Māori people peaceful tribes from their productive turangawaewae, such as the Moriori in the Chatham Islands by invading forces from North Taranaki, had a catastrophic effect on these conquered tribes. At the same time, the Māori suffered high mortality rates for new Eurasian infectious diseases, such as influenza, smallpox and measles, which killed an unknown number of Māori: estimates vary between ten and fifty percent. The spread of epidemics resulted largely from the Māori lacking acquired immunity to the new diseases. A huge influx of European settlers in the 1870s increased contact among many of the indigenous people with the newcomers. Te
Fish disease and parasites Fish can limit the impacts of pathogens and parasites with behavioural or biochemical means, and such fish have reproductive advantages. Interacting factors result in low grade infection becoming fatal diseases. In particular, things that causes stress, such as natural droughts or pollution or predators, can precipitate outbreak of disease. Disease can also be particularly problematic when pathogens and parasites carried by introduced species affect native species. An introduced species may find invading easier if potential predators and competitors have been decimated by disease. Pathogens which can cause fish diseases comprise: Parasites in fish are a common natural occurrence. Parasites can