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.

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 Modelling dispersal of eggs and quantifying connectivity among Norwegian coastal cod subpopulations

2013 ◽  
Vol 71 (4) ◽  
pp. 957-969 ◽  
Author(s):  
Mari S. Myksvoll ◽  
Kyung-Mi Jung ◽  
Jon Albretsen ◽  
Svein Sundby
Keyword(s):  
Ocean Model ◽  
Small Scale ◽  
Coastal Current ◽  
Life Stages ◽  
Early Life Stages ◽  
Dispersal Patterns ◽  
Norwegian Coast ◽  
Spawning Areas ◽  
Numerical Ocean Model ◽  
Norwegian Coastal Current

Abstract The Norwegian coast is populated by two cod populations: Northeast Arctic cod and Norwegian Coastal cod. In this paper, we use a further division based on life history: oceanic cod, coastal cod, and fjord cod. A numerical ocean model was implemented for the northern Norwegian coast where all these populations have spawning areas. The model results were used to simulate connectivity and retention of cod eggs from the different subpopulations. The model reproduced the observed variability and mesoscale activity in the Norwegian Coastal Current. Eggs released at an oceanic spawning area were transported northwards along the coastline. Coastal cod eggs had intermediate connectivity with each other and fjord cod eggs had high local retention. Although the high retention of eggs in fjord areas is mainly caused by a subsurface distribution of eggs, the intermediate retention of eggs from coastal spawning areas is caused by small-scale eddies in-between many small islands. The high-resolution ocean model made it possible to reveal these specific dispersal patterns. The high retention of early life stages in fjords combined with strong homing to spawning areas indicates that fjord subpopulations may be described as a metapopulation.

scholarly journals Effect of solar ultraviolet radiation (280–400 nm) on the eggs and larvae of Atlantic cod (Gadus morhua)

1999 ◽  
Vol 56 (6) ◽  
pp. 1058-1067 ◽  
Author(s):  
France Béland ◽  
Howard I Browman ◽  
Carolina Alonso Rodriguez ◽  
Jean-François St-Pierre
Keyword(s):  
Water Column ◽  
Gadus Morhua ◽  
Atlantic Cod ◽  
Outdoor Exposure ◽  
Ultraviolet B ◽  
Solar Ultraviolet Radiation ◽  
Mortality Effect ◽  
Eggs And Larvae ◽  
Very High ◽  
Solar Ultraviolet

In the Gulf of St. Lawrence, Canada, solar ultraviolet B radiation (UV-B, 280-320 nm) penetrates a significant percentage of the summer mixed-layer water column: organisms residing in this layer, such as the eggs of Atlantic cod (Gadus morhua), are exposed to UV-B. In outdoor exposure experiments, Atlantic cod eggs were incubated in the presence versus the absence of UV-B and (or) UV-A (320-400 nm). We tested two hypotheses: H1, UV-B induces mortality in Atlantic cod eggs, and H2, UV-A either exacerbates or mitigates any such UV-B-induced mortality. Hypothesis H1 was supported: there was a significant mortality effect on Atlantic cod eggs exposed to UV-B at the surface and at a depth of 50 cm. Hypothesis H2 was not supported: there was no effect of UV-A. These experiments indicate that Atlantic cod eggs present in the first metre of the water column (likely only a small percentage of the total egg population) are susceptible to UV-B. However, UV-B must be viewed as only one among many environmental factors that produce the very high levels of mortality typically observed in the planktonic early life stages of marine fishes.

scholarly journals Vertical distribution of eggs and larvae of Maurolicus japonicus (Sternoptychidae, Pisces) in Tosa Bay, Japan

2019 ◽  
Vol 14 (2) ◽  
pp. 80-85
Author(s):  
Liezel C. Paraboles ◽  
Donna M. Guarte ◽  
Izumi Kinoshita
Keyword(s):  
Vertical Distribution ◽  
Tosa Bay ◽  
Eggs And Larvae

Biochemical composition and performance of Atlantic cod (Gadus morhua L.) eggs and larvae obtained from farmed and wild broodstocks

Aquaculture ◽  
2012 ◽  
Vol 324-325 ◽  
pp. 267-275 ◽  
Author(s):  
Carlos Frederico Ceccon Lanes ◽  
Teshome Tilahun Bizuayehu ◽  
Sylvie Bolla ◽  
Camila Martins ◽  
Jorge Manuel de Oliveira Fernandes ◽  
...  
Keyword(s):  
Biochemical Composition ◽  
Gadus Morhua ◽  
Atlantic Cod ◽  
And Performance ◽  
Eggs And Larvae

scholarly journals Genetic characteristics of broodstock collected from four Norwegian coastal cod (Gadus morhua) populations

2006 ◽  
Vol 63 (2) ◽  
pp. 209-215 ◽  
Author(s):  
G. Dahle ◽  
K.E. Jørstad ◽  
H.E. Rusaas ◽  
H. Otterå
Keyword(s):  
Gadus Morhua ◽  
White Muscle ◽  
Atlantic Cod ◽  
Genetic Differences ◽  
Offspring Performance ◽  
Genetic Characteristics ◽  
Aquaculture Industry ◽  
Initial Selection ◽  
Selection Of ◽  
Spawning Sites

Abstract The aquaculture industry in Norway is now focused on developing economically viable farming based on the Atlantic cod, Gadus morhua. Extensive research has been carried out on this species for the past two decades, much of it in connection with stock enhancement. Until now, most of the intensive cage culture has been based on wild broodstock. However, a future cod aquaculture industry must be based on a domesticated broodstock, and the initial selection of wild cod becomes an important issue. Genetic differentiation between coastal cod populations in Norway has been reported, and it is of interest to evaluate offspring from some of these populations under farmed conditions. Live mature cod were collected at four selected spawning sites along the Norwegian coast (Porsangerfjord, Tysfjord, Herøy/Helgeland, and Øygarden). The fish were transported to Parisvatnet, a cod aquaculture facility west of Bergen, where they were kept in net pens. Individual tagging and extensive sampling (blood, white muscle, and fin clips) for genetic characterization were carried out. Each potential broodstock fish was genotyped at the haemoglobin and pantophysin I loci in addition to five allozyme (LDH-3∗, GPD∗, IDH-2∗, PGM∗, PGI-1∗) and ten microsatellite loci (Gmo2, Gmo3, Gmo8, Gmo19, Gmo34, Gmo35, Gmo36, Gmo37, Gmo132, Tch11). Comparison of allele frequencies revealed significant genetic differences among some of the coastal cod samples, and offspring performance of the broodstock is now being compared under farmed conditions. The overall test revealed significant genetic differences among the coastal broodstocks, with the HbI, PanI and the microsatellite Gmo132 loci being most informative.

Spatial and seasonal distribution of eggs and larvae of sandy sprat, Hyperlophus vittatus (Clupeidae), off south-western Australia

1996 ◽  
Vol 47 (8) ◽  
pp. 971 ◽  
Author(s):  
DJ Gaughan ◽  
WJ Fletcher ◽  
RJ Tregonning
Keyword(s):  
Continental Shelf ◽  
Western Australia ◽  
Surf Zone ◽  
Temporal Distribution ◽  
Seasonal Distribution ◽  
Spawning Season ◽  
Marine Waters ◽  
Spawning Areas ◽  
Spatio Temporal ◽  
Eggs And Larvae

Ichthyoplankton surveys were employed to determine the distribution and spawning season of Hyperlophus vittatus off south-western Australia. Eggs and larvae of H. vittatus were sampled with 500-μm-mesh bongo-nets monthly during 1992, and less regularly during 1993, close to the beach and at 5.5 and 11 km offshore in four areas within the region of the fishery. The spatio-temporal distribution and abundance of eggs indicates that H. vittatus spawns in nearshore marine waters from May to September, with a peak in June and July. Larvae were rarer and less abundant than the eggs and therefore were less reliable indicators of spawning areas and season. Samples taken along transects across the continental shelf in July of both 1993 and 1994 indicated that H. vittatus did not spawn further than 14 km from the coast. Samples taken in July 1994 just beyond the surf zone at beaches, and at corresponding sites 5.5 km offshore, at 3.7-km intervals along 150 km of coastline indicated that H. vittatus spawns throughout the distribution of the fished stock off south-westem Australia.

scholarly journals Contribution of different spawning components to the mixed stock fishery for cod in Icelandic waters

2007 ◽  
Vol 64 (9) ◽  
pp. 1749-1759 ◽  
Author(s):  
Ingibjörg G. Jónsdóttir ◽  
Gudrun Marteinsdottir ◽  
Steven E. Campana
Keyword(s):  
Maximum Likelihood ◽  
Gadus Morhua ◽  
Fish Length ◽  
Minor Importance ◽  
Otolith Chemistry ◽  
Marine Science ◽  
Otolith Shape ◽  
Mixed Stock ◽  
Feeding Grounds ◽  
Icelandic Waters

Abstract Jónsdóttir, I. G., Marteinsdottir, G., and Campana, S. E. 2007. Contribution of different spawning components to the mixed stock fishery for cod in Icelandic waters. – ICES Journal of Marine Science, 64: 000–000. Otolith chemistry and length-at-age were used to estimate the contribution of different spawning components to the harvested stock of cod (Gadus morhua) at two of their main feeding grounds northwest and east of Iceland. Spawning cod were sampled at different spawning locations around Iceland in spring of 2002 and 2003. Significant differences were detected between cod from the different spawning locations. Cod of unknown stock origin were also sampled at two of the main feeding grounds in October of the same years. Analyses based on maximum likelihood were used to estimate the proportion of each spawning group in the mixed stock catches using otolith chemistry and fish length-at-age. Attempts to use otolith shape to estimate the contribution of the spawning groups to the mixed harvested stock were, however, unsuccessful. The results indicated that spawning locations northwest and north of Iceland, as well as in water deeper than 125 m south of Iceland, contributed the most to the harvested stock. Cod spawning shallower than 125 m south of Iceland did not contribute to the feeding grounds in October of 2002 and 2003. Therefore, exploitation of the feeding stock mixtures seems to be based on spawning components that have previously been considered to be of minor importance to the Icelandic cod stock.

Vertical distribution of pilchard (Sardinops sagax) eggs and larvae off Southern Australia

1999 ◽  
Vol 50 (2) ◽  
pp. 117 ◽  
Author(s):  
W. J. Fletcher
Keyword(s):  
Vertical Distribution ◽  
Accurate Estimation ◽  
Relative Depth ◽  
Sardinops Sagax ◽  
Bottom Depth ◽  
Shelf Region ◽  
Opening And Closing ◽  
Egg Stages ◽  
Eggs And Larvae ◽  
Egg Abundance

Plankton samples were obtained from four to six discrete depths at 33 stations in July 1994 by using the ‘EZ’ multiple opening and closing net during a cruise along the shelf region from Adelaide to Albany, southern Australia. At the 19 stations (88 tows) where pilchard eggs were common, recently spawned eggs were most abundant at depths of 40–60 m, or 60% of total bottom depth. Most older egg stages were found closer to, or at, the surface. During day-time, most pilchard larvae were caught at the surface. At night, pilchard larvae appeared to spread out, with lower overall rates of capture but a bigger proportion caught below the surface. The effects of these changes in relative depth with age are discussed in relation to the accurate estimation pilchard egg abundance for biomass calculations.

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