That the society is interested in political gains through science is clear from this quote regarding the society's very first resolution:
Connections between coyote control and rabbit outbreaks are speculation at best.The Society’s first resolution (1927) called for science, not politics, to inform government policy on predator control.
I followed up a couple of the references, e.g. Alcock 1990 (in the LA Times, a highly respected scientific outlet), who cites his colleague Gerald Cole as having "written a paper on this". The paper in question turns out to be a piece in the "Defenders of Wildlife" newsletter from 1970! Hardly a peer reviewed source!
Now, their arguments may in fact be correct, but there certainly is no peer reviewed evidence supporting their assertions. If there was, they should be citing it! On the face of it, scientific or not, killing ~560 river otters per year while simultaneously trying to reintroduce them seems counterproductive, but if the animals are abundant in places where they are being accidentally trapped, then there isn't really an issue. In fact having them turn up in beaver traps may be an indication of stunning success!
The idea of mesopredator release is relatively well supported in the literature, although not specifically with coyotes and wolves. However, the society should pay close attention to the articles it cites, e.g. Prugh et al (2009) cited in support of mesopredator release, also say:
" ... predator management is characterized by complex ecological, economic, and social trade-offs. While large predators present many ecological benefits, they can also pose a serious threat to species of conservation concern. For instance, cougars (Puma concolor) contributed to the near extinction of endangered Sierra bighorn sheep in the 1990s (Ovis canadensis sierrae; Wehausen 1996). Any proposal to protect or reintroduce apex predators must acknowledge the full range of trade-offs involved in predator management."The key phrase is that there is a range of tradeoffs involved in predator management - what they don't say is that those tradeoffs are highly political, not scientific. The society's letter also cite Estes et al 2011 - a paper in Science - as support for apex predator effects. Again, no denying that trophic cascades have occurred, but also no strong evidence for the particular effects cited in the letter. In fact Estes et al say
"We propose that many ecological surprises that have confronted society over past centuries—pandemics, population collapses of species we value and eruptions of those we do not, major shifts in ecosystem states, and losses of diverse ecosystem services—were caused or facilitated by altered top-down forcing regimes associated with the loss of native apex consumers or the introduction of exotics."
The key word is PROPOSE. This is a plausible hypothesis, but far from a proven theory.
Stealth issue advocacy. Devalues the science and misdirects the political debate.