Alex Mustard,Alex Mustard / A female (in front) and male Sockeye salmon (Oncorhynchus nerka) over eggs in their spawning river. Adams River, British Columbia, Canada, October.

Alex Mustard / A split level photo of group of Sockeye salmon (Oncorhynchus nerka) fighting their way upstream as they migrate back to the river of their birth to spawn, trees showing autumnal colours. Adams River,...

Alex Mustard / Group of dead Sockeye salmon (Oncorhynchus nerka) washed up alongside their spawning river. Salmon die after spawning, but the nutrient boost provided by the decaying bodies, powers the food chain tha...