Swimbladder: maintaining equilibrium

I've been thinking about a new blog title for some time. "Swimbladder" was available and, I think, appropriate. This organ is found in most fish. The bladder contains gas, "air" if you will, which the fish controls to maintain neutral buoyancy at whatever depth the fish exists. Without the swimbladder, fish could not have developed body structures, like bones, that are more dense than water. The swim bladder gives the fish equilibrium in water, keeps them upside up, allows them to focus energy on movement, sensing, feeding and eluding being eaten.

The swimbladder is also the fish equivalent of an "Achilles heel." The abrupt change in density of the fish's body to air in the swimbladder reflects underwater sound. Undoubtedly, marine creatures with echolocation capabilities can detect prey in this manner. For the past 50 years, humans with electronic technology have also been able to detect fish this way. Modern fishfinders are an indispensable tool for catching fish. Having decimated most fish populations already, we need more sophisticated fishfinders to hunt down those that remain.

During my life as a marine electrician I installed increasingly more powerful fishfinders as they were developed. I've read the literature on the much more sophisticated equipment employed on commercial vessels. The fish haven't a chance if they exist in quantities economically worth catching. I don't feel guilt for installing recreational fishfinders, but I no longer eat fish either. As a general statement, I believe there is no such thing as a sustainable fishery. Experts may disagree, but the historical examples are of cascading collapse, not full recovery. We eat fish today that were considered valueless "trash fish" 50 years ago. But this is not a polemic against fishing. As I watch the charter boats leave the harbor where I keep my boat, I am pleased that the fishermen on board will experience the ocean and some of its creatures.

For me, the swimbladder represents adaptation which maintains equilibrium. "Swimbladder" is not as euphonious as "cricketwing," the title of Lissa Clark Adkins' blog, which I follow and respect very much, but "swimbladder" is a meaningful metaphor for me. The comparison makes me smile a little.