Density-dependent growth of young-of-the-year Atlantic salmon (Salmo salar) revisited

Imre I, Grant JWA, Cunjak RA. Density-dependent growth of young-of-the-year Atlantic salmon ( Salmo salar ) revisited. Ecology of Freshwater Fish 2010: 19: 1–6. © 2009 John Wiley & Sons A/S
Abstract –  The length of individual young-of-the-year (YOY) Atlantic salmon ( Salmo salar ) in Catamaran Brook decreases with increasing population density following a negative power curve. Because most of this decrease in growth rate occurs at low densities (<1 fish·m⁻²), ( Imre et al. 2005 ; Journal of Animal Ecology, 74: 508–516) suggested that exploitation competition for drifting prey rather than space limitation might be responsible for this pattern. Recently, ( Ward et al. 2007 ; Journal of Animal Ecology, 76: 135–138) showed that the negative power curve of growth rate versus density can be caused by other mechanisms and suggested that Imre et al.'s evidence for density-dependent growth would have been stronger if we had analysed final size versus initial density rather than final density. We examined (i) whether the negative power curve of size versus density was also apparent in an analysis of final size versus initial density and tested two predictions that emerge from Ward et al.'s model, (ii) the variance in body size increases with population density, and (iii) the maximum fish size at a site is density-independent. The final size of YOY salmon decreased with increasing initial density following a negative power curve. Our data did not provide strong support for the above predictions emerging from Ward et al.'s model. Our analyses of different years, sites and seasons were consistent with the hypothesis of density-dependent growth of YOY salmon.     

Air bubbling results in carbon loss during microalgal cultivation in bicarbonate-enriched media: experimental data and process modeling

Turbulence is a major variable controlling growth of microalgae. When turbulence is provided by means of air bubbling, mass transfer phenomena take place between the culture medium and the air bubbles. A mathematical model has been developed to evaluate the effects of air bubbling in bicarbonate-enriched media for microalgae cultivation, and in cultures of the halotolerant alga Dunaliella viridis. Simulations have been made using a four order Runger–Kutta method combined with Marquardt's algorithm to establish the parameters of the system. The model permits: (i) simulation of the experimental behavior of organic (cellular) and inorganic (CO₂ + H₂CO₃ + HCO₃⁻ + CO₃²⁻) carbon in the cultures; (ii) performance of a sensitive analysis of the effects of varied operative conditions and (iii) development of strategies for optimizing the use of culture media and subsidiary energy. Simulation of the model demonstrated that in air-bubbled HCO₃⁻ enriched media there is a loss of CO₂ from the medium to the air bubbles, which escapes from the culture vessel, and no transference of CO₂ from the air bubbles to the water occurred. Validation of the model has been carried out by comparison of experimental and predicted values under different conditions.     

Development and application of fluorescence in situ hybridization (FISH) method for simple and rapid identification of the toxic dinoflagellates Alexandrium tamarense and Alexandrium catenella in cultured and natural seawater

ABSTRACT:   The toxic dinoflagellates Alexandrium tamarense (Lebour) Balech and A. catenella (Whedon and Kofoid) Balech produce potent neurotoxins, such as saxitoxin and gonyautoxin and have been mainly responsible for paralytic shellfish poisoning (PSP) in Japan. To prevent a negative effect on the fishery industry, it is necessary to identify these toxic species precisely and rapidly before and during the bloom. In this paper, a rapid and simple protocol of a fluorescence in situ hybridization (FISH) method using ribosomal RNA (rRNA)-targeted probes has been established for identifying the cultured strains and natural cells of A. tamarense and A. catenella . Using the FISH method established in this study, it was possible to identify these toxic species species-specifically and rapidly, within 30 min. The procedure of detection constituted three steps: (i) fixation/dehydration; (ii) hybridization; and (iii) washing; this made the identification simple. Moreover, this method did not require either special techniques or equipment, and the cost for detection was low. The specificity, rapidity, and simplicity of the developed method suggest that it might be useful for routine monitoring of these toxic microalgae.     

The effect of dietary n-3 and n-6 fatty acid balance on the growth of the prawn Penaeus monodon

A post-hoc study of the influence of dietary fatty acids of the n-3 and n-6 series on the growth of the prawn, Penaeus monodon showed a clear example of interaction by these nutrients to influence growth. Data from three independent growth studies examining the dietary requirements for linoleic (LOA, 18:2n-6), linolenic (LNA, 18:3n-3), arachidonic (ARA, 20:4n-6), eicosapentaenoic (EPA, 20:5n-2) and docosahexaenoic (DHA, 22:6n-3) acids were standardized through a common reference to allow comparison. Analysis of the variation within the experiments was able to define effects attributable to the individual experiments or the overall dietary n-3 and n-6 levels. A generalized additive model (GAM) indicated that both parameters (experiment, and n-3 and n-6 levels) had significant ( P  < 0.05) effects on growth. Loess nonparametric modelling of the data clearly demonstrates `the effect of relationship' on prawn growth to the levels of dietary n-3 and n-6 fatty acids. The response surface model shows clear effects of both n-3 and n-6, and that the effect of n-3 changes with the level of n-6 (and vice versa). Parametric examination of the relationship ( y =–37.149 x ³ + 160.84 x ² – 118.64 x  + 290.6, r ²=0.492, P  < 0.05) between growth and the ratio between the two fatty acid classes suggested that the optimal ratio of n-3 and n-6 fatty acid is about 2.5 to 1. The results of this study demonstrated that the interaction of the dietary n-3 and n-6 fatty acid classes is an important factor of prawn fatty acid nutrition.     

Age, growth, and reproduction of silky sharks, Carcharhinus falciformis, in northeastern Taiwan waters

To examine the age, growth and reproduction of silky sharks, Carcharhinus falciformis, in the waters off northeastern Taiwan, 469 specimens (213 females and 256 males) were collected from August 2000 to January 2002 at the Nanfanao fish market, northeastern Taiwan. The relationship between body weight (W) and total length (TL) for both sexes combined was expressed as: W = 2.92 × 10⁻⁶ TL^3.15 (n = 469, p < 0.01). The relationship between TL and vertebral centrum radius (R) for both sexes combined data was estimated as: TL = 25.979 + 18.197R (n = 250, p < 0.01). Growth bands (including translucent and opaque zones) in precaudal vertebrae formed once a year between December and January and were counted up to 11 and 14 for females and males, respectively. The von Bertalanffy growth function (VBGF) was used to model the observed length at age data. The sexes combined VBGF predicted an asymptotic length (L_∞) = 332.0 cm TL, growth coefficient (k) = 0.0838 year⁻¹, age at zero length (t₀) = −2.761 year (n = 250, p < 0.01). Size at 50% maturity for males was estimated to be 212.5 cm based on the logistic curve, which corresponded to 9.3 years. Females matured at 210–220 cm, which correspond to 9.2–10.2 years. The length at birth was estimated to be 63.5–75.5 cm TL. The number of embryos per litter was 8–10 and sex ratio of embryos was 1:1.     

Correlates of growth in juvenile three-spined sticklebacks: potential predictors of growth rates in natural populations

Abstract - The possibility of using indices to quantitatively predict short-term growth rates of juvenile three-spined sticklebacks ( Gasterosteus aculeatus L.) was assessed. A range of weight-specific growth rates ( G _W) was obtained in experiments with individual sticklebacks fed enchtraeid worms at different daily rations over 21 days. There was a strong, positive correlation between G _W and the RNA : DNA ratio in white muscle ( r ²  = 0.90) and lipid concentration (as percentage dry weight) of the carcass ( r ²  = 0.92). There were smaller, but significant correlations between G _W and the percentage of dry matter in the carcass ( r ²  = 0.67), and the residuals from the weight–length relationship ( r ²  = 0.49). Regressions relating growth to RNA : DNA ratio and lipid concentration offer a means of estimating short-term growth rates in natural populations. A test of such predictions using the results from a 56-day experiment on stickleback growth suggested that predictions from percentage lipid were biased and inefficient, while predictions from the RNA : DNA ratio were unbiased but inefficient. Predictions from percentage lipid were higher than from the RNA : DNA ratio.     

Age and growth of yellowstriped butterfish, <Emphasis Type="Italic">Labracoglossa argentiventris</Emphasis>, around Izu Oshima Island

ABSTRACT:   Age and growth of the yellowstriped butterfish, Labracoglossa argentiventris , around Izu Oshima Island were studied using a total of 1450 fish. Age was determined by counting the edge of the opaque zones as a ring mark on sectioned sagittal otoliths. Formation of the first ring was observed during spring or summer, corresponding to 1.5 years after hatching. Thereafter, one ring was formed each year in the same season as the previous year. The growth of the butterfish was rapid until 2 years of age. The maximum likelihood method was applied to the age and length data for estimating parameters in von Bertalanffy, Gompertz, and Logistic growth models. The selected model, based on the Akaike Information Criterion, was the von Bertalanffy growth model, which indicated differential asymptotic length and variance by sex.     

Predicting the growth of gilthead sea bream (Sparus aurata L.) farmed in marine cages under real production conditions using temperature- and time-dependent models

The growth of gilthead sea bream ( Sparus aurata ) has been studied considering five multiple exponential regression models using data from 20 lots of gilthead sea bream growing in 20 marine cages from a Mediterranean commercial fish farm. The final weight ( W _f) of fish was predicted in relation to the initial weight ( W _i), time ( n ) and temperature ( T ), or the sum of effective temperatures (∑ T _ef). The estimated weight results from the simulation using the five models have been compared with the real final weight values using the mean of the absolute values of the prediction errors in short and long term (the precision value). All models presented a high determination coefficient, above 96%, and good prediction values in the short term. Regression models were tested using data from six new cages. The best models for predicting the growth of sea bream long term were the ones where final weight is expressed in relation to the initial weight and the sum of effective temperature,     and     obtaining long-term prediction errors 12.9% and 10.7% respectively.     

Life cycle of Crangon crangon in the North Sea: a simulation of the timing of recruitment as a function of the seasonal temperature signal

The brown shrimp C. crangon supports a large commercial fishery in British, Belgian, Dutch, German and Danish waters. It produces eggs throughout the year with two seasonal peaks in summer and winter, respectively. Uncertainty exists with regard to the relative importance of the two egg production seasons for the mass invasion of juvenile recruits of 10–20 mm length in May/June, which is the dominant seasonal signal in the German and Dutch Wadden Sea, and which is presumed to grow into the exploitable stock by the autumn, causing the typical rise of commercial catches at that time of the year. A simulation model was developed that predicts the daily abundance of juvenile recruits attaining a given length, typically in the range of 10–20 mm. The model uses: (i) experimental data on the development times of eggs and larvae and the growth rates of juveniles; (ii) field data on the seasonal temperature cycle in different years (1986, 1992 and 1993 or mean conditions) and areas (German and Dutch Wadden Sea) of the North Sea; and (iii) a calculated index of the relative seasonal egg production intensity of adult C. crangon . Predictions of the simulations are compared with field observations on the seasonal occurrence of juvenile recruits in the German and Dutch Wadden Sea. Using temperature data from German waters, in the simulations peak recruitment was predicted to occur 1–2 months later than that observed in the field. However, if seasonal temperature data from Dutch waters were used, the predicted time of the first mass occurrence of recruits matched the field observations more closely. Simulations revealed that the first mass invasion of juveniles originates almost entirely from the winter egg production. It was also found that the simulated recruitment is condensed into a peak, which is narrower after a cold winter.     

Growth model for the endangered cyprinid fish Tribolodon nakamurai based on otolith analyses

A growth model for the endangered cyprinid fish Tribolodon nakamurai was derived following otolith analyses of 16 wild and 53 reared specimens. The asteriscus was the most appropriate to measure size among three otolith elements, and its height OH  mm was used as size index of otolith. Standard length L  cm was best back-calculated using the Gompertz model, L  = 70.0·exp[–exp{−0.553 (OH   –  2.73)}]. Translucent zones on the lapilli, analyzed from 5-year-old-reared fish, were regarded as winter slow-growing zones. The ages of 10 wild specimens of 37.0–48.1 cm standard length were calculated as 7–10 years by counting the translucent zones on the lapilli. Age t was best back-calculated using the allometry model, t  = 1.33· OH ^1.37. The growth trajectory of T.   nakamurai followed a slender S curve, three typical growth models, von Bertalanffy, Logistic and Gompertz, and Richards' model, which is a general formula of the above three, being fitted using the maximum likelihood method. The Gompertz model, L_t  = 60.2·exp[–exp{−0.258( t  − 4.68)}], was found by Akaike's information criterion (AIC) to be the statistically most acceptable growth model.     

A proposal for modelling the thermal‐unit growth coefficient and feed conversion ratio as functions of feeding rate for gilthead sea bream (Sparus aurata,L.) in summer conditions

Modelling growth as a function of feeding rate (FR) could be one of the most important tools for fish farms, because this knowledge allows growth to be maximized, or the feed conversion ratio (FCR) to be minimized, thereby improving profits. All growth models should include the three principal variables involved in growth: initial body weight, temperature and feeding rate. The thermal‐unit growth coefficient (TGC) already includes water temperature variation and initial body weight. Studying variation in TGC for fish fed the same diet, but at several feeding rates provides interesting information for modelling. Six different trials were conducted where gilthead sea bream of several different initial weights (24, 38, 50, 110, 220 or 289 g) were fed increasing amounts, and growth and the conversion index response were measured. The TGC response was modelled as a function of FR, and both asymptotic and quadratic responses were examined. The asymptotic model, TGC × 1000 = 2.037*(1?e ^{(?0.8*(FR?0.22)}), had an adjusted R² value of 96.18, whereas the quadratic model, TGC × 1000 = ?0.381 + 1,715 × FR?0,382 × FR², had an adjusted R² value of 96.42. Simulations of the FCR and the economical profitability index (EPI) were conducted to provide tools for maximizing efficiency and profitability, and the results suggest that these tools will be useful for future investigations.     

Confidence interval estimation of CPUE year trend in delta-type two-step model

Abstract:   A procedure is suggested for estimation of the approximate confidence intervals of the extracted catch per unit effort (CPUE) year trend in the delta-type two-step model used for CPUE standardization with a lot of zero-catch data. This method is a simple way to combine the Taylor expansion and delta method and is suitable for practical use. This model was applied to the catch and effort data with more than 80% zero catch for silky shark in the North Pacific Ocean caught by Japanese training vessels. As a result, realistic values of the 95% confidence interval of CPUE year trend are obtained. A method for left–right unsymmetrical interval estimation based on the asymptotic normality of the natural logarithm of CPUE is also suggested. In the example of silky shark, both CPUE year trends obtained from these two methods are similar.     

基于个体生态模型在渔业科学中的应用研究现状

基于个体生态模型(IBM)于20世纪70年代提出,数十年间在渔业科学领域得到广泛应用,现已成为渔业科学研究的重要手段之一。本文主要介绍了IBM的基本概念和研究方法,概述了国内外研究现状以及在渔业科学中的应用,分析了模型在应用中存在的问题、未来发展方向及趋势。研究认为,IBM在渔业科学研究和应用过程中需充分考虑以下问题:(1)了解模拟对象的生活史过程生物学特性,以及其栖息地环境特征;(2)针对不同的对象选用合适的环境因子和参数;(3)参考经典的生态学理论框架和方法来建立和分析个体模型;(4)综合统计分析、海洋遥感、地理信息系统等方法;(5)利用野外和敏感性试验获得实测数据,以校正IBM模型并提高精度。     

Mesh selectivity of encircling gill net for gizzard shad Konosirus punctatus in the coastal sea of Korea

ABSTRACT:   Fishing experiments were carried out in Yeongil Bay, Korea using an encircling gill net with four different mesh sizes and two different hanging ratios to measure the mesh selectivity for gizzard shad Konosirus punctatus . Twenty-six trials were conducted giving a total catch of 485 gizzard shad. The 'share each length's catch total' (SELECT) analysis with maximum likelihood method was used to fit the different functional models, the normal, lognormal, and bi-normal model, for a selectivity curve to the catch data. In addition, two cases in which the relative fishing intensity was either estimated or fixed were compared. The bi-normal model with the fixed relative fishing intensity was found to fit the data best. For the selectivity curve on the bi-normal model, the relative length (the ratio of fish length to mesh size) with the maximum efficiency was obtained as 3.70. From this, the focal fish lengths in the commercial encircling gill net, with mesh size ranging from 5.0 to 6.0 cm, were inferred to be 18.5–22.2 cm.     

Age and growth of the silky shark Carcharhinus falciformis from the Pacific Ocean

ABSTRACT:   The present study estimated the age and growth of the silky shark Carcharhinus falciformis in the Pacific Ocean. Samples and biological data were collected from Japanese tuna longline and purse seine fisheries from 1992 to 1999. Vertebra centra were picked from 145 males and 153 females for age determination. The number of annual rings observed for males and females was 0–8 and 0–13, respectively. Combined sex von Bertalanffy growth equations were obtained as follows: L_t  = 216.4(1 − e^{−0.148( t +1.76)}) where L_t is precaudal length in cm at age t . A mature size for males was considered to be approximately 135–140 cm (precaudal length), with an estimated age of 5–6 years, whereas corresponding values for females were 145–150 cm and 6–7 years, respectively. Birth size ranged from 48 to 60 cm. There was no remarkable difference in growth, birth size and age at maturity between the Pacific and Atlantic Oceans. The life history parameters of the silky shark are approximately the same in both oceans.     

Age and growth of Sebastes vulpes in the coastal waters of western Hokkaido, Japan

ABSTRACT:   Age and growth of Sebastes vulpes collected from the coastal waters of western Hokkaido were studied. Observation of the otolith margin verified that annuli (outer margins of the opaque zone) were produced chiefly from July to August. This period was associated with parturition and the birth season. The maximum age estimated by the surface method was 12 years but the oldest fish was aged at 35 years by the cross-section method. The surface method was inadequate for aging of S. vulpes older than 6 years because of the underestimation of age. No significant difference was found in the parameters of the growth equations between both sexes. The von Bertalanffy growth curve combined for both sexes was as follows: SL _t  = 358.6(1 − exp^{−0.156( t +0.820)}), where SL _t is standard length (mm) at age t (after parturition in years). It seems likely that S. vulpes grows slowly and lives longer than previously thought.     

Supplemental effect of <Emphasis Type="Italic">Porphyra</Emphasis> spheroplasts on the growth and feed utilization of black sea bream

ABSTRACT:   A 56-day feeding trial was conducted to evaluate the effects of Porphyra spheroplasts (PS) as a feed additive on growth, carcass composition and feed utilization of black sea bream. Four experimental diets with or without PS (0, 1, 3, 5% inclusion level) were formulated to determine the proper incorporation level for best growth and utilization using white fishmeal as the principal protein source. Three replicate groups of fish averaging 1.28 ± 0.05 g (mean ± SD) were maintained in flow-through thermo-controlled sea water (32–34 psu, 25°C) aquaria (100 L) under the laboratory conditions (L12 : D12) and fed three times a day at 09:00, 13:00 and 17:00 hours by hand at approximately 3% body weight on each diet. The rearing trial revealed that growth performance (in terms of weight gain, specific growth rate) are almost the same level in all the dietary groups, nevertheless the survival, nutrient utilizations and retentions (feed efficiency, protein efficiency ratio, protein retention rate, lipid retention rate) were significantly higher ( P  < 0.05) in a group fed on the diet containing 3% spheroplasts. Further, the fish fed on the diet containing PS had significantly higher ( P  < 0.05) crude lipid level in their dorsal muscles and viscera. The fish fed a PS-based diet showed higher level of eicosapentaenoic acid and docosahexaenoic acid (DHA) in viscera and DHA in dorsal muscles. The results obtained in this feeding trial suggest that the optimum dietary PS supplementation level up to 3% for black sea bream can be considered as improved consequence on growth performance, nutrient utilization or body composition were noticed.     

Juvenile growth of two tilapia species in lakes Naivasha and Baringo, Kenya

Abstract –  Tilapia species in East African lakes often form the basis of commercial fisheries, with information on their population biology assisting their management. This study utilised otolith microstructure, with validation by modal progression analysis, to provide growth data for two tilapia species in two Kenyan lakes for the first time. Otolith microstructure revealed the growth rate of Oreochromis niloticus baringoensis , a sub-species endemic to Lake Baringo, was fast compared with populations of Oreochromis niloticus ; mean daily growth rates were >0.50 mm·d⁻¹ in fish between 12 and 53 mm total length. Growth of Oreochromis leucostictus in Lake Naivasha was also relatively fast when compared with the growth rates of other tilapia species, with mean daily growth rates of approximately 0.35–0.48 mm·d⁻¹ in fish between 10 and 56 mm total length. Growth rates of both species were well described by the Gompertz model and were corroborated by modal progression analysis that revealed similar daily growth rates in modes of young-of-the-year fish.     

Age, growth and reproductive characteristics of round scad Decapterus maruadsi in the waters off west Kyushu, the east China Sea

ABSTRACT:   The purpose of this study was to determine the growth and reproductive characteristics of round scad Decapterus maruadsi in the East China Sea. The characteristics regarding growth and reproduction of round scad based on otolith reading and gonad histology, respectively, were estimated. The von Bertalanffy's growth model for round scad was estimated as follows:
FL _t  = 342[1 − exp{−0.55( t  + 0.58)}], (1 <  t  < 7)
where FL _t is fork length (mm) at age in years t . The maturation stage of the ovary was observed by histological techniques. June was the main spawning period; the maturation and migratory nucleus stage of the oocyte was observed when the gonad somatic index value was approximately greater than 4.     

基于Bootstrap的ELEFAN方法在评估方氏云鳚群体生长参数中的应用

渔业数据有限性是小型渔业资源评估所面临的常见问题。电子体长频率分析(electroniclengthfrequency analysis,ELEFAN)常用于年龄数据难以获取或缺失的渔业,但该方法的可靠性尚待检验。本研究根据2013―2018年春、秋季共11个航次的海州湾底拖网调查数据,分别使用传统的ELEFAN与结合Bootstrap的ELEFAN方法,比较了2013―2015年与2016―2018年两个时间段内海州湾方氏云鳚(Pholis fangi)群体von-Bertalanffy生长方程中参数之间的变化。结果显示,在海州湾海域,方氏云鳚的生长参数具有显著变化, 2013―2018年,群体的极限体长变小,生长速率加快,说明海州湾方氏云鳚群体近年来呈现小型化的趋势。相比传统的ELEFAN方法,结合Bootstrap的ELEFAN方法能够给出较为稳健的参数估计,受采样随机性的影响较小,可以较好地应用于数据缺乏的小型渔业中。本研究加深了对方氏云鳚种群动态的认识,并推动了基于体长频率的生长参数估算方法在数据有限资源评估中的应用。