The negative impact of fish farming
Fish farms attract predators
Fish farms have many negative impacts on the wild population and they include how they attract predators .Predators find it as easier target to prey on fish farms because they have large quantities of wild and rear fish and also are a short distance towards the coastal line .Many examples of predators can include fin fish, sharks, and marine mammals such as seals and sea otters. These predators go after salmons that are inside the cage and damage the netting when in the process.
Fisheries and escapes from sea cages
Rainbow trouts ,arctic charr ,halibut ,sea bream , sea bass , and meager are a few examples of fish that have escaped from cages .Most fish farms are usually located close to wild fish habitats and it is likely when the fish escape they mix with the habitat .But fish that escape may interact negatively with wild population ,and it can involve competition ,transfer of diseases and pathogens and interbreeding .
Effects on diseases and parasites
Diseases and parasites are a principal constraint to the development of many fish species because the increased of intensification and commercialization of aquatic production. Therefore, the aquaculture industry has been overwhelmed with its share of diseases and problems caused by viruses, bacteria, fungi, parasites and other undiagnosed and emerging pathogens and the transmission of disease between wild animals and farm animals is investigated. The most studied example is the infection of sea lice from farmed salmon to wild salmon.
Other factors that may be affecting the survival of the wild salmon population
There are many factors that may cause fishfarms to affectthe survival of wild salmon populations .When salmon escape from the fishfarms and hatcheries ,they may have a negative impact and can be a threat to native atlantic salmon population that live in the coastal marine rivers .When the fish escape then it can result to the interactions with native stocks .The problems that occur when fishfarm salmon escape are that they disrupt redds of salmon ,compete with wild salmon for food and habitats ,they may also breed with the wild salmon ,as well as transfer diseases and parasites.
Advantages and disadvantages of fish farming
Advantages
Produces high yields despite small volume of water.
Contains Essential nutrients, with a high protein and low to moderate fat in comparison to terrestrial animals.
Overpopulated
Easily-maintained, requires much less attention than cattle and other farm animals
Part of an aquatic food chain, therefore it is not taking prey from omnivorous and carnivorous predators.
Disadvantages
Fishing costs (most of modern fishing utilizes technology such as weights, nets, seine nets (e.g. beach seine), trawls (e.g. bottom trawl), dredges, hooks and line (e.g. long line and hand line), lift nets, gillnets, entangling nets and traps
Aquatic contamination and pollution:(e.g. Oil spills, human material thrown in water often harms fish)
High density to volume ratio, fish often clustered together thus causing high stress level which increases susceptibility to disease and transfers disease at an accelerated
Mercury: Fish and shell-fish are able to concentrate mercury in their bodies, due to this being a toxin it can show negative effects if it is consumed.