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.

scholarly journals Life-history traits of the spiny dogfish Squalus acanthias in the Adriatic Sea

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Giada Bargione ◽  
Fortunata Donato ◽  
Mario La Mesa ◽  
Carlotta Mazzoldi ◽  
Emilio Riginella ◽  
...  
Keyword(s):  
Life History ◽  
Life History Traits ◽  
Adriatic Sea ◽  
Growth Parameters ◽  
Sampling Period ◽  
Squalus Acanthias ◽  
Spiny Dogfish ◽  
The North ◽  
Size At Sexual Maturity ◽  
The Individual

Abstract Pivotal life history traits concerning age structure and reproduction of the spiny dogfish (Squalus acanthias, Linnaeus 1758) were investigated in the Adriatic Sea from mid February 2012 to mid July 2013 and in 2016. The whole sample consisted of 176 females and 150 males, ranging between 217–1025 mm and 219–875 mm, respectively. The individual age, which was estimated using a cross-sectioning technique of the second dorsal-fin spine, ranged from 0 to 13+ years for females and from 0 to 9+ years for males. Based on the length-at-age estimates, the Gompertz growth parameters were L∞ = 1130 mm, k = 0.18 and L∞ = 920 mm, k = 0.24 for females and males, respectively. The size at sexual maturity (L50) was 659 mm for females and 575 mm for males, corresponding to 7.5 and 5.5 years of age (A50), respectively. Mean biennial fecundity was approximately 11 embryos/female and 12 ripe oocytes/female. Mature males occurred during much of the sampling period, while mature females with nearly full-term embryos were exclusively recorded in May 2013 and July 2016. Monitoring of catches conducted in a sample port of the north Adriatic (Chioggia) over the past 20 years has shown fluctuating trends in landings, with peaks during the summer reproductive season.

Annulus Development on the Second Dorsal Spine of the Spiny Dogfish (Squalus acanthias) and Its Validity for Age Determination

1985 ◽  
Vol 42 (11) ◽  
pp. 1799-1805 ◽  
Author(s):  
Richard J. Beamish ◽  
Gordon A. McFarlane
Keyword(s):  
Life History ◽  
Age Determination ◽  
Squalus Acanthias ◽  
Dorsal Spine ◽  
Spiny Dogfish ◽  
Stem Base ◽  
Life History Parameters ◽  
Upward Growth

Annual marks were visible in three different areas of the dogfish (Squalus acanthias) spine. The annuli in the mantle, the stem base, and the inner dentine develop independently of each other. Annuli that formed on the mantle were readily identifiable externally, making them the most useful for age determination. The mantle annulus is an accumulation of pigment that appears to form because enamel deposition is not synchronous with the upward growth of the spine, resulting in the production of darkened bands that often form ridges. We validated our interpretation of annuli from fish aged 20–70 yr by tagging and recovering dogfish that were injected with oxytetracycline. Through validation we were able to demonstrate that some previous studies have underestimated age, resulting in a misunderstanding of important life history parameters.

Biology and Management of Dogfish Sharks

2009 ◽  
Keyword(s):  
Ecosystem Management ◽  
Management Strategies ◽  
Puget Sound ◽  
Specific Region ◽  
Boundary Management ◽  
Spiny Dogfish ◽  
Strait Of Georgia ◽  
The Usa ◽  
Georgia Basin ◽  
Complex Movement

Abstract.—The development of effective ecosystem management requires an understanding of the movements of the species of interest within and between ecosystems. The present study examines the movement of spiny dogfish <em>Squalus acanthias </em>within the Georgia basin (Strait of Georgia and Puget Sound). A total of 51,063 dogfish were tagged in the Strait of Georgia from 1978 to 1988. In general, dogfish tagged in a specific region tended to be recaptured within the same region regardless of years at liberty. However, a complex movement of dogfish within the Strait of Georgia proper (which includes north Puget Sound) as well as south Puget Sound was noted. The findings of this study have important implications for the development of trans-boundary management strategies to ensure sustained dogfish fishing opportunities for both Canada and the USA.

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.

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.

Age Determination of an Elasmobranch (Squalus acanthias) by X-ray Spectrometry

1977 ◽  
Vol 34 (1) ◽  
pp. 44-48 ◽  
Author(s):  
Barry C. Jones ◽  
Glen H. Geen
Keyword(s):  
Age Determination ◽  
Element Composition ◽  
Squalus Acanthias ◽  
Spiny Dogfish ◽  
Strait Of Georgia ◽  
X Ray ◽  
Spectrometric Technique

Ages of spiny dogfish (Squalus acanthias) in the Strait of Georgia, B.C., have been estimated by an X-ray spectrometric technique which involves measuring variations in the element composition within vertebrae.

Life history aspects of two species of the Squalus genus in the Eastern Ionian Sea

2017 ◽  
Vol 98 (4) ◽  
pp. 937-948 ◽  
Author(s):  
Aikaterini Anastasopoulou ◽  
Chryssi Mytilineou ◽  
Panayiota Makantasi ◽  
Christopher J. Smith ◽  
Stefanos Kavadas ◽  
...  
Keyword(s):  
Life History ◽  
Squalus Acanthias ◽  
Spiny Dogfish ◽  
Ionian Sea ◽  
Single Specimen ◽  
Spawning Activity ◽  
Positive Allometry ◽  
The Mean ◽  
Continuous Reproduction ◽  
First Maturity

Data on life history aspects of two species of Squalus genus were collated from five different studies carried out in the Eastern Ionian Sea from 1995 to 2014. Data were collected from 948 longnose spurdogs Squalus blainville (Risso, 1827) and 65 spiny dogfish Squalus acanthias Linnaeus, 1758 caught by trawl and longlines. The mean length of both species increased with depth. Sexual segregation was observed for S. blainville, whereas a segregation of immature and mature individuals was detected for S. acanthias. The length–weight relationship for S. blainville indicated positive allometry (b > 3) for both sexes, whereas a negative allometry (b < 3) was found for S. acanthias for the combined sexes. The sex ratio of both species was in favour of males. For S. blainville, the gonadosomatic and hepatosomatic indices differed significantly between sexes but not between seasons with the maturity data supporting the hypothesis of continuous reproduction throughout the year. Length at first maturity (L50) for female and male S. blainville was 603 and 413 mm respectively. For S. acanthias, males collected in autumn had finished their spawning activity; the single specimen caught in summer was reproductively active. Females, caught only in summer, were all gravid. Prey identified in the stomachs of S. blainville belonged to three major groups: fish, cephalopods and shrimps. Other groups such as echinoderms and ascidians were also found. Identified prey in the stomachs of S. acanthias belonged to two main groups, fish and cephalopods, although other groups (including echinoderms and polychaetes) were also present.

Mercury Content of Spiny Dogfish (Squalus acanthias) in the Strait of Georgia, British Columbia

1972 ◽  
Vol 29 (10) ◽  
pp. 1487-1490 ◽  
Author(s):  
C. R. Forrester ◽  
K. S. Ketchen ◽  
C. C. Wong
Keyword(s):  
Total Mercury ◽  
River Estuary ◽  
Mercury Content ◽  
Squalus Acanthias ◽  
Spiny Dogfish ◽  
Fraser River ◽  
Female Fish ◽  
Male And Female ◽  
Strait Of Georgia ◽  
Total Length

Total mercury content of Squalus acanthias sampled in the Strait of Georgia reached levels of 0.5 ppm at fish lengths of 72 and 77 cm for male and female fish, respectively. For any given length above 65 cm the mercury content was higher among males than females and higher in samples taken off the Fraser River Estuary than in other areas of the Strait. Levels of mercury reached 1.7 ppm in males (to 95 cm in total length) and almost 2.0 ppm in females (to 120 cm in total length).

Spring migration routes and chronology of surf scoters (Melanitta perspicillata): a synthesis of Pacific coast studies

2009 ◽  
Vol 87 (11) ◽  
pp. 1069-1086 ◽  
Author(s):  
S.E.W. De La Cruz ◽  
J. Y. Takekawa ◽  
M. T. Wilson ◽  
D. R. Nysewander ◽  
J. R. Evenson ◽  
...  
Keyword(s):  
British Columbia ◽  
San Francisco ◽  
Pacific Coast ◽  
Puget Sound ◽  
Spring Migration ◽  
Seasonal Effect ◽  
Migration Route ◽  
Migration Routes ◽  
Strait Of Georgia ◽  
Melanitta Perspicillata

Understanding interconnectivity among wintering, stopover, and breeding areas of migratory birds is pivotal to discerning how events occurring in each might have a cross-seasonal effect on another. Such information can guide the location and timing of conservation efforts. Thus, we examined spring migration routes, chronology, and stopover use of 85 surf scoters ( Melanitta perspicillata (L., 1758)) marked with satellite transmitters at four Pacific Flyway wintering sites: San Quintin Bay, Baja California; San Francisco Bay, California; Puget Sound, Washington; and Strait of Georgia, British Columbia. Eighty-three percent of marked scoters followed two main routes to the breeding area: a Southern Inland route involving staging in Puget Sound and Strait of Georgia and protracted inland migration, or a Northern Coastal route characterized by short movements along the Pacific coast of British Columbia and southeast Alaska with inland migration initiating from Lynn Canal and surrounding areas. Route choice was related to nesting site latitude in the Canadian Northern Boreal Forest. Data from birds tracked over 2 years indicated strong migration route fidelity, but altered chronology and stopover locations between years. Departure date varied by wintering site, but arrival and apparent settling dates were synchronous, suggesting individuals adjusted migration timing to meet an optimized reproductive schedule.

Biology and Management of Dogfish Sharks

2009 ◽  
Keyword(s):  
East China Sea ◽  
Pacific Coast ◽  
Japan Sea ◽  
Squalus Acanthias ◽  
Small Scale ◽  
Spiny Dogfish ◽  
Western Coast ◽  
The Pacific ◽  
The Japan Sea ◽  
Hokkaido Island

Abstract.—Around Japan, spiny dogfish <em>Squalus acanthias </em>occur off the Pacific coast of Hokkaido Island and northern Honshu and off the western coast of Japan from the East China Sea to the Japan Sea. They have been caught and used historically on both coasts. This species is usually caught as bycatch except in some small-scale local fisheries which directly target it.

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