Abundance and distribution of pelagic 0-group cod (Gadus morhua) in Newfoundland waters: inshore versus offshore

1995 ◽  
Vol 52 (1) ◽  
pp. 115-125 ◽  
Author(s):  
J. T. Anderson ◽  
E. L. Dalley ◽  
J. E. Carscadden
Keyword(s):  
Large Scale ◽  
Gadus Morhua ◽  
Offshore Area ◽  
The North ◽  
Spawning Areas ◽  
Northern Cod ◽  
Primary Habitat ◽  
Abundance And Distribution ◽  
Eggs And Larvae ◽  
Pelagic Juvenile

The Northern cod stock has previously been described as undergoing a large-scale denatant–contranatant migration during which spawning occurs primarily in the north off Labrador. Eggs and larvae are advected southward to the inshore areas along the NE coast of Newfoundland where they settle as juveniles, then there is a gradual return migration to the northern spawning areas. We examined abundance distributions of pelagic juvenile (0-group) cod in the fall between inshore and offshore areas to determine if these fish occurred predominantly inshore following pelagic drift. Comparison between areas demonstrated no differences in abundances and mean sizes. Our results do not support the concept of large-scale advection of eggs and larvae spawned offshore to inshore areas, but indicate that cod eggs spawned offshore remain offshore. Back calculations of spawning times indicate the pelagic juvenile cod sampled offshore were spawned predominantly in April, whereas fish caught inshore were spawned predominantly in May-June, as well as April. Estimates of spawning abundance indicate that the inshore areas along the NE coast of Newfoundland may represent <10% of eggs spawned annually. Historically, the offshore area appears to have been the primary habitat for pelagic juvenile cod.

scholarly journals Local cod (Gadus morhua) revealed by egg surveys and population genetic analysis after longstanding depletion on the Swedish Skagerrak coast

2018 ◽  
Vol 76 (2) ◽  
pp. 418-429 ◽  
Author(s):  
Henrik Svedäng ◽  
Julia M I Barth ◽  
Anders Svenson ◽  
Patrik Jonsson ◽  
Sissel Jentoft ◽  
...  
Keyword(s):  
North Sea ◽  
West Coast ◽  
Population Genetic ◽  
Gadus Morhua ◽  
Atlantic Cod ◽  
Early Stage ◽  
Population Genetic Analysis ◽  
Swedish West Coast ◽  
The North ◽  
Spawning Areas

Abstract Dramatic and persistent reductions in Atlantic cod (Gadus morhua) are common in many coastal areas. While offshore cod stocks still were abundant and productive, the Swedish west coast showed signs of diminishing adult cod abundance at the beginning of the 1980s, where the local cod component was considered to be extirpated. To survey the present cod spawning activity and stock composition, we initiated egg trawling over two consecutive years (203 hauls in total) in combination with population genetic analyses (425 individually genotyped eggs). Here, we provide evidence of cod spawning at the Swedish Skagerrak coast, suggesting recolonization or that local cod has recovered from a nearly depleted state. Early stage eggs were found inside fjords too far to have been transported by oceanic drift from offshore spawning areas. The cod eggs were genetically similar in early to late life-stages and cluster mainly with the local adult cod, indicating that eggs and adults belong to the same genetic unit. The cod eggs were genetically differentiated from adult North Sea cod, and, to a lesser degree, also from the Kattegat and Öresund cod, i.e. indicating a possible recovery of local coastal stock. The patterns of the genetic structure in the inshore areas are, however, difficult to fully disentangle, as Atlantic cod in the North Sea-Skagerrak area seem to be a mixture of co-existing forms: local cod completing their entire life cycle in fjords and sheltered areas, and oceanic populations showing homing behaviours. The egg abundances are considerably lower compared with what is found in similar studies along the Norwegian Skagerrak coast. Nevertheless, the discovery of locally spawning cod along the Swedish west coast—although at low biomasses—is an encouraging finding that highlights the needs for endurance in protective measures and of detailed surveys to secure intraspecific biodiversity and ecosystem services.

Survival of Northern Atlantic Cod (Gadus morhua) Eggs and Larvae when Exposed to Ice and Low Temperature

1992 ◽  
Vol 49 (12) ◽  
pp. 2588-2595 ◽  
Author(s):  
Paul F. Valerio ◽  
Sally V. Goddard ◽  
Ming H. Kao ◽  
Garth L. Fletcher
Keyword(s):  
Low Temperature ◽  
Newfoundland And Labrador ◽  
Direct Contact ◽  
Gadus Morhua ◽  
Atlantic Cod ◽  
Ice Crystals ◽  
Freeze Resistance ◽  
Northern Cod ◽  
Northern Atlantic ◽  
Eggs And Larvae

Freeze resistance of eggs and larvae of Atlantic cod (Gadus morhua) from the northern cod stock was investigated to determine whether ice contact could affect survival during the spring spawning season off Newfoundland. Egg and larval homogenates did not appear to contain antifreeze proteins (mean freezing points −0.78 and −0.88 °C, respectively). However, cod eggs did not freeze at −1.8 °C in icy aerated seawater, could be undercooled to −4.0 °C in ice, and froze at temperatures between −4.1 and −1 7 °C; freeze resistance depended on the integrity of the chorion. Larvae withstood undercooling to −1.8 °C, provided they were not brought into direct contact with ice crystals, if directly touched with ice, larvae froze at −1.36 °C (feeding stage) or −1.34 °C (yolk-sac), approximately 0.5 °C lower than would be expected from the freezing temperatures of their body fluids. The nature of their external epithelium and delayed development of sensitive gill structures below 0 °C may contribute to larval freeze resistance. Cod eggs and larvae are found in spring off Newfoundland and Labrador, when sea temperatures can be as low as −1.8 °C and ice cover extensive. While cod eggs are remarkably freeze resistant, such environmental conditions may cause freezing mortalities in larval cod.

scholarly journals Buoyancy and vertical distribution of Norwegian coastal cod (Gadus morhua) eggs from different areas along the coast

2008 ◽  
Vol 65 (7) ◽  
pp. 1198-1202 ◽  
Author(s):  
Erling Kåre Stenevik ◽  
Svein Sundby ◽  
Ann Lisbeth Agnalt
Keyword(s):  
Vertical Distribution ◽  
Density Gradient ◽  
Surface Waters ◽  
Gadus Morhua ◽  
Genetic Differences ◽  
Marine Science ◽  
Norwegian Coast ◽  
Spawning Areas ◽  
Subsurface Waters ◽  
Eggs And Larvae

Abstract Stenevik, E. K., Sundby, S., and Agnalt, A. L. 2008. Buoyancy and vertical distribution of Norwegian coastal cod (Gadus morhua) eggs from different areas along the coast. – ICES Journal of Marine Science, 65: 1198–1202. There are significant genetic differences in coastal cod (Gadus morhua) along the Norwegian coast, and in order to maintain these differences, there must be mechanisms that ensure local retention of eggs and larvae in the spawning areas. The buoyancy of eggs from four different areas along the Norwegian coast was measured using a density gradient column, and the results from modelling experiments showed that in three of the groups (Tysfjord, Helgeland, and Øygarden), the buoyancy in combination with local hydrography would place the eggs in subsurface waters where retention is greater than in surface waters.

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.

scholarly journals Does redistribution or local growth underpin rebuilding of Canada’s Northern cod?

2018 ◽  
Vol 75 (6) ◽  
pp. 825-835 ◽  
Author(s):  
George A. Rose ◽  
Sherrylynn Rowe
Keyword(s):  
Gadus Morhua ◽  
Local Population ◽  
Latitudinal Gradients ◽  
Individual Growth ◽  
Late Winter ◽  
Local Growth ◽  
Multiple Spawning ◽  
Spawning Areas ◽  
Northern Cod ◽  
Acoustic Surveys

The stock structure of Canada’s Northern cod (Gadus morhua), the largest of many depleted groundfish stocks having multiple spawning areas, is rebuilding by redistribution and not solely by local population growth. In 2007–2008, late winter acoustic surveys suggested initial rebuilding in the southern-most part of the offshore range (Bonavista Corridor, NAFO Divisions 3KL), likely including fish dispersing from the inshore. Thereafter, acoustically determined biomass increases averaged 30% per annum (to near 240 000 t in 2014). In contrast, formerly dominant stock areas farther north retained few fish, mostly juveniles. In 2015, however, biomass in the northern stock range (NAFO Division 2J) reached 65 000 t and mid-north Notre Dame Channel (3K) reached 101 000 t, with Bonavista Corridor declining to 136 000 t. Biomass pooled over all surveyed regions totaled 302 000 t, consistent with sustained 30% growth. Latitudinal gradients in cod size, age distributions, and individual growth existed both historically and recently, but not in 2015. The evidence suggests that the rapid increases of depopulated northern groups resulted from redistribution from the south within a metapopulation.

scholarly journals Recolonization history and large-scale dispersal in the open sea: the case study of the North Atlantic cod, Gadus morhua L.

2008 ◽  
Vol 94 (2) ◽  
pp. 315-329 ◽  
Author(s):  
CHRISTOPHE PAMPOULIE ◽  
MAGNÚS ÖRN STEFÁNSSON ◽  
THÓRA DÖGG JÖRUNDSDÓTTIR ◽  
BRET S. DANILOWICZ ◽  
ANNA KRISTÍN DANÍELSDÓTTIR
Keyword(s):  
North Atlantic ◽  
Large Scale ◽  
Gadus Morhua ◽  
Atlantic Cod ◽  
The North ◽  
Open Sea ◽  
The North Atlantic

Large scale distribution of dioxins, PCBs, heavy metals, PAH-metabolites and radionuclides in cod (Gadus morhua) from the North Atlantic and its adjacent seas

Chemosphere ◽  
2016 ◽  
Vol 149 ◽  
pp. 294-303 ◽  
Author(s):  
Horst Karl ◽  
Ulrike Kammann ◽  
Marc-Oliver Aust ◽  
Monika Manthey-Karl ◽  
Anja Lüth ◽  
...  
Keyword(s):  
Heavy Metals ◽  
North Atlantic ◽  
Large Scale ◽  
Gadus Morhua ◽  
Pah Metabolites ◽  
The North ◽  
The North Atlantic
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