Piscine Erythrocytic Necrosis Virus in Atlantic Cod, Gadus morhua, and Other Fish: Ultrastructure and Distribution

1977 ◽  
Vol 34 (8) ◽  
pp. 1188-1195 ◽  
Author(s):  
Roland Walker ◽  
Stuart W. Sherburne
Keyword(s):  
Blood Cells ◽  
Gadus Morhua ◽  
Viral Infections ◽  
Atlantic Cod ◽  
Atlantic Coast ◽  
Red Cells ◽  
Georges Bank ◽  
Necrosis Virus ◽  
Intensity Of Infection ◽  
Obvious Relation

Electron microscopy of erythrocytes of Atlantic cod, Gadus morhua, with piscine erythrocytic necrosis (PEN) shows a small cytoplasmic viroplasm (~ 1 μm), often with an adjacent coherent group of large (330 nm) icosahedral virions. The viroplasm is Feulgen-positive, so the agent is an erythrocyte icosahedral cytoplasmic deoxyribovirus (EICDV) analogous to others reported in red cells of poikilotherms. PEN lesions in cod blood cells were found in 11–16% of samples from New Brunswick, Maine, and Georges Bank. PEN was found in cod of 15–80 cm total length taken at depths of 5–90 m. Incidence in the Georges Bank area was higher at depths of about 55 m. Intensity of infection varied from < 0.01 to ~ 99% of mature red cells, without obvious relation to cod size, sex, or condition, or to depth at which taken. PEN infections are reported in various other fish species and in other areas. Key words: viral infections, cytology, ultrastructure, morphology, pathology, Atlantic coast fishes

Recent Growth, Biochemical Composition and Prey Field of Larval Haddock (Melanogrammus aeglefinus) and Atlantic Cod (Gadus morhua) on Georges Bank

1987 ◽  
Vol 44 (1) ◽  
pp. 14-25 ◽  
Author(s):  
L. J. Buckley ◽  
R. G. Lough
Keyword(s):  
Gadus Morhua ◽  
Atlantic Cod ◽  
Dry Weight ◽  
Melanogrammus Aeglefinus ◽  
Good Growth ◽  
Georges Bank ◽  
Larval Population ◽  
Prey Biomass ◽  
Recent Growth ◽  
Haddock Melanogrammus Aeglefinus

A transect across southern Georges Bank in May 1983 showed higher levels of available prey for haddock (Melanogrammus aeglefinus) and cod (Gadus morhua) larvae at two stratified sites than at a well-mixed site. At the stratified sites, prey biomass was high (30–300 μg dry wt∙L−1) near the surface above the thermocline; values were lower and more uniform with depth (10–30 μg dry wt∙L−1) at the well-mixed site. Larval population centers generally coincided with prey biomass vertically. Recent growth in dry weight of haddock larvae as estimated by RNA–DNA ratio analysis was higher at the stratified sites (8–13%∙d−1) than at the well-mixed site (7%∙d−1). Larvae appeared to be in excellent condition at the stratified sites, but up to 50% of haddock larvae from the well-mixed site had RNA–DNA ratios in the range observed for starved larvae in the laboratory. Cod collected at the same site were in better condition and growing faster than haddock. The data support the hypotheses that (1) stratified conditions in the spring favor good growth and survival of haddock larvae and (2) cod larvae are better adapted to grow and survive in well-mixed waters at lower levels of available food than haddock larvae.

Small-scale temporal and spatial variation in Atlantic cod (Gadus morhua) life history

2003 ◽  
Vol 60 (9) ◽  
pp. 1111-1121 ◽  
Author(s):  
Tara M McIntyre ◽  
Jeffrey A Hutchings
Keyword(s):  
Body Mass ◽  
Life Histories ◽  
Gadus Morhua ◽  
Atlantic Cod ◽  
Spatial Scales ◽  
Gonadosomatic Index ◽  
Small Scale ◽  
Hepatosomatic Index ◽  
Georges Bank ◽  
High Fecundity

Life histories of Atlantic cod (Gadus morhua) from the Gulf of St. Lawrence south to Georges Bank differ significantly through time and space. Within the Southern Gulf, fecundity per unit body mass differed by more than 40% over short (2 years) and long (42–45 years) periods of time. Significant variation in size-specific fecundity is also evident among populations: Southern Gulf cod produce almost 30% more eggs per unit body mass than those on Georges Bank, whereas fecundity of Scotian Shelf cod is almost half that of cod in Sydney Bight. Compared with those on Georges Bank, Southern Gulf cod life histories are characterized by high fecundity, late maturity, high gonadosomatic index, and large eggs. Relative to the influence of body size, neither temporal nor spatial differences in fecundity can be attributed to physiological condition, as reflected by liver weight, hepatosomatic index, and Fulton's K. Delayed maturity and higher reproductive allotment among Southern Gulf cod can be explained as selection responses to slower growth, higher prereproductive mortality, and fewer lifetime reproductive events. Patterns of covariation in heritable, fitness-related traits suggest the existence of adaptive variation and evolutionarily significant units at spatial scales considerably smaller than the species range in the Northwest Atlantic.

scholarly journals Fecundity estimation of Atlantic cod (Gadus morhua) and haddock (Melanogrammus aeglefinus) of Georges Bank: Application of the autodiametric method

2009 ◽  
Vol 99 (1) ◽  
pp. 47-54 ◽  
Author(s):  
Alexandre Alonso-Fernández ◽  
Ann Carole Vallejo ◽  
Fran Saborido-Rey ◽  
Hilario Murua ◽  
Edward A. Trippel
Keyword(s):  
Gadus Morhua ◽  
Atlantic Cod ◽  
Melanogrammus Aeglefinus ◽  
Georges Bank ◽  
Haddock Melanogrammus Aeglefinus

scholarly journals Stock identification of Atlantic cod (Gadus morhua) in US waters: an interdisciplinary approach

2014 ◽  
Vol 71 (6) ◽  
pp. 1490-1506 ◽  
Author(s):  
Douglas R. Zemeckis ◽  
David Martins ◽  
Lisa A. Kerr ◽  
Steven X. Cadrin
Keyword(s):  
Population Structure ◽  
Gadus Morhua ◽  
Management Practices ◽  
Gulf Of Maine ◽  
Atlantic Cod ◽  
Biological Information ◽  
Composition Analysis ◽  
Georges Bank ◽  
Biological Population ◽  
Bank Stock

Abstract Mismatches between biological population structure and management unit boundaries often violate the unit-stock assumption, which can reduce the accuracy and relevance of stock assessment results and lead to ineffective fishery management. Since 1972, Atlantic cod (Gadus morhua) have been managed in US waters as two units: the Gulf of Maine and the Georges Bank stocks, both of which have experienced recent difficulties in rebuilding. An interdisciplinary review of available biological information was conducted to investigate cod population structure in US waters and to evaluate the biological appropriateness of the current two-stock model. Our review demonstrates that spawning components in the Great South Channel, Nantucket Shoals, southern New England, and Middle Atlantic are more connected with spawning components in the Gulf of Maine than on eastern Georges Bank, with which they are currently managed. Therefore, a modification of current stock boundaries is recommended to provide a more accurate representation of biological population structure. Proposed alternatives divide inshore and offshore spawning components into separate management units, thereby separating the current Georges Bank stock longitudinally. Continued research, including stock composition analysis, is required to evaluate uncertainties, delineate biological stocks, and develop sustainable management practices that account for intrastock diversity (e.g. winter and spring-spawning components that overlap spatially).

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