The main issue is whether or not humans need to be concerned about the effects that whaling is having on the population and if whaling is purely to blame for large population decreases.
The relevance of this issue to humans is that we are the cause of this problem. To ignore this would be an act of ignorance and stupidity from the whole world. We know that extinction of any species causes an imbalance in the food chain but we don't know what the extinction of some whales would cause and so there needs to be much care about our actions.
The relevant biological concepts are that if the whale's population in general keep decreasing at the current rate then before we know it we will have more extinct species then species in the ocean. This will probably pose a huge problem to the food chain beneath the ocean and humans do not have a clue how the environment or humans will handle the extinction of whales. .
Everyone agrees that taking a specie or species of animals out of the food chain and out of their environment will dramatically affect the other creatures that live with and compete against the whales.
The culling of whales to suit human interests can be related to the culling of the Tasmanian tiger in the 1920's and this cull did lead to that species of animal becoming extinct. .
There was no protection for this animal and it was seen by man to be a pest. So the tiger was hunted and eradicated until there were no more left and no thought was given to what would happen after they were all dead. .
If we are not careful and don't do enough to protect the whale then it too could be in for the same fate. .
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The reason given by Japan and Norway and other whaling nations for the continuation of this industry is that scientists are using the whales for research. But what the scientists don't use is sold to restaurants and fish markets around the country and a rather large profit is being made. What these countries seem to leave out in their statements trying to justify the hunting of these animals are how much pain they cause the animal when they are actually trying to kill it but the damage they are having on the whale population.