As is shown in the pictures,
with the rampancy of commercial fishing,
the number of fish has dramatically shrunk.
In the first picture,
we learn that the year 1900 witnessed a quite encouraging scene of world fishing.
There were various kinds of fish and only one fishing-boat.
On the contrary, in the second picture,
in 1995 there was only one fish swimming freely but many fishing-boats sailing in the sea.
It is apparent that a disastrous change has occurred.
The purpose of the pictures is to tell us
that due attention has to be paid to the reduction of ocean resources.
Owing to the over-exploitation of marine resources,
the number of fish has declined at an accelerating rate.
If we let this situation continue as it is,
we do not know where the fish will be in the future.
By that time, our environment will suffer a great destruction.
Hence, it is imperative for us to take drastic measures to reverse this disturbing trend illustrated in the above pictures.
For one thing, we should appeal to the authorities to make strict laws to control commercial fishing.
For another, we should cultivate the awareness of people that ocean resources are of great significance to us.
Only in this way can we protect our natural environment.
I believe that we humans can surmount this difficulty and we will have a brilliant future.