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

Larval Anisakis simplex (Nematoda: Ascaridoidea) Infection in the Musculature of Atlantic Cod, Gadus morhua, from Newfoundland and Labrador

1992 ◽  
Vol 49 (12) ◽  
pp. 2635-2647 ◽  
Author(s):  
John Brattey ◽  
Claude A. Bishop
Keyword(s):  
Newfoundland And Labrador ◽  
Gadus Morhua ◽  
Atlantic Cod ◽  
Body Cavity ◽  
The Body ◽  
Anisakis Simplex ◽  
South Coast ◽  
The South ◽  
Eastern Canada ◽  
Examination Method

Larvae of Anisakis simplex were found in the flesh of Atlantic cod, Gadus morhua, collected in 21 regions around Newfoundland and Labrador during 1985–87. Prevalence and abundance increased with cod size and varied geographically; cod off Labrador had the fewest larvae whereas those from the south coast of Newfoundland were the most heavily infected. Most larvae (~95%) occurred in flesh surrounding the body cavity (napes), with a significantly higher percentage of the nematodes (~58%) in the flesh on the left side. In 505 cod in which all tissues were examined, 85.6, 10.8, and 3.5% of the A. simplex resided in the body cavity and viscera, napes, and fillets, respectively. Cod surveyed tended to have more A. simplex in the musculature than those from other areas off eastern Canada, but are lightly infected compared with most other Atlantic cod stocks. The examination method (candling combined with slicing) recovered, on average, 42% of the A. simplex present in the flesh; consequently, infection statistics reported here are underestimates. Numbers of A. simplex in cod off Labrador and eastern Newfoundland are similar to those observed during 1947–53, but the abundance of A. simplex appears to have increased among cod from NAFO Subdivision 3Pn.

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.

scholarly journals Acoustic monitoring of Atlantic cod (Gadus morhua) in Massachusetts Bay: implications for management and conservation

2013 ◽  
Vol 70 (3) ◽  
pp. 628-635 ◽  
Author(s):  
Keith M. Hernandez ◽  
Denise Risch ◽  
Danielle M. Cholewiak ◽  
Micah J. Dean ◽  
Leila T. Hatch ◽  
...  
Keyword(s):  
Gadus Morhua ◽  
Atlantic Cod ◽  
Second Harmonic ◽  
Low Frequency ◽  
Acoustic Monitoring ◽  
Massachusetts Bay ◽  
Night Time ◽  
Western Atlantic ◽  
Management Measures ◽  
Management And Conservation

Abstract Hernandez, K. M., Risch, D., Cholewiak, D. M., Dean, M. J., Hatch, L. T., Hoffman, W. S., Rice, A. N., Zemeckis, D., and Van Parijs, S. M. 2013. Acoustic monitoring of Atlantic cod (Gadus morhua) in Massachusetts Bay: implications for management and conservation. – ICES Journal of Marine Science, 70: 628–635. Atlantic cod (Gadus morhua) stocks in northeastern US waters are depleted and stock recovery has been slow; research into the spawning behaviour of this species can help inform conservation and management measures. Male cod produce low-frequency grunts during courtship and spawning. Passive acoustic monitoring (PAM) offers a different perspective from which to investigate the occurrence, spatial extent and duration of spawning cod aggregations. A marine autonomous recording unit was deployed in the “Spring Cod Conservation Zone” (SCCZ) located in Massachusetts Bay, western Atlantic, to record cod grunts from April–June 2011. Cod grunts were present on 98.67% of the recording days (n = 75 days). They occurred across all 24 h, although significantly more grunts were found during the day than night-time (p = 0.0065). Grunt durations ranged from 57–360 ms, and the fundamental frequency and second harmonic had mean peak frequencies of 49.7 ± 5.6 and 102.9 Hz ± 10.9 sd, respectively. Cod grunt rates were low compared with those reported for other spawning fish, and may be indicative of diel movement patterns. Next steps will focus on expanding PAM coverage within the SCCZ, alongside prospecting for unknown spawning grounds within existing archival data.

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.

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.

Genomic tools for management and conservation of Atlantic cod in a coastal marine protected area

2018 ◽  
Vol 75 (11) ◽  
pp. 1915-1925 ◽  
Author(s):  
Marion Sinclair-Waters ◽  
Paul Bentzen ◽  
Corey J. Morris ◽  
Daniel E. Ruzzante ◽  
Matthew P. Kent ◽  
...  
Keyword(s):  
Gadus Morhua ◽  
Marine Protected Area ◽  
Atlantic Cod ◽  
Marine Species ◽  
Effective Population ◽  
Coastal Marine ◽  
Genomic Tools ◽  
Snp Panel ◽  
Surrounding Areas ◽  
Management And Conservation

Marine protected areas (MPAs) can serve as effective tools for the management and conservation of exploited marine species. The Gilbert Bay MPA in coastal Labrador was created to protect a genetically distinct population of Atlantic cod (Gadus morhua); however, decreases in abundance continue to occur potentially due to exploitation outside the MPA. We developed a single-nucleotide polymorphism (SNP) panel to identify Gilbert Bay cod in areas outside MPA boundaries where mixing with offshore cod occurs. In total, 361 individuals from Gilbert Bay, surrounding areas, and offshore were genotyped for 10 913 SNPs. Using FST rankings and guided regularized random forest, we selected 23 SNPs that together generate 100% accuracy in individual assignment and accurately estimate the proportion of Gilbert Bay cod in fishery samples from sites outside MPA boundaries: on average, fishery samples included 17.3% Gilbert Bay cod. Estimates of effective population size for the Gilbert Bay population ranged from 655 to 1114. Our findings demonstrate the power of using genomic approaches for management of an exploited marine species and enhancing the design of MPAs.

Atlantic Cod Populations along the Southern Canadian Mainland as shown by Vertebral Count Studies

1955 ◽  
Vol 12 (5) ◽  
pp. 698-705 ◽  
Author(s):  
R. A. McKenzie ◽  
G. F. M. Smith
Keyword(s):  
Nova Scotia ◽  
Atlantic Cod ◽  
South Coast ◽  
The South ◽  
Vertebral Number ◽  
Vertebral Count ◽  
Seasonal Migrations

Analysis of vertebral counts of 28,097 cod (Gadus callarias L.) in 184 samples from the Canadian mainland coast demonstrates some segregation of inshore and offshore populations and little mixing between the cod on various sections of the coast. Four populations are recognized in the Gulf of St. Lawrence. Three offshore populations and at least four inshore populations are also recognized along the south coast of Nova Scotia. Seasonal migrations northward in summer and southward in winter are indicated by changes in vertebral numbers. Small cod (less than 21/2 lb.) exhibit less variability in vertebral number than larger ones, suggesting increased mixing with growth.

Effects of temperature on life history set the sensitivity to fishing in Atlantic cod Gadus morhua

2014 ◽  
Vol 514 ◽  
pp. 217-229 ◽  
Author(s):  
HY Wang ◽  
LW Botsford ◽  
JW White ◽  
MJ Fogarty ◽  
F Juanes ◽  
...  
Keyword(s):  
Life History ◽  
Gadus Morhua ◽  
Atlantic Cod ◽  
Effects Of Temperature
Sign in / Sign up

Export Citation Format

Share Document