Biology and Management of Dogfish Sharks

2009 ◽  
Keyword(s):  
Reproductive Cycle ◽  
Reproductive Tract ◽  
Puget Sound ◽  
Squalus Acanthias ◽  
Spiny Dogfish ◽  
Embryo Size ◽  
Adult Females ◽  
Males And Females ◽  
One Year ◽  
Appearance Changes

Abstract.—The fishery for spiny dogfish <em>Squalus acanthias </em>in Washington State has been ongoing for over a century. Management efforts have historically been limited and recent interest in increasing management efforts has led to renewed interest in the biology of the species. This project was undertaken to aid in management by describing the reproductive cycle of the dogfish in Puget Sound. Reproductive tracts were sampled from 170 male and 358 female dogfish from the catch of a commercial trawler over one year. Size at 50% maturity was 89.9 cm for females and 74.1 cm for males (total length extended). Reproductive stages were developed for adult females based on the proportion of yolk absorbed by the developing embryo. Size, weight, and appearance changes in the reproductive tract for both males and females throughout maturation and reproduction are described. There did not appear to be a significant seasonality to the reproductive timing, in that the onset of pregnancy and pupping were observed year round, however, peaks in activity were observed in December for the onset of pregnancy and October for pupping.

Maturity, reproductive cycle and fecundity of the spiny dogfish Squalus acanthias (Chondrichthyes: Squalidae) off the Languedocian coast (southern France, northern Mediterranean)

2011 ◽  
Vol 91 (8) ◽  
pp. 1627-1635 ◽  
Author(s):  
C. Capapé ◽  
C. Reynaud
Keyword(s):  
Reproductive Cycle ◽  
Squalus Acanthias ◽  
Hepatosomatic Index ◽  
Spiny Dogfish ◽  
Male And Female ◽  
Southern France ◽  
Short Period ◽  
Wide Range ◽  
Males And Females ◽  
Near Term

The spiny dogfish Squalus acanthias is widely distributed in Atlanto-Mediterranean regions, being captured off the Languedocian coast (southern France, northern Mediterranean), despite a decline of landings. The male and female sexually matured between 635–700 mm and 860–880 mm total length (TL), respectively. The largest male and female were 800 mm and 1110 mm TL, respectively and weighed 2220 g and 8900 g, respectively. There was a significant relationship for total mass versus TL, and liver mass versus TL between males and females. The diameter of the largest yolky oocytes ranged between 43 and 47 mm (mean 45.08 ± 0.98), while the mass ranged between 29.5 and 37.4 g (mean 31.79 ± 2.20). Near- term embryos ranged from 245 to 271 mm TL (mean: 258.85 ± 7.28) and weighed from 47.5 to 55.9 g (mean 53.35 ± 2.26). Ovarian fecundity ranged from 6 to 15 (mean = 10.38 ± 2.66). Uterine fecundity or litter size ranged from 4 to 12 (mean = 8.15 ± 2.07). Both fecundities showed a positive relationship with TL of females. A chemical balance of development based on mean dry masses of yolky oocytes and near-term embryos was 0.87 and suggested that S. acanthias is a pure lecithotrophic species. Hepatosomatic index (HSI) and gonadosomatic index (GSI) significantly increased with size in both males and females. HSI reached the highest values in both sub-adult and adult specimens, reflecting the role of the liver in the gonadal production as well as in buoyancy, while in the GSI the highest values were observed in pregnant females. Vitellogenesis proceeds in parallel with embryonic development. Near-term females were captured in different months of the year while a short period of resting could not be excluded between parturition and the beginning of a new pregnancy, so it appears difficult to delineate the length of gestation. However, a reproductive cycle with a wide range from 18 to 24 months remains a suitable hypothesis.

Biology and Management of Dogfish Sharks

2009 ◽  
Keyword(s):  
Life History ◽  
Pacific Coast ◽  
Puget Sound ◽  
Squalus Acanthias ◽  
Spiny Dogfish ◽  
Dietary Analysis ◽  
Strait Of Georgia ◽  
Food Items ◽  
Abundance Estimates ◽  
Commercial Species

Abstract.—Spiny dogfish <em>Squalus acanthias </em>have been an important commercial species on Canada’s Pacific coast for more than 130 years. In this study we show that the spiny dogfish life history results in juveniles remaining in pelagic waters for 10–15 years after birth, with lengths up to about 60 cm. Abundance estimates show that the numbers of these young dogfish, as well as some older dogfish in the pelagic waters, appear to represent a relatively large percentage of the population in these two regions. Dietary analysis shows that while euphausiids and teleosts constitute the major food items, regardless of size/age, dogfish feed on a number of species within the ecosystem. After about 15 years, there is a movement into demersal habitats where individuals eventually mature. Because dogfish are long lived, and because they are found throughout the pelagic zone and demersal habitats, it is probable that they play a key role in the Strait of Georgia and Puget Sound ecosystems.

Biology and Management of Dogfish Sharks

2009 ◽  
Keyword(s):  
Puget Sound ◽  
Squalus Acanthias ◽  
Spiny Dogfish ◽  
New Markets ◽  
Gill Nets ◽  
Two Phases

Abstract.—Spiny dogfish <em>Squalus acanthias </em>in Puget Sound have undergone two phases of high fishery harvests followed by rapid declines. Dogfish were heavily fished during WWII for their vitamin-rich livers, and annual catches approached 4,000 metric tons (mt) per year. This fishery declined from the early 1950s until new markets developed during the mid-1970s that led to increased commercial catches by trawl, set net (sinking gill nets), and setline (long lines) gear types. Annual harvests again approached 4,000 mt per year but declined to 1,000 mt after 1997 and have fallen to less than 300 mt in recent years. Dogfish caught by recreational fishers now account for the greatest catches of dogfish in Puget Sound.

Maturation, fecundity and reproductive cycle of spiny dogfish,Squalus acanthias, in the Adriatic Sea

2013 ◽  
Vol 9 (2) ◽  
pp. 198-207 ◽  
Author(s):  
Romana Gračan ◽  
Bojan Lazar ◽  
Ivan Posavec ◽  
Gordana Gregorović ◽  
Gordana Lacković
Keyword(s):  
Reproductive Cycle ◽  
Adriatic Sea ◽  
Squalus Acanthias ◽  
Spiny Dogfish

scholarly journals Seasonal Dynamics of the Leaffooted Bug Leptoglossus zonatus and Its Implications for Control in Almonds and Pistachios

Insects ◽  
2019 ◽  
Vol 10 (8) ◽  
pp. 255 ◽  
Author(s):  
Kent M. Daane ◽  
Glenn Y. Yokota ◽  
Houston Wilson
Keyword(s):  
Western Hemisphere ◽  
Economic Damage ◽  
Adult Males ◽  
Hatch Rate ◽  
Adult Females ◽  
Monitoring Programs ◽  
Males And Females ◽  
One Year ◽  
The One ◽  
Successive Generations

Leptoglossus zonatus is a polyphagous pest found throughout much of the Western Hemisphere. In California, L. zonatus attacks almond, pistachio, pomegranate, and walnut crops, but the seasonal use of and economic damage to these crops varies. To better understand the seasonal changes of L. zonatus populations and to improve monitoring programs in California’s San Joaquin Valley, we caged overwintering adult males and females and then followed the resulting population dynamics over a one-year period. There were three generations over the one-year period, although eggs, nymphs, and adults overlapped among successive generations. From an initial 75 overwintering adult females, there were 1214 egg strands, 16,692 nymphs, and 4900 adults recorded during the one-year period. Depending on the generation, the number of nymphs per egg strand ranged from 11.3 to 14.3; the sex ratio was close to 1:1 with the exception of one female-biased cage; and nymph mortality ranged from 22.0% to 39.5%. Adult females isolated from each generation produced 2.4–5.1 egg strands per female that totaled 41.7–61.7 eggs per female with a 67.1–86.8% successful hatch rate. We find that the adult is the overwintering stage, as more adults (without food provisions) survived the winter compared to medium-sized or large-sized nymphs provided with both food and water. The results are discussed with respect to the development of L. zonatus control and monitoring programs for California’s multi-billion-dollar (US) nut crops.

Biology and Management of Dogfish Sharks

2009 ◽  
Keyword(s):  
Pacific Ocean ◽  
Puget Sound ◽  
Squalus Acanthias ◽  
Spiny Dogfish ◽  
Commercial Fishery ◽  
Stock Assessments ◽  
Northeastern Pacific ◽  
Georgia Basin ◽  
Hexanchus Griseus

Abstract.—Predatory interactions of bluntnose sixgill shark <em>Hexanchus griseus </em>and spiny dogfish <em>Squalus acanthias </em>were evaluated as part of a longline tagging study for sixgill sharks in a northeastern Pacific Ocean estuary, the Puget Sound/Georgia Basin (PSGB). This study shows that sixgill sharks will prey upon dogfish. Dogfish were caught in one of three ways: as whole individuals, with parts of their bodies consumed, or as whole individuals with sixgill sharks retained on the hook as well. Bait experiments showed that for one of two sampling periods, hooks baited with dogfish were preferred by sixgill sharks over hooks baited with herring. Analysis of sequential hook data revealed that sixgill sharks were caught on the longline at areas where dogfish were caught in low to intermediate densities, suggesting little preference for the movement of a hooked dogfish. Given that the dogfish population in the PSGB supports a commercial fishery, the importance of the dogfish as sixgill-shark prey may need to be considered in future fishery stock assessments and allowable catch limits may need to be lowered to leave a sufficient source of nutrients for the sixgill-shark population.

Reproductive biology of the banded guitarfish, Zapteryx exasperata, from the Gulf of California, México

2009 ◽  
Vol 89 (8) ◽  
pp. 1655-1662 ◽  
Author(s):  
María-Del-Pilar Blanco-Parra ◽  
J. Fernando Márquez-Farías ◽  
Felipe Galván-Magaña
Keyword(s):  
Reproductive Biology ◽  
Reproductive Cycle ◽  
Gulf Of California ◽  
Average Length ◽  
Common Species ◽  
Management Plans ◽  
Males And Females ◽  
One Year ◽  
Gravid Females ◽  
Critical Aspects

The banded guitarfish, Zapteryx exasperata, is a common species in the artisanal elasmobranch fisheries in the Gulf of California. Fishery-derived specimens were examined to determine critical aspects of the reproductive biology of this poorly known group of rays. Two functional testes and ovaries were found in males and females respectively. Median size at maturity (L50%) for males was 64 cm total length (TL) and for females 69 cm TL. Average length of gravid females was 78.8±3.8 cm TL. Histological analysis showed no evidence of sperm storage in the oviducal gland. Gestation was estimated to occur over a five to six month period (February–July) and was concurrent with vitellogenesis. Mean uterine fecundity was estimated as 7 (range 2–13, SD. = 3). The sex-ratio of embryos was 1:1. The reproductive cycle for Z. exasperata from the Gulf of California was estimated to last one year with parturition, ovulation and copulation occurring during the summer months. Differences found in the reproductive cycle of Z. exasperata between the Gulf of California and the west coast of Baja California could have implications in the future management plans for this fishery in the Gulf of California.

Reproduction and Embryonic Development of Spiny Dogfish (Squalus acanthias) in the Strait of Georgia, British Columbia

1977 ◽  
Vol 34 (9) ◽  
pp. 1286-1292 ◽  
Author(s):  
Barry C. Jones ◽  
Glen H. Geen
Keyword(s):  
Embryonic Development ◽  
Length Distribution ◽  
Uterine Cavity ◽  
Mesh Size ◽  
Squalus Acanthias ◽  
Population Characteristics ◽  
Spiny Dogfish ◽  
Total Catch ◽  
Strait Of Georgia ◽  
Males And Females

Lengths at 50% maturity of spiny dogfish (Squalus acanthias) in the Strait of Georgia, B.C., are 78.5 and 93.5 cm, corresponding to ages 19 and 29 yr, for males and females, respectively. Modal lengths of mature males and females are 85 and 100 cm, respectively.Mating occurs from October to January, with a peak in December. Males are capable of mating every year, with smaller dogfish mating earlier in the year than larger ones. Females mate every 2nd yr. Ovulation of 4 cm diam eggs closely follows mating. The fertilized eggs are enclosed in gelatinous capsules for 4 mo after which the embryos are released into the uterine cavity. The external yolk supply of the embryos is totally absorbed by parturition, although the internal yolk is not fully utilized until 2 mo later. Parturition occurs from September to January, with a peak in November. Gestation is roughly 23 mo. Breeding females produce a mean of 7.14 progeny.These population characteristics indicate that regulation of a future fishery should be by total catch limit rather than net mesh size selection. Key words: spiny dogfish, reproduction, length distribution, survivorship, fecundity, fishery regulation

New Coccidia from the Spiny Dogfish Shark (Squalus acanthias) and Great Sculpin (Myoxocephalus polyacanthocephalus)

1975 ◽  
Vol 32 (5) ◽  
pp. 649-651 ◽  
Author(s):  
Paul R. Fitzgerald
Keyword(s):  
Puget Sound ◽  
Squalus Acanthias ◽  
Spiny Dogfish ◽  
San Juan ◽  
San Juan Islands ◽  
Dogfish Shark ◽  
Cartilaginous Fishes ◽  
Great Sculpin Myoxocephalus Polyacanthocephalus

New coccidia from the spiny dogfish shark, Squalus acanthias, and the great sculpin, Myoxocephalus polyacanthocephalus, from waters around the San Juan Islands, Puget Sound, Washington, are described and named. Thirty-one species of bony and two species of cartilaginous fishes were examined. Twenty-eight of 71 dogfish and one of four sculpins were infected with coccidia.

Selenium Role in Reproduction, Pregnant/Postpartum Women and Neonates: A Current Study

2020 ◽  
Vol 17 (1) ◽  
pp. 28-37
Author(s):  
Tabinda Sattar
Keyword(s):  
Infant Development ◽  
Selenium Deficiency ◽  
Human Reproduction ◽  
Postpartum Women ◽  
Female Reproduction ◽  
Pregnancy And Lactation ◽  
Males And Females ◽  
One Year ◽  
Selenium Supplements

Background: Selenium is a micronutrient, although required in low amounts, its importance in male and female reproduction is well known. Objectives: The core purpose of this study is to evaluate the role of selenium in human reproduction, during pregnancy/ lactation in women and newborns. The review explains side by side the sources of selenium, required amounts of selenium in humans and during pregnancy or lactation. Methods: Selenium deficiency is a major cause of male infertility. Similarly, selenium deficiency, both in pregnant and postpartum women, would greatly affect the health of the newborn baby in all respects. The effect of maternal selenium upon the fetus and the neonates even one year after birth has been explained with some recent examples. Results: The study elaborates the fact that the selenium deficiency in pregnancy and lactation is common due to fetal/infant development, so selenium supplements must be provided in order to overcome these deficiency symptoms. Conclusions: The better reproductive health in humans is possible due to the sufficient amounts of selenium present both in males and females as well.

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