Fertility and Sperm Quality of Virgin and Repeat-Spawning Atlantic Cod (Gadus morhua) and Associated Hatching Success

1992 ◽  
Vol 49 (10) ◽  
pp. 2118-2127 ◽  
Author(s):  
Edward A. Trippel ◽  
John D. Neilson
Keyword(s):  
Gadus Morhua ◽  
Hatching Success ◽  
Atlantic Cod ◽  
Sperm Quality ◽  
High Capacity ◽  
Video Camera ◽  
Grid Pattern ◽  
Mean Values ◽  
High Prevalence ◽  
Total Variability

Sperm performance of virgin and repeat spawners of Atlantic cod (Gadus morhua) was compared. Our results indicate that sperm extracted from either virgin or repeat-spawning male cod exhibit a high capacity (usually >95%) to fertilize eggs at semen:seawater dilutions ranging from 1:1 to 1:100. Fertilization rates at higher dilutions, however, decreased to averages of 47 and 53% at 1:1000, with no statistically significant differences occurring betwen the two types of spawners. Spermatocrit and proportion of sperm cells exhibiting progressive forward motion together accounted for, at most, 14% of the total variability in success of fertilization at semen:seawater dilutions of 1:250, 1:500, and 1:1000. Individuals of both spawner types had immotile sperm, sometimes at high prevalence levels, but these individuals achieved fertiliztion rates comparable with those with high sperm motility. Hatching success of eggs fertilized by virgin males was more variable but, based on mean values, was almost identical to that of repeat spawners. Use of a video camera to record enlarged images of sperm with a haemacytometer grid pattern in the background has permitted the first documented measurements of sperm swimming speeds of a marine teleost fish; the fastest recorded speed was 1000 μm∙30 s−1.

Influence of climatic changes on the parasites of Atlantic cod Gadus morhua off coastal Labrador, Canada

2006 ◽  
Vol 80 (2) ◽  
pp. 193-197 ◽  
Author(s):  
R.A. Khan ◽  
C.V. Chandra
Keyword(s):  
North Atlantic ◽  
Gadus Morhua ◽  
Atlantic Cod ◽  
Age Groups ◽  
Climatic Conditions ◽  
Otter Trawl ◽  
Commercial Fishery ◽  
Metazoan Parasites ◽  
Mean Values ◽  
The North

AbstractA study was conducted in 2000 and 2003, following the collapse of the commercial fishery in 1990, to compare metazoan parasites of Atlantic cod Gadus morhua, captured off coastal Labrador, with samples taken in 1980 and 1986. Fish were captured by otter trawl offshore in the North Atlantic Fish Organisation subarea 2J. Parasites were removed from the digestive tract, stained, identified and compared between the different groups. Both the prevalence and mean abundance of trematodes, larval nematodes and E. gadi were significantly lower in fish taken in 2000 and 2003 than in 1980. While mean values of trematodes and nematodes declined in 1986, those of Echinorhynchus gadi remained unchanged in 1986 and 1990. Four-year-old cod sampled in 1990 harboured significantly fewer E. gadi than older age groups. The most commonly occurring trematodes included Podocotylereflexa, Lepidapedon elongatum, Derogenes varicus and Hemiurus levinseni while the larval nematode, Anisakis sp. was predominant. Comparison of offshore samples taken in 2000 and 2003 with others taken in previous years suggests an overall decline of parasites coincident with a change in climatic conditions, the absence of a major food source, namely capelin Mallotus villosus, of cod and ultimately the decline of the Labrador population.

Annual and spatial variability in endo- and ectoparasite infections of North Sea cod (Gadus morhua Linnaeus, 1758) larvae, post-larvae and juveniles

2014 ◽  
Vol 59 (2) ◽  
Author(s):  
Foojan Mehrdana ◽  
Qusay Bahlool ◽  
Alf Skovgaard ◽  
Jesper Kuhn ◽  
Per Kania ◽  
...  
Keyword(s):  
Spatial Variability ◽  
North Sea ◽  
Gadus Morhua ◽  
Sea Water ◽  
Atlantic Cod ◽  
The North ◽  
Infection Pressure ◽  
High Prevalence ◽  
Atlantic Cod Larvae ◽  
The North Sea

AbstractA parasitological investigation was performed on a total of 5380 Atlantic cod larvae, post-larvae and small juveniles sampled from the North Sea during a period of five years. The copepod Caligus elongatus (Von Nordmann, 1832) and the nematode Hysterothylacium aduncum (Rudolphi, 1802) were found at a relatively high prevalence of infection (4.6% and 5.2%, respectively). The infection by both parasites showed annual and spatial variability. C. elongatus showed a higher prevalence in 1992 compared to the following years, whereas the prevalence of H. aduncum increased from 1992 to 2001.We observed a relation between parasite distribution and parameters such as latitude and water depth. Adult digeneans (Lecithaster gibbosus and Derogenes varicus) and larval cestodes were also found with lower infection rates. Since changes of infection levels coincided with increasing North Sea water temperature in the studied period, it is hypothesized that temperature may affect parasite population levels. However, it is likely that other environmental factors may contribute to the observed variations. Absence of infection intensities higher than one nematode per fish in small larvae and post-larvae suggests that host survival may be affected by a high infection pressure. The relatively high levels of infection in the younger stages of cod, and the annual/spatial variability of these infections should be considered in the understanding of the early life dynamics of the species.

Fathers modify thermal reaction norms for hatching success in Atlantic cod, Gadus morhua

2016 ◽  
Vol 474 ◽  
pp. 148-155 ◽  
Author(s):  
F.T. Dahlke ◽  
S.N. Politis ◽  
I.A.E. Butts ◽  
E.A. Trippel ◽  
M.A. Peck
Keyword(s):  
Gadus Morhua ◽  
Hatching Success ◽  
Atlantic Cod ◽  
Thermal Reaction ◽  
Reaction Norms

scholarly journals Changes in Atlantic cod (Gadus morhua L.) sperm quality during the spawning season

2008 ◽  
Vol 39 (4) ◽  
pp. 434-440 ◽  
Author(s):  
Catherine Rouxel ◽  
Marc Suquet ◽  
Jacky Cosson ◽  
Armelle Severe ◽  
Loic Quemener ◽  
...  
Keyword(s):  
Gadus Morhua ◽  
Atlantic Cod ◽  
Sperm Quality ◽  
Spawning Season

scholarly journals Fermentation and Effect on the Microbial Loads of Atlantic Cod, Gadus morhua

2020 ◽  
Vol 24 (3) ◽  
pp. 459-465
Author(s):  
J.A. Daramola ◽  
T.O. Oladosu ◽  
K.S. Ismail
Keyword(s):  
Gadus Morhua ◽  
Atlantic Cod ◽  
Storage Period ◽  
Total Coliform ◽  
Distilled Water ◽  
Mean Values ◽  
Microbial Counts ◽  
The Mean ◽  
Fermentation Period ◽  
Saline Medium

The study was carried out to evaluate the effect of fermentation on the microbial loads of Atlantic cod (Gadus morhua). Eviscerated samples of Atlantic cod were fermented in three media: sterile distilled water, 14% saline medium and 14% salt with potash for 24 hours. The fermented Atlantic cod samples were oven-dried at 600C for one hour and thereafter, 1000C for three hours, cooled and stored in plastic baskets at ambient  temperature for four weeks. Analyses of the dried fermented Atlantic cod was carried out weekly for Salmonella shigella, total bacterial,  Staphylococcal, total fungal and total coliform counts. Results from the mean values indicated variations in the effects of the additives and  processing treatments over the 24 hours fermentation period which were significant (p < 0.05). The dressed fish sample fermented with both salt and potash (DRSFP), recorded the least mean microbial counts during the 4-week storage period, followed by the sample which was fermented with salt (DRSF) while the highest occurrence of microorganisms was recorded in the sample which was fermented with sterile distilled water (DRF). Hence, fermentation of fish with salt and potash is recommended. Meanwhile, in relation to the standard recommended microbial limits, the loads of microbes on the fermented Atlantic cod samples from the three treatments still fall within the safe and acceptable level. Keywords: Gadus morhua, Fermentation, Salt, Potash, Microbial load

Sperm competition and fertilization success in Atlantic cod (Gadus morhua): effect of sire size and condition factor on gamete quality

1999 ◽  
Vol 56 (12) ◽  
pp. 2315-2323 ◽  
Author(s):  
Ana Rakitin ◽  
Moira M Ferguson ◽  
Edward A Trippel
Keyword(s):  
Body Size ◽  
Sperm Competition ◽  
Gadus Morhua ◽  
Condition Factor ◽  
Atlantic Cod ◽  
Sperm Quality ◽  
Fertilization Success ◽  
Male Body ◽  
Single Female ◽  
Male Condition

Sperm competition experiments were conducted to test the null hypothesis that sperm quality is not affected by male body size in Atlantic cod (Gadus morhua). Genetic markers (allozymes) were used to determine the proportion of larvae sired by pairs of males when their sperm was combined with eggs of a single female simultaneously. Significant differences in fertilization success between males were not explained by differences in body size. Fertilization success was positively associated with male condition factor (K) and with spermatozoa density in each male's semen when equal volumes of semen from each male were used. Male K was positively associated with male fertilization success when the volume of semen used from each male was adjusted to add approximately equal numbers of spermatozoa from each male. The relative fertilization success of males varied depending on which female was the egg donor, suggesting that female "choice" at the gamete level may be occurring in cod.

Habitat loss, climate change, and emerging conservation challenges in Canada1This review is part of the virtual symposium “Flagship Species – Flagship Problems” that deals with ecology, biodiversity and management issues, and climate impacts on species at risk and of Canadian importance, including the polar bear (Ursus maritimus), Atlantic cod (Gadus morhua), Piping Plover (Charadrius melodus), and caribou (Rangifer tarandus).

2011 ◽  
Vol 89 (5) ◽  
pp. 435-451 ◽  
Author(s):  
Laura E. Coristine ◽  
Jeremy T. Kerr
Keyword(s):  
Climate Change ◽  
Habitat Loss ◽  
Gadus Morhua ◽  
Rangifer Tarandus ◽  
Atlantic Cod ◽  
Climate Impacts ◽  
Charadrius Melodus ◽  
Species Dispersal ◽  
Mean Values ◽  
Pests And Diseases

In Canada, habitat loss has pushed many more species to the brink of extinction than expected in a region with extensive wilderness. However, species richness gradients depend strongly on climate, so species are concentrated in southern regions, where agricultural and urban land uses are both intensive and extensive. Agricultural pesticide use is associated with increasing rates of species endangerment in the south, but long-range transport of persistent organic pollutants is an emerging issue in remote northern regions. Because their distributions reflect climate so strongly, climate change threatens species throughout Canada. Evidence indicates that species’ distributions, phenologies, and interactions with pests and diseases are changing more rapidly in response to climate change than global mean values. Nevertheless, climate change is expected to impose dispersal requirements that surpass species’ maximum rates. Habitat losses may interact with climate change to impair species’ dispersal still further, creating the potential for widespread disruption of biological systems in the most diverse areas of Canada. New research is urgently needed to address questions, and the ethics, around species translocation, ecosystem engineering to anticipate future environmental conditions, and strategies to facilitate the persistence of rare species in landscapes dominated by human activities.

Prevalence of a Trypanosome in Atlantic Cod (Gadus morhua) Especially in Relation to Stocks in the Newfoundland Area

1980 ◽  
Vol 37 (10) ◽  
pp. 1467-1475 ◽  
Author(s):  
R. A. Khan ◽  
J. Murphy ◽  
D. Taylor
Keyword(s):  
Gadus Morhua ◽  
Atlantic Cod ◽  
South Coast ◽  
The South ◽  
High Prevalence ◽  
Management And Conservation

A study was initiated to ascertain the prevalence of a trypanosome in Atlantic cod (Gadus morhua) especially in relation to stocks in the Newfoundland area and as an aid in management and conservation. Highest prevalences were recorded in fish taken off the Labrador coast (ICNAF divisions 2J and 3K, 94 and 90%, respectively). Trypanosomes were not as prevalent in fish collected from the northern Grand Bank (46%, division 3L) or from the southern Grand Bank (13 and 16%, divisions 3N and 3O, respectively). A further decrease in prevalence occurred among fish collected on the Flemish Cap (10%,, division 3M) and St. Pierre Bank (8%, subdivision 3Ps), while the lowest levels (4%) were apparent in cod taken from the Gulf of St. Lawrence (divisions 4R and 4S). Fish sampled at inshore localities reflected prevalences corresponding to some extent to offshore localities. Cod taken on coastal Labrador and from northern Newfoundland have a high prevalence of trypanosome infections while in the more easterly bays, intermediate levels occur. A conspicuous decrease in prevalence was apparent in a sample taken from the most easterly inshore locality (Portugal Cove) and from two others on the south coast of Newfoundland. Lowest prevalences were noted among fish taken at four inshore localities in the Gulf of St. Lawrence. These results, based on prevalences of infection, support conclusions from other studies that there are at least six stocks of cod in the Newfoundland area with some degree of mixing.Key words: trypanosome, prevalence, cod stocks, Newfoundland–Labrador, ICNAF

scholarly journals Benthic scavenger community composition and carrion removal in Arctic and Subarctic fjords

Polar Biology ◽  
2020 ◽  
Author(s):  
K. Dunlop ◽  
P. E. Renaud ◽  
J. Berge ◽  
D. O. B. Jones ◽  
R. P. Harbour ◽  
...  
Keyword(s):  
Gadus Morhua ◽  
Atlantic Cod ◽  
Benthic Communities ◽  
Time Lapse ◽  
Atlantic Water ◽  
Clupea Harengus ◽  
Removal Rates ◽  
Ecosystem Responses ◽  
Mean Values ◽  
The Mean

AbstractIn high latitude coastal regions, benthic scavenger communities are largely composed of invertebrates that play a key role in the cycling of organic matter. Factors including temperature and depth can structure Arctic and Subarctic fjord benthic communities, but the response of scavenging communities to these factors is poorly known. To address this, we compared scavenging fauna in eight fjords with different physical characteristics in Svalbard and northern Norway using time-lapse imagery of scavengers consuming Atlantic herring (Clupea harengus) bait. Fjords influenced by relatively warm Atlantic waters, both in Norway and Svalbard, had high scavenger richness. However, Svalbard fjords with negative bottom temperatures had the lowest species richness and were dominated by lysianassoid amphipods and ophiuroids. In these cold Svalbard fjords, the mean carrion removal rates were almost 20 times higher than mean values noted elsewhere, except in the warm Norwegian fjord Kaldfjorden. Amphipods and ophiuroids quickly reduced the bait to bones (207.6–304.7 g removed per hour (g h−1); mean 290.6 ± 7.3 g h−1, n = 4) in cold Svalbard fjords. In the warmer Svalbard fjords, carrion removal rates were low (0–51.5 g h−1; mean 14.6 ± 9.0 g h−1, n = 5). Carrion removal rates in Kaldfjorden were higher than other Atlantic Water influenced fjords (132.1 and 372.5 g h−1, n = 2) owing to the scavenging activity of Atlantic cod (Gadus morhua). The results demonstrate potential ecosystem responses to warming in Arctic and Subarctic fjords, particularly effects related to range expansion of boreal species.

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