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Fishes are aquatic vertebrates that have fins, gills and
scales. Gills are the part of the respiratory system that
provide surface area for exchanging oxygen and carbon dioxide
under water.
Fish are ectotherms, commonly referred to as
'cold-blooded', meaning their temperature is regulated by the
temperature of their environment. They have a range of diets,
being herbivores, carnivores, or omnivores. Some fish reproduce
by laying eggs, while others reproduce by bearing live young.
California fish species reside in freshwater and coastal/marine
waters. Coastal, or marine fish are an abundant and valuable
resource. However, the ocean's supply is not limitless, and
therefore careful planning and education must be undertaken to
ensure the sustainability of the world's largest food source.
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The sharks and the rays have certain things in common which
differentiate them from other animals with backbones. For this
reason the scientist places them in a subdivision of the
vertebrates, apart from the true or bony fishes, called
Chondrichthyes.
Sharks are found in all the oceans of the world. Some rove the
high seas but most of them live along the coasts in relatively
shallow water. Some are surface dwellers; others live at or near
the bottom, certain kinds at very great depths. A few species
move at times far enough up great rivers to enter fresh water,
and one lives in a fresh water lake, Lake Nicaragua.
At least 34 species of sharks have been recorded off the Pacific
Coast of North America. There are at least 29 species of shark
indigenous to or visiting the California coast. The sharks
and rays represent a very muddled group as far as scientific
understanding of the species is concerned.
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Particularly with the larger sharks, it is hard to preserve
specimens in museums, and a proper comparison of similar
individuals from different parts of the world is very difficult.
The literature is confused and much remains to be done in
determining just what kinds do exist. It may well be that some
kinds which we now regard as species separate from, say, their
Atlantic counterparts actually do not differ from them at all.
Conversely, some of those species now credited with a world-wide
distribution may prove to be divisible into several species each
with a limited range.
Sharks have and will attack man and there are many authentic
records of such attacks which have resulted in serious injury or
death. None are from the Pacific coast of the United States,
where large sharks of the dangerous species are rare, but there
are documented cases on file for the Atlantic seaboard.
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Of the sharks known from California, the great white, the
tiger and the hammerhead are unquestionably dangerous but they
are so uncommon in our waters as to present a negligible hazard.
Many others are catholic feeders, and any shark of sufficient
size should be regarded as a potential danger to a bleeding man
in the water. None of our common inshore species are large
enough or voracious enough to be of concern to swimmers.
A bill was introduced in the California Assembly that would ban
all trade in shark fins. A public meeting was held. Supporters
said that the large California market encourages the use of the
cruel practice of shark finning (which is exactly what it sounds
like). The sharks are then put back in the water to die. Some
scientists say that the collapse of the international shark
population is due to the skyrocketing demand for shark fins all
over the world.
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