Tree growth and stand development of four Populus clones in large monoclonal plots     

DEBELL  DEAN S.  HARRINGTON  CONSTANCE A.  CLENDENEN  GARY W.  ZASADA  JOHN C. 《New Forests》1997,14(1):1-18

Four clones of Populus were planted in replicated monoclonal plots near Olympia, WA, to evaluate their suitability for use in short-rotation culture. All clones were easily established and had minimal problems from damaging agents during the first five years. Observed differences among clones in pattern and amount of growth appeared to be associated with differences in number and density of buds, sylleptic branching, and phenology. In addition, differences in drought tolerance and stockability may also have influenced clonal differences in annual growth and stand productivity. Individual tree growth was limited by the dense 1.0-m spacing, but the best-growing clones averaged 13 to 16 m tall, 7 to 9 cm in breast-high diameter (1.3 m), and produced stand basal areas exceeding 38 m²ha^-1at 8 years. Mortality was negligible for 7 years, after which various combined effects of competition, stem borer damage (Cryptorhyncus lapathi), and a severe windstorm caused mortality ranging from 18 to 36% in the three fastest growing clones.  相似文献   

Influences of mean advection and simple behavior on the distribution of cod and haddock early life stages on Georges Bank   总被引：2，自引：0，他引：2  

FRANCISCO E. WERNER  FRED H. PAGE  DANIEL R. LYNCH  JOHN W. LODER  R. GREGORY LOUGH  R. IAN PERRY  DAVID A. GREENBERG  MICHAEL M. SINCLAIR 《Fisheries Oceanography》1993,2(2):43-64

Results of a modeling study designed to explore the influences of physical advection and certain biological mechanisms on the distribution of cod (Gadus morhua) and haddock (Melarwgrammus aeglefinus) early life stages on Georges Bank are described. Using a late-winter/early-spring 3-D circulation field driven by the M₂ tidal current, mean wind stress and Scotian Shelf inflow, we examine the distribution of cod and haddock larvae spawned on the Northeast Peak of the Bank. The sensitivity to a March-April baroclinic field is also explored. Results indicate that larvae remaining in the surface Ekman layer are generally advected off-bank. However, downwelling associated with Ekman layer convergence near the shelf break provides a mechanism for larvae to exit from the off-bank surface drift. Larvae below the surface layer are transported south-westward along the southern flank of Georges Bank and are retained on the Bank if their position immediately upstream of the Great South Channel is shoalward of (roughly) the 70 m isobath. Within the Great South Channel region and between the 50 and 70 m isobaths, retention can depend on the phase of the tide. Spawning shoalward of the 50 m isobath on the Northeast Peak greatly increases the chances of retention. These results apply to passive larvae and to those with specified vertical distributions and migration based on observations. Directional on-bank swimming at rates of 0.5 to 1 body length per second would substantially enhance shoalward displacement, resulting in larval distributions during the first 2 months that are consistent with field observations.  相似文献   

Eulerian views of layered water currents, vertical distribution of some larval fishes, and inferred advective transport over the continental shelf off North Carolina, USA, in winter   总被引：1，自引：0，他引：1  

JOHN J. GOVONI  LEONARD J. PIETRAFESA 《Fisheries Oceanography》1994,3(2):120-132

Currents that effect the shoreward transport of the larvae of estuarine-dependent fishes spawned in winter in Onslow Bay, North Carolina, USA, were driven by winds and pressure gradients, and influenced by the Gulf Stream. Aside from storms, winds over the continental shelf in Onslow Bay blew predominantly alongshore with velocities approaching 14 m s^-1 during February and March 1986, and January and February 1989. Water masses and currents observed at two current-meter moorings, one at mid-shelf and the other on the outer shelf, reflected the onshore (or offshore) advection of interior water in compensation for the offshore (or onshore) advection of wind-driven surface water. Winds and currents reversed direction approximately every 4 to 6 days. The larvae of Atlantic menhaden, Brevoortia tyrannus , spot, Leiostomus xan- thurus, and Atlantic croaker, Micropogonias undulatus , were most abundant in 17–19^oC and 20–21^oC water of the outer shelf and Gulf Stream fronts. There was little indication of diel vertical migration; larval Atlantic menhaden were most abundant in mid- and surface water, while spot and Atlantic croaker were most abundant in mid- and deep water. Given this distribution, the inferred advective transport of larvae was at times onshore, but at other times it was offshore. Within a spawning season, the prevalence of either reciprocation could determine the number of larvae that reach coastal inlets.  相似文献   

Sampling error resulting from depth-dependent plankton distributions and current differentials in a two-layered system     

JOHN T. ANDERSON†  IAN T. WEBSTER‡ 《Fisheries Oceanography》1992,1(3):208-215

We evaluate a source of error observed in standard ichthyoplankton bongo tows in which volumes of water filtered did not result in increased catches of red-fish. Our analyses demonstrate that, under conditions where redfish larvae are distributed in surface waters in a two-layered system, current differentials between surface and subsurface layers resulted in biased, standardized estimates of larval abundances as a result of filtering varying amounts of subsurface waters. Analysis of standard survey results on Flemish Cap demonstrated that this source of bias was limited to the May-June period, after waters became stratified and before redfish passed from the larvae to pelagic juvenile stage. Correcting for this source of sampling bias wIII result in more accurate absolute estimates of ichthyoplankton abundance, and we estimate that variation (CV) for replicate samples may be reduced by 10%.  相似文献   

The effect of organic fertilizer and formulated feed in pond culture of the freshwater prawn, Macrobrachium rosenbergii (de Man): prawn production     

MARLIE H. MACLEAN  K. J. ANG  JANET H. BROWN  K. JAUNCEY 《Aquaculture Research》1989,20(4):399-406

Abstract. The potential of organic fertilizer as a partial replacement for formulated feeds in pond culture of Macrobrachium rosenbergii (de Man) was assessed. Stocking densities reflected commercial semi-intensive levels and the duration of the trial approached a complete grow-out cycle. Mean weight and growth rate were examined in four treatments receiving varying levels of feed and manure. Heaviest prawns and fastest growth were evident in the treatment with decreased-feed-increased-manure. Production assessed as marketable percentages (74.56, 52.21, 13.28 and 11.12) resulted in significantly different marketable yields of 2029, 1284, 336 and 103 kg/ha/year for decreased-feed-increased-manure, feed-plus-manure, feed-only, and manure-only respectively assuming 2-6 batch cycles per year under prevailing conditions. Total survival was significantly highest in feed-only (72.80%), intermediate in feed-plus-manure (40.59%) and decreased-feed-increased-manure (36.32%), and lowest in manure-only (26.77%) treatments. Prawns were separated at harvest into four morphotypes as berried females, females without eggs, immature males and adult males. Average individual weight and group bicmass were determined for each morphotype.
Only prawn production data are presented here. Analyses of water, soil and benthic fauna will be presented in future publications.  相似文献   

Adherence, haemagglutination and cell surface characteristics of motile aeromonads virulent for fish   总被引：4，自引：0，他引：4  

F. DEL  CORRAL  E. B. SHOTTS JR  J. BROWN 《Journal of fish diseases》1990,13(4):255-268

Abstract. Motile Aeromonas spp. virulent for fish were studied with regard to their adhesion profile. Electron microscopy demonstrated the presence of fimbriae (pili) on Aeromonas cells regardless of virulence potential. The results show no significant correlations between ability to haemagglutinate, yeast cell co-agglutination and virulence. All strains expressed mannose-sensitive haemagglutinin activity against guinea pig erythrocytes. Using four types of red blood cells no characteristic haemagglutinin pattern related to virulence could be discerned. Expression of surface haemagglutin(s) on Aeromonas hydrophila appears to be medium dependent; strains grown in liquid media demonstrated enhanced haemagglutination activity. Both virulent and avirulent strains had in vitro epithelial cell adhesive capabilities. Cell surface characteristics measured by agglutination in acriflavine and stability after boiling indicated that most virulent strains agglutinated in the presence of acriflavine, but not all sedimented after boiling. The ability of 10 selected strains of A hydrophila to grow in normal pooled catfish serum was determined. Only 17% of the virulence variations can be explained by their sensitivity to serum.  相似文献   

Pathology of experimental infections of the sablefish, Anoplopoma fimbria (Pallas), with Renibacterium salmoninarum, the agent of bacterial kidney disease in salmonids     

G. R. BELL  R. W. HOFFMANN  L. L. BROWN 《Journal of fish diseases》1990,13(5):355-367

Abstract. The susceptibility of sablefish, Anoplopoma fimbria (Pallas), a potential candidate for commercial mariculture, to the devastating salmonid pathogen Renibacterium salmoninarum (Rs) and the pathology of the infection were investigated. Sablefish became moribund or died of apparently uncomplicated infections of Rs within 50-71 days following intrapcritoncal inoculation of the pathogen and pure cultures of Rs were re-isolated from some affected individuals. At least one sablefish carried the pathogen up to 165 days post-inoculation when the experiment was terminated. The pathology of the Rs infection in this strictly marine fish is described and the implication of the findings to the operation of salmon marinefarms is discussed.  相似文献   

An assessment of yellow perch, Perca flavescens, stocking contributions in eastern South Dakota lakes     

M. L. BROWN  T. St. SAUVER 《Fisheries Management and Ecology》2002,9(4):225-234

The success and value of yellow perch, Perca flavescens (Mitchill), stocking programmes are largely unknown because of the difficulties in differentiating between naturally recruited and translocated stocks. To determine stocking contributions of yellow perch, fingerlings and adults were collected from natural rearing ponds in south-eastern South Dakota. Prior to stocking, all fish were marked for 6 h in transfer tanks containing 700 mg L⁻¹ oxytetracycline hydrochloride. Six lakes containing yellow perch populations were supplemented at low, medium and high stocking densities of about 25, 135 or 200 fish ha⁻¹, respectively. Yellow perch populations were subsequently sampled with experimental gill nets during late summer; two lakes were resampled with additional gears (electric fishing, trap nets and cloverleaf traps). Yellow perch were processed for routine measurements, and saggital otoliths were removed to determine the origin of the fish. Stock contribution estimates determined from gill-net samples for Island (low), Oak (low), Twin (medium) and Wall (high) lakes were approximately 18, 5, 41, and 38%, respectively. Samples from other gears provided stock contributions of 15 and 10% for Cavour Lake and 41% for Diamond Lake (high density stockings). Although these results showed that supplemental stockings were successful, variability in stock contributions among populations indicates a need for further assessment of variables that may influence the stocking success of yellow perch.  相似文献   

Age-dependent accumulation of macrophage aggregates in the yellow perch, Perca flavescens (Mitchill)     

C. L. BROWN  C.J. GEORGE 《Journal of fish diseases》1985,8(1):135-138

  相似文献   

Evaluation of two soybean meals fed to yellow perch (Perca flavescens)     

C.S. KASPER  B.A. WATKINS  & P.B. BROWN 《Aquaculture Nutrition》2007,13(6):431-438

Aquaculture of yellow perch (Perca flavescens) has been increasing, yet there have been few nutritional studies and no evaluations of alternative protein sources in diets. Solvent‐extracted, dehulled soybean meal (SBM) and expelled‐extruded soybean meal (exSBM) were fed to yellow perch to evaluate their effectiveness in replacing dietary fish meal (FM) in isonitrogenous practical feed formulations. Both soy ingredients were incorporated in graded amounts from 100 to 730 g kg⁻¹ of the diet. Feed consumption, weight gain, feed efficiency (FE) and survival were significantly affected by type of soy ingredient, concentration and the interaction of the two main effects. Consumption was significantly lower in fish fed diets containing 400, 600 and 730 g kg⁻¹ compared to fish fed diets containing lower concentrations. Weight gain was significantly lower in fish fed diets containing 600 g kg⁻¹ and FE significantly lower in fish fed diets containing 500 g kg⁻¹ compared to fish fed the control diet or lower concentrations of soy ingredients. Most fatty acid concentrations were affected by feeding exSBM compared to fish fed the control diet, but long chain fatty acids remained at relatively high concentrations. Based on feed consumption, weight gain and FE data, yellow perch are able to effectively utilize both soy ingredients in practical diets. A conservative recommendation of 300 g kg⁻¹ diet appears appropriate for growout diets.  相似文献