Distribution shifts and overfishing the northern cod (Gadus morhua): a view from the ocean

2000 ◽  
Vol 57 (3) ◽  
pp. 644-663 ◽  
Author(s):  
G A Rose ◽  
B deYoung ◽  
D W Kulka ◽  
S V Goddard ◽  
G L Fletcher
Keyword(s):  
Gadus Morhua ◽  
Environmental Changes ◽  
Rapid Decline ◽  
Trawl Survey ◽  
The South ◽  
The North ◽  
Northern Cod ◽  
Before And After ◽  
Distribution Shifts ◽  
Size At Age

Research on northern cod (Gadus morhua) from 1983 to 1994 indicated that a southward shift in distribution in the early 1990s was real and not an artifact of sequentially fishing down local populations. In the early 1990s, seasonal fishery and survey data showed distribution changes where there was no fishery, and large tonnage and densities (450 000 t, densities fourfold higher than 1980s levels) appeared in the south concurrent with declines in the north. All fishery, acoustic, and trawl survey indices increased in the south, while the stock declined. Southern-caught cod in the early 1990s exhibited northern characteristics: (i) antifreeze production capacities above historical norms and equivalent to those of northern fish, (ii) vertebral counts above historic norms and equalling northern counts, and (iii) declines in size-at-age to levels associated with northern fish. The cause of the shift is thought to be a combination of abiotic (climate) and biotic (capelin (Mallotus villosus)) environmental changes and cumulative long-term fisheries effects on cod behavior. The shifted distributions increased vulnerability to Canadian and foreign fisheries and led to a rapid decline in abundance, both before and after the moratorium on fishing in Canadian waters in 1992. Rebuilding will occur in three steps: environmental restoration, recolonization by adults, and enhanced recruitment across the shelf.

Population abundance and body size of Calanus sinicus in marginal habitats in the coastal seas of south-eastern Hong Kong

2012 ◽  
Vol 93 (1) ◽  
pp. 135-142 ◽  
Author(s):  
G.-T. Zhang ◽  
C.K. Wong
Keyword(s):  
Hong Kong ◽  
Yellow Sea ◽  
Local Population ◽  
The Yellow Sea ◽  
Rapid Decline ◽  
The South ◽  
Calanus Sinicus ◽  
China Sea ◽  
The North ◽  
Chinese Coast

The species range of Calanus sinicus along the Chinese coast extends from the Bohai Sea and the Yellow Sea in the north to the northern part of the South China Sea in the south. The subtropical seas along the southern coast of China mark the southern edge of the range of C. sinicus. In coastal seas off eastern Hong Kong, C. sinicus appears first in December, but densities comparable to those in the Yellow Sea and the East China Sea are reached only in January and February when temperature is <15°C. Density decreases in March as temperature increases. No individuals remain after May when temperature is >25°C. The average prosome length of females collected in February is comparable to that of females from the Yellow Sea, but females collected after mid-March are smaller than the smallest females from the Yellow Sea. Reproduction occurred mainly between January and March. Rapid decline of the population in April and the absence of a summer population suggest that the local population is derived from individuals advected from the north by ocean currents. Eggs produced locally probably did not hatch or develop into adults.

scholarly journals Current freezing and thawing scenarios employed by North Atlantic fisheries: their potential role in Newfoundland and Labrador’s northern cod (Gadus morhua) fishery

PeerJ ◽  
2021 ◽  
Vol 9 ◽  
pp. e12526
Author(s):  
Pete Brown ◽  
Deepika Dave
Keyword(s):  
Product Quality ◽  
North Atlantic ◽  
Gadus Morhua ◽  
Freezing And Thawing ◽  
The North ◽  
Freeze And Thaw ◽  
Northern Cod ◽  
Seafood Industry ◽  
Additional Processing ◽  
Preservation Technique

Seafood is very perishable and can quickly spoil due to three mechanisms: autolysis, microbial degradation, and oxidation. Primary commercial sectors within the North Atlantic fisheries include demersal, pelagic, and shellfish fisheries. The preservation techniques employed across each sector can be relatively consistent; however, some key differences exist across species and regions to maintain product freshness. Freezing has long been employed as a preservation technique to maintain product quality for extended periods. Freezing allows seafood to be held until demand improves and shipped long distances using lower-cost ground transportation while maintaining organoleptic properties and product quality. Thawing is the opposite of freezing and can be applied before additional processing or the final sale point. However, all preservation techniques have limitations, and a properly frozen and thawed fish will still suffer from drip loss. This review summarizes the general introduction of spoilage and seafood spoilage mechanisms and the latest preservation techniques in the seafood industry, focusing on freezing and thawing processes and technologies. This review also considers the concept of global value chains (GVC) and the points to freeze and thaw seafood along the GVC to improve its quality with the intention of helping Newfoundland and Labrador’s emerging Northern cod (Gadus morhua) fisheries enhance product quality, meet market demands and increase stakeholder value.

Phanerozoic accretionary history of Japan and the western Pacific margin

2018 ◽  
Vol 158 (1) ◽  
pp. 13-29 ◽  
Author(s):  
Koji Wakita ◽  
Takanori Nakagawa ◽  
Masahiro Sakata ◽  
Natsuki Tanaka ◽  
Nozomu Oyama
Keyword(s):  
North China ◽  
Japan Sea ◽  
Detrital Zircons ◽  
Oceanic Plate ◽  
The South ◽  
The North ◽  
Before And After ◽  
History Of ◽  
Japanese Islands ◽  
Plate Subduction

AbstractIt is generally accepted that oceanic plate subduction has occurred along the eastern margin of Asia since about 500 Ma ago. Therefore, the Japanese Islands have a >500 Ma history of oceanic plate subduction in their geological records. In this paper, the accretionary history of the Japanese Islands is divided into six main stages based on the mode and nature of tectonic events and the temporal gaps in the development of accretionary processes. In the first stage, oceanic plate subduction and accretion started along the margin of Gondwana. After detachment of the North and South China blocks in Devonian time, accretionary complexes developed along island arcs offshore of the South and North China blocks. After the formation of back arc basins such as the Japan Sea, accretionary processes occurred only along the limited convergent margin, e.g. Nankai Trough. Detrital zircons of sandstones revealed the accretionary history of Japan. An evaluation of a comprehensive dataset on detrital zircon populations shows that the observed temporal gaps in the development of the Japanese accretionary complexes were closely related to the intensity of igneous activity in their provenance regions. Age distributions of detrital zircons in the accretionary complexes of Japan change before and after the Middle Triassic period, when the collision of the South and North China blocks occurred.

scholarly journals A Community‐Engaged Stroke Preparedness Intervention in Chicago

2020 ◽  
Vol 9 (18) ◽  
Author(s):  
Shyam Prabhakaran ◽  
Christopher T. Richards ◽  
Soyang Kwon ◽  
Erin Wymore ◽  
Sarah Song ◽  
...  
Keyword(s):  
Ischemic Stroke ◽  
The South ◽  
Hospital Arrival ◽  
South Side ◽  
Intervention Hospital ◽  
The North ◽  
North Side ◽  
Before And After ◽  
Ambulance Transports ◽  
Suspected Stroke

Background We evaluated a community‐engaged stroke preparedness intervention that aimed to increase early hospital arrival and emergency medical services (EMS) utilization among patients with stroke in the South Side of Chicago, Illinois. Methods and Results We compared change in early hospital arrival (<3 hours from symptom onset) and EMS utilization before and after our intervention among patients with confirmed ischemic stroke at an intervention hospital on the South Side of Chicago with concurrent data from 6 hospitals in nonintervention communities on the North Side of Chicago and 17 hospitals in St Louis, Missouri. We assessed EMS utilization for suspected stroke secondarily, using geospatial information systems analysis of Chicago ambulance transports before and after our intervention. Among 21 497 patients with confirmed ischemic stroke across all sites, early arrival rates at the intervention hospital increased by 0.5% per month (95% CI, −0.2% to 1.2%) after intervention compared with the preintervention period but were not different from North Side Chicago hospitals (difference of −0.3% per month [95% CI, −0.12% to 0.06%]) or St Louis hospitals (difference of 0.7% per month [95% CI, −0.1% to 1.4%]). EMS utilization at the intervention hospital decreased by 0.8% per month (95% CI, −1.7% to 0.2%) but was not different from North Side Chicago hospitals (difference of 0.004% per month [95% CI, −1.1% to 1.1%]) or St Louis hospitals (difference of −0.7% per month [95% CI, −1.7% to 0.3%]). EMS utilization for suspected stroke increased in the areas surrounding the intervention hospital (odds ratio [OR], 1.4; 95% CI, 1.2–1.6) and in the South Side (OR, 1.2; 95% CI, 1.1–1.3), but not in the North Side (OR, 1.0; 95% CI, 0.9–1.1). Conclusions Following a community stroke preparedness intervention, early hospital arrival and EMS utilization for confirmed ischemic stroke did not increase. However, ambulance transports for suspected stroke increased in the intervention community compared with other regions. Registration URL: https://www.clini​caltr​ials.gov ; Unique identifier: NCT02301299.

Spatial and temporal microsatellite variation in spawning Atlantic cod, Gadus morhua, around Iceland

2013 ◽  
Vol 70 (8) ◽  
pp. 1151-1158 ◽  
Author(s):  
Guðni Magnús Eiríksson ◽  
Einar Árnason
Keyword(s):  
Allele Frequency ◽  
Gadus Morhua ◽  
Atlantic Cod ◽  
Genetic Difference ◽  
North Coast ◽  
The South ◽  
Microsatellite Variation ◽  
The North ◽  
Significant Difference ◽  
The Difference

The present study suggests that the observed genetic difference between Atlantic cod, Gadus morhua, off the south and the north coast of Iceland may be caused by natural selection affecting genetic variation at a microsatellite loci (Gmo34). When disregarding this locus from the analysis, no genetic difference was observed between northern and southern Iceland. The methods applied here were very sensitive, and differences as small as FST = 0.0005 are unlikely to go unnoticed. The difference between cod off the south and the north coast of Iceland is thus likely to be smaller than that. Such a small difference is negligible and is not likely to have any biological meaning. Genetic drift was detected by allele frequency comparison among different cohorts (FST = 0.0007, P = 0.0209). A small but significant difference was observed among allele frequency for cod grouped by depth at the south coast of Iceland (FST = 0.0017, P = 0.0002). This difference is very subtle and needs to be interpreted with caution.

The Craig-Collins pacts of 1922: two attempted reforms of the Northern Ireland government

1990 ◽  
Vol 27 (106) ◽  
pp. 145-158 ◽  
Author(s):  
Michael Hopkinson
Keyword(s):  
Northern Ireland ◽  
Equal Weight ◽  
British Government ◽  
The South ◽  
North East ◽  
The North ◽  
Treaty Negotiations ◽  
Before And After ◽  
The Stability ◽  
Shipyard Workers

The six months following the Anglo-Irish treaty of 1921 saw an appalling level of violence in Belfast and on the border, which threatened the stability of the newly formed Northern Ireland government. Official figures for the period between 6 December 1921 and 31 May 1922 listed seventy-three protestants and 147 catholics killed in Belfast and eight protestants and twenty-two catholics killed in the six counties outside Belfast. In that period two wide-ranging agreements aimed to reform the northern government and security system: they became known, somewhat inaccurately, as the Craig-Collins pacts, of 21 January and 30 March 1922. This article discusses the motivation behind the pacts and the reasons for their failure in a wide context, by giving equal weight to the attitudes of the British government and to opinion on both sides of the Irish border.The Northern Ireland government was established in 1920–21. It was unrecognised by the dáil government in the south and by much of the northern catholic minority. The province developed against a background of violence and upheaval, including the expulsion of catholic shipyard workers from their work in the summer of 1920; the dáil retaliated by boycotting Belfast goods. The period also saw increasing I.R.A. activity in the north during the latter stages of the Anglo-Irish war, and the five-month truce that followed it. Though the northern government was not a party to the treaty negotiations, only reluctantly accepting the granting of dominion status to the south, the months before and after the settlement greatly increased tensions in the north-east.

scholarly journals Combination of genetics and spatial modelling highlights the sensitivity of cod (Gadus morhua) population diversity in the North Sea to distributions of fishing

2013 ◽  
Vol 71 (4) ◽  
pp. 794-807 ◽  
Author(s):  
Michael R. Heath ◽  
Mark A. Culling ◽  
Walter W. Crozier ◽  
Clive J. Fox ◽  
William S. C. Gurney ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Spatial Patterns ◽  
North Sea ◽  
Gadus Morhua ◽  
Atlantic Cod ◽  
Population Diversity ◽  
Trawl Survey ◽  
The North ◽  
Animal Populations ◽  
The North Sea

Abstract Conserving genetic diversity in animal populations is important for sustaining their ability to respond to environmental change. However, the “between-population” component of genetic diversity (biocomplexity) is threatened in many exploited populations, particularly marine fish, where harvest management regions may be larger than the spatial extent of genetically distinct subpopulations. Using single-nucleotide polymorphism data, we delineated the geographic limits of three population units of Atlantic cod (Gadus morhua) in northwest European waters. Two of the populations cohabit the North Sea, and trawl survey data showed differing trends in their abundances. We developed a spatial model of these units to simulate population dynamics under spatial patterns of harvesting. Competition between units during the pelagic juvenile stages in the model led to suppression of the more localized northern North Sea (Viking) unit by the more widespread (Dogger) unit, and its premature extinction under some spatial patterns of fishing. Fishery catch limits for cod are set at the scale of the whole North Sea without regard to such subpopulation dynamics. Our model offers a method to quantify adjustments to regional fishing mortality rates to strike a balance between maximizing sustainable yield and conserving vulnerable populations.

Effect of environmental change on parasites of Atlantic cod (Gadus morhua) as bioindicators of populations in the north-western Atlantic Ocean

2007 ◽  
Vol 81 (2) ◽  
pp. 129-135 ◽  
Author(s):  
R.A. Khan
Keyword(s):  
Gadus Morhua ◽  
Environmental Changes ◽  
Atlantic Cod ◽  
Metazoan Parasites ◽  
Sea Temperature ◽  
Western Atlantic ◽  
Virtual Absence ◽  
The North ◽  
Over Exploitation ◽  
North Western

AbstractStudies conducted in the 1980s suggested that parasites were useful in distinguishing adjacent populations of Atlantic cod Gadus morhua in the north-western Atlantic. During the mid-1980s, cod populations began to decline, culminating in closure of the fishery in 1992. A marked decrease of cod off the coast of Labrador was coincident with climatic shifts, including a decline of bottom sea temperature, and virtual absence of capelin Mallotus villosus, its main food prey. These changes in some components of the ecosystem were independent of anthropogenic influences. An initial survey of cod parasites in 2000 from coastal Labrador revealed a dramatic decline in abundance of metazoans and also a change in dominance of species of digenetic trematodes compared to 1980–1981. Comparison of metazoan parasites in three other populations of cod inhabiting the Grand (northern and southern) and St. Pierre Banks, where there was no apparent evidence of environmental changes but only commercial over-exploitation, revealed no major alterations in abundance or dominance between 1980–1981 and 2003. The results of this current study suggest that environmental changes in the food web affected the abundance of metazoan parasites only off coastal Labrador but did not influence the use of the parasites to distinguish between cod populations inhabiting the Grand or St. Pierre Banks.

scholarly journals Evidence from survey data for regional variability in cod dynamics in the North Sea and West of Scotland

2008 ◽  
Vol 65 (2) ◽  
pp. 206-215 ◽  
Author(s):  
Steven J. Holmes ◽  
Peter J. Wright ◽  
Robert J. Fryer
Keyword(s):  
Survey Data ◽  
North Sea ◽  
Gadus Morhua ◽  
Temporal Trends ◽  
Trawl Survey ◽  
Regional Variability ◽  
The North ◽  
Spawning Areas ◽  
General Decline ◽  
The North Sea

Abstract Holmes, S. J., Wright, P. J., and Fryer, R. J. 2008. Evidence from survey data for regional variability in cod dynamics in the North Sea and West of Scotland. – ICES Journal of Marine Science, 65: 206–215. Although cod (Gadus morhua) in the North Sea and ICES Division VIa are assessed as single units, recent research suggests that the stocks consist of reproductively isolated subpopulations within a metapopulation. We investigate whether temporal trends in stock indicators are asynchronous across subpopulations, which would support the metapopulation hypothesis. First quarter trawl survey data for the years 1983–2005 were aggregated into putative areas of high spawner fidelity (three in VIa, seven in the North Sea) to obtain indices of spawning–stock biomass (SSB) and recruitment (numbers-at-age 1). Asynchrony was investigated by fitting a smoother to the data for each of the ten spawning areas and testing whether the smoothers were parallel. Trends in SSB differed between spawning areas in both VIa and the North Sea. In VIa, SSB collapsed in the most southwesterly area, but remained more constant elsewhere. In the North Sea, there was a general decline in SSB, but areas thought to contain resident inshore populations showed more rapid declines than those in adjacent offshore areas. Recruitment results offered less support for a metapopulation, although recruitment in the southern North Sea declined rapidly before any trend was seen for the North Sea as a whole.

Influence of environmental changes in the north-western Atlantic Ocean on a parasite, Echinorhynchus gadi (Acanthocephala) of Atlantic cod (Gadus morhua) occurring off coastal Labrador, Canada

2008 ◽  
Vol 82 (3) ◽  
pp. 203-209 ◽  
Author(s):  
R.A. Khan
Keyword(s):  
North Atlantic ◽  
Marine Mammals ◽  
Gadus Morhua ◽  
Small Schools ◽  
Environmental Changes ◽  
Atlantic Cod ◽  
Primary Source ◽  
Western Atlantic ◽  
The North ◽  
North Western

AbstractA study was conducted to determine the influence of environmental change on an endoparasite, Echinorhynchus gadi (Acanthocephala) of Atlantic cod (Gadus morhua) over a 30-year period off the coast of Labrador in the north-western Atlantic, North Atlantic Fisheries Organization subareas 2J–3K. Cod, once an abundant fish species that had been commercially exploited for many decades, declined precipitously during the mid-1980s onwards. This decline was attributed to climatic changes that affected the entire food chain from zooplankton to fish, sea birds and marine mammals. A monitoring programme was introduced, sampling cod by otter trawling using research vessels. The fish, after capture, were frozen at − 20°C, subsequently thawed and the digestive tract removed and examined for the parasite in 2006. Data from samples taken in 1976, 1980–81, 1986, 1990, 2000 and 2003 were compared statistically with those collected in 2006. The results indicate a decline in the prevalence and mean abundance of E. gadi in 1986 with a minimum in 2000 but increasing gradually in 2003 and 2006. These changes were coincident initially with a decline of oceanic temperature and the entire food web, including capelin (Mallotus villosus), a preferred prey of cod and primary source of E. gadi. The increase in prevalence and mean abundance of the parasite in 2006 were associated with an increase of oceanic temperature and the return of small schools of capelin to offshore areas. Cod older than 4 years harboured a greater abundance of E. gadi than younger fish, while no difference was observed between the sexes. The results suggest that the abundance of E. gadi can be useful as a bioindicator of environmental changes in the north-western Atlantic.

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