how did they become so?
Poaching is one of the main reasons, others being habitat destruction and degradation
Giant otter
 Poaching has long been a problem. 
what is giant otter? It is a South American carnivorous mammal. where did it get the name from? Giant otter" translates literally as "nutria gigante" .and "lontra gigante" in Spanish and Portuguese which family does it belong to? Weasel family what sort of habitat does it select to live in? It seems to choose clear, black waters with rocky or sandy bottoms is there a need for it to be conserved? Yes, The IUCN listed the giant otter as "endangered".
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Giant otter [SEP] Threats
The animal faces a variety of critical threats. Poaching has long been a problem. Statistics show between 1959 and 1969 Amazonian Brazil alone accounted for 1,000 to 3,000 pelts annually. The species was so thoroughly decimated, the number dropped to just 12 in 1971. The implementation of CITES in 1973 finally brought about significant hunting reductions, although demand did not disappear entirely: in the 1980s, pelt prices were as high as US$250 on the European market. The threat has been exacerbated by the otters' relative fearlessness and tendency to approach human beings. They are extremely easy to hunt, being active through the day and highly inquisitive.