acteristic that distinguishes marine
ecosystems from freshwater ecosystems is the salinity of the water.
Marine ecosystems have water containing a mixture of salts, which
make up 3.5% of the mass of a
quantity of seawater. There are basically 5 types of marine ecosystems: estuaries, intertidal zones,
neritic zones, oceanic zones, and
coral reefs.
Threatened Species:
History is littered with incidents of
spectacular losses of fish stock due
to overfishing, the dramatic collapse of the herring fishery being
one. Some of the most notorious
examples of overexploitation, as
well as the most unusual, are featured hear. Among them are the
taking of sharks for their fins, an
essential ingredient in the worldfamous shark fin soup so highly
regarded in the Orient. Another is
the devastation of totoaba
(Totoaba macdonaldi) stocks for
their swim bladders – another soup
delicacy – but there are many others. In our own country the local
abalone species is under serious
threat because of illegal poaching.
The Human Factor:
Many factors contribute to the loss
of fish species and the degradation
of their habitat. These include:
Dams and impoundments;
Water pollution, especially spills
of toxic wastes (oil, industrial
acids, pesticides, and fertilizers);
Sedimentation from agriculture,
Steelhead Trout
construction, logging and mining;
Introduction of exotic species;
Overfishing.
es and improve their habitats are
very successful abroad and something our government should seriously consider.
Dams block fish spawning migrations and isolate fish from upstream
spawning and nursery areas, causing populations of anadromous and
catadromous fish to decline. As
streams and rivers are transformed
into lakes and reservoirs, alterations
in downstream water flows and
water temperatures, negatively impact fish communities. River fish
that have evolved and adapted to
inhabit free-flowing rivers may not
survive in lakes and reservoirs.
Conservation:
Your help is needed to foster
healthy and diverse native fish populations, and to safeguard rivers
and streams for future generations.
One way to do this is to learn about
fish, fish habitats, and the dangers
they face. You can also become a
“river or stream watcher” and
promptly report any water pollution
problems to your province natural
resource departments.
Water pollution threatens fish.
Heated water (thermal discharge),
low dissolved-oxygen levels, toxic
chemicals, and coal-mine acids impact water quality and fish. Fish
may temporarily avoid water pollution by swimming into small, clean
tributary streams. However they
cannot live continuously in a polluted stream.
Exotic, introduced fish (especially
predator species) also stress native
species. They compete with natives
for habitat, spawning sites, and
food. Exotic fish like bass are aggressive predators that eat native
fish. Aquarium pets should never be
released into the wild where they
can threaten native aquatic animals.
Conservation efforts and recovery
projects by the state to artificially
culture and reintroduce native fish-
Recreational Fishing in Idaho
Be alert to the following symptoms
of water pollution:
Muddy water,
Oil slicks,
Fish and crustacean kills,
Algae and weed problems,
Odour and gas,
Unusual flows,
Discoloured water,
Foaming water, and
Litter
Organize a local “river watchers”
group to keep an eye on your
streams and conduct stream improvement projects. Get involved in
programs that restore coastal and
streamside areas. Planting native
trees and shrubs along riverbanks
protects water quality and improves
wildlife habitat.
Catch-and release fishing allows
anglers the enjoyment of catching
fish and, then, freeing them to be
Snakeriver, Idaho