What do you do to then market your photos to have someone ask? Do you actively send then to publishers or do they find you? Are you represented?
Since it isn't my full time job I try and make my efforts as efficient as possible. Scuba mags are tough to break into (lots of pros out there and it is a small tight market) and I hadn't bothered until recently when one of them approached me (and then I pursued it very rigourously and continue to do so). The majority of my success has been with textbooks and non-diving related magazines.
I initially became a member of a couple of photo marketing organizations that have 'want lists' - they send out daily requests from various sources. One also produces a book of photographers which it send to photo buyers which is a great way to get in front of people. Initially it looks like an expensive investment, but in the end it is cheap marketing and a cheap way to get to a lot of potential clients that you would likely never get to by yourself.
Once you have an opportunity to submit images for something in particular to a client, you now also have the opportunity to ask for additional opportunities with the same client. Many magazines have 'editorial calendars' of planned articles for the coming year which means many opportunities to submit images and plan for images you may get the opportunity to shoot before an article deadline.
My website is regularly updated with new images, has good search facilities and reasonable organizations and captioning. This means that your website should have a solid database behind it (I use PHOTOPOST which isn't bad at all) Captions MUST contain location, common names, important details and most crucial - SCIENTIFIC NAME. Without the scientific name you will miss a lot of opportunities especially from web searches. Image filenames MUST also be meaningful in some way for easy location of originals when requested - basicaly good cataloging.
I also paid for intial submissions for various websites which I stopped after 3 months - once the google/yahoo spiders get on your website they never go away.
I also create web galleries using the Web Gallery function of Photoshop for potential clients to allow them to browse specific images on request.
I am represented, but it has produced sporadic results - mainly because I don't spend a lot of time sending new submissions etc to my agencies. If it was my full time job I would be spending a lot more time pursuing this but I don't think I can currently justify the effort required to be top of an agencies mind who may represent a large group of photographers.
There is a lot of other little things I do as well, but this is plenty to get you started :-)
M