Populations of Euphausia pacifica Hansen in the Strait of Georgia region which have recently been commercially harvested were studied with respect to life history, distribution and population dynamics in order to examine aspects of the management of the resource. The potential use of local euphausiids as a food item for fish rearing was also evaluated through chemical analyses and feeding trials with juvenile coho salmon. The maximum life span in local populations was 19 months for males and 22 months for females. Spawning, which occurred from May to September, appeared to be closely related to phytoplankton abundance. First-year growth was maximal in summer (0.094 mm/day) but slowed in autumn and halted in winter. Growth in the following year showed a similar pattern. Males appeared to grow faster and experienced size-selective mortality following early maturity (11-12 mm). Survival increased with life phase changes between egg (6%/mo) and early adult stages (68%/mo) but declined sharply for individuals over 18 mm. Total biomass, B, in each population reached a maximum in October-November. Production by E. pacifica , P, in Saanich Inlet during July-November was 26.8 mgC/m²/day (P/B = 8.8), which is similar to that for herbivorous copepods, but higher than a previous estimate for E. pacifica . Juvenile coho salmon at 9 C showed mean growth rates of 3.8%/day on freeze-dried euphausiids compared to 3.0%, 2.7% and 3.1%/day on diets of euphausiid meal, frozen euphausiids and Oregon Moist Pellet, respectively. Local euphausiids have a well-balanced spectrum of amino acids in their proteins and high carotenoid concentrations (80-219 μ/g tissue) , making them suitable for use in aquacultural feeds. British Columbia's euphausiid fishery harvested about 100 metric tons during early 1977; the main uses are as an aquarium fish food and as a dietary supplement in salmon aquaculture. Yield calculations and other management considerations have indicated that the optimal harvesting time for E. pacifica is between October and December rather than from January to March as suggested by government guidelines on plankton harvesting, a limited and carefully monitored euphausiid fishery in the Strait of Georgia region appears to have potential value to the new plankton harvesting industry and to managers of associated fisheries who need further information on zooplankton population dynamics. / Science, Faculty of / Zoology, Department of / Graduate

<p>The systematic and population genetic relationships were characterised for three ecologically related euphausiid species: Euphausia lucens, E. recurva and E. vallentini. These species have different geographical distributions and life histories. All three species have a circumpolar distribution in the Southern Hemisphere while E. recurva is also distributed in the North Pacific. DNA sequence variation was determined for three regions of mitochondrial DNA and a single nuclear gene. It was conclusively demonstrated that both E. lucens and E. vallentini represent valid taxonomic species with fixed differences observed in both the nuclear and mitochondrial genes and that the low divergences previously reported for these species with 16SrRNA and CO1 resulted from a species misidentification. It was also shown that previous attempts to date the divergence between Antarctic and Sub-Antarctic euphausiid species based on 16SrRNA distances suffer from a large overestimation due to a calculation error.</p>

<p>The systematic and population genetic relationships were characterised for three ecologically related euphausiid species: Euphausia lucens, E. recurva and E. vallentini. These species have different geographical distributions and life histories. All three species have a circumpolar distribution in the Southern Hemisphere while E. recurva is also distributed in the North Pacific. DNA sequence variation was determined for three regions of mitochondrial DNA and a single nuclear gene. It was conclusively demonstrated that both E. lucens and E. vallentini represent valid taxonomic species with fixed differences observed in both the nuclear and mitochondrial genes and that the low divergences previously reported for these species with 16SrRNA and CO1 resulted from a species misidentification. It was also shown that previous attempts to date the divergence between Antarctic and Sub-Antarctic euphausiid species based on 16SrRNA distances suffer from a large overestimation due to a calculation error.</p>

The Fisheries Research Board of Canada has sponsored several expeditions in Canadian waters since 1947. A large number of specimens of euphausids and pelagic amphipods have been collected from the various expeditions. [...]

No description available.

Thesis (M.Sc. (Zoology & Entomology)) - Rhodes University, 2009.

No description available.

No description available.

Graduation date: 1966

Philosophiae Doctor - PhD / The systematic and population genetic relationships were characterised for three ecologically related euphausiid species: Euphausia lucens, E. recurva and E. vallentini. These species have different geographical distributions and life histories. All three species have a circumpolar distribution in the Southern Hemisphere while E. recurva is also distributed in the North Pacific. DNA sequence variation was determined for three regions of mitochondrial DNA and a single nuclear gene. It was conclusively demonstrated that both E. lucens and E. vallentini represent valid taxonomic species with fixed differences observed in both the nuclear and mitochondrial genes and that the low divergences previously reported for these species with 16SrRNA and CO1 resulted from a species misidentification. It was also shown that previous attempts to date the divergence between Antarctic and Sub-Antarctic euphausiid species based on 16SrRNA distances suffer from a large overestimation due to a calculation error. / South Africa