I would like to explain how a Marine fish, those that procreate and live in salt water survive in thier sodium saturated environment, this is important to learn and apply to your sea fishing. Most Marine fish are always at risk of dehydration and they have some interesting mechanisms to combat this.
The process of osmosis is in action all across mother-nature, inside sea fish and even inside your body. It relates to how molecules pass through a semi permeable membrane in a solution. To think of it simply it’s a filter, where the larger molecules are kept on one side allowing the smaller molecules to pass through. Things in this world strive to be in balance, and the stronger solution of sea water wants to be diluted by fresh water.
This process happens across a large amount of the body surface of a fish, including the gills and gut. Fresh water is striving to leave the sea fish, capturing salt inside the fish’s body. Sea fish use their kidneys, and they have specially developed glands in the gills to deposit the salt. This process is called Osmoregulation.
There are fish that interest us Sea anglers that can live in many environments: Fresh water, Salt water and Brackish water, Flounder and Salmon come to mind which are targeted in salt, fresh and brackish water when sea fishing. This is managed in differing ways. Some fish have glands that can excrete either fresh water or salt depending on the environment, others do not have a semi permeable skin, hence resolving the problem.
Applying Osmosis to Sea fishing
All this science has some practical applications for anglers, most of which are common sense. For example a gold fish used as bait will die quickly! But it also effects how Marine fish may react in heavy rain fall, when the salinity of the sea close by to estuaries dramatically falls making an unsuitable environment and the fish will move away making a sea fishing trip pointless. The applications for this are endless and worth considering before you go sea fishing, don’t just consider the species you are targeting, but think about the food stuffs your target species hunt and how they may be effected.