Sustainable Fisheries & Role of Biotechnology | Biology for Grade 10 PDF Download

Sustainable Fisheries

Fish Stocks

• Fish stocks (the populations of fish that we catch for food) in the oceans are declining
• This is mainly due to overfishing
• This could potentially result in:
  • Some species of fish completely disappearing in certain areas or even going extinct (eg. we are at risk of losing cod completely in the north-west Atlantic)
  • Ocean food chains being disrupted, affecting many other aquatic species
  • Fewer fish for human consumption – this would be especially problematic for populations that rely on fish as a main source of food
• For these reasons, it is important to maintain fish stocks at a level where breeding continues
• Sustainable fisheries are required to achieve this – these are fisheries in which the overall population size of fish species does not decrease, because the number of fish caught does not exceed the number of new fish born

Control of Nets

• Control of net size and the introduction of fishing quotas play important roles in the conservation of fish stocks at a sustainable level
• Increasing the size of gaps in fishing nets can help in two main ways:
  • Fewer unwanted species (that are often simply discarded) will be caught and killed, as they can escape through larger net gaps (as long as they are smaller than the species being caught – the accidental capture and killing of larger species is still a problem that is reducing the populations of these species)
  • Juvenile fish of the fish species being caught can escape through larger net gaps, meaning they can reach breeding age and have offspring before they are caught and killed. This ensures the population of the fish species being caught can be replenished
• In addition to tighter controls on net size, fishing quotas that limit the number and size of particular fish species that can be caught in a given area have been introduced by many countries to stop species becoming overfished

Role of biotechnology – Crop modification

• Biotechnology is the alteration of living organisms to develop or make products that help us. This is quite a broad definition and so many different organisms or processes are involved. Humans have used biotechnology for thousands of years in agriculture and used selective breeding to produce better foods and medicines. More recent examples of biotechnology include cloning and genetic modification. Biotechnology can help us meet the food demands of our ever increasing population.
• Crops directly feed us or animals we keep for food. They are commonly cereals, fruit and vegetables. We can change (or modify) crops in two key ways - selective breeding and genetic modification.

Genetic modification

• Scientists can now identify the genes in some species that control some characteristics. These genes can be removed using enzymes and inserted into the genome of other species. This is genetic modification (or engineering). The organism that has been modified is called transgenic.
• A common example of genetic modification involves the transfer of the glow-in-the-dark gene from jellyfish into mammals such as mice or rabbits. This gene is inserted into the embryo of the mammal so only a small number of cells need to be altered. As the embryo develops, all of its newly grown cells will contain the transferred gene.
• We have genetically modified bacteria to contain the human gene for insulin. These bacteria therefore produce human insulin which is used by diabetics to manage their diabetes.

The process of genetically modifying bacteria to produce insulin

• Golden rice is a variety of rice that has been genetically modified to contain beta-carotene which helps people who do not get enough vitamin A in their diet. This deficiency disease kills over half a million children each year. We have also genetically modified soybeans, cotton and corn to also include beta-carotene.
• Other crops have been genetically modified to be resistant to insects. A bacterium called Bacillus thuringiensis naturally produces a toxin which kills many insects. The gene responsible for this has been identified, removed and inserted into crop plants.
• Other crops have also been genetically modified to be resistant to pesticides. The genes that occurs naturally in some plants will be identified, removed and inserted into crop plants. This means that farmers can spray whole fields with pesticides and kill the pests, not the crops.
• It is likely that all crops have been selectively bred to have greater yields.

Selective breeding

• For thousands of years farmers have instinctively known to breed together - a big bull and a big cow to have big calves. This is selective breeding. It occurs when animals or plants with a desirable characteristic are selected to breed with each other. Because of inheritance, their offspring are likely to have the desired characteristic. Over generations these characteristics have become enhanced.
• All breeds of dog belong to the same species. They were all originally bred from wolves. Dogs have been bred for a variety of reasons including protecting livestock, hunting, providing company and for their different shapes, sizes and colours. They have all been selectively bred for these different characteristics.

All these breeds of dog are the results of selective breeding from a common ancestor

Other specific examples include:

1. Friesian cows to produce large volumes of milk and Jersey cows to produce creamy milk
2. Wheat that is resistant to some diseases

Unlike selective breeding, genetic modification is an ethical issue which means some people disagree with it for religious or other personal reasons. Some people believe scientists are playing God and others worry that the genes might spread to other species.

Role of biotechnology – Novel foods

1. The pH and temperature are maintained at the optimum
2. The temperature is controlled by a water jacket that surrounds the whole fermenter
3. Sterile oxygen is added to make sure that aerobic respiration occurs
4. A food source like glucose syrup is added
5. The mixture inside is stirred to make sure all the oxygen and nutrients are equally distributed

Diagram of a fermenter

After the fungus has fully grown in the fermenter, it is harvested and purified and the process is then repeated with a new batch of ingredients.
Producing protein from fungus is much more efficient than from meat from livestock. Only about 10% of the energy found in grass is transferred to the animals like cows that eat it. 1000 g of plant carbohydrate can produce up to 14 g of beef, 49 g of chicken or 136 g of mycoprotein. Additionally, fermenters can be used to produce protein in places where grass and livestock cannot grow.