Hello marine biology students.
This week we're going to talk about what resources
we as humans get from the oceans.
[Intro Music]
So this week we're going to talk about resources
harvested from the oceans and also fisheries
and their managements.
So what are the things that we get from the
oceans?
Well, living resources from the oceans are
used for food, also pharmaceutical products,
a variety of other materials and products
and also recreation.
Some people go fishing simply for the joy
of fishing.
Of the marine organisms that are harvested
for food, about 90% of them are known in the
fisheries business as finfish.
These include both bony fish and cartilaginous
fish and are contrasted with shellfish
being primarily molluscs and crustaceans.
There are some other marine species that are
collected, such as: seaweeds, sea cucumbers,
and sea urchins, and jellyfish, but most of
the marine catch comes either in the form
of finfish or shellfish.
While seafood represents only about 1% of
the food consumed each year, it provides about
30% of the total animal protein consumed worldwide.
This tells us that seafood is a very important
source of protein for many countries of the
world.
When we look at fisheries as an industry,
from the 1950s to present there's been a five-fold
increase in fishing effort, meaning the number
of boats, the number of days fishing, the
number of resources trying to catch fish,
we've been increasing our effort since the
1950s.
And yet, from 1980s to present, the worldwide
catches of seafood have been relatively constant
despite the increased fishing effort.
This is a very bad sign.
It means that we are over exploiting our fisheries
and it's taking more and more effort to catch
the same or in some cases, fewer fish.
And that's because the wild stocks are depleting.
Many of the world's most important catches
are overexploited
or exhausted, especially in the Atlantic,
Pacific, and Mediterranean.
In this chart, when we look at some of these
fisheries and the reported numbers of commercial
catches worldwide, we see down on the bottom
row that the total catch in marine fishing
areas has not changed significantly over these
past 30 to 40 years, yet effort has markedly
increased.
When we look at the countries and their fisheries
and their methods of fishing, we can see that
that worldwide marine catch has not changed
drastically.
Some countries are now catching significantly
more than they had previously, but as we see
with many of these other fisheries, the overall
production of those fisheries have been dropping
for the last 20 to 30 years.
In this chart we also see several of the commercially
important fishes from around the world, including:
herrings, and sardines, and anchovies, menhadens,
and cods, pollock, haddock, hakes, flatfish,
tunas, mackerels, and salmon.
When we look at where the major fishing areas
are, we see that they are mostly over continental
shelf 
and there are several reasons for this.
For one, it is easier to catch demersal or
bottom species in the shallow waters of the
continental shelf.
Many of these species are caught using dragging
trawlers.
These continental shelf areas also have a
high primary production, which means there
are more species present and more abundance.
These include areas such as the Grand Banks
of Newfoundland, the North Sea, also the Bering
Sea.
So let's talk about some of the major categories
of food fish species.
The first of these are the clupeoid fishes.
These include things like sardines, menhadens,
shad and herrings.
Now, how are they used?
Some of them are eaten directly, however many
are noted for having an especially fishy taste,
so another use of these clupeoid fishes are
in industrial fisheries.
And in industrial fisheries, these fish are
not used directly for human consumption but
instead are used for a variety of diverse
products.
This can include things such as fish flour,
which is a powder that can be used as a dietary
supplement or added to other types of foods
to increase its protein content.
These clupeoid fish are also used as fish
meal, which can then be used as feed for poultry,
livestock, and even in aquaculture, raising
of other marine organisms.
Fish oils are also collected from these.
They can be used in everything from margarine,
to cosmetics and paints, and even omega-3
fatty acid supplements.
The next group of fish that we’ll talk about
are demersal fish and they are often consumed
directly.
These are the cods, haddock, hakes, pollock,
and whiting.
They are demersal, coldwater species and they've
been harvested for centuries.
In modern times, they are sold either fresh
or frozen, but in the past they would also
be salted to be preserved over long periods
before refrigeration.
Now traditionally, these have been a vital
source of relatively inexpensive protein
in many parts of the world.
They also give us one of the clearest examples
of what it means to over harvest a fishery
and to result in that fishery crashing.
The cod fishery peaked in the 1960s and then
began to decline and instead of saying that
the fisheries and fishing amounts should be
reduced, more and more effort was put out
to collect fewer and fewer fish year after
year.
A moratorium was declared in 1992 to attempt
to save the fishery.
This closure of the fishery caused high unemployment
among American and Canadian fishermen.
This fishery may never fully recover as cod
is still listed as an endangered species
in the Grand Banks.
Part of the issue is that the remaining stocks
are insufficient to rapidly bring the populations
back to their original sizes and many other
species are now feeding on the young cod which
used to be just a very small part of the population,
but now make up significantly larger percentages
of it.
Other species collected for food include jacks,
mullets, rockfish, and mackerel.
These end up being important species when
it comes to worldwide tonnage of finfish caught.
Canned mackerel is a source of inexpensive
protein in some parts of the world.
I remember growing up in Hawaii, we would
use canned mackerel along with wheat flour
to make a type of bait that we would use to
catch local fish, but many people that I knew
would also eat the canned mackerel directly.
It's something I never got the taste for myself.
Another very important commercial species
are the tunas.
Now, this is a species that is caught in open
water and they can command very high prices.
They're caught in long lines or in gill nets,
although some modern changes in how they're
caught are further decimating their populations.
Fishing boats are equipped with freezers so
that they can stay out at sea longer, catching
more and more of the population.
When we look at some of the other species
that are collected for food, molluscs are
the second most valuable catch after finfish.
These can include cephalopods, such as squids,
cuttlefish, and octopuses, which are particularly
important in the Far East and happen to be
my favorite form of seafood as well, and then
also clams, oysters, mussels, scallops, and
abalone in the worldwide market.
Crustaceans are another important food source.
They’re prized worldwide and can command
high prices.
These include shrimps, lobsters, and crabs.
Seaweeds, jellyfish and sea urchins are also
harvested, especially in Japan.
Gooseneck barnacles are harvested in Spain,
and polychaete worms are harvested in the
South Pacific.
Sea turtles and their eggs are also harvested
and eaten even where they are protected by
law.
Seals and whales are also still eaten in some
cultures, despite laws to protect them.
And this takes us to the end of our initial
discussion of resources from the ocean.
Before our next video I would like you to
think about “What would inspire you to stop
fishing before you've caught as much as you
could?”
Well, we'll talk about that in the next video.
See you then.
