My suggestion is to do some quick research in trade and financial journals serving the industry...that way you will be able to draw your own conclusions regarding the industry. For trade press, check out "Maritime Executive" magazine. Also check out "Workboat Magazine" and "Marine Log" I think all have online editions that can be accessed for free. You may have to register your e-mail but that's about it. They cover the industry with a rather broad brush (from technology to regulation to markets), so you may have to do some digging in back issues to get your answers. I also would suggest you check out the later SEC form 10-Ks and Annual reports from companies such as SEACOR Holdings, Kirby Corporation (especially discussion on offshore marine), and International Shipholding Corporation. These should give you some idea of the relative economic health of the various sectors. SEACOR is offshore transportation (primarily liquids) for both Jones Act and international markets, as well as oilfield services and harbor tug services. Kirby has Jones Act shallow and deep draft marine transportation, while I believe International Shipholding Corp. is primarily containers, dry bulk, break bulk and ro/ro traffic.
I hope this helps.