Almost every accredited college near the water will have some form of fisheries science curriculum, even though it may not be a major. Some locations offer the cirriculum as a minor. Either way, they both provide the basic classes necessary to get yourself at least past the initial HR screening. Another option is volunteering with your local DEQ (Dept. of Environmental Quality), DNR (Dept. of Natural Resources) or GIF (Game & Inland Fisheries) programs. Most of them allow volunteers during their fish or water studies performed on an annual basis. Another option is volunteering with your local waterway conservation group. The catch to this approach is that some groups focus more on negative education/marketing/lobbying and propaganda versus actually improving the waterway, so be careful with this one.
The fastest way to "prove" your loyalty to a given firm is to work for free. I know that is somewhat contrarian to the normal method of job hunting but think about it. You approach a prospective firm interested in employment, but you throw them a curve ball by offering your services at no cost. Now there is a method to the madness here, so pay close attention. First, you should head into this type of role with the understanding that you will most likely be working two jobs to supplement your income during this period. If you decide to go down this road, you need to ensure that there is an end goal of paid employment when the internship is done. That means you need to negotiate your start date of employment ahead of time when the employer agrees to hire you. As a finance major when I was in college, the best scenario I have seen in practice was a 90-day internship with the agreement that the individual would be hired at the end of the internship at an agreed upon rate before ever accepting the internship. Get it in writing.
Another great option to hone your writing skills is to become a blogger. One of the biggest challenges as a blogger is creating content that is not only useful and informative, but also delivering that content in a manner that is not offensive or one-sided. As an avid kayak angler, I have had the pleasure of sharing my experiences over the course of the last 3-4 years through my blog. These experiences have included fishing reports, kayak modifications, rigging techniques and product reviews. When you share your personal perspective through the web, you have to be both objective and fair regardless of your personal feelings about a given topic or product.
Once you have established a "portfolio", you have a greater chance of gaining full time employment in the field.
Good luck!!