Unit # 1
This course explores the environmental impacts of fisheries and fishing on the marine ecosystems. The properties and effects of pollution and the impact of climate change on the oceans and marine ecosystem is examined in this course.
Ocean Conservation Course
While fisheries are an important way for people to make a living and to feed the ever growing human population there are some very significant implications for the environment and, without regulation, humans threaten to wipe out the very resource on which they so strongly depend.
Bottom trawling is a very destructive method of fishing. Intent on catching as many flatfish or bottom-dwelling shellfish as it possibly can, the gear is often equipped with huge steel teeth with which it can dig deep into the sea bed to disturb the catch. The catch is then collected in its large, trailing bag or cage.
Environmental impacts of fisheries and fishing on the marine ecosystems
It is estimated that a single pass of a bottom trawler’s gear removes as much as 20% of the life that thrived there, with multiple passes a seafloor community has little chance of surviving the carnage brought by a bottom trawl. This is because not only does the heavy gear gouge into the seabed and tear up habitats but it both removes organisms from the habitat in the catch and crushes and kills the rest. The actual level of impact can vary greatly and is dependent on the specificities of the gear being used (e.g. its weight and construction), the type of sea bed being dredged and the speed at which the area is being dredged – faster dredging with heavier gear will cause an incredible amount of damage and an extremely high mortality rate amongst bottom-dwelling organisms. Over fishing is probably the primary major problem our oceans face currently. We have already touched on the fact that the human population continues to grow and grow; in fact, it is thought it may reach a staggering 10 billion by the year 2050.
Human Impact on Worldwide Fish Stocks
This ever-increasing population means that more and more food resources need to be found, and humans have turned to the ocean as an immediate source of food. The problem arises when it is forgotten that this food source is not infinite. Thanks to significant advances in fishing technology, it is estimated that nearly 80 million metric tons of fish are taken from the sea every year worldwide.
85% of the world’s fish stocks are thought to be fished at the absolute maximum rate the population can handle and, are already beyond that stage. They are being overexploited or they are in the process of gradually recovering from overexploitation. While the human population continues to rise, it is expected the demand and strain on fish stocks will also continue to be pushed to its limits.
In fishing techniques that use nets there is also another part to this story – the catching of juvenile individuals. As the stocks of a species drop because they have been fished at a rate that cannot be sustained fisheries turn to nets with smaller holes and remove the discrimination between larger adult individuals and smaller juvenile individuals. Taking juvenile individuals as well as the adults multiplies the problem many times; a population that already cannot reproduce quick enough to sustain the yields being taken stands absolutely no chance if the individuals are not being left in the ocean long enough to reach sexual maturity.