) are 1.32 year -1 and 0.63 year -1 for males and females of Guilan, respectively, that of males in Mazanderan is 1.04 year -1 and of females 0.86 year -1 . The natural mortality rates ( M ) were 0.48 year -1 for males and 0.26 year -1 females in Guilan, and was found to be as 0.26 year -1 and 0.45 year -1 for males and females of Caspian kutum caught in Mazanderan. The exploitation ratio ( E ) was found to be higher than 0.5 for both sexes from Guilan, and to be lower than the expected optimum level of exploitation in Caspian kutum males and females caught in Mazanderan.

Length-weight relationship, growth parameters and mortality rates ofAnadara granosain the intertidal zone of Balik Pulau, Penang Island, West Coast of Malaysia were investigated based on monthly length-frequency data (December 2011 to November 2012). A total of 548 individuals ranging from 11.25 to 33.13 mm size were subjected to analysis. Logarithmic relationship between the length and weight was LogW = 2.328LogL − 2.537 (R2 = 0.922) for combined sexes. From this equation it was clear that the exponent ‘b’ value forA. granosashowed a negative allometric growth (b < 3). A von Bertalanffy growth function with an asymptotic length (L∞) of 35.40 mm and a growth constant (K) of 1.1 year−1was established from length frequency distributions. Thet0(−0.140) was estimated by substituting theL∞andKin the Pauly's equation. The sizes attained byA. granosawere 10.13, 14.36, 17.89, 20.82, 23.56 and 25.29 mm at the end of 2, 4, 6, 8, 10 and 12 months, respectively. The estimated growth performance index (Ø) was 3.13 while the estimated lifespan of the cockles was about 2.72 years at the study area. The estimated value of total mortality based on length-converted catch curve wasZ = 3.02 year−1. The natural mortality (M) and fishing mortality (F) rates were 1.84 and 0.48 year−1, respectively. The exploitation level (E) ofA. granosawas 0.20, which indicated slight fishing pressure on the stock.

The small tuna known as the Atlantic bonito (Sarda sarda) is one of the most important fishery species on the Black Sea coast of Türkiye. In this study, we sought to define some population parameters of Atlantic bonito based on indirect ageing using length frequency distributions. The aim of this study is to provide data that will serve the management of the bonito fishery. For analysis, the ELEFAN routine in the LFDA and FiSAT programs was utilized. During the migration period, we collected 2110 samples from purse seine (n=1009), gillnet (n=867) and hand lines (n=234) fishing in the Black Sea waters of Türkiye. The fork length varied between 13.1 and 60 cm, and the female-to-male ratio was 1:0.79. The length-weight relationships (LWRs) were calculated W=0.0037FL3.3784 and Fulton’s K:1.01±0.001. The growth was found to be positive allometric (Student’s t-test, p < 0.05). von Bertalanffy Growth Parameters (VBGP) were computed as L∞:71.59 cm, K:0.56 year-1, t0:-0.18 year. The seasonal oscillation in growth rate was calculated (C: 0.98) and winter point (WP): 0.54, growth performance index of Ø’: 3.46, natural mortality (M: 0.74 yr-1), fishing mortality (F: 2.81 yr-1), total mortality (Z: 3.55 yr-1) and exploitation coefficient (E: 0.79 yr-1). As a result, the exploitation rate of S. sarda in the study area was found to be high.

This study compared sexual differences in growth parameters of pure and hybrid African catfishes (Clarias gariepinus and Clariabranchus) raised in a monosex culture. The two species were obtained from 281 fishes comprising 150 pure breed and 131 hybrids in an earlier study and grouped by sex separately as male and female in four separate plastic tanks, representing two replicates per sex. Ten each of the pure clarias and its hybrid were reared in each tank. In all, 40 male and 40 female fish comprising 20 each of the pure clarias and its hybrid for each sex were evaluated for the growth parameters. A total of 80 fish were included in this study and the study lasted nine (9) weeks. The fish were fed commercially compounded feed twice daily throughout the period of the experiment. Length-weight relationship and growth parameters such as Mean Growth Rate (MGR), Specific Growth Rate (SGR), Absolute Growth Rate (AGR), Relative Growth Rate (RGR), Condition Factor (CF) were computed and evaluated for sex effect. All statistical analyses involving descriptive, general linear model analysis of variance (ANOVA) and post hoc test were done using Minitab® 17 Statistical Software. Sex had significant (P<0.05) effects on all growth parameters except Absolute Growth Rate (AGR) albeit at different levels, but specie only had significant (P<0.05) effect on Mean Growth Rate (MGR), while the interaction of sex x specie exerted significant (P<0.05) effects on all growth parameters except Condition Factor (CF). This study revealed that growth performance is significantly (P<0.05) affected by sexual dimorphism and also by interaction of sex and specie.

We measured growth parameters of Roseate Tem (Sterna dougallii) chicks at two contrasting colonies: Bird Island, Massachusetts, and Falkner Island, Connecticut, from 1987 through 1990. Differences in growth parameters among individual chicks are used to explore differences in parental performance, whereas differences in average growth parameters among colonies and years are used to explore differences in average environmental conditions. Chicks were marked at hatching and weighed at one- or two-day intervals. For each chick that survived to fledging, we calculated two measures of growth: linear growth rate and asymptotic mass. There were no significant differences between growth parameters of first-hatched chicks in broods of one and two. Both measures of growth were significantly lower and more variable for second-hatched chicks than for first-hatched chicks. Both measures were significantly positively related to egg mass and negatively related to hatch date. After controlling for these variables, differences between colonies and among years were relatively small and inconsistent. Mean survival of second-hatched chicks was positively correlated with the mean growth rate of survivors across colonies and years. These findings are consistent with a general hypothesis that growth of chicks reflects individual parental performance and parental quality

Linking habitat conditions and growth in the European anchovy (Engraulis encrasicolus)

Length frequency data of small yellow croaker (Larimichthys polyactis) were acquired from the survey vessel in May, July, September and December, 2011 in Haizhou Bay of China. In this study, 921 fish individuals were analyzed for the estimation of growth and mortality parameters. Between length and weight, the power coefficient b was 2.7321, 2.9703, 3.0418 and 2.7252 for the 4 surveying months, respectively. The estimated von Bertalanffy growth function parameters were 230mm (L ∞) and 0.26yr−1 (K) as were calculated with ELEFAN method equipped in FiSAT computer package. With length-converted catch curve analysis, the total mortality rate (Z) and its 95% confidence interval were 2.16 (1.69–2.64) yr−1, 0.59 (0.15–1.04) yr−1, 1.16 (0.80–1.52) yr−1 and 0.96 (0.70–1.23) yr−1 for the 4 surveying months, respectively, with the pooled data the value was 1.15 (0.81–1.48) yr−1. The natural mortality rate (M) was 0.516 yr−1 as was calculated with Pauly’s equation (the annual average sea water temperature was 11°C). Therefore, fish mortality rate was 0.634 yr−1. The yield-per-recruit analysis indicated that when t c was 1, F max was 0.7 and F 0.1 was 0.55. Currently, the age at first capture is about 1 year and F current was 0.634. Therefore, F current was larger than F 0.1 and less than F max. This indicates that current fish mortality is at a dangerously high level. With Gulland method, the biological reference point for fishery (F opt) was estimated as 0.516 yr−1, lower than current fish mortality. Accordingly, reducing catch in the region was strongly recommended.

The length–weight relationships (LWR) of the common seadragon Phyllopteryx taeniolatus (Lacepède, 1804) and the leafy seadragon Phycodurus eques (Günther, 1865), Syngnathidae, are presented in this paper, based on specimens raised in the Birch Aquarium at Scripps, La Jolla, California. Furthermore, we used the length at known age of 40 specimens of common and 15 leafy seadragons to estimate the parameter of the von Bertalanffy growth function (VBGF) for these species. Some of the pros and cons of the newly proposed length type used, ‘scalene length’ are presented. The parameters of the LWR and the VBGF parameters are discussed, with an emphasis on the rearing conditions, the peculiar anatomy of seadragons, especially of P. eques, and on the Gill-Oxygen Limitation Theory (GOLT).

Growth and mortality parameters, exploitation rates, annual recruitment patterns and length-weight relationships were estimated using FiSAT program from monthly length-frequency and weight samples of Indo-Pacific king mackerel, Scomberomorus guttatus, captured mainly by drift gill nets from the upper Bay of Bengal off Bangladesh coast. The aim was to estimate growth parameters, mortality rates, exploitation rate and recruitment pattern of S. guttatus for sustainable management. The von Bertalanffy growth parameters asymptotic length L∞ (cm) and growth constant K (per year) were 73.5 and 0.6, respectively. The L∞ and Z/K estimates provided by Wetherall plot were 73.3 and 2.3 cm. The annual rate of fishing mortality (F = 0.806) was low compared to the relatively high natural mortality (M = 0.994). The exploitation rate (E = 0.45) shows that the species was not over-exploited in the region. About 77.1% of S. guttatus were recruited during May-July and 23.0% during September-October. The growth performance index (φ′) was 3.5. The total length and body weight relationship was W = 0.0101 L 2.8622 suggesting that the growth rate was negative allometric (b<3). The growth parameters derived in the current study are comparable with previous estimates available for the same species. DOI: 10.3329/bvet.v27i2.7558 Bangl. vet. 2010. Vol. 27, No. 2, 82-90

Plant species from unproductive or adverse habitats are often characterized by a low potential relative growth rate (RGR). Although it is generally assumed that this is the result of selection for specific trait combinations that are associated with a low rate of net biomass accumulation, few studies have directly investigated the selective (dis-)advantage of specific growth parameters under a set of different environmental conditions. Aim of the present study was to quantify the impact of inherent differences in growth parameters among phenotypes of a single plant species, Lychnis flos-cuculi, on their performance under different soil nutrient conditions. Growth analysis revealed significant variation in RGR among progeny families from a diallel cross between eight genotypes originating from a single population. Differences in RGR were due to variation in both leaf area ratio (LAR) and in net assimilation rate (NAR). A genetic trade-off was observed between these two components of growth, i.e. progeny families with high investment in leaf area had a lower rate of net biomass accumulation per unit leaf area. The degree of plasticity in RGR to nutrient conditions did not differ among progeny families. Inherent differences in growth parameters among progeny families had a significant impact on their yield in competition with Anthoxanthum odoratum and Taraxacum hollandicum. In nutrient-rich conditions, progeny families with an inherently high leaf weight ratio (LWR) achieved higher yield in competition, but variation in this trait could not explain differences in competitive yield under nutrient-poor conditions. Inherent differences in growth parameters among progeny families were poorly correlated with differences in survival and average rosette biomass (a good predictor of fecundity) among these progeny families sown in four field sites along a natural gradient of soil fertility. In the more productive sites none of the growth parameters was significantly correlated with rosette biomass, but in the least productive site progeny families with an inherently high specific leaf area (SLA) tended to produce smaller rosettes than low-SLA families. These results are consistent with the view that a selective advantage may accrue from either high or low values of individual RGR components, depending on habitat conditions, and that the selective advantage of low trait values in nutrient-poor environments may result in indirect selection for low RGR in these habitats.

The present study reports length-weight relationships (LWRs) and Fulton’s condition factor (K) of five marine finfish species [(Siganus vermiculatus (Valenciennes, 1835), Kathala axillaris (Cuvier, 1830), Exocoetus volitans, Linnaeus, 1758, Chaetodon collare Bloch, 1787 and Boleophthalmus dussumieri Valenciennes, 1837)] from Parangipettai (East coast, Tamil Nadu) and Mumbai (West coast, Maharashtra) of India. A total of 1451 specimens representing five fin fish species were collected monthly from January 2018 to December 2018 and the sex ratio were calculated. Based on the estimates of total length (TL) and body weight (BW), the growth parameters (b), sex-specific differences in growth parameter and their monthly variation were calculated. The sex ratio was female-biased and significantly different from 1:1 in all species except E. volitans. The value of parameter ‘b’ of LWRs varied from 2.734 to 3.201 (r2 > 0.96 and P < 0.0001 for all species) and fall within the expected value of 2.5 to 3.5. The value of parameter ‘b’ for E. volitans and B. dussumieri did not fall within the 95% confidence intervals of Bayesian predictions. However for S. vermiculatus, C. collare, and K. axillaris the value of parameter ‘b’ was within the range of Bayesian predictions. Monthly variation in the value of parameter ‘b’ of the LWRs for all species was noticeable. The sample size had no effect on the ‘b’ value. Sex-specific variation in ‘b’ value was only observed for C. collare. The condition factor value ranged from 0.52 to 2.25 and was highest in K. axillaris and lowest in C. collare. Owing to the importance of LWRs and K data to understand the relative condition of populations, species ecology, demographic assessment, and species management, the present study has a great significance in fishery biology.