Marine fish life history strategies: applications to fishery management

The life history traits of 42 marine fish species were grouped according to the theoretical classifications of life history strategies. This provides a conceptual framework of management options, because life history strategies are the underlying determinants for population responses to climate and ocean changes, they can be used to classify typical population responses. When faced with providing management advice for species for which there is no information on absolute or relative biomass, such as newly exploited species, life history traits can be used to classify the species into a strategist grouping and the appropriate management options can be selected from the conceptual framework.     

Automated image analysis as a tool to quantify the colour and composition of rainbow trout (Oncorhynchus mykiss W.) cutlets

The goal of this paper is to propose and evaluate automated image analysis methods for describing muscle cutlets in rainbow trout. The proposed automated image analysis methods were tested on a total of 983 scanned images of trout cutlets, and included quality traits such as fat percentage, flesh colour and the size of morphologically distinguishable subparts of the cutlet. A sub-sample of 50 images was randomly selected for manual segmentation of the cutlet, the dorsal fat depot and the red muscle and regions. The identification of these regions by manual and automatic image analysis correlated strongly (r = 0.97, r = 0.95 and r = 0.91, respectively). The estimated fat percentage obtained from image analysis, based on the area of visible fat and the colour of the cutlet flesh, correlated well with chemical fat percentage measured by mid-infrared transmission spectroscopy (MIT) (r = 0.78). The automated image analysis methods are therefore a reliable means of predicting the fat percentage of trout cutlets. Principal component analysis (PCA) loading plots were used to identify subsets of variables from the image analysis of special significance for further studies; cutlet area, dorsal fat depot area, red muscle area, back height, cutlet width, and width of left and right abdomen wall were among the variables selected. PCA loading plots of different colour variables indicated that simple statistical coefficients such as percentiles and mean values can be used to quantify different aspects of flesh colour. In conclusion, the methods presented here provide a powerful toolbox for describing important morphological structures and quality traits of trout cutlets.     

Genetic covariation in production traits of sub-adult black bream Acanthopagrus butcheri after grow-out

Predicting the suitability and reliability of traits associated with juvenile growth as indirect selection criteria for choosing future broodstock requires accurate and repeatable estimates of genetic (co)variation for growth traits at different ages. We compared juvenile wet weight of black bream Acanthopagrus butcheri (Munro) at 6 months of age with wet weight, dressed weight, fillet yield and gonad weight in tagged individuals at 18 months of age, following 12 months of farm grow‐out. Fish survival and tag retention was high, and there was significant among‐family variation for all traits. The phenotypic correlations among wet weight, dressed weight and fillet yield at 18 months of age were very high (0.93–0.97) and similar to their genetic correlations (0.96). Importantly, the phenotypic correlations between wet weight at 6 months and wet weight, dressed weight and fillet yield at 18 months were high (0.63–0.65), and so too were their genetic correlations (0.66–0.73), indicating the potential for using wet weight in the hatchery as a selection criterion for improved weight and meat yield of fish at harvest. Gonad weight shared little or no phenotypic or genetic correlation with these other traits, suggesting that selection for faster growing fish will not affect fecundity or sexual maturation rate. It appears, however, that cultured black bream do become sexually mature more rapidly than wild fish, as 78% of all fish harvested in this study had developing or mature gonads, whereas less than 50% of fish in wild populations are reproductively mature by the same age. Precocious sexual development may lead to uncontrolled spawning in grow‐out ponds and a potential loss of selection gains.     

Reproductive performance of cultured brown trout (Salmo trutta L.) in Chile

Data on reproductive traits in a cultured population of brown trout (Salmo trutta L.) in southern Chile were collected over three consecutive reproductive seasons: 1999, 2000 and 2001, corresponding to the first (at 3 years), second and third spawnings in females. Data were collected from individual females (n=238, 273 and 169 respectively). The reproductive season lasted mainly from June to August. The peak (July) tended to increase with each season (55.46%, 62.27% and 80.81% of total spawning fish respectively). Female body weight (470.8±102.5, 735.0±150 and 1263.9±263.4 g), total fecundity (1182±344, 1904±595 and 2744±605) and egg diameter (4.64±0.11, 4.67±0.27 and 5.24±0.12 mm) increased significantly (P<0.01) over successive reproductive seasons, particularly between the second and third spawnings. Relative fecundity, on the other hand, decreased significantly with each season (3577±471, 2591±900 and 2181±360). Following analysis of the variables over the three seasons, the correlation pattern of female body weight with total fecundity (r=0.91, n=458; P<0.001) and relative fecundity (r=?034, n=451; P<0.001) proved similar to that described in other salmonid females. Fertilization rate and survival to the eyed egg stage were also positively correlated (r=0.73, n=453; P<0.001). The systematically high values obtained for these latter variables over the seasons evaluated (consistently above 90%) are clearly greater than those we registered in other species of salmonids bred in Chile under similar conditions and suggest highly efficient biological variables that determine the gamete fertilization of this species. The brown trout is, therefore, an interesting potential aquaculture resource in Chile.     

热带水稻优异种质资源的表型遗传多样性分析

有效管理和充分挖掘遗传多样性丰富的稻种资源对水稻育种具有重要意义。利用15个表型性状对来自9个热带国家和地区的127份热带水稻育种优异种质进行综合评价,比较分析不同来源热带水稻优异种质的表型差异和遗传多样性指数。结果表明：热带水稻种质资源表型性状差异明显,数量性状的变异系数为7.0%～23.8%,平均为12.04%,其中单株穗数比较大,谷粒长较小;Shannon-Wiener多样性指数分析结果表明,15个表型性状遗传多样性指数变化为0.603～2.066,平均为1.579,其中每穗总粒数比较高,穗型较小;9个不同来源地的热带水稻资源多样性指数为0.780～1.547,平均为1.219。不同来源的热带水稻种质各性状变异范围较大,各性状间存在显著差异,遗传多样性指数较高,可进一步发掘优异资源和有利基因,为培育和筛选优良热带水稻品种提供亲本来源。     

23份耐寒腰果种质农艺性状分析初报

对23份耐寒腰果种质的坚果产量、坚果重量、坚果大小、坚果出仁率、果仁重量等农艺性状进行了综合分析比较。结果表明,其中17份腰果种质的农艺性状表现优良,可进入下阶段的种质比较试验。     

Effects of N and K fertilizers on durum wheat quality in different environments

Eight genotypes from two different genetic pools (high yielding varieties and landraces) were assessed for grain yield (GY) and for five quality traits: protein content (P), thousand kernel weight (TKW), yellow berry (YB), gluten content (G_c) and gluten index (G_i) in sub-humid and semi-arid areas using four combinations of nitrogen and potassium fertilizers during two cropping seasons. Genotype × Environment × Fertilizers (G × E × F) was significant only for protein content (p < 0.05); and E × F was found significant (p < 0.05) for all parameters. Greater quality related traits expression was noted in the semi-arid areas for both genetic pools. Excessive rainfall in semi-arid areas resulted in gluten elasticity reduction. N-fertilizers seemed to enhance protein content and to reduce thousand kernel weight. K-fertilizer, might enhance the increase in both proteins and thousand kernel weight in favorable growing conditions of water availability. Semolina yielding ability was higher in landraces as compared to high yielding varieties particularly using recommended fertilizer management. This group of cultivars showed superiority over high yielding cultivars for quantitative quality parameters.     

不同施肥方式对早植烟生长发育的影响

为提高早植烟移栽施肥技术水平,通过对早植烟移栽时散施农家肥、条施中层肥、环施中层肥3种施肥方式进行大田小区对比试验。结果表明：环施中层肥能使早植烟生长高峰期提前,整个生育周期延长约10 d,农艺性状、经济性状与对照组差异显著,环施中层肥对提升早植烟种植水平有一定指导意义。     

不同类型果林间套播花生性状的相关分析和因子分析

通过花生品种花育31号在新疆和田地区农科所4种果林间的套播栽培试验,对调查的6个性状的数据利用DPS软件进行相关分析和因子分析,探讨在不同果林中套播花生性状间的相互关系及其差异,并对性状因子结构和因子中主要载荷性状间的关系进行分析,评价在不同果林间花生套播种植的效果。结果表明,在4种果林中套播种植花生时,以在3年生红枣林中产量最高,效益最好;在7年生红枣林中产量位列第二;对6个性状的相关分析和因子分析结果表明,在相应的4个类型的果林中套播种植花生时,不同果林中的花生性状之间的相关关系、性状的因子结构和因子内主要载荷性状间的关系均发生了较大变化。