This paper presents a comprehensive summary of development, mortality, and survival rates of fish eggs, yolk-sac larvae, and postlavae in relation to temperature and size. The general temperature- and, where applicable, size-dependent models explained 30–81% of the variance in vital rates. Daily development and mortality rates generally increased with increasing temperature. Temperature had an equal but opposite effect on stage-specific cumulative mortality rates of eggs and yolk-sac larvae. Stage-specific (length-dependent) cumulative mortality rates of postlarval fish were independent of temperature due to equal effects of temperature on daily growth and daily mortality rates. Size had no significant effect on daily or cumulative mortality rates of egg and yolk-sac stages. Daily mortality rates of postlarval fish were significantly influenced by mean size (i.e. length). The compensation of temperature effects between stages and/or vital rates may reduce the impact of environmental uncertainty on survival rates. It is suggested that the general temperature- and/or size-dependent relationships described in this study can serve as basic frameworks to assess whether there are significant effects resulting from species/stock-specific characteristics or environmental factors on the vital rates of the early life history stages of fish.

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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.

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