Molecular systematics of gadid fishes: implications for the biogeographic origins of Pacific species

1999 ◽  
Vol 77 (1) ◽  
pp. 19-26 ◽  
Author(s):  
Steven M Carr ◽  
David S Kivlichan ◽  
Pierre Pepin ◽  
Dorothy C Crutcher
Keyword(s):  
Gadus Morhua ◽  
Barents Sea ◽  
Atlantic Cod ◽  
Molecular Data ◽  
Pacific Basin ◽  
Bering Strait ◽  
Pacific Cod ◽  
The Pacific ◽  
Phylogenetic Lineages ◽  
Pacific Species

Phylogenetic relationships among 14 species of gadid fishes were investigated with portions of two mitochondrial DNA (mtDNA) genes, a 401 base pair (bp) segment of the cytochrome b gene, and a 495 bp segment of the cytochrome oxidase I gene. The molecular data indicate that the three species of gadids endemic to the Pacific Basin represent simultaneous invasions by separate phylogenetic lineages. The Alaskan or walleye pollock (Theragra chalcogramma) is about as closely related to the Atlantic cod (Gadus morhua) as is the Pacific cod (Gadus macrocephalus), which suggests that T. chalcogramma and G. macrocephalus represent separate invasions of the Pacific Basin. The Pacific tomcod (Microgadus proximus) is more closely related to the Barents Sea navaga (Eleginus navaga) than to the congeneric Atlantic tomcod (Microgadus tomcod), which suggests that the Pacific species is derived from the Eleginus lineage and that Eleginus should be synonymized with Microgadus. Molecular divergences between each of the three endemic Pacific species and their respective closest relatives are similar and consistent with contemporaneous speciation events following the reopening of the Bering Strait ca. 3.0-3.5 million years BP. In contrast, the Greenland cod (Gadus ogac) and the Pacific cod have essentially identical mtDNA sequences; differences between them are less than those found within G. morhua. The Greenland cod appears to represent a contemporary northward and eastward range extension of the Pacific cod, and should be synonymized with it as G. macrocephalus.

Otolith growth and zone formation during first maturity and spawning of Atlantic cod (Gadus morhua)

2020 ◽  
Vol 77 (1) ◽  
pp. 113-123 ◽  
Author(s):  
Christian Irgens ◽  
Arild Folkvord ◽  
Håkon Otterå ◽  
Olav S. Kjesbu
Keyword(s):  
Gadus Morhua ◽  
Barents Sea ◽  
Atlantic Cod ◽  
Somatic Growth ◽  
Otolith Growth ◽  
Zone Formation ◽  
Stock Biomass ◽  
Tank Experiment ◽  
The Individual ◽  
First Maturity

Specific impacts of somatic growth, sexual maturation, and spawning events on otolith zone formation in Atlantic cod (Gadus morhua) were assessed in a 33-month tank experiment, using Barents Sea cod and Norwegian coastal cod. High and low feeding ration combinations were used to mimic environmental stressors in the field. For both stocks, apparent macrostructural “spawning zones” in otoliths are registered in statutory stock monitoring programs to estimate age at maturity, thus adding key information to stock biomass assessments. We found that substantial energy investments in reproduction caused reductions in otolith growth and altered proportional width between translucent and opaque zones. These effects, however, were only statistically significant among individuals with high reproductive investments, while otoliths from individuals with low investments did not differ from the otoliths for immatures. Reproduction may thus not necessarily induce spawning zones, and alternatively, spawning zones may not necessarily reflect reproduction. Altogether, this suggests that the individual energy level, as a premise for metabolic activity, plays a key role in the formation of such zones and thus is related to environmental conditions.

Mitochondrial genomics of gadine fishes: implications for taxonomy and biogeographic origins from whole-genome data sets

Genome ◽  
2006 ◽  
Vol 49 (9) ◽  
pp. 1115-1130 ◽  
Author(s):  
Mark W. Coulson ◽  
H. Dawn Marshall ◽  
Pierre Pepin ◽  
Steven M. Carr
Keyword(s):  
Atlantic Cod ◽  
Distinct Species ◽  
Walleye Pollock ◽  
Polar Cod ◽  
Data Sets ◽  
Amino Acid Residues ◽  
Bering Strait ◽  
Genome Data ◽  
Gadus Macrocephalus ◽  
Pacific Species

Phylogenetic analysis of 13 substantially complete mitochondrial DNA genome sequences (14 036 bp) from 10 taxa of gadine codfishes and pollock provides highly corroborated resolution of outstanding questions on their biogeographic evolution. Of 6 resolvable nodes among species, 4 were supported by >95% of bootstrap replications in parsimony, distance, likelihood, and similarly high posterior probabilities in bayesian analyses, one by 85%–95% according to the method of analysis, and one by 99% by one method and a majority of the other two. The endemic Pacific species, walleye pollock (Theragra chalcogramma), is more closely related to the endemic Atlantic species, Atlantic cod (Gadus macrocephalus), than either is to a second Pacific endemic, Pacific cod (Gadus macrocephalus). The walleye pollock should thus be referred to the genus Gadus as originally described (Gadus chalcogrammus Pallas 1811). Arcto-Atlantic Greenland cod, previously regarded as a distinct species (G. ogac), are a genomically distinguishable subspecies within pan-Pacific G. macrocephalus. Of the 2 endemic Arctic Ocean genera, Polar cod (Boreogadus) as the outgroup to Arctic cod (Arctogadus) and Gadus sensu lato is more strongly supported than a pairing of Boreogadus and Arctogadus as sister taxa. Taking into consideration historical patterns of hydrogeography, we outline a hypothesis of the origin of the 2 endemic Pacific species as independent but simultaneous invasions through the Bering Strait from an Arcto-Atlantic ancestral lineage. In contrast to the genome data, the complete proteome sequence (3830 amino acids) resolved only 3 nodes with >95% confidence, and placed Alaska pollock outside the Gadus clade owing to reversal mutations in the ND5 locus that restore ancestral, non-Gadus, amino acid residues in that species.

Pseudobranchial tumours in Atlantic cod, Gadus morhua L., from the Barents Sea

1981 ◽  
Vol 4 (6) ◽  
pp. 527-532 ◽  
Author(s):  
E. C. EGIDIUS ◽  
J. V. JOHANNESSEN ◽  
E. LANGE
Keyword(s):  
Gadus Morhua ◽  
Barents Sea ◽  
Atlantic Cod ◽  
The Barents Sea

scholarly journals A nanopore based chromosome-level assembly representing Atlantic cod from the Celtic Sea

2019 ◽  
Author(s):  
Tina Graceline Kirubakaran ◽  
Øivind Andersen ◽  
Michel Moser ◽  
Mariann Arnyasi ◽  
Philip McGinnity ◽  
...  
Keyword(s):  
Gadus Morhua ◽  
Barents Sea ◽  
Atlantic Cod ◽  
Population Based ◽  
Linkage Groups ◽  
Long Read ◽  
Study Population ◽  
Celtic Sea ◽  
Genome Assemblies ◽  
Inversion Breakpoints

ABSTRACTCurrently available genome assemblies for Atlantic cod (Gadus morhua) have been constructed using DNA from fish belonging to the Northeast Arctic Cod (NEAC) population; a migratory population feeding in the cold Barents Sea. These assemblies have been crucial for the development of genetic markers which have been used to study population differentiation and adaptive evolution in Atlantic cod, pinpointing four discrete islands of genomic divergence located on linkage groups 1, 2, 7 and 12. In this paper, we present a high-quality reference genome from a male Atlantic cod representing a southern population inhabiting the Celtic sea. Structurally, the genome assembly (gadMor_Celtic) was produced from long-read nanopore data and has a combined contig size of 686 Mb with a N50 of 10 Mb. Integrating contigs with genetic linkage mapping information enabled us to construct 23 chromosome sequences which mapped with high confidence to the latest NEAC population assembly (gadMor3) and allowed us to characterize in detail large chromosomal inversions on linkage groups 1, 2, 7 and 12. In most cases, inversion breakpoints could be located within single nanopore contigs. Our results suggest the presence of inversions in Celtic cod on linkage groups 6, 11 and 21, although these remain to be confirmed. Further, we identified a specific repetitive element that is relatively enriched at predicted centromeric regions. Our gadMor_Celtic assembly provides a resource representing a ‘southern’ cod population which is complementary to the existing ‘northern’ population based genome assemblies and represents the first step towards developing pan-genomic resources for Atlantic cod.

scholarly journals Methods and results of in situ target-strength measurements of Atlantic cod (Gadus morhua) during combined trawl-acoustic surveys

2009 ◽  
Vol 66 (6) ◽  
pp. 1225-1232 ◽  
Author(s):  
Viacheslav A. Ermolchev
Keyword(s):  
Gadus Morhua ◽  
Barents Sea ◽  
Atlantic Cod ◽  
Biological Data ◽  
Target Strength ◽  
Fish Length ◽  
The Barents Sea ◽  
Total Fish ◽  
Acoustic Surveys

Abstract Ermolchev, V. A., 2009. Methods and results of in situ target-strength measurements of Atlantic cod (Gadus morhua) during combined trawl-acoustic surveys. – ICES Journal of Marine Science, 66: 1225–1232. This paper presents methods for collecting acoustic and biological data, including in situ target-strength (TS) estimates of fish, with results presented for Atlantic cod (Gadus morhua) obtained from combined trawl-acoustic surveys. These include fish in the small, average, and maximum length classes, within the range 5–136 cm (total fish length, LT). The investigations were done using Simrad EK500/EK60 echosounders with split-beam transducers and special post-processing software. Based on an analysis of data collected in the Barents Sea during 1998–2007, a relationship TS = 25.2 log10(LT) − 74.8 was obtained for Atlantic cod at 38 kHz, with TS in dB and LT in centimetres. Seasonally, and for depths between 50 and 500 m, the variability in cod TS was 3.1 dB, decreasing with depth. The largest day–night difference in mean TS was in August–September, with changes as large as 1.0–1.7 dB. In the other seasons, the day–night difference was <1.0 dB.

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