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):  
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):  
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.

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.

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.

Metabolic Rate and Energy Expenditure of the Spiny Dogfish, Squalus acanthias

1978 ◽  
Vol 35 (6) ◽  
pp. 816-821 ◽  
Author(s):  
J. R. Brett ◽  
J. M. Blackburn
Keyword(s):  
Energy Expenditure ◽  
Metabolic Rate ◽  
Key Words ◽  
Swimming Performance ◽  
Squalus Acanthias ◽  
Spiny Dogfish ◽  
Metabolic Rates ◽  
Performance Curve ◽  
Power Performance ◽  
General Energy

The metabolic rate of spiny dogfish, Squalus acanthias, was determined in both a tunnel respirometer and a large, covered, circular tank (mass respirometer). Swimming performance was very poor in the respirometer, so that a power–performance curve could not be established. Instead, resting metabolic rates were determined, with higher rates induced by causing heavy thrashing (active metabolism). Routine metabolic rates were measured for the spontaneous activity characterizing behavior in the circular tank. For fish of 2 kg mean weight, the metabolic rates at 10 °C were 32.4 ± 2.6 SE (resting), 49.2 ± 5.0 SE (routine), and 88.4 ± 4.6 SE (active) mg O2∙kg−1∙h−1. Assuming that the routine rate represents a general energy expenditure in nature, this is equivalent to metabolizing about 3.8 kcal∙kg−1∙d−1 (15.9 × 103 J∙kg−1∙d−1). Key words: dogfish, metabolic rates, energetics, respiration

scholarly journals Bounds on Biomass Estimates and Energetic Consequences of Ctenophora in the Northeast U.S. Shelf Ecosystem

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
Michael D. Ford ◽  
Jason S. Link
Keyword(s):  
Feeding Strategy ◽  
Marine Ecosystem ◽  
High Energy ◽  
Gelatinous Zooplankton ◽  
Squalus Acanthias ◽  
High Energy Density ◽  
Spiny Dogfish ◽  
Sampling Device ◽  
Large Marine Ecosystem ◽  
Major Increase

Previous descriptions have noted that the stomach samples of spiny dogfish, Squalus acanthias, showed a major increase in the overall occurrence and hence implied abundance of Ctenophora. This apparent and persistent gelatinous zooplankton outbreak is increasingly more common in the world’s oceans. We briefly explore the energetic ramifications of ctenophores in the spiny dogfish diet, inferring that the presence of gelatinous zooplankton represents an ambient feeding strategy. Relative to other prey, ctenophores are not a high energy density prey item. However, given varying assumptions of the amount of ctenophores consumed, they may be an important staple in the diet of spiny dogfish. We also examine the utility of using spiny dogfish as a gelatinous zooplankton sampling device. Using five calculation methodologies, we provide bounds on potential abundance and biomass estimates of ctenophores in the Northeast U.S. shelf ecosystem. We then contextualize these findings relative to the implications for the Northeast U.S. and any large marine ecosystem.

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