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):  
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):  
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.

scholarly journals Landscape-Scale Physiology: Site Differences in Refueling Rates Indicated by Plasma Metabolite Analysis in Free-Living Migratory Sandpipers

The Auk ◽  
2006 ◽  
Vol 123 (2) ◽  
pp. 563-574 ◽  
Author(s):  
Dana A. Acevedo Seaman ◽  
Christopher G. Guglielmo ◽  
Robert W. Elner ◽  
Tony D. Williams
Keyword(s):  
Physiological State ◽  
Puget Sound ◽  
Landscape Scale ◽  
Plasma Triglyceride ◽  
Mass Change ◽  
Free Living ◽  
Calidris Mauri ◽  
Metabolite Profiles ◽  
Georgia Basin ◽  
Plasma Metabolite

Abstract Variation in plasma metabolite profiles can provide information on physiological state and relative rates of mass change in free-living birds caught only once, and this technique could be used to compare rates of mass change (fattening) among populations or sites in relation to habitat quality. We compared plasma metabolite levels, as an index of relative refueling rates, in migratory Arctic-nesting Western Sandpipers (Calidris mauri), on a landscape scale at as many as nine sites over two years and during three different migratory stages within the Georgia Basin-Puget Sound region of British Columbia and Washington. There was significant intersite variation in plasma triglyceride levels in both years, but only for the northward migration. By contrast, there was little evidence of intrasite variability (i.e. metabolite profiles of birds using the same site were consistent between years and migratory stages), though we documented intrasite variation resulting from birds' use of different microhabitats at the same site. Plasma glycerol levels did not vary systematically among sites, though they varied among years; on average, birds had higher glycerol levels during northward migration than during southward migration. For the northward migration only, there was a positive relationship between plasma triglyceride levels and total macrofaunal prey abundance among sites. Birds using smaller sites with a lower index of mudflat exposure (mean number of kilometer-hours of mudflat exposed in a 24-h period, reflecting the opportunity to forage at each site) tended to have lower triglyceride levels. Fisiología a Escala de Paisaje: Diferencias entre Sitios en las Tasas de Reabastecimiento Indicadas por Análisis de Metabolitos del Plasma en Chorlos Migratorios Silvestres

scholarly journals Limits to Change

2016 ◽  
Vol 37 (2) ◽  
pp. 99-113
Author(s):  
Roel Puijk
Keyword(s):  
Public Service ◽  
Innovation Management ◽  
Management Strategies ◽  
Production Studies ◽  
The Enlightenment ◽  
External Pressures ◽  
The Usa ◽  
The Uk ◽  
Main Programme ◽  
New Situation

Abstract Production studies have become popular over the past decade. Recent studies have analysed, amongst other things, innovation, management strategies and the effects of convergence on editorial processes. There have only been a few studies that have analysed what happened inside media organisations in the earlier transformative stages (outside the UK and the USA). This paper analyses how the Norwegian public service broadcaster (NRK) adapted to the loss of its monopoly and the beginning of competition during the mid-1980s. It provides a window into how the flagship of public service, the Enlightenment Department, dealt with the new situation. If one follows the production process of the main programme of the department (with the revealing working title ‘Flagship’) from its conception to its realisation as a weekly programme broadcast in prime time, this reveals how innovation at the time was restricted by organisational arrangements, internal values and external pressures. The programme makers included many elements that are still today considered to be advantageous in factual programming (humour, dramatization, popularisation, serialization, recognition, and even interactivity). Along the way several of these were changed: what had started as a proposal for a documentary series turned into something that was predominantly a discussion programme.

scholarly journals When Facebook Becomes a Part of the Self: How Do Motives for Using Facebook Influence Privacy Management?

2021 ◽  
Vol 12 ◽  
Author(s):  
Hyunjin Kang ◽  
Wonsun Shin
Keyword(s):  
Information Management ◽  
Online Survey ◽  
Management Strategies ◽  
Psychological Factor ◽  
The Self ◽  
Boundary Management ◽  
Privacy Management ◽  
Highly Sensitive ◽  
Boundary Turbulence ◽  
Self System

This study examines how three different motivations for using an SNS (i.e., self-expression, belonging, and memory archiving) influence multi-facets of privacy boundary management on the platform mediated by self-extension to it. In recognition of the fact that information management on SNSs often goes beyond the “disclosure-withdrawal” dichotomy, the study investigates the relationships between the three SNS motives and privacy boundary management strategies (i.e., collective boundary and boundary turbulence management). An online survey with Facebook users (N = 305) finds that the three Facebook motivations are positively correlated to users’ self-extension to Facebook. The motivations for using Facebook are positively associated with the management of different layers of privacy boundaries (i.e., basic, sensitive, and highly sensitive), when Facebook self-extension is mediated. In addition, the three motives have indirect associations with potential boundary turbulence management mediated by Facebook self-extension. Extending the classic idea that privacy is deeply rooted in the self, the study demonstrates that perceiving an SNS as part of the self-system constitutes a significant underlying psychological factor that explains the linkage between motives for using SNSs and privacy management.

Biology and Management of Dogfish Sharks

2009 ◽  
Keyword(s):  
Juvenile Fish ◽  
Catch Rate ◽  
Spiny Dogfish ◽  
Commercial Fishery ◽  
Sources Of Information ◽  
Strait Of Georgia ◽  
The Status ◽  
Mean Size ◽  
Catch Rates ◽  
Mature Fish

Abstract.—Spiny dogfish <em>Squalus acanthias </em>have been an important component of the Strait of Georgia fisheries from the late 1800s to the late 1940s, when the fishery collapsed owing to overfishing and changes in market demand. The stock population levels have sustained a commercial fishery of approximately 2,000 metric tons since 1978. Recent concerns regarding the status of dogfish stocks worldwide have reprioritized the status assessment of dogfish in British Columbia. Longline research surveys were conducted for dogfish in the Strait of Georgia in 1986, 1989, and 2005. Additional sources of information are catch and effort data collected through logbook records from the commercial longline fishery. Recent improvements in gear configuration resulted in a switch in the mid-1990s from traditional J hooks to circle hooks, which makes direct comparison of catch rates difficult. In November 2004 a calibration experiment using J hooks and circle hooks demonstrated that, overall, spiny dogfish catch per unit effort (CPUE) for circle-hook gear was 1.6–1.7 times higher than that for J-hook gear. After applying this conversion to the commercial longline CPUE data available for 1980–1984 and 2000–2004, no significant trend in catch rate over time was detected. The catch rate observed in the longline research survey actually increased in 2005 compared to 1986 and 1989. In both fisheries and research data, the proportion of smaller spiny dogfish in the size distribution has increased, reducing the overall mean size. The decline in mean size is probably due to an increase in recruitment of juvenile fish. However, caution in management of this stock is warranted given that the current commercial fishery is now landing a large proportion (estimated 80%) of immature fish. Increased fishing pressure on juveniles could have implications for the abundance of mature fish in upcoming decades.

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