Polygyny, with dominant males keeping harems and preventing other males from mating, is clearly not working well among otters.
The article implies that perhaps as many as a quarter of female otter deaths result from rape/murder. Just combine these facts:
...overall mortality rate in the otter population is increasing, and disproportionately affecting females...
... trauma related to mating was responsible for 11 percent of deaths in fresh southern sea otter carcasses examined between 2000 and 2003...
So females make up less than 50% of the otter population and 11% of all otter deaths are "trauma related to mating". How much more than 22% of females die from rape/murder isn't specified.
Meanwhile the testosterone crazed excluded males turn to the dark side, raping to death female otters and juvenile harbor seals, including necromancy.
On some occasions, they further note, otters would guard and copulate with the seals long after their victims had died – as much as seven days afterward, in fact.
Bizarre as this behavior may seem, Harris and her co-authors point out that it is not dissimilar to standard sea otter mating protocol,...
Here, too, the encounters may prove fatal for the female, either as a result of wounds inflicted from the male’s bites and scratches or because of drowning. [emphasis mine]