Reproductive seasonality in harbour porpoises, Phocoena phocoena, from the Bay of Fundy

1990 ◽  
Vol 68 (2) ◽  
pp. 284-288 ◽  
Author(s):  
Andrew J. Read
Keyword(s):  
Seasonal Variation ◽  
Seasonal Changes ◽  
Birth Date ◽  
Bay Of Fundy ◽  
Corpora Lutea ◽  
Commercial Fishing ◽  
Follicular Growth ◽  
Phocoena Phocoena ◽  
Reproductive Seasonality ◽  
Duration Of Gestation

I examined the reproductive tracts from 244 harbour porpoises, Phocoena phocoena, captured incidentally in commercial fishing operations in the Bay of Fundy during June to September, 1985–1988. Evidence from follicular growth and the development of corpora lutea suggests that ovulation and conception occur in late June. This interpretation is supported by subtracting the duration of gestation from estimated mean birth date, and also by seasonal changes in testicular mass. Six or 7 weeks of preimplantation pregnancy follows conception and foetuses are first detectable in early August. Gestation lasts for approximately 10.6 months and parturition occurs during mid-May. Females that fail to conceive during the breeding season must wait 12 months for another opportunity to mate. Estimates of pregnancy rate must account for the seasonal nature of reproduction. The observed pattern of reproductive seasonality may reflect seasonal variation in prey quality, and perhaps availability.

Reproductive seasonality of the bush rat (Rattus fuscipes greyi) South Australia

1996 ◽  
Vol 23 (3) ◽  
pp. 317 ◽  
Author(s):  
RM White ◽  
DJ Kennaway ◽  
RF Semark
Keyword(s):  
Seasonal Variation ◽  
Vegetative Growth ◽  
Seasonal Changes ◽  
Seasonal Pattern ◽  
South Australia ◽  
Reproductive Seasonality ◽  
Catch And Release ◽  
Rattus Fuscipes ◽  
Conservation Park ◽  
By Catch

The reproductive seasonality of the bush rat (Rattus fuscipes greyi) was investigated in Scott Creek Conservation Park near Adelaide, South Australia, by catch and release trapping conducted at irregular intervals over a 4-year period in a population of higher density than previously reported for this species. A seasonal pattern in breeding activity was observed with the production of young in spring and summer (October-February) with a peak in December. There was seasonal variation in the testicular index of males with minimal values from April to June. Some animals may have retained the ability to mate throughout the year but there was no evidence of offspring surviving from any winter matings. Differences were seen in the timing and intensity of the non-breeding season between years. Possible causes of reproductive seasonality were seasonal changes in vegetative growth and the abundance of fungi and insects and predictive cues provided by seasonal changes in ambient temperature and photoperiod.

Estimation of body condition in harbour porpoises, Phocoena phocoena

1990 ◽  
Vol 68 (9) ◽  
pp. 1962-1966 ◽  
Author(s):  
Andrew J. Read
Keyword(s):  
Body Size ◽  
Body Condition ◽  
The Body ◽  
Bay Of Fundy ◽  
Commercial Fishing ◽  
Direct Measure ◽  
Phocoena Phocoena ◽  
Indirect Measures ◽  
Lactating Females ◽  
Residual Values

I examined the body condition of 220 harbour porpoises (Phocoena phocoena) killed incidentally in commercial fishing operations in the Bay of Fundy between July and September, 1985–1988. Condition was assessed using a direct measure (blubber mass) and two indirect measures (blubber thickness and girth). To compare condition among porpoises of different sizes, each measure was regressed against an appropriate measure of body size, and the residuals of these regressions were used as indices of condition. Mean residuals of blubber mass varied significantly among both reproductive classes and sampling years. Calves and nonlactating mature females had greater mean residual values for blubber mass than immature porpoises and mature males; lactating females possessed intermediate levels. Porpoises sampled in 1987 had greater mean residual blubber mass than porpoises sampled in other years. Although the residuals of girth and blubber thickness demonstrated similar trends to those of blubber mass, they were poorly correlated with the residuals of blubber mass and are not robust indices of condition in harbour porpoises.

scholarly journals Seasonal feeding plasticity can facilitate coexistence of dominant omnivores in Neotropical streams

2021 ◽  
Author(s):  
Mayara P. Neves ◽  
Pavel Kratina ◽  
Rosilene L. Delariva ◽  
J. Iwan Jones ◽  
Clarice B. Fialho
Keyword(s):  
Seasonal Variation ◽  
Fish Species ◽  
Resource Availability ◽  
Seasonal Changes ◽  
Dry Season ◽  
Diet Overlap ◽  
Isotopic Niche ◽  
Neotropical Streams ◽  
Feeding Plasticity ◽  
The Impact

AbstractCoexistence of ecomorphologically similar species in diverse Neotropical ecosystems has been a focus of long-term debate among ecologists and evolutionary biologists. Such coexistence can be promoted by trophic plasticity and seasonal changes in omnivorous feeding. We combined stomach content and stable isotope analyses to determine how seasonal variation in resource availability influences the consumption and assimilation of resources by two syntopic fish species, Psalidodon aff. gymnodontus and P. bifasciatus, in the Lower Iguaçu basin. We also tested the impact of seasonality on trophic niche breadth and diet overlap of these two dominant omnivores. Seasonal changes in resource availability strongly influenced the consumption and assimilation of resources by the two fish species. Both species exhibited high levels of omnivory, characterized by high diversity of allochthonous resources in the wet season. Terrestrial invertebrates were the main component of diet during this season. However, in the dry season, both species reduced their isotopic niches, indicating diet specialization. High diet overlap was observed in both seasons, but the isotopic niche overlap was smaller in the dry season. Substantial reduction in the isotopic niche of P. bifascistus and a shift toward aquatic invertebrates can facilitate coexistence during this season of resource shortage. Feeding plasticity allows omnivorous fish to adjust their trophic niches according to seasonality, promoting the exploitation of different resources during periods of greater resource diversity. This seasonal variation could be an important mechanism that contributes to the resource partitioning and coexistence of dominant omnivores in Neotropical streams.

scholarly journals Seasonal Variation in the Spatial Distribution of Basking Sharks (Cetorhinus maximus) in the Lower Bay of Fundy, Canada

PLoS ONE ◽  
2013 ◽  
Vol 8 (12) ◽  
pp. e82074 ◽  
Author(s):  
Zachary A. Siders ◽  
Andrew J. Westgate ◽  
David W. Johnston ◽  
Laurie D. Murison ◽  
Heather N. Koopman
Keyword(s):  
Spatial Distribution ◽  
Seasonal Variation ◽  
Bay Of Fundy ◽  
Cetorhinus Maximus

Fishing-gear threat to right whales (Eubalaena glacialis) in Canadian waters and the risk of lethal entanglement

2011 ◽  
Vol 68 (12) ◽  
pp. 2174-2193 ◽  
Author(s):  
Angelia S.M. Vanderlaan ◽  
R. Kent Smedbol ◽  
Christopher T. Taggart
Keyword(s):  
Relative Risk ◽  
North Atlantic ◽  
Eubalaena Glacialis ◽  
Bay Of Fundy ◽  
Commercial Fishing ◽  
Fishing Gear ◽  
Critical Habitat ◽  
North Atlantic Right Whale ◽  
Right Whale ◽  
Right Whales

Commercial fishing gear can potentially entangle any whale, and this is especially true for the endangered North Atlantic right whale ( Eubalaena glacialis ), for which entanglement is second only to vessel strike as being responsible for documented right whale deaths. We use right whale survey data and Canadian fishing-gear deployment data to estimate the relative threat of gear entanglement in a Scotia–Fundy study area and the relative risk of lethal entanglement in the Bay of Fundy and on Roseway Basin, Scotian Shelf, where Critical Habitat has been legislated. We focus on groundfish and pelagic hook-and-line; groundfish gillnet; and crab-, hagfish-, and inshore and offshore lobster-trap gear. Our analyses demonstrate that groundfish hook-and-line gear poses the greatest threat to right whales among the seven gear types analysed during the summer-resident period in Critical Habitat and that gear from the lobster fisheries poses the greatest threat during the spring and autumn periods when whales are migrating to and from Critical Habitat. We suggest that area-specific seasonal closures of some fisheries would reduce threat and risk to whales without unduly compromising fishing interests.

Vitamin D (25-OH) concentrations in hospitalized patients, outpatients and dialysis patients depending on seasonal variation

2015 ◽  
Vol 51 (3) ◽  
pp. 209-212
Author(s):  
Magdalena Maria Ostrowska ◽  
Ewa Szulc-Mysińska ◽  
Dagna Bobilewicz ◽  
Marta Faryna
Keyword(s):  
Vitamin D ◽  
Seasonal Variation ◽  
Seasonal Changes ◽  
Hospitalized Patients ◽  
Optimum Concentration ◽  
Dialysis Patients ◽  
Total Vitamin ◽  
Different Seasons ◽  
Mean Concentration ◽  
Global Health Problem

Vitamin D deficiency, which is a global health problem, may result in numerous diseases, such as rickets in children and osteoporosis and osteomalacia in adults. The occurrence of the above-mentioned disorders is promoted by the wintertime and higher latitudes. The aim of the study was to compare the concentrations of vitamin D (25-OH) in hospitalized patients and outpatients in different seasons of the year (summer and winter), as well as in dialysis patients in December and May. The Roche test for the quantitativedetermination of total vitamin D (25-OH) was used in the study. The range from 30 to 80 ng/ml was accepted as the optimum concentration. In hospitalized patients and outpatients, both in summer and winter mean concentration of vitamin D (25-OH) reached the values below 30 ng/ml in over 80% of the patients. Only in the hospitalized patient group mean concentration of vitamin D (25-OH) in the summer was significantly higher than in the winter (p=0.0016). In the dialysis patients mean concentration of vitamin (25-OH) in May was significantly higher than in December (p=0.0085) and the percent of the results below 30 ng/ml amounted to 96.39% in December and 77.27% in May. In conclusion, the 25(OH)D concentrations in the whole population under study are lower than those recommended and undergo periodical seasonal changes in hospitalized patients.

Seasonal Changes in General Condition and Lipid Content of Cod from Inshore Waters

1967 ◽  
Vol 24 (3) ◽  
pp. 607-612 ◽  
Author(s):  
P. M. Jangaard ◽  
H. Brockerhoff ◽  
R. D. Burgher ◽  
R. J. Hoyle
Keyword(s):  
Seasonal Variation ◽  
Nova Scotia ◽  
Lipid Content ◽  
General Condition ◽  
Seasonal Variations ◽  
Seasonal Changes ◽  
Oil Content ◽  
Gadus Morhua ◽  
Male Fish ◽  
Inshore Waters

The seasonal variations in lipid content and general "condition" of cod, Gadus morhua L., from an inshore population have been determined.Four female and four male fish were chosen from 20 live cod brought in monthly from Terence Bay, Halifax County, Nova Scotia, the fish were pooled and the lipid content determined on the flesh, livers, and gonads. The flesh lipids varied from 0.57% to 0.74% and the oil content of the livers from 15% to 75%.The general "condition" of the fish as expressed by [Formula: see text], the liver condition by [Formula: see text], and the fat content of the liver all showed seasonal variation with maxima in the fall and minima in the spring. KF varied from 0.79 to 1.05 and KL from 1.0 to 4.5. No seasonal variation in the amount of flesh lipids could be detected.

Changes in Growth and Reproduction of Harbour Porpoises, Phocoena phocoena, from the Bay of Fundy

1990 ◽  
Vol 47 (11) ◽  
pp. 2158-2163 ◽  
Author(s):  
Andrew j. Read ◽  
David E. Gaskin
Keyword(s):  
Sexual Maturity ◽  
Prey Availability ◽  
Simultaneous Increase ◽  
Bay Of Fundy ◽  
Commercial Fisheries ◽  
Phocoena Phocoena ◽  
Pronounced Change ◽  
Younger Age ◽  
Incidental Mortality ◽  
Growth And Reproduction

Changes in the growth and reproduction of harbour porpoises from the Bay of Fundy are described by comparing samples collected in 1969–73 and 1985–88. The most pronounced change was an increase in the length of calves, from 92.1 cm (SE 1.6) in 1969–73 to 108 cm (SE 1.3) in 1985–88. Females in 1985–88 attained sexual maturity at a significantly younger age (3.44 yr) and shorter length (143 cm) than females from the older sample (3.97 yr and 147 cm). These changes may be attributable to an increase in prey availability to individual porpoises. This presumed increase in prey availability may have resulted from a decrease in porpoise density caused by incidental mortality in commercial fisheries, a simultaneous increase in prey abundance, or a combination of these factors.

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