#### Answer

snakes 94k, mosquitoes 755k, and snails 200k.

#### Work Step by Step

Step 1. Assume that the deaths by snakes are given by $x$ thousand. Then, the deaths by mosquitoes are $x+661$ and the deaths by snails are $x+106$.
Step 2. Combined, we have $x+x+661+x+106=1049$ or $3x=282$ and $x=94$ thousand.
Step 3. The number of human deaths per year, in thousands, by snakes, mosquitoes, and snails are 94, 755, and 200 respectively.