On the Biology and Fishery of the Canadian Atlantic Halibut, Hippoglossus hippoglossus L.

1958 ◽  
Vol 15 (6) ◽  
pp. 1269-1311 ◽  
Author(s):  
F. D. McCracken
Keyword(s):  
Nova Scotia ◽  
Deep Water ◽  
Early Spring ◽  
Large Female ◽  
Late Winter ◽  
Atlantic Halibut ◽  
Large Numbers ◽  
Water Edge ◽  
Mature Fish

Exploratory fishing in the northern Gulf of St. Lawrence in 1945 and 1946 and off western Nova Scotia in 1947 caught 739 halibut, of which 229 were tagged and released. About 590 fish from the commercial fishery of the two regions were also examined.Larger, older halibut were caught in the northern part of the Gulf of St. Lawrence than off western Nova Scotia. Tagged halibut recaptures, size and age composition of commercial landings, and differences in rate of growth suggest generally separate stocks in the two regions.Younger, immature halibut were most available in shallower water; larger, mature fish usually in deep water. Most halibut were caught at temperatures between about 3° and 9 °C. Seasonal, inshore, relatively shallow water halibut fisheries in the northern part of the Gulf of St. Lawrence and off western Nova Scotia occur as the bottom water warms. Large female halibut predominate in such catches.Mature halibut, about 9 to 11 years and older, must spawn in late winter and early spring, probably along the deep-water edge of the banks. Mature halibut grow slowly though the females exceed the mature males and reach a much larger size. The faster-growing, immature halibut of both sexes grow at about the same rate.Halibut landings from ICNAF Subareas 3 and 4 which were at a low level between 1940 to 1948 increased sharply to about 13 million pounds in 1950. More recent landings approximate the long-term annual average of about 5 million pounds. Changes in the level of landings are related to changes in the magnitude of the Canadian fishery which, since 1940, has produced most of the halibut from Subareas 3 and 4.Offshore and inshore fisheries specifically for large halibut produce most of the landings. Catches of halibut taken incidentally in other fisheries contribute little by weight but take large numbers of small, faster-growing individuals. With a continuation of present fishing practices and intensities an annual yield of about 5 million pounds may be expected to continue, but some increased yield might result from controlling the incidental catches of younger halibut. Ways and means of effecting such control should be explored.

The productivity of breeding ewes grazing on lucerne or grass and clover pastures on the tablelands of Southern Australia. III. Lamb mortality and weaning percentage

1984 ◽  
Vol 35 (5) ◽  
pp. 709 ◽  
Author(s):  
JR Donnelly
Keyword(s):  
Early Spring ◽  
Practical Significance ◽  
Cold Weather ◽  
Late Winter ◽  
Maternal Weight ◽  
Risk Of Death ◽  
Probability Of Death ◽  
The Difference ◽  
Stocking Rates

Weaning percentage and perinatal mortality of lambs born in late winter or early spring to Merino and Border Leicester x Merino ewes grazing at several stocking rates on lucerne or phalaris-clover pastures were measured over 2 years. Weaning percentages for mature crossbred ewes declined linearly from 136 lambs per 100 ewes joined when stocked at 9 ha-1 to 100 for those at 18 ha-1. For mature Merino ewes, the values were 109 and 70 respectively. Weaning percentages were similar on lucerne and phalaris pastures, although 8% more lambs were born to ewes grazing on phalaris; higher mortality in lambs born as multiples eliminated the difference. Death from exposure during the first 3 days of life was the most important cause of lamb losses. For lambs born as singles to Merino ewes the probability of death from exposure was up to 0.4, and reached 0.6 for lambs born as multiples. For single and multiple lambs born to crossbred ewes equivalent probabilities were 0.25 and 0.4 respectively. These probabilities were reduced if maternal weight was high at lambing, the reduction being of practical significance in very cold weather, particularly if the proportion of multiple births was high. Under mild conditions, where the probability of death from exposure was low, reductions in mortality from high ewe weight at lambing were of little consequence. Long-term weather records kept at the experimental site near Canberra show that a high risk of death in new-born lambs is likely from early June to mid-September. Throughout this period deaths from exposure could be expected to exceed 30% in lambs born as multiples to Merino ewes.

Long-term changes in the frost-free season on the Canadian prairies

2004 ◽  
Vol 84 (4) ◽  
pp. 1085-1091 ◽  
Author(s):  
Herb Cutforth ◽  
EG (Ted) O’Brien ◽  
Jason Tuchelt ◽  
Rick Rickwood
Keyword(s):  
Climate Change ◽  
Early Spring ◽  
Late Winter ◽  
Past Century ◽  
Canadian Prairies ◽  
Spring Frost ◽  
Growing Seasons ◽  
Spring Frosts ◽  
Agricultural Regions

The climate of the prairies has warmed over the past century, especially during late winter and early spring. Some regions of the prairies have warmed faster than others. Climate change has been documented to affect living systems in North America, such as promoting earlier phenological development and longer growing seasons. We examined weather records gathered at several long-term weather-recording sites across the agricultural regions of the Canadian prairies for evidence of trends in last spring frosts, first fall frosts, and frost-free durations. During the latter half of the 20th century, the trends were towards earlier last spring frost dates and towards longer frost-free seasons in the agricultural regions of the Canadian prairies. Across most of the prairies the trends towards later first fall frost dates were smaller and generally not significant. The largest changes have occurred in the central and northern agricultural regions of Alberta, whereas the least change occurred over much of southern Alberta and in southern Manitoba. Key words: Last spring and first fall frost dates, frost-free season, agroclimatic indices, climate change, Canadian prairies

Effect of the Outflow from the Gulf of St. Lawrence on Nova Scotia Shelf Zooplankton

1992 ◽  
Vol 49 (5) ◽  
pp. 857-869 ◽  
Author(s):  
D. D. Sameoto ◽  
A. W. Herman
Keyword(s):  
Nova Scotia ◽  
Surface Water ◽  
Large Population ◽  
Early Spring ◽  
Zooplankton Biomass ◽  
Shelf Break ◽  
Late Winter ◽  
Scotian Shelf ◽  
Calanus Glacialis

Significant differences in concentrations (per square metre) of the copepods Calanus glacialis and C. hyperboreus found between the northeastern (NE) and southwestern (SW) halves of the Scotian Shelf were apparently related to the Gulf of St. Lawrence outflow. This outflow introduces these species to the Shelf during late winter and early spring and is probably responsible for maintaining their populations on the Shelf. Deep basins on the NE half of the Shelf are also sources of breeding animals of these two species. The influence of the Gulf outflow on C. finmarchicus was less clear because a large population of this species was found in the basins and beyond the Shelf break. Temora was the only other copepod genus to show a relationship with the Gulf outflow, indicating that it is carried onto the Shelf from the Gulf. The outflow dominated the surface water of the NE Shelf over the entire year; its influence was less marked on the SW Shelf due to mixing with slope water. This mixing in turn dilutes the concentrations of the Gulf Calanus spp. introduced by the Nova Scotia Current. The Gulf outflow is responsible for the high zooplankton biomass concentrations on the NE Shelf in June and October.

Mouse plagues in South Australia cereal-growing areas III. Changes in mouse abundance during plague and non-plague years, and the role of refugia

1991 ◽  
Vol 18 (5) ◽  
pp. 593 ◽  
Author(s):  
GJ Mutze
Keyword(s):  
Survival Rates ◽  
South Australia ◽  
Breeding Population ◽  
Early Spring ◽  
Late Spring ◽  
Late Winter ◽  
Population Declines ◽  
Population Changes ◽  
Railway Line ◽  
Large Numbers

Mouse populations were monitored at 15 sites between 1980 and 1990, during which time one severe mouse plague, in 1980, and one minor outbreak, in 1984, were recorded. Smaller annual peaks in autumn to early winter were followed by winter population declines. Crops were colonised each year in late winter or early spring by mice from winter refuge habitats with dense, low vegetation, including roadsides and grassland along a railway line. In most years mouse numbers in crops declined during summer, but in 1983-84 they rose continuously during summer and autumn, and reached very high levels. Crops planted in 1984 were invaded by large numbers of mice which had survived through winter in the paddocks, but population levels again crashed in late spring and summer. Recorded population changes were generally consistent with plague probabilities predicted from environmental variables, except in 1985 when numbers failed to reach the predicted high levels at most sites. Population changes in crops during late spring appear to be critical in the development of mouse plagues. Large litter sizes and pregnancy rates, and variable survival rates and size of the breeding population, appear to be important factors at that time.

Climate change in the semiarid prairie of southwestern Saskatchewan: Late winter–early spring

1999 ◽  
Vol 79 (3) ◽  
pp. 343-350 ◽  
Author(s):  
H. W. Cutforth ◽  
B. G. McConkey ◽  
R. J. Woodvine ◽  
D. G. Smith ◽  
P. G. Jefferson ◽  
...  
Keyword(s):  
Climate Change ◽  
Early Spring ◽  
Late Winter ◽  
Spring Temperature ◽  
Spring Frost ◽  
The Past ◽  
Spring Runoff ◽  
Key Words Climate Change ◽  
Spring Maximum

Long-term weather and hydrological data were analyzed to study climate change during late winter–early spring within an approximately 15 000 km2 area in the semiarid prairie near Swift Current, Saskatchewan. The climate has changed over the past 50 yr. Winter and spring maximum and minimum temperatures have warmed, snowfall amounts have decreased, and spring runoff has started earlier now than during past years. The percentage of precipitation as snow has decreased as temperatures have warmed. As well, even though temperatures have warmed, the date of the last spring frost has not gotten earlier with time. Key words: Climate change, semiarid prairie, winter and spring, temperature, snow, spring runoff

scholarly journals Long-term changes in the optimum planting date of gladiolus in southern Brazil

2021 ◽  
Vol 43 ◽  
pp. e50939
Author(s):  
Regina Tomiozzo ◽  
Nereu Augusto Streck ◽  
Camila Coelho Becker ◽  
Lilian Osmari Uhlmann ◽  
Natalia Teixeira Schwab ◽  
...  
Keyword(s):  
Air Temperature ◽  
Early Spring ◽  
Planting Date ◽  
Late Winter ◽  
Historical Trend ◽  
Development Cycle ◽  
Historical Series ◽  
Mother’S Day ◽  
Run Test

The objective of this work was to test long-term trends in the planting date of gladiolus to ensure marketing of these flowers on Mother’s Day and All Souls’ Day in Santa Maria (latitude: 29° 43’ S, longitude: 53° 43’ W, and altitude: 95 m), Rio Grande do Sul State, Brazil. Minimum and maximum air temperature data from 106 years were used (1912-2017) to simulate the optimum planting date indicated through the PhenoGlad model, aiming to harvest floral stems for both market dates for early, intermediate I, intermediate II and late cultivars. The homogeneity of the historical series was tested using the run test, and the historical trend was tested by the Mann-Kendal test. The magnitude of the trend was estimated with simple linear regression, and the descriptive statistics were calculated. For marketing on Mother’s Day, there was no historical trend that implied a change in the planting date of gladiolus for any of the development cycles. For marketing on All Souls’ Day, there was a positive historical trend only for the early and intermediate cycles I and II; thus, the increase in air temperature implied a delay of 9.2 days, 9.5 days and 6.9 days for the planting date, respectively, indicating that a shortening of the gladiolus development cycle occurred, mainly in late winter/early spring.

scholarly journals EARLY SPRING FLOWERING IN NOVA SCOTIA: AN EXTREME SPRING IS REFLECTED IN ADVANCED FLOWERING

2013 ◽  
Vol 47 (2) ◽  
Author(s):  
Nicholas M. Hill ◽  
David J. Garbary
Keyword(s):  
Climate Change ◽  
Nova Scotia ◽  
Regional Climate ◽  
Regional Climate Change ◽  
Flowering Phenology ◽  
Early Spring ◽  
Late Winter ◽  
Climate Conditions ◽  
Precocious Flowering ◽  
Native Group

Twenty species of herbaceous plants and four non-amentiferous shrubs were found in flower in March-April in Nova Scotia during the spring of 2012. Plants were observed primarily in Kings and Antigonish Counties, with several observations from Inverness County. The precocious flowering is attributed to an abnormally warm late winter and spring (February-March) in which climate normals for monthly average temperature were exceeded by a minimum of 1.2°C in February (Tracadie) to a maximum of 8.5°C in March (Kentville). Flowering was an average of 17 days earlier than herbarium records in the largest regional herbaria (ACAD, NSAC). Proportional contribution to the early flowering guild was greater for exotic species which featured weedy families not represented in the native group. These observations of spring climate conditions and flowering phenology are consistent with regional climate change associated with milder and earlier springs.Key Words: climate change, Nova Scotia, phenology, spring flowering, exotic range expansion.

Computer Analyses in Preventive Health Research

1967 ◽  
Vol 06 (01) ◽  
pp. 8-14 ◽  
Author(s):  
M. F. Collen
Keyword(s):  
Medical Research ◽  
Preventive Medicine ◽  
Health Research ◽  
Large Scale ◽  
Preventive Health ◽  
New Era ◽  
Large Numbers ◽  
Normal Test ◽  
Computer Analyses

The utilization of an automated multitest laboratory as a data acquisition center and of a computer for trie data processing and analysis permits large scale preventive medical research previously not feasible. Normal test values are easily generated for the particular population studied. Long-term epidemiological research on large numbers of persons becomes practical. It is our belief that the advent of automation and computers has introduced a new era of preventive medicine.

Multiple Fertilization and Consecutive Spawning in Large American Lobsters, Homarus americanus

1986 ◽  
Vol 43 (11) ◽  
pp. 2291-2294 ◽  
Author(s):  
S. L. Waddy ◽  
D. E. Aiken
Keyword(s):  
Body Size ◽  
Carapace Length ◽  
Homarus Americanus ◽  
Large Female ◽  
Bay Of Fundy ◽  
Relative Fecundity ◽  
Logarithmic Relationship

Large female American lobsters, Homarus americanus (> 120 mm carapace length), maintained at nearshore Bay of Fundy temperatures often spawn twice without an intervening molt (consecutive spawning). Consecutive spawning occurs in two forms: successive-year (spawning in two successive summers, a molt in the first and fourth years) and alternate-year (spawning in alternate summers, a molt in the first and fifth years). In both types, females often are able to fertilize the two successive broods with the sperm from a single insemination (multiple fertilization). Twenty of 21 large females that were held for up to 13 yr displayed one of these types of consecutive spawning. Consecutive spawning and multiple fertilization enable large lobsters to spawn more frequently over the long term than their smaller counterparts. This, combined with the logarithmic relationship between body size and numbers of eggs produced, means that very large lobsters have a much greater relative fecundity than previously thought.

Seasonal activity and estivation of lumbricid earthworms in the midlands of Tasmania

Soil Research ◽  
1994 ◽  
Vol 32 (6) ◽  
pp. 1355 ◽  
Author(s):  
RB Garnsey
Keyword(s):  
Soil Moisture ◽  
Adult Development ◽  
Survival Rates ◽  
Soil Surface ◽  
Early Spring ◽  
Lumbricus Rubellus ◽  
Late Winter ◽  
Cocoon Production ◽  
Density And Biomass ◽  
Earthworm Activity

Earthworms have the ability to alleviate many soil degradational problems in Australia. An attempt to optimize this resource requires fundamental understanding of earthworm ecology. This study reports the seasonal changes in earthworm populations in the Midlands of Tasmania (<600 mm rainfall p.a.), and examines, for the first time in Australia, the behaviour and survival rates of aestivating earthworms. Earthworms were sampled from 14 permanent pastures in the Midlands from May 1992 to February 1994. Earthworm activity was significantly correlated with soil moisture; maximum earthworm activity in the surface soil was evident during the wetter months of winter and early spring, followed by aestivation in the surface and subsoils during the drier summer months. The two most abundant earthworm species found in the Midlands were Aporrectodea caliginosa (maximum of 174.8 m-2 or 55.06 g m-2) and A. trapezoides (86 m-2 or 52.03 g m-2), with low numbers of Octolasion cyaneum, Lumbricus rubellus and A. rosea. The phenology of A. caliginosa relating to rainfall contrasted with that of A. trapezoides in this study. A caliginosa was particularly dependent upon rainfall in the Midlands: population density, cocoon production and adult development of A. caliginosa were reduced as rainfall reduced from 600 to 425 mm p.a. In contrast, the density and biomass of A. trapezoides were unaffected by rainfall over the same range: cocoon production and adult development continued regardless of rainfall. The depth of earthworm aestivation during the summers of 1992-94 was similar in each year. Most individuals were in aestivation at a depth of 150-200 mm, regardless of species, soil moisture or texture. Smaller aestivating individuals were located nearer the soil surface, as was shown by an increase in mean mass of aestivating individuals with depth. There was a high mortality associated with summer aestivation of up to 60% for juvenile, and 63% for adult earthworms in 1993 in the Midlands. Cocoons did not survive during the summers of 1992 or 1994, but were recovered in 1993, possibly due to the influence of rainfall during late winter and early spring.

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