摘要:

The one-dimensional channel equations with linear bottom friction are integrated numerically to determine the modification of the M2tide for several cases of barriers in the bay. The barriers are treated as "complete barriers" in the sense that no flow is permitted through them.

ISSN:0706-652X    

DOI:10.1139/f69-274

出版商:NRC Research Press    

年代:1969

数据来源: NRC

摘要:

Effects of high, medium, and low levels of copper on the morphology of winter flounder were investigated using routine histological techniques and electron microscope analyses.High and medium levels of copper resulted in fatty metamorphosis in the liver, necrosis in the kidney, destruction of the hemopoetic tissue, and gross changes in gill architecture. Seven other structures and organs were examined for copper-induced morphological changes but none were found.Light microscope studies showed that low levels of copper caused an extracted appearance in gill lamellae; the epithelial layer appeared vacuolated; the basi-lamellar region was reduced in thickness. Lamellar mucus cells were few compared with control specimens and chloride cells appeared in their stead.Electron microscope study of gill lamella from fish exposed to low levels of copper confirmed vacuolation in the epithelial layer. Also found were myelinlike figures, various membrane-bound vesicles, and apical homogeneous layers of reduced thickness. Increased amounts of particulate matter adhering to the external surface of the epithelial cells were apparent. Chloride cells were found instead of mucus cells.

ISSN:0706-652X    

DOI:10.1139/f69-275

出版商:NRC Research Press    

年代:1969

数据来源: NRC

摘要:

Egg production by two cyprinids in the River Thames at Reading, England, was studied quantitatively from January to June 1966. Roach (Rutilus rutilus) had a short spawning period, shedding all their eggs in one batch, whereas bleak (Alburnus alburnus) had a protracted spawning period and produced two or three batches of eggs. The relationship between egg numbers (Y) and age (X) for roach was given by log Y = 0.0840X + 3.2085; the estimated fecundity of a 6-year-old fish was 5157 with 95% confidence limits at 4725 and 5631. For bleak the relationship was log Y = 0.0564X + 3.5221, and the estimated fecundity of a 5-year-old fish was 6356 with 95% confidence limits at 5987 and 6776. Combining previously obtained data on population density with new data on sex ratio and percentage breeding in each age class, the population fecundity for roach was about 600 eggs/m2and for bleak about 3000 eggs/m2.The roach population had lower fecundity than roach populations in other studies and there was some evidence that a proportion of females ceased egg production during the period of the study. The possibility that low fecundity was a response to food shortage is discussed.

ISSN:0706-652X    

DOI:10.1139/f69-276

出版商:NRC Research Press    

年代:1969

数据来源: NRC

摘要:

Oxygen consumption ofTilapia nilotica(L.) at 25 C was measured for various swimming speeds at salinities of 0, 7.5, 11.6, 22.5, and 30‰.Oxygen consumption for a given swimming speed and salinity increased linearly with weight when expressed on a double logarithmic grid. Slopes of regression lines relating oxygen consumption and weight were less than unity, ranging from 0.5117 to 0.9887.Generally, oxygen consumption at 0, 7.5, and 22.5‰ was approximately equal; values at 11.6‰ were lowest and those at 30‰ highest. Presumably, energy required for osmoregulation was least in the absence of an osmotic gradient (11.6‰) and greatest when the osmotic gradient was highest (30‰). Assuming energy required for osmoregulation was zero at the isosmotic salinity (11.6‰), it was estimated that approximately 29% of the total oxygen consumption was required for osmoregulation at 30‰ and 19% at 0, 7.5, and 22.5‰.Plasma osmotic concentration was used as an index of capacity for osmotic regulation. Concentrations for unexercised fish remained about the same at 0, 15, and 30‰. At no salinity were plasma osmotic concentrations for exercised and unexercised fish statistically different atP < 0.05. However, there was a trend for concentrations for exercised fish to decrease from the unexercised level at 0‰ and to increase from the unexercised level at 30‰. Only at 15‰ were concentrations similar for exercised and unexercised fish. Of the salinities tested, fish were able to osmoregulate most efficiently at 15‰, the salinity closest to the isosmotic salinity.

ISSN:0706-652X    

DOI:10.1139/f69-277

出版商:NRC Research Press    

年代:1969

数据来源: NRC

摘要:

This study was initiated to determine changes in chemical composition, coefficient of condition, and body morphology for juvenile steelhead trout from premigratory through postmigratory periods, January through July. Winter-run steelhead trout, originating from Big Creek and the Sandy River, in Oregon, were used as experimental animals.A discriminant analysis indicated that coefficient of condition and fork length were nearly as powerful in separating smolts from parr as were 10 morphological measurements.The parr–smolt transformation in winter steelhead is size-dependent and characterized by a marked decrease in body depth and coefficient of condition. Changes in depth measurements and coefficient of condition provided the most meaningful measure of morphological change at the time of parr–smolt transformation.During the migratory period, lipid content was substantially lower than in the premigratory period for migrant-sized fish (≥ 160 mm) but remained relatively constant in nonmigrants (≤ 159 mm) throughout all periods. Seasonal changes in moisture and protein levels occurred in the larger fish, although moisture and protein content for the smaller fish remained relatively constant. The amount of ash did not change within a size group.The coefficient of condition of migrant-sized fish declined continuously from February through May but increased in June and July. The mean coefficient of condition for nonmigrants declined from December through February, but remained relatively stable from March through June, with an upward trend in July.

ISSN:0706-652X    

DOI:10.1139/f69-278

出版商:NRC Research Press    

年代:1969

数据来源: NRC

摘要:

A nonstationary Markov chain was developed to analyze and model the passage of energy through an ecological system composed of the Pacific sardine, the northern anchovy, their competitors, their predators, and their prey; then to carry the model forward through time projecting the biomasses of the relevant species if anchovy or hake fisheries, or both, are begun. The model seemed to agree adequately with observed data.The hypothesis of some earlier work of the author that the abundances of populations could be completely controlled by fishing intensities was rejected. Although no measure was made of the robustness of the ecosystem, it was concluded to be relatively impervious to artificial pressures, although there was seen a measurable boundary beyond which the ecological interactions became unstable and the system collapsed.Specifically, based on 1950–59 data, the sardine catch was projected to stabilize in the vicinity of 20 metric kilotons per year. Overfishing did not seem to have been a cause of the sardine "disappearance." To maximize sardine catch, the introduction of anchovy and hake fisheries with annual catches limited to certain percentages (depending on the maximizing criterion) of abundances would double or triple sardine catch and stabilize the fishing industry, but sardines couldnotbe reinstated as the most abundant species as a result of selective fishing. To maximize the combined catch of the three fisheries, annual catches of 30% and 20% (for all criteria) of abundances of anchovy and hake, respectively, would yield nearly 1800 metric kilotons of fish, although most of it would be of less commercial interest than the sardine.

ISSN:0706-652X    

DOI:10.1139/f69-279

出版商:NRC Research Press    

年代:1969

数据来源: NRC

摘要:

A hematological study was made based on 10 specimens each of the buffalofishesIctiobus cyprinellusandI.bubalus(Catostomidae). Average results of analyses of selected blood characteristics ofI.cyprinellusandI.bubalus, respectively, were: hemoglobin content, 7.8 and 8.5 g/100 ml; erythrocyte count, 1.08 and 1.28 millions/mm2; hematocrit, 34.6 and 32.9%; mean corpuscular hemoglobin, 67 and 64 μμg; and leucocyte count, 23916 and 29004 cells/mm3. Types of leucocytes noted were lymphocytes, neutrophils, "secretory granulocytes," eosinophils, and thrombocytes. No basophils were found. The secretory granulocyte is apparently derived from the neutrophil series. The status of the secretory granulocyte in buffalofishes is discussed with reference to pertinent literature.

ISSN:0706-652X    

DOI:10.1139/f69-280

出版商:NRC Research Press    

年代:1969

数据来源: NRC

摘要:

Considerable progress has been made in the understanding of the concepts underlying the exploitation of tidal energy during the last 20 years; this progress has culminated in the actual construction of a tidal plant at the mouth of the Rance River near St. Malo, France. Since the Bay of Fundy is one of the largest reservoirs of tidal energy in the world, the theory of exploitation of tidal energy has been reviewed with a view to its application to the Bay of Fundy.The rate of change of the energy contained in an oscillating mass of water in a basin on a rotating earth can be written out using the equations of hydrodynamics. The concept of power transfer arises immediately, which enables one to follow the transit of power from one part of the basin to another. This makes it possible to establish a balance of the power present in the basin.Only the potential energy present in the tide can be profitably exploited, and it is obtained by enclosing part of the basin by a dam in which some turbines and pumps are imbedded, as well as some complementary sluices. The emptying and filling of the enclosed part of the basin through the turbines during the fall and rise of the sea leads to the production of energy. The upper bounds of the energy available in this way can be easily established and it can also be readily shown that the use of pumps increases the amount of energy available. The actual amount of energy drawn from the reservoir is limited by the smaller range of the tide inside the reservoir and the efficiency of the turbines. The timing and duration of the various operations involved in the operation of a tidal plant, pumping, generating power, opening or closing the sluices, waiting for a head to develop, can be studied quantitatively.For this purpose the type and number of fundamental operations are carefully studied and accurate definitions are given of them, permitting calculations on a number of possible sequences of operations up to 25 tidal periods. The number of possible sequences is very large and it is not possible to study all of these sequences individually.Under some circumstances a given sequence of operations for the actual times of starting and stopping the turbines, starting and stopping the pumps, opening and closing the sluices, waiting for a head, and the changes of level inside the reservoir can be calculated with the help of the calculus of variations. For instance, these quantities yield to systematic calculation if the plant is operated with the purpose of producing the maximum amount of energy. The calculus of variations, however, cannot help directly when other modes of operation are considered, such as operating the plant in such a way as to supply power only during peak demand.The response of the basin to the oscillating ocean will be altered after the construction of the reservoir needed for the operation of the tidal plant. This modification may be important when the plant draws considerable amounts of energy from the tide.With the help of the concepts developed it becomes an easy task to make a balance sheet for the tidal power present in the Bay of Fundy, restricting ourselves to M2, the main lunar semidiurnal constituent that is representative of average conditions. Many sites in the Bay of Fundy are found to be suitable for the generation of energy; some involve relatively simple engineering and yield modest amounts of energy such as the Digby site; others, such as the Minas Channel site, could yield very considerable amounts of energy but the engineering difficulties associated with their construction might prove prohibitive.

ISSN:0706-652X    

DOI:10.1139/f69-281

出版商:NRC Research Press    

年代:1969

数据来源: NRC

摘要:

Growth rates ofMonochrysis lutheriDroop increased with light intensity in seawater medium (SWM), whereas cells grown at either low NaCl (0.013 M) or high NaCl (1.02 M) showed reduced growth at higher light intensities with an optimal intensity near 0 05 g cal/cm2per min.Chlorophyll and total carotenoids usually declined with increasing light intensity except in cells maintained on a high salt regime, when the carotenoid content remained high at all light intensities.The concentration of intracellular cyclohexanetetrol in SWM cells was approximately 0.3 Mand was dependent upon the osmotic properties of the medium. Added NaCl, mannitol, sucrose, but not glycerol, caused accumulation of the cyclitol, whereas dilution of the medium caused its expulsion from the cells. Addition of 0.5 moles/liter of NaCl to SWM cells caused an 80–90% increase in cyclitol concentration within 4 hr; dilution of the medium reduced the cyclitol to the new steady state level within 10 min.

ISSN:0706-652X    

DOI:10.1139/f69-282

出版商:NRC Research Press    

年代:1969

数据来源: NRC

摘要:

The chemical composition and yield of edible shrimp (Parapenaeusspp.) were determined. Shrimp of 15.5–23.4 cm and mean weight of 37.3 g yielded from 47.2 to 55.1% of flesh (mean 51.3%). Average composition of flesh was: water 76.74%, fat 0.91%, ash 1.71%, total phosphorus 0.49%, and total protein 22.07%, the last being made up of 76.5% pure protein. Shrimp flesh protein contained a large amount of arginine, histidine, and proline, but not so much threonine, methionine, valine, lysine, and tryptophane. Amine nitrogen constituted 39.5% of the total nonprotein nitrogen. Its composition was mainly of the following free amino acids: glycine, arginine, proline, and alanine. In contrast to the flesh of fish, that of shrimps contained a considerable amount of free methionine.

ISSN:0706-652X    

DOI:10.1139/f69-283

出版商:NRC Research Press    

年代:1969

数据来源: NRC