Behaviour and physiology of sockeye salmon homing through coastal waters to a natal river

Adult sockeye salmon (Oncorhynchus nerka, N = 179) from six Fraser River populations (British Columbia) were intercepted in continental shelf waters ∼215 km from the Fraser River mouth, gastrically implanted with acoustic transmitters, non-lethally biopsied for blood biochemistry, gill Na⁺,K⁺-ATPase activity and somatic energy density and then released. Migration behaviour and travel times to the river mouth and into the river were monitored by underwater telemetry receivers positioned at the river mouth and in the river. Post-release survival of salmon was excellent, with 84% (N = 150) of fish reaching the furthest receiving station ∼85 km upriver. Fish from Late-summer run populations (Adams and Weaver Creek) averaged a migration rate of ∼20 km day⁻¹ through the marine area and held at the river mouth and adjacent areas for 7–9 days before entering the river. Summer-run populations (Birkenhead, Chilko, Horsefly and Stellako) had a migration rate ∼33 km day⁻¹ and held for only 1–3 days. Once in river, similar patterns were observed: Late-run populations migrated at ∼28 km day⁻¹ and Summer-run populations at ∼40 km day⁻¹. From point of release to the river mouth, males migrated faster than females, but once in river migration rates did not differ between sexes. Among all females, a correlation was discovered between levels of circulating testosterone and river entry timing. This correlation was not observed among males. Plasma K⁺, Cl⁻, glucose, lactate and osmolality were also correlated with entry timing in both sexes.     

Pollution,habitat loss,fishing, and climate change as critical threats to penguins

Cumulative human impacts across the world's oceans are considerable. We therefore examined a single model taxonomic group, the penguins (Spheniscidae), to explore how marine species and communities might be at risk of decline or extinction in the southern hemisphere. We sought to determine the most important threats to penguins and to suggest means to mitigate these threats. Our review has relevance to other taxonomic groups in the southern hemisphere and in northern latitudes, where human impacts are greater. Our review was based on an expert assessment and literature review of all 18 penguin species; 49 scientists contributed to the process. For each penguin species, we considered their range and distribution, population trends, and main anthropogenic threats over the past approximately 250 years. These threats were harvesting adults for oil, skin, and feathers and as bait for crab and rock lobster fisheries; harvesting of eggs; terrestrial habitat degradation; marine pollution; fisheries bycatch and resource competition; environmental variability and climate change; and toxic algal poisoning and disease. Habitat loss, pollution, and fishing, all factors humans can readily mitigate, remain the primary threats for penguin species. Their future resilience to further climate change impacts will almost certainly depend on addressing current threats to existing habitat degradation on land and at sea. We suggest protection of breeding habitat, linked to the designation of appropriately scaled marine reserves, including in the High Seas, will be critical for the future conservation of penguins. However, large‐scale conservation zones are not always practical or politically feasible and other ecosystem‐based management methods that include spatial zoning, bycatch mitigation, and robust harvest control must be developed to maintain marine biodiversity and ensure that ecosystem functioning is maintained across a variety of scales. Contaminación, Pérdida de Hábitat, Pesca y Cambio Climático como Amenazas Críticas para los Pingüinos     

Mechanistic basis of individual mortality in Pacific salmon during spawning migrations

Reproductive-based migration is a challenging period for many animals, but particularly for Pacific salmonids, which must navigate from the high seas to freshwater natal streams. For the first time, we attempt to answer the question as to why some migratory adult Pacific salmon die en route to spawning grounds. Summer-run sockeye salmon (Oncorhynchus nerka) were used as a model, and the migration behavior of 301 fish was followed by intercepting them in the ocean about 215 km from the mouth of the Fraser River, British Columbia, Canada, and implanting a gastric radio transmitter. Before release, telemetered fish were also bio-sampled, which included drawing a blood sample, collecting a gill biopsy, and quantifying energetic status with a microwave energy meter. We tested the predictions that the fish that died prematurely would be characterized by low energy reserves, advanced reproductive development, elevated indicators of stress, and low osmoregulatory preparedness compared with fish that completed their river migration. Just over half (52.3%) of the sockeye tagged were subsequently detected in the Fraser River. Salmon that failed to enter the river had exhibited indicators of stress (e.g., elevated plasma lactate, glucose, and cortisol). Contrary to our prediction, fish that failed to enter the river tended to have higher gross somatic energy and be larger at the time of sampling in the ocean than fish that successfully entered the river. Of the fish that were detected in the river (i.e., 134 fish excluding fishery removals), 9.7% did not migrate beyond the lower reaches (approximately 250 km from ocean), and a further 14.2% reached the upper reaches but failed to reach natal sub-watersheds, whereas the remainder (76.1%) reached natal sub-watersheds. Of these, fish unsuccessful in the lower reaches tended to have a high plasma osmolality in the ocean, whereas fish failing in the upper reaches had lower levels of reproductive hormones in the ocean.     

Environmental impact of apparel supply chain and textile products

Environment, Development and Sustainability - Textiles products have high environmental impact compared to other products. Numerous studies have been performed on the environmental impact of...