I haven't been to the Shedd in quite a few years but looking at it from the
perspective of someone who worked in a couple of zoos for several years, I
can unfortunately say that it sounds like the Shedd is in the same boat as
all other animal exhibiting organizations. Updating exhibits is expensive
in all phases including design, construction and maintenance. Labor costs
in zoos/aquariums are high. Some facilities, and the Shedd may be one, are
union shops and the keepers make pretty fair salaries (most deserve them,
some do not). People are willing to pay admission to see the exhibited
animals and most can't tell a healthy specimen from any other. People also
want to see high profile animals or trained animals performing in shows.
Hence, the Sea World trend in zoos and aquaria.
The AZA (American Zoo and Aquarium Association) states that these facilities
serve four primary purposes: Education, Conservation, Recreation, and
Research. Of the four purposes, the only one that is truly universal among
the facilities is Recreation. That brings in the dollars. Unfortunately,
recreation doesn't require naturalized exhibits, healthy animals, or any
connection to what is relevant to the visitor. In many ways this ties
directly into the earlier discussion of why television shows us hundreds of
hours of sharks, lions, and dinosaurs and virtually nothing on native fish.