Growth Function Parameters Research Articles

A hierarchical model of persistent and transient growth variation applied to Lake Superior lake trout

Variability in individual fish growth both within and among populations can interact with mortality to affect variation in size-at-age and other critical features of populations. Herein, we developed and applied mixed-effects, hierarchical growth models to back-calculated length-at-age data from six lake trout (Salvelinus namaycush) populations in Lake Superior to quantify how growth variation was attributable to persistent sources within and among populations and transient (short-term and not consistent over time for an individual) sources. Persistent variation in growth among individuals explained more variability in length-at-age than transient variation, and most of this variation was within populations rather than among populations. Simulations showed that the modeling approach could robustly estimate most growth function parameters, even with mismatches between true and assumed among-population covariation, although a higher number of populations enabled better estimation of certain population-level parameters. An implicit assumption to our interpretation was that lake trout populations in Lake Superior had not experienced substantial size-selective mortality, so their length-at-age patterns largely reflected growth variation rather than size-selective mortality. This assumption should be tested when interpreting future applications of this growth modeling approach.

Age, Growth, and Otolith Morphometrics of Trachinus draco (L., 1758) and Trachinus radiatus (Cuvier, 1829) in the Eastern Mediterranean

Trachinus draco and Trachinus radiatus are two bycatch species of low commercial value and no sufficient knowledge on their biological features. In the present study, the weight–length relationship, age, growth, and ten otolith morphometric variables of these species were investigated in the southwestern Aegean Sea for the first time. Positive allometric and isometric growth in the weight were defined in T. draco and T. radiatus. The weight–length relationship was described by the parameters α = 0.002415 and b = 3.35745 in T. draco and α = 0.007582 and b = 3.09452 in T. radiatus. The von Bertalanffy growth function parameters were L∞ = 44.51 cm, k = 0.15 year−1, and t0 = −1.31 years for T. draco and L∞ = 58.47 cm, k = 0.16 year−1, and t0 = −0.78 years for T. radiatus. Ten otolith variables (radius, length, width, area, perimeter, roundness, circularity, form factor, rectangularity, and ellipticity) showed a significant relationship with size for both species, except the ellipticity in T. radiatus. The mean values of all the otolith variables were higher in T. radiatus than in T. draco. The otolith of T. radiatus was found to become more rectangular with size as compared to the otolith of T. radiatus. The results of this work can support further research on the behavioral and ecological features of the two species.

On the biology of the alien Red Sea goatfish, Parupeneus forsskali (Fourmanoir & Guézé, 1976) in the Aegean Sea, eastern Mediterranean

ABSTRACT The alien Red Sea goatfish (Parupeneus forsskali) was recently reported in the Mediterranean Sea, as a species that migrated two decades ago through the Suez Canal. In this work, efforts are being made to fill knowledge gaps on its biology, through information based on 131 Red Sea goatfish specimens collected from commercial fishing vessels in the south-eastern coasts of the Aegean Sea, Greece (Eastern Mediterranean). The largest specimen examined measured 26 cm in total length (Lmax), while otolith annual ring determination showed that the maximum recorded age was 4 years. The Von Bertalanffy growth function parameters were estimated as follows: L∞ = 32.44 cm, Κ = 0.31 y−1 and t0 = −0.08 y. The diet of the specimens was dominated by Decapoda and Amphipoda (IRI = 66%) with an estimated trophic level of 3.58 (±0.53), characterizing the species as carnivorous with preference for Crustacea prey. Length (Lm) and age (tm) at maturity were estimated to be 19.6 cm and 2.8 years, respectively. The species exhibited larger reproductive load (Lm/Lmax) in the non-native regions compared with its native distribution in the non-native regions compared with its native distribution. In conclusion, further research is required in order to elucidate differences of the species’ life-history traits between its native and non-native distribution.

Age, growth and length-to-weight relationship of largehead hairtail (Trichiurus lepturus) in south-eastern Australia suggest a distinct population

The age, growth rates and length to weight relationships for the south-eastern Australian population of largehead hairtail (Trichiurus lepturus) were investigated for the first time. Age was estimated by counting annuli in sectioned sagittal otoliths, with a maximum age of 8 years estimated for males and females. We found no significant differences in the growth rates of males and females over the size (12–78 cm pre-anal length (PL)) and age (0–8 years) ranges sampled. However, females in our collection were larger on average than males, and all fish sampled >60 cm PL were female, suggesting that females may grow to larger sizes than males and that sampling of greater numbers of larger and older fish may be required in future. T. lepturus growth was described by the von Bertalanffy growth function parameters L∝ = 74.89 cm PL, K = 0.13yr−1 and t0 = −0.80 yr, with the L∝ being amongst the largest reported for the species. Growth was variable, with the sizes at any given age spanning up to 50 cm PL. Female T. lepturus increased in body weight relative to length faster than males, as has been reported in other populations. The length/weight relationship for the south-eastern Australian population was significantly different, with almost no overlap, from that reported for T. lepturus in the Arabian Sea. The substantial differences in growth rates, maximum sizes and body morphometrics of T. lepturus from south-eastern Australia in comparison to other populations globally are consistent with the hypotheses that it represents a distinct population, although investigations using additional population markers are required to verify this.

Population dynamics and stock assessment of two major eels (Muraenesox bagio and Congresox talabonoides) from the marine waters of Bangladesh

Muraenesox bagio (black eel) and Congresox talabonoides (brown eel) are two major eels (Muraenesocidae) species which are commercially significant in the marine catch of Bangladesh, but population dynamics and stock assessment of marine eel fishery in Bangladesh are yet to be studied. This study is the first endeavour to analyze the population dynamics and stock assessment of this marine eels collected from July 2021 to May 2022 using three length-based methods namely TropFishR, the Length Based-Spawning Potential Ratio (LB-SPR) & the length-Based Indicators (LBI) and two catch-based methods including Depletion-Based Stock Reduction Analysis (DB-SRA) and the Catch-Maximum Sustainable Yield (CMSY). A slightly positive allometric growth pattern (b=3.10) for the black eel and a negative allometric growth pattern (b=2.33) for the brown eel were observed in the length-weight relationship. The parameters of von Bertalanffy Growth Function (VBGF) and the linearized length-converted catch curve (LCCC) analysis for black eel and brown eel were L∞=190.67cm and 166.63cm, k=0.18 year-1 and 0.16 year-1, and the total mortality, Z=0.70 year-1 and 0.45 year-1. The eel fishery is calculated to be overfished due to overexploitation and the stock’s spawning biomass (SPR=19% for black eel and 21% for brown eel) is close to the limit reference point but well outside the targeted range because the majority of the catches were found to have below-maturity levels. This study advised an optimum length limit to catch from 93 to 114 cm for black eel and 83 to 101 cm for brown eel. Though the estimated reference points of the CMSY were more optimistic than those from the DB-SRA, the tendency of the status of eel stock has been displayed moving towards overexploitation from a safe stock scenario. This study, therefore, recommended an annual landing limit of 250 mt as OFL (Over fishing limit) for the next ten years in association with existing management measures to maintain the present stock biomass of eel fishery over the BMSY level.

Assessing the Size-Structured Stock of the Swimming Crab Callinectes amnicola (Crustacea: Portunidae) in the Cross River, Nigeria

Abstract An important aspect of the size-structured stock is the assumption that individuals progress from one size class to another after a certain time. In this study, a total of 2581 monthly samples of the swimming crab Callinectes amnicola were collected from the landings of the artisanal crab fishery in the Cross River, Nigeria over a period of 13 months, from January 2021 to January 2022. Crabs ranged in length from 6.5 cm to 15.5 cm, with most crabs caught during the dry season. The fewest crabs (n=23) were caught in August 2021, and the most (n=662) were caught in January 2021. Because moulting and other physiological obstacles make it difficult to determine crab age, length frequency data were used instead. Swimming crab assessment was based on some basic growth parameters of the von Bertalanffy growth function and the Beverton and Holt growth model. The results showed that the asymptotic length and growth rate were 16.28 cm and 0.940 per year, respectively. The best growth index was estimated to be 2.40, while longevity and mortality were 3.19 years and 3.46 per year, respectively. The calculated exploitation rate of 0.41 was below the guideline of 0.5 and the maximum yield per recruit of 0.421, confirming an underfished stock. Sustainable exploitation of the Cross River swimming crab was recommended by reducing efforts on already exploited fishery resources.

Life history traits of the Pacific longnose parrotfish Hipposcarus longiceps (Labridae, tribe: Scarinae) in subtropical waters

The Pacific longnose parrotfish, Hipposcarus longiceps, is an important target species in tropical and subtropical waters of the Indo-Pacific. However, its life history traits have yet to be characterized in the northern hemisphere. Thus, the age, growth, maturity, spawning season, sex structure, and sex reversal of this species were investigated for the first time in the subtropical Yaeyama region, Japan. According to the age composition of the sexes and the structure of the gonads, this species displayed diandric hermaphroditism with a primary male. The maximum fork length and ages of females, primary males, and secondary males were 506 mm and 17 years, 537 mm and 12 years, and 578 mm and 13 years, respectively. The estimated parameters of the von Bertalanffy growth function for all specimens were L∞=562, k=0.18, and t0=−0.81. The spawning season in the Yaeyama region was estimated to be between April and October according to the gonadal development of both sexes. Compared with previous studies on this species conducted in tropical waters, the Yaeyama population in subtropical waters lives longer, grows larger, and matures and changes sex later. However, previous studies in subtropical waters have shown similar life history parameters as those observed in this study, and spawning was inactive during the low water temperature periods. These features suggest that vulnerability to fishing pressure would be higher in subtropical populations than in tropical populations. This study also confirmed that H. longiceps has an obvious spawning period when the average water temperature is ≥24.6°C. The unique features of H. longiceps in the Yaeyama region are thought to reflect the lower temperature of the region’s subtropical waters. These findings suggest that the future effects of global warming could extend the spawning season of subtropical H. longiceps populations.

Stock assessment of landlocked ayu Plecoglossus altivelis altivelisin Japan through length-based models.

Ayu Plecoglossus altivelis altivelis is a key commercially and culturally important freshwater osmeroid in Japan. Its native population is mostly an amphidromous form migrating between rivers and the sea, and not only native but also artificially landlocked forms are found in lakes and dam reservoirs. This study was undertaken to execute population feasibility and maximum sustainable yield (MSY) analysis of an artificially landlocked form of ayu during January 2018 to December 2020 in the Haidzuka reservoir and its connected Tabusa River, western Japan. FAO-ICLARM Stock Assessment Tools-II and empirical models were employed to estimate the growth function and population parameters. The estimated asymptotic length was 19.50cm, and the growth coefficient was 0.73year-1 with a growth performance index of 2.443. The length at first maturity and length at optimum yield were calculated as 10.77cm and 12.63cm, respectively, which were lower than the length at first capture (Lc = 13.15cm), suggesting the mesh size of fishing gear favoring the sustainability of the reproductive potential of this population. The calculated total, natural, and fishing mortalities were 2.45, 1.19, and 1.26year-1, respectively. The recruitment pattern was continuous round the year with two pulses where the peak was during July. The current level of exploitation (0.51) was slightly higher than the maximum exploitation rate (0.45), indicating a little overharvesting. The MSY of ayu in the Haidzuka reservoir was estimated to be 211 metric tons if the recommended Lc is maintained. Results of this study illustrate the first information on population characteristics of landlocked ayu and will help the development of suitable management policies for ayu fishery in lakes and dam reservoirs.

Reassessing growth and mortality estimates for the Ordovician trilobite Triarthrus eatoni

AbstractA length–frequency sample (n = 295) from a fossil population of the Ordovician trilobite Triarthrus eatoni Hall, 1838, assembled and analyzed by J. L. Cisne in 1973 is here reexamined using methods of length–frequency analysis commonly used in fishery science and marine biology. Theoretical considerations and the empirical data at hand suggest that the growth of T. eatoni was not “linear,” but asymptotic, as is the growth of most Recent marine invertebrates. The parameters of the von Bertalanffy growth function (L∞ = 41 mm, K = 0.29 yr−1) suggest that T. eatoni, which apparently lived in a challenging environment, grew somewhat more slowly than the extant marine isopod Ceratoserolis trilobitoides (Eights, 1833), used here as Recent analogue to T. eatoni. This trilobite probably lived up to 10 years, rather than the suggested 4 years, and its mortality rate was 15%–20% per year rather than 30%–40% per year. These represent the first estimates of trilobite absolute growth characteristics using methods known to accurately model growth in extant water-breathing ectotherms. These provide a baseline for trilobite growth that can be used to make inferences about growth in other species. The approach used here may also be applied to other trilobites for which suitable length–frequency data exist.

Genetic Parameters of Diameter Growth Dynamics in Norway Spruce Clones

The breeding of Norway spruce in northern Europe has substantially contributed to the production of high-quality wood. The vegetative propagation of robust elite clones could help to sustain the provision of high-quality timber in the face of changing climates. For the adequate evaluation of genetic gains, the altered tree growth dynamics of the clones need to be understood, yet essential information about the long-term growth dynamics of improvedboreal trees is still lacking. We examined a 50-year-old clonal plantation in Latvia to distinguish the clonal effects on diameter growth function parameters and estimate the genetic parameters. A mixed-effect modelling approach was used, in which the clones were applied as random effects on the parameters of the Chapman–Richard equation. All model parameters showed significant variance in the genotypic coefficients of variation CVg which ranged between 11.0 and 17.1%, with the highest being for the growth rate. The heritability (H2) of the diameter at breast height (DBH) reached 0.35 at the age of 40, while CVg decreased from 12.9% to 7.8% between the ages of 20 and 45. Age–age genotypic correlations were positive and were strong or very strong (>0.76). The realised genetic gain varied from −6.3 to +24.0% around the trial mean. A substantial improvement in DBH was indicated when elite clones were selected for vegetative propagation based not only on early measurements, but also considering the genetic variance in the model parameters.

Influences of Dietary Supplementation with Maca (Lepidium meyenii) on Performance, Parameters of Growth Curve and Carcass Characteristics in Japanese Quail.

Simple SummaryIt is known that the bioactive compounds (N-benzyl-palmitamide, benzyl isothiocyanate, glucosinolates and phenolics) in the maca plant are appetizing, as well as having antioxidant effects and improving reproductive ability. The aim of this study was to determine the effects of adding maca plant powder to the ration at different levels on growth, slaughter carcass, partial egg production and some reproductive characteristics of Japanese quail (Coturnix coturnix japonica). Addition of maca powder to the diet increased the feed consumption but did not affect growth, slaughter carcass, partial egg production or fertility. In addition, maca powder reduced embryonic deaths and improved chick quality. According to these results, the positive effects of short-term application of maca powder are not observed during the fattening period in Japanese quails.Maca plant contains rich nutrients and in addition, it has various bioactive substances (N-benzyl-palmitamide, benzyl isothiocyanate, glucosinolates and phenolics). It is used to improve reproductive properties and has antioxidant effects for both humans and animals. The aim of this study was to determine the effects of adding maca plant powder to the ration at different levels on growth, slaughter carcass, partial egg production and some reproductive characteristics in Japanese quail (Coturnix coturnix japonica). The experimental groups were formed by adding 0% (control), 0.05% and 0.1% maca powder to the diet, and a total of 300 birds were used. Growth (weekly body weights, parameters of Gompertz growth function), feed efficiency and carcass characteristics of quails in the 42-day fattening trial were determined. Reproductive characteristics were measured up to 22 weeks of age. Addition of maca powder to the diet increased the feed consumption (p < 0.05) but did not affect body weights at 35 and 42 days of age, β0 and β1 parameters or point of inflection weight of the Gompertz model, carcass traits, partial egg production or fertility. It may be advisable to add 0.1% maca powder to the diets of breeders. Besides, maca powder reduced embryonic deaths and improved chick quality (both p < 0.05). It is thought that different results for reproductive traits can be obtained if maca powder is used for a longer period in the diets of breeder quail flocks.

STOCK ASSESSMENT OF BLUE SWIMMING CRAB FOR SUSTAINABLE MANAGEMENT IN ASID GULF, MASBATE PHILIPPINES

Fishermen in the Asid Gulf rely heavily on the income, livelihood, and food security that Blue Swimming Crab (BSC) provides. A study was conducted in January-December, 2018 to investigate the present status of the BSC fishery in the gulf. A total of 3991 BSC were collected for length-frequency data and analysis was done using an analytical length-based fish stock assessment, FISAT (version 1.2.2). Results on Von Bertalanffy growth function parameters were -1 CW?=170.43 mm and K=0.93year (ELEFAN method). The current exploitation rate was 0.79 which was higher than the threshold at E=0.37. Also, an excess of 29% in the E current suggested reducing the 28% fishing effort of the current year to fulfill the MSY and FMSY. On this basis, it is safe to presume that BSC fishery from Asid Gulf is experiencing overexploitation, hence, the need to recommend interventions supportive of the sustainable management and conservation of BSC in Asid Gulf.

Age, growth, mortality, and exploitation rate of blueline snapper, Lutjanus coeruleolineatus (Actinopterygii: Perciformes: Lutjanidae), from Dhofar Governorate, Sultanate of Oman

The blueline snapper, Lutjanus coeruleolineatus (Rüppell, 1838), is a significant commercial fish species harvested from the traditional fishery in the Sultanate of Oman. Deficient data on this species, however, make the management strategies challenging, especially in fisheries ecology. A total of 978 specimens were obtained from Dhofar Governorate off the coast of the Arabian Sea during the period between February 2015 and March 2016. In total, 296 sectioned otoliths were analyzed and growth was estimated from non-seasonal growth by using von Bertalanffy method. The parameters of von Bertalanffy growth function, total mortality (Z), natural mortality (M), fishing mortality (F), and exploitation rate (E) were determined and compared with those for Lutjanidae fishes elsewhere. The age structure of male fishes was between 1 and 14 years for males while the age of females ranged from 1 to 18 years. Growth rate (K) was 0.21 y–1 and 0.16 y–1 for males and females, respectively. The hypothetical length of female (L∞ = 46 cm) was relatively higher than that of male (L∞ = 42 cm). The natural mortality (M) was 0.296, total mortality (Z) was 0.372, fishing mortality was 0.076, and exploitation rate (E) was estimated as 0.2. The presently reported study is conducted to examine this fish in relation to growth parameters by analyzing otolith structure. The results of the presently reported study will contribute towards planning the regional fishery management policies in Oman.

Living on the edge: population parameters of the wedge clamDonax hanleyanusin the southernmost limit of its distribution range, southwestern Atlantic, Argentina

The wedge clam Donax hanleyanus Philippi, 1845 is a conspicuous member of the sandy beach macrofauna along hundreds of kilometres in the northern coasts of Argentina. Age, growth, mortality, and productivity of this species were assessed in the southernmost limit of its distribution range (Mar del Plata, Buenos Aires province, Argentina). The parameters of the von Bertalanffy growth function were SL∞ = 23.23 mm, K = 1.62 year−1, and t0 = 0.08 years. The maximum individual production was 7.9 × 10−7g shell-free wet mass (SFWM)·year−1at a shell length of 14–16 mm. Individuals between 10 and 12 mm contributed the most to the secondary production (P) of 0.01 g SFWM·m−2·year−1. The mean annual biomass (B) was 0.002 g SFWM·m−2·year−1. Annual P/B ratio and mortality coefficient (Z) were 4.48 year−1and 4.78 year−1, respectively. Low production and high mortality could be caused by a sharp decrease in habitat quality, given the suboptimal temperatures at the southernmost edge of the species distribution. These results strongly limit its potential for future commercial exploitation.

Climate Change May Cause Shifts in Growth and Instantaneous Natural Mortality of American Shad Throughout Their Native Range

AbstractAmerican 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.

Density‐Dependent Changes in Grass Carp Growth and Mortality in Long‐Term Aquatic Plant Management

AbstractThe Grass Carp Ctenopharyngodon idella is an herbivorous fish that has been stocked throughout the United States for aquatic plant control, commonly to manage hydrilla Hydrilla verticillata. Triploid Grass Carp were purported to have a mean life span of about 11 years based on otolith‐assigned ages and mortality estimates for fish associated with large stocking efforts through which aquatic plants were eliminated. Recent studies in aquatic systems where preferred foods were not eliminated have found that Grass Carp may live up to 30 years or more, but information about growth and mortality is lacking. About 130,000 Grass Carp have been stocked since 1995 to manage hydrilla in combination with fluridone application in Lake Gaston, Virginia–North Carolina, USA. Hydrilla coverage peaked at about 1,300 ha in 2003 and was reduced to about 130 ha by 2014. Since 2006, a total of 419 Grass Carp have been collected for age and growth analysis. A Bayesian approach was used to estimate von Bertalanffy growth function parameters that incorporated the effects of a linear trend in year, hydrilla abundance, or Grass Carp density and to assess population changes. Fish that were stocked in 1995 persisted through 2017. Mean maximum length (L∞) of Grass Carp decreased by about 200 mm with an increasing number of Grass Carp per hectare of hydrilla, and fish reached maximum size earlier in life. Indirect mortality estimates derived from growth parameters increased with Grass Carp density. Because preferred food availability affects mortality rates, stocking numbers should vary accordingly to maximize the effectiveness of hydrilla control programs.

Multidisciplinary approach to paediatric aerodigestive disorders: A single-centre longitudinal observational study.

Aerodigestive clinics (ADCs) are multidisciplinary programmes for the care of children with complex congenital or acquired conditions affecting breathing, swallowing and growth. Our objective was to describe the demographic, clinical, etiological and investigational profile of children attending the inaugural ADC at a tertiary paediatric centre in Queensland. Children referred to the ADC at Queensland Children's Hospital from August 2018 to December 2019 were included. Data on clinical, growth and lung function parameters, bronchoscopy and upper gastrointestinal endoscopy findings, thoracic imaging and comorbidities were retrospectively analysed. Fifty-six children (median (range) age 4 years (3 months-15 years); 18 female) attended the ADC during this 17-month period. Forty-six (82%) children had previous oesophageal atresia with tracheo-oesophageal fistula; 43 of these were type C. Previous isolated oesophageal atresia, congenital diaphragmatic hernia and congenital pulmonary malformation were the underlying disorder in three (5%) children each, with one child having a repaired laryngeal cleft. Vertebral Anal Tracheo Esophageal Renal Limb anomalies (VACTERL)/Vertebral Anal Tracheo Esophageal renal anomalies (VATER) association was seen in 21 (38%) children. Growth was adequate (median weight and body mass index z-score -0.63 and -0.48, respectively). Thirty-four (61%) children reported ongoing wet cough, with 12 (21%) requiring previous hospital admission for lower respiratory tract infection. Fourteen (25%) had bronchiectasis on computed tomography chest and 33 (59%) had clinical tracheomalacia, apparent on bronchoscopic examination in 21 patients. Dysphagia was reported in 15 (27%) children, 11 (20%) were gastrostomy feed-dependent and 5 (9%) had biopsy-proven eosinophilic oesophagitis. High proportion of children attending the ADC have ongoing respiratory symptoms resulting in chronic pulmonary suppuration and bronchiectasis. Potential benefits of this model of care need to be studied prospectively to better understand the outcomes.

Age and growth of the Japanese butterfish Psenopsis anomala in the waters off north-eastern Taiwan

AbstractThe catch of Japanese butterfish, Psenopsis anomala in Taiwan is greater than those of any other nation; however, the biology, particularly the age and growth, of this economically important fish species is little known. This study describes the age and growth of P. anomala based on 734 specimens (340 females, 363 males, 31 unsexed) caught by trawl fishery in the north-eastern waters off Taiwan from March 2007 to July 2008. The age of specimens was estimated by counting the growth annuli in sagittal otoliths. The periodicity of annulus deposition on otolith was estimated to be one year with opaque zone deposited between July and August based on marginal increment analysis. The maximum age for both sexes was estimated to be ~4. The female portion of the population was dominated by the 3+ age class, while the male portion was dominated by the 2∞ age class. The parameters of the von Bertalanffy growth function with standard error estimated based on the observed length at age using a non-linear method are as follows: L∞ = 25.47 ± 0.65 cm, k = 0.30 ± 0.03 year−1, and t0 = −1.84 ± 0.16 year for females (n = 350), and L∞ = 22.39 ± 0.45 cm, k = 0.46 ± 0.04 year−1, and t0 = −1.38 ± 0.13 year for males (n = 378). The growth performances of P. anomala reported from different geographic regions were compared, and the potential influences of sample size distribution on the estimated growth parameters were further discussed.

Life history of northern Gulf of Mexico Warsaw grouper Hyporthodus nigritus inferred from otolith radiocarbon analysis.

Warsaw grouper, Hyporthodus nigritus, is a western Atlantic Ocean species typically found at depths between 55 and 525 m. It is listed as a species of concern by the U.S. National Marine Fisheries Service and as near threatened by the International Union for the Conservation of Nature. However, little information exists on the species’ life history in the northern Gulf of Mexico (nGOM) and its stock status in that region is currently unknown. Age of nGOM Warsaw grouper was investigated via opaque zone counts in otolith thin sections (max age = 61 y), and then the bomb 14C chronometer was employed to validate the accuracy of age estimates. Otolith cores (n = 14) were analyzed with accelerator mass spectrometry and resulting Δ14C values overlain on a loess regression computed for a regional coral and known-age red snapper Δ14C time series. Residual analysis between predicted Δ14C values from the loess regression versus Warsaw grouper otolith core Δ14C values indicated no significant difference in the two data series. Therefore, the accuracy of otolith-based aging was validated, which enabled growth and longevity estimates to be made for nGOM Warsaw grouper. Dissolved inorganic carbon (DIC) Δ14C values collected from the nGOM support the inference that juvenile Warsaw grouper occur in shelf waters (<200 m) since DIC Δ14C values in this depth range are enriched in 14C and similar to the Δ14C values from otolith cores. A Bayesian model was fit to fishery-dependent age composition data and produced von Bertalanffy growth function parameters of L∞ = 1,533 mm, k = 0.14 y-1, and t0 = 1.82 y. Fishing mortality also was estimated in the model, which resulted in a ratio of fishing to natural mortality of 5.1:1. Overall, study results indicate Warsaw grouper is a long-lived species that is estimated to have experienced significant overfishing in the nGOM, with the age of most landed fish being <10 y.

Population dynamics of Rainbow Sardines, Dussumieria acuta (Valenciennes, 1847) from Pakistani waters

Length frequency data of Rainbow Sardines, Dussumieria acuta were collected and measured from the coast of Pakistan during 2015, ranging from 5 to 19 cm (total length). Weight ranges were measured from 2 to 64 g. The length frequency data were analysed for the estimation of population dynamics, so b was estimated at 2.70. The estimated von Bertalanffy growth function parameters of 19.95 cm (L∞) and 0.730 year-1 (K). The mortality rate Z= 1.84 year-1, M= 1.59 year-1 F= 0.25 year-1 and E= F/Z= 0.135. The yield-per-recruit analysis indicated that when tc was 1, Fmax was 1 year-1. Currently, the age at first capture is about 1 year and Fcurrent was 0.25 year-1. Therefore, Fcurrent was smaller than Fmax. With Gulland method, the biological reference point for fishery (Fopt) was estimated as 1.59 year1, which is also higher than current fish mortality. Therefore, the present study shows that the Dussumieria acuta fishery is safe in Pakistan.