Persistent high hatchery recruitment despite advanced reoligotrophication and significant natural spawning in a whitefish

Many lakes of the pre-Alpine region suffered from severe eutrophication that affected the natural reproduction of whitefish (Coregonus spp.) and necessitated large-scale supportive breeding programs. With the advanced reoligotrophication, it is now important to evaluate the relevance of continued artificial breeding for population dynamics. We focused on a whitefish population of a lake that has reached phase III of the reoligotrophication, i.e., lake biomass production is declining since 2012 in response to low phosphorus concentrations. We show that most eggs are naturally spawned, the observed oxygen concentrations would again support embryo development at all depths, and ready-to-hatch embryos can indeed be found on spawning grounds. We marked all hatchery-produced eggs of the 2014 cohort with Alizarin red, stocked them as usual (at larval or early juvenile stages), and recaptured them over a period of five years. Fish were aged from yearly growth rings on scales, and otoliths were checked for marks. We found 90.3% of the 2014 cohort to be hatchery-born. This ratio did not decline with fish age. We also determined juvenile growth of the cohorts 2012-2020 (based on the first annual ring on scales) and found that stocking intensity predicted juvenile growth (r2 = 0.67). This strong density dependence of individual growth suggests that stocking has largely determined cohort size over the first nine years of reoligo¬trophication phase III. We conclude that large areas of spawning grounds allow again for successful embryogenesis, that large quantities of eggs are naturally spawned, but that natural recruitment is significantly reduced by ecological or evolutionary factors, e.g., competition with hatchery-born fish, desynchronization of trophic interactions, or long-term effects of fishing- or hatchery-induced evolution

Small vessel disease burden and risk of recurrent cerebrovascular events in patients with lacunar stroke and intracerebral haemorrhage attributable to deep perforator arteriolopathy.

INTRODUCTION Deep perforator arteriolopathy (DPA) causes intracerebral haemorrhage (ICH) and lacunar strokes (LS). We compare patient characteristics, MRI findings and clinical outcomes among patients with deep ICH and LS. PATIENTS AND METHODS We included patients with MRI-confirmed LS or ICH in the basal ganglia, thalamus, internal capsule or brainstem from the Bernese Stroke Registry. We assessed MRI small vessel disease (SVD) markers, SVD burden score, modified Rankin Scale (mRS) and ischaemic stroke or ICH at 3 months. RESULTS We included 716 patients, 117 patients (16.3%) with deep ICH (mean age (SD) 65.1 (±15.2) years, 37.1% female) and 599 patients (83.7%) with LS (mean age (SD) 69.7 (±13.6) years, 39.9% female). Compared to LS, deep ICH was associated with a higher SVD burden score (median (IQR) 2 (1-2) vs 1 (0-2)), aORshift 3.19, 95%CI 2.15-4.75). Deep ICH patients had more often cerebral microbleeds (deep ICH: 71.6% vs LS: 29.2%, p < 0.001, median count (IQR) 4(2-12) vs 2(1-6)) and a higher prevalence of lacunes (deep ICH: 60.5% vs LS: 27.4% p < 0.001). At 3 months, deep ICH was associated with higher mRS (aORshift 2.16, 95%CI 1.21-3.87). Occurrence of ischaemic stroke was numerically but not significantly higher in deep ICH (4.3% vs 2.9%; p = 0.51). One patient (1.1%) with ICH but none with LS suffered ICH recurrence. DISCUSSION/CONCLUSION DPA manifesting as ICH is associated with more severe MRI SVD burden and worse outcome compared to LS. The short-term risks of subsequent ischaemic stroke and recurrent ICH are similar in ICH and LS patients. This implies potential consequences for future secondary prevention strategies