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Box (standard error) and whisker (standard deviation) plots of mean catch per unit effort (CPUE) (number of spiny dogfish per 1,000 hooks) by J-hook gear (squares) and circle-hook gear (circles) by depth strata from gear calibration study November 12-24, 2004. Depth stratum 1 = 0-55 m; 2 = 56-110 m; 3 = 111-165 m; 4 = 166-220 m.
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Spiny dogfish Squalus acanthias 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 regard...
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... < 0.0001). Slope analysis in ANCOVA indicates that CPUE for circle-hook gear increases by depth at a greater rate than CPUE for J-hook gear (t -0.05(2),43 = 3.47; P = 0.001; Figure 4) and subsequent paired t-tests by depth strata indicate significant differences (P < 0.05) in CPUE for the two deepest depth strata only. The circle hook CPUE is 1 ...
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... Ever since, Squalus acanthias have become extremely rare along the Italian peninsula, especially in the last 60 years. Similar situations were described in other maritime sectors, such as the northeastern Pacific and in the Atlantic Ocean [54][55][56][57][58]. This worldwide reduction has been caused by overexploitation [59], as well as habitat degradation and loss due to coastal development and pollution [60]. ...
Chondrichthyans are one of the most threatened marine taxa worldwide. This is also the case in the Mediterranean Sea, which is considered an extinction hotspot for rays and sharks. The central position of the Italian peninsula makes it an ideal location for studying the status and changes of this sea. There is a lack of biological, ecological and historical data when assessing shark populations, which is also highlighted in the Red List of Threatened Species compiled by the International Union for the Conservation of Nature (IUCN). Historical data can provide important information to better understand how chondrichthyan populations have changed over time. This study aims to provide a clearer understanding of the changes in distribution and abundance of eight shark species in the Italian seas that are currently classified as at risk of extinction by the IUCN. In this respect, a bibliographic review was conducted on items from the 19th century to the first half of the 20th century, focusing on the selected species. The results show that all sharks were considered common until the beginning of the 20th century but have declined since, with a clear negative trend, mainly in the past 70 years. The strong local decline has been attributed to overexploitation, bycatch, habitat loss, depletion of prey items and environmental pollution. Furthermore, historical data also allow us to avoid the issue of a ‘shifting baseline’, in which contemporary abundances are assumed to be “normal”. Using historical data to further our knowledge of the marine environment is becoming increasingly common, and is fundamental in understanding human impact and evaluating mitigation measures to manage and conserve marine species and environments.
... Данные по размерному составу катрана в северной части Тихого океана до последнего времени были довольно ограниченными и фрагментарными. И лишь в ряде недавно опубликованных работ ( Brodeur et al., 2009;Palsson, 2009;King, McFarlane, 2009;Beamish, Sweeting, 2009;Tribuzio et al., 2009) приведены сведения по размерному составу катрана из уловов различных орудий лова, однако эти данные ограничены водами западного побережья США и Канады. В целом в северной части Тихого океана чаще всего вылавливаются особи длиной 80-90 см (Фадеев, 1984). ...
Обобщены данные по пространственному и вертикальному распределению северотихоокеанской колючей акулы (катрана) Squalus suckleyi в тихоокеанских водах Курильских островов и Камчатки из уловов лососевых дрифтерных и ставных сетей и донных тралов в 2005-2008 гг. Приведены новые данные по внешней морфологии особей, выловленных в тихоокеанских водах Курильских островов и Камчатки, а также северо-западной части Японского моря. Рассмотрены некоторые вопросы, связанные с репродуктивной биологией вида, и состав пищи в различных районах.
... These data were included as an index of relative abundance in the inside stock model runs. King and McFarlane (2009b) examined the trends in abundance from 1986, 1989 and 2005 surveys and determined that there was a significant difference in annual median CPUE (Kruskal-Wallis ANOVA: F 0.05(1),2,87 = 18.03; P < 0.001; n = 90). ...
... Bonferroni corrected comparison of mean ranks determined that the median CPUE was higher in 2005 than the other three years ( Figure 13). These data support King and McFarlane's (2009b) conclusion there is no evidence that the relative abundance of spiny dogfish has declined in the Strait of Georgia over the last 20 years. From 1986-2006 the mean annual spiny dogfish landings (longline and trawl fisheries) for the inside stock was 947 tonnes (Tables 3 and 4). ...
... Commercial and research length data Biological data were not included in the surplus production model, but commercial and research length data have been collected and were reported in King and McFarlane (2009b). For the period 1974-2004, there was a dramatic decline in the mean size of females in the longline fishery data from 124 cm (1975)(1976)(1977)(1978)(1979) to 80 cm (2000)(2001)(2002)(2003)(2004). ...
Spiny dogfish (Squalus acanthias) is a small shark that inhabits temperate waters off the east
and west coasts of North America. They are ovoviviparous and gestation is 2 years. Females
produce 2-16 pups, averaging between 26-27 cm in length at birth. Spiny dogfish are a longlived
species with maximum ages in the Pacific population of between 80-90 years and a
maximum size of 130 cm. Age-at-maturity of females is approximately 35-36 years
corresponding to approximately 94 cm. Length-at-maturity for males is 70 cm.
Spiny dogfish have a long history of commercial exploitation in British Columbia dating back to
1870. From 1870-1916, spiny dogfish were harvested for their liver and body oils for use in
industrial lubrication and lighting. Spiny dogfish livers were used as a source of Vitamin A, and
a large liver fishery took place from 1937-1950 with recorded annual landings between 5,139-
31,187 tonnes. Stock declines, market shifts and production of synthetic Vitamin A led to a
collapse of the liver fishery. By 1977, market demand for spiny dogfish as food fish revived the
fishery and since 1980 annual landings have ranged between 139 tonnes (in 1986) to 4,952
tonnes (in 2003). The longterm mean annual total fishing mortalities for the food fishery era
(1978-2008) are 1,599 tonnes for the inside fishery and 1,690 tonnes for the outside fishery.
The spiny dogfish population in British Columbia is assessed as two distinct stocks: an inside
stock inhabiting the Strait of Georgia (Statistical Area 4B); and an outside stock inhabiting all
remaining coastal areas (Statistical Areas 3C through 5E). This stock assessment employs
generalized Schaefer and Pella-Tomlinson surplus production models to estimate the current
biomass of each stock. Model parameter estimates for the intrinsic rate of population increase
(r) were available from the literature, and a range of estimates between 0.017-0.07 were used.
The carrying capacity (K) estimates were based on estimates of biomass at the start of the liver
fishery in the 1940s which were 166,667 and 333,333 tonnes for the inside and outside stock
respectively. Catch per unit effort data available from the longline and trawl fisheries and from
several research surveys were used as indices of relative abundance.
Model runs that use intermediate r values and that allow the model to estimate K are
recommended for consideration in assessing the status of the inside and outside stocks and
selecting yield limits. For the inside stock both the Schaefer and the Pella-Tomlinson model
runs estimate that the population is in the Cautious zone, i.e. between 40-80% of BMSY. The
yield limit derived from the Schaefer model is 525 tonnes, and the limit derived from the Pella-
Tomlinson model is 168 tonnes. For the outside stock both model runs estimate that the
population is in the Healthy zone, i.e. greater than 80% of BMSY. The yield limit derived from the
Schaefer model is 5,964 tonnes, and the limit derived from the Pella-Tomlinson model is 10,087
tonnes.
... Although spiny dogfish Squalus acanthias are among the most widely distributed species of sharks and are common in temperate waters of both the Pacific and Atlantic oceans (Ferguson and Caillet 1990), very little is known about their feeding ecology and movements. They are a long-lived species, reaching an age of approximately 35–40 years in the Atlantic (Nammack et al. 1985) and up to 80 years in the North Pacific (McFarlane and Beamish 1987;King and McFarlane 2009, this volume). In the northern Pacific, dogfish inhabit depths up to 900 m, usually occupying benthic habitats (Allen and Smith 1988), although juveniles are usually found closer to the surface (Beamish et al. 1982). ...
Spiny dogfish Squalus acanthias are an abundant and commercially important species of fish
off both the Atlantic and Pacific coasts of North America. They are opportunistic feeders and have a
varied diet that can include many fish species, especially small forage fish such as herring, capelin, and
sand lance as well as crustaceans, worms, euphausiids, gelatinous zooplankton, and cephalopods. The
purpose of our present study is to investigate the utility of the second dorsal spine in providing multiyear
information on the feeding habits of dogfish using stable isotope (C and N) analysis. The outer
dentine and enamel layers of a spine from three dogfish (caught off the coast of British Columbia) were
analyzed to obtain their stable nitrogen and carbon isotope composition (δ15N and δ13C, respectively).
Each sample had annuli from multiple years, allowing possible seasonal migrations to be averaged over
samples. The δ15N ranged from a low of 11.6‰ to a high of 14.9‰ over the three spines and δ13C
ranged from –11.5‰ to –18.4‰. The variable isotopic signatures along the spine indicate that the
method may be used to assess ecological changes. Stable isotope measurements of dogfish spines could
be a valuable means of determining long-term changes in habitat usage and feeding ecology.
... Recent attempts to list spiny dogfish Squalus acanthias under Appendix II of the Convention on International Trade in Endangered Species (CITES) (Fordham 2009, this volume) have led to a renewed interest in Canadian stock assessment and management for this species. The Strait of Georgia has long supported commercial fisheries for dogfish (King and McFarlane 2009, this volume), and since the late 1970s has been managed by quota based on an assessment model by Wood et al. (1979). Dogfish are long lived and slow growing, attaining ages in the North Pacific in excess of 100 years, and sizes in excess of 130 cm (Saunders and McFarlane 1993). ...
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 Squalus acanthias 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.
... In contrast, DFO research longline surveys do not indicate that the spiny dogfish in the Strait have declined over this period, but rather indicate a small increase from the late 1980s to 2005-8. Likewise, the average abundance trends (CPUE) from commercial fisheries in the Strait do not indicate any clear changes in abundance during1980(King and McFarlane 2009. ...
There is intense public interest surrounding the conservation and management of sharks, including a debate over whether sustainable shark fisheries are possible or fishing bans on sharks are needed to conserve these animals. An important but rarely discussed data point in discussions of global shark fisheries is the case of British Columbia's fishery for Pacific spiny dogfish, Squalus suckleyi, which in 2011 became the first Marine Stewardship Council−certified shark fishery anywhere in the world. A few years later, despite reportedly healthy local stocks and thriving global markets for this shark, the fishery voluntarily withdrew its MSC certification, and in recent years more than 95% of the quota for Pacific spiny dogfish has been left in the water. This study provides insight into what happened to this fishery through a review of grey literature and a series of stakeholder interviews with British Columbian fishermen, fish processors, managers and environmentalists. It is a rare case study of a fishery that largely ceased operations without a clear mechanistic explanation like a stock collapse, a government mandate to limit fishing or a clear shift in market demand. This fishery appears to have been affected by the combination of several factors, including a temporary reduction in biomass due to oceanographic effects, potential blowback from overly broad environmental messaging that did not distinguish between sustainable and unsustainable shark fisheries, management changes resulting in altered fishing incentives and changes to processing capacity associated with consolidating the fishing industry into ownership by relatively few large companies.
