Current fishing methods are rather destructive, with 17% of the fish caught commercially being unintended bycatch, according to NOAA's first national assessment of bycatch. That damages the environment, and costs those who fish time and money.
The assessment uses 2005 data to evaluate 481 bycatch species, including fish, turtles, marine mammals, and seabirds. Data has been gathered from a variety of sources, with some not directly comparable. In addition, various parties have taken steps since 2005 to try to reduce bycatch.
Despite its limitations, the report can be useful for covering various issues. For instance, there is extensive detail for any given region, allowing you to explore many local aspects of the bycatch issue. And to some degree, you can provide national context for local conditions; current data show large differences between regions in the percentage of bycatch (due in part to the fish targeted and fishing methods used).
The next update, which is expected to be based on more current data and the next generation of the comprehensive methodology developed for this first report, is scheduled for 2013.