No, you can always replenish your recruits as long as you have points.

On a side note, you can right click on the "RCT" button right below a sailor. This
automatically replenishes the shortfall in recruits, bringing it up to the maximum number
allowed.

Further reading can be found here:
http://www.nf-guides.com/sailors.htm

Thanks for your advice. My recruits are depleting, is it possible that time will come I
cannot recruit anymore even I have enough points?

Medics don't work till high level say 80+. Some one please correct me if I am wrong.
Also you should vet and expert it to maximize its ability. It won't gain experience on the
essex. Thats nearly 40 levels difference between the ship and sailor. Level it on a CA
to the mid 50s then put it on a bb until level 75. That should get it to a point that it will
gain decent exp on your cv.