Redefining the oceanic distribution of Atlantic salmon.

Determining the mechanisms driving range-wide reductions in Atlantic salmon marine survival is hindered by an insufficient understanding of their oceanic ecology and distribution. We attached 204 pop-up satellite archival tags to post-spawned salmon when they migrated to the ocean from seven European areas and maiden North American salmon captured at sea at West Greenland. Individuals migrated further north and east than previously reported and displayed increased diving activity near oceanographic fronts, emphasizing the importance of these regions as feeding areas. The oceanic distribution differed among individuals and populations, but overlapped more between geographically proximate than distant populations. Dissimilarities in distribution likely contribute to variation in growth and survival within and among populations due to spatio-temporal differences in environmental conditions. Climate-induced changes in oceanographic conditions will alter the location of frontal areas and may have stock-specific effects on Atlantic salmon population dynamics, likely having the largest impacts on southern populations.

Detective quantum efficiency of intensified CMOS cameras for Cherenkov imaging in radiotherapy.

In this study the metric of detective quantum efficiency (DQE) was applied to Cherenkov imaging systems for the first time, and results were compared for different detector hardware, gain levels and with imaging processing for noise suppression. Intensified complementary metal oxide semiconductor cameras using different image intensifier designs (Gen3 and Gen2+) were used to image Cherenkov emission from a tissue phantom in order to measure the modulation transfer function (MTF) and noise power spectrum (NPS) of the systems. These parameters were used to calculate the DQE for varying acquisition settings and image processing steps. MTF curves indicated that the Gen3 system had superior contrast transfer and spatial resolution than the Gen2+ system, with [Formula: see text] values of 0.52 mm-1 and 0.31 mm-1, respectively. With median filtering for noise suppression, these values decreased to 0.50 mm-1 and 0.26 mm-1. The maximum NPS values for the Gen3 and Gen2+ systems at high gain were 1.3 × 106 mm2 and 9.1 × 104 mm2 respectively, representing a 14x decrease in noise power for the Gen2+ system. Both systems exhibited increased NPS intensity with increasing gain, while median filtering lowered the NPS. The DQE of each system increased with increasing gain, and at the maximum gain levels the Gen3 system had a low-frequency DQE of 0.31%, while the Gen2+ system had a value of 1.44%. However, at a higher frequency of 0.4 mm-1, these values became 0.54% and 0.03%. Filtering improved DQE for the Gen3 system and reduced DQE for the Gen2+ system and had a mix of detrimental and beneficial qualitative effects by decreasing the spatial resolution and sharpness but also substantially lowering noise. This methodology for DQE measurement allowed for quantitative comparison between Cherenkov imaging cameras and improvements to their sensitivity, and yielded the first formal assessment of Cherenkov image formation efficiency.

Recent salmon declines: a result of lost feeding opportunities due to bad timing?

As the timing of spring productivity blooms in near-shore areas advances due to warming trends in global climate, the selection pressures on out-migrating salmon smolts are shifting. Species and stocks that leave natal streams earlier may be favoured over later-migrating fish. The low post-release survival of hatchery fish during recent years may be in part due to static release times that do not take the timing of plankton blooms into account. This study examined the effects of release time on the migratory behaviour and survival of wild and hatchery-reared coho salmon (Oncorhynchus kisutch) using acoustic and coded-wire telemetry. Plankton monitoring and near-shore seining were also conducted to determine which habitat and food sources were favoured. Acoustic tags (n = 140) and coded-wire tags (n = 266,692) were implanted into coho salmon smolts at the Seymour and Quinsam Rivers, in British Columbia, Canada. Differences between wild and hatchery fish, and early and late releases were examined during the entire lifecycle. Physiological sampling was also carried out on 30 fish from each release group. The smolt-to-adult survival of coho salmon released during periods of high marine productivity was 1.5- to 3-fold greater than those released both before and after, and the fish's degree of smoltification affected their downstream migration time and duration of stay in the estuary. Therefore, hatchery managers should consider having smolts fully developed and ready for release during the peak of the near-shore plankton blooms. Monitoring chlorophyll a levels and water temperature early in the spring could provide a forecast of the timing of these blooms, giving hatcheries time to adjust their release schedule.

Genetic versus rearing-environment effects on phenotype: hatchery and natural rearing effects on hatchery- and wild-born coho salmon.

With the current trends in climate and fisheries, well-designed mitigative strategies for conserving fish stocks may become increasingly necessary. The poor post-release survival of hatchery-reared Pacific salmon indicates that salmon enhancement programs require assessment. The objective of this study was to determine the relative roles that genotype and rearing environment play in the phenotypic expression of young salmon, including their survival, growth, physiology, swimming endurance, predator avoidance and migratory behaviour. Wild- and hatchery-born coho salmon adults (Oncorhynchus kisutch) returning to the Chehalis River in British Columbia, Canada, were crossed to create pure hatchery, pure wild, and hybrid offspring. A proportion of the progeny from each cross was reared in a traditional hatchery environment, whereas the remaining fry were reared naturally in a contained side channel. The resulting phenotypic differences between replicates, between rearing environments, and between cross types were compared. While there were few phenotypic differences noted between genetic groups reared in the same habitat, rearing environment played a significant role in smolt size, survival, swimming endurance, predator avoidance and migratory behaviour. The lack of any observed genetic differences between wild- and hatchery-born salmon may be due to the long-term mixing of these genotypes from hatchery introgression into wild populations, or conversely, due to strong selection in nature--capable of maintaining highly fit genotypes whether or not fish have experienced part of their life history under cultured conditions.

An investigation into the poor survival of an endangered Coho salmon population.

To investigate reasons for the decline of an endangered population of coho salmon (O. kisutch), 190 smolts were acoustically tagged during three consecutive years and their movements and survival were estimated using the Pacific Ocean Shelf Tracking project (POST) array. Median travel times of the Thompson River coho salmon smolts to the lower Fraser River sub-array were 16, 12 and 10 days during 2004, 2005 and 2006, respectively. Few smolts were recorded on marine arrays. Freshwater survival rates of the tagged smolts during their downstream migration were 0.0-5.6% (0.0-9.0% s.e.) in 2004, 7.0% (6.2% s.e.) in 2005, and 50.9% (18.6% s.e.) in 2006. Overall smolt-to-adult return rates exhibited a similar pattern, which suggests that low freshwater survival rates of out-migrating smolts may be a primary reason for the poor conservation status of this endangered coho salmon population.

Localized lymphoid relapse in the pancreas following allogeneic hematopoietic stem cell transplant for chronic myelogenous leukemia.

The incidence of isolated extramedullary disease (EMD) following allogeneic hematopoietic stem cell transplant (allo-HSCT) for chronic myelogenous leukemia (CML) is not fully known. One review found the incidence of isolated myeloid EMD, or granulocytic sarcoma (GS), in an allo-HSCT treated CML/myelodysplastic subgroup to be just 0.22%. The incidence of lymphoid EMD in similar patients is extremely rare with only two cases reported in the literature. While the etiology of EMD in the post-transplant setting is not entirely clear, there may be inefficacy of immune surveillance function outside of the bone marrow cavity. Isolated CML GS following allo-HSCT carries a median interval to bone marrow relapse between 7 and 10 months and a median survival of 12 months. Less is known about lymphoid EMD. The treatment in these cases is ill defined with modalities ranging from involved field radiation to second allo-HSCT. We present a case of isolated pancreatic lymphoid EMD diagnosed 15 months after allo-HSCT for CML. Our patient was also treated with withdrawal of his immunosuppressive regimen. Unfortunately, at just over 4 months following pancreatic resection, he developed systemic relapse and died. While EMD can occur anywhere in the body, CML associated pancreatic EMD is not previously reported.