Fish Farming Reducing Genetic Diversity of Baltic Salmon in Sweden: Study
Fish are considered a lean, clean and tasty food source and are one of the most popular sources of protein and meat in the world. The popularity of fish as a food source has risen in recent times, with people understanding the benefits of lean and clean protein. ‘
In fact, according to this research published in MDPI, this figure has been rising steadily in the past 50 years, congruent with the rising popularity of foods like sushi and fish burgers. According to the Global Journal of Health Science, fish is an integral part of the human diet and supplements us with several vital trace minerals and also provides dense and high-quality proteins, n-3 polyunsaturated fatty acids and other nutrients. It is also proven to help bodily functions and beneficial to muscle growth, brain function and improving the vascular system in the body, and countering certain types of cancer cells.
With the recent push towards more sustainable sources of protein, humans are looking at the adverse impacts of meat farming on the planet too. The global switch towards veganism has highlighted several areas within the livestock and meat industry that are alarming. Often overlooked in this aspect of the analysis is the impact of fish farming on natural ecosystems and populations. This is crucial to study because unlike other commonly consumed animal meat, fish cannot be domesticated and any human involvement could trickle down to the naturally occurring genetic makeup of the species.
Along these lines, a team of researchers from Sweden, the U.K., and the U.S.A have studied the impact of fish farming on baltic salmon, a popular fish in the meat industry. The findings of the study, published in Proceedings of the Royal Society B, highlight the negative impacts of artificial methods employed to increase yield.
Study and Findings
The team of researchers studied baltic salmon populations from 13 rivers in Sweden to evaluate the impacts of genetic selection. The team found that such a study had never been conducted on baltic salmon and in a bid to gain an accurate picture, the researchers collected scale samples from catches dating back 100 years.
In the past 50 years, fishermen in this region have been stocking lines of salmon that grow faster. In a bid to increase meat yield, these salmon are cordoned off from the wild population. These fish are often fed by the fishermen in large quantities to increase size, causing these genetic lines to lose the instincts that help them find food, fend for themselves and live successful lives in the wild.
The issue with this is, the fish escape these enclosures frequently and blend in with the wild population. When these fish, carefully bred for 50 years, breed with the wild population, it causes a line of offspring unfit for life amongst other wild salmon. Using scale samples from 1,680 fish from over 100 years of fishing in the area, the team found a reducing genetic diversity amongst the wild population in modern times.
The baltic salmon chosen exclusively for their size and growth rate are sheltered from the wild populations, which reduces their life skills and ability to sustain in the wild. The team of researchers found that the salmon escaped and bred with the local wildlife and this has caused a much less genetically diverse population with a large percentage of the wild salmon lacking survival skills. Also, the team realized that introducing inferior gene lines to the stock has caused a number of weaker gene samples found in the wild too. This causes various issues during growth, reproduction, and in potential offspring too.
Why Is This Data Important?
Knowing the health and genetic make-up of an indigenous species in an ecosystem is crucial to figure out how balanced the food chain is. Salmon are wonderful fish that dominate any freshwater ecosystem they occupy. Their healthy genes ensure a healthy population that can continue their survival with optimal health and knowledge.
Introducing selective breeding or favoring a gene line has never ended well for animals domesticated by us. Cows, dogs, pigs, and several other species that we depend on for protection, meat or dairy alp show relatively high levels of genetic defects.
In cows raised for meat, there is a spate of highly debilitating genetic disorders that are prevalent. These can be directly linked to harmful breeding practices, overbreeding, and trying to isolate gene pools. These disorders include Bovine Syndactylism (known as mule foot disease), Bovine leukocyte adhesion deficiency (BLAD), deficiency of uridine monophosphate synthase (DUMPS), complex vertebral malformation (CVM), bovine citrullinaemia (BC), and factor XI deficiency (FXID) are autosomal recessive hereditary disorders, according to this research paper.
Impact of Findings
Similarly, diseases are prevalent across all of the meat, poultry, and dairy industry and are seeping into fish farming too. Fish farming is relatively a new practice compared to the age-old domestication of the bovine and avian species we rely on. This discovery goes to highlight the potential harm we could cause if fish farming becomes the norm, compared to fishing in open waters.
The fish selected for this study is very comparable to these land-dwelling species discussed above. They are widely regarded as an excellent source of meat and a delicacy in several parts of the world. They also feature as a crucial ingredient in sushi, a cuisine that is growing in popularity globally. There is a push to create an efficient supply chain that can keep up with the market demand.
This will force more fishermen to opt for fish farming methods and this will exacerbate the issue of genetic abnormalities spreading into healthy gene pools. If stringent housing methods are put in place, this is an avoidable issue. Having land-based fisheries can help negate this issue further and prevent the intermingling of gene lines.
There also needs to be a cognizant effort to analyze the impact of human involvement on other species of freshwater fish that are staples across various cuisines. In a push to regulate fish production, we could end up introducing a spate of diseases to fish and crustaceans too. This should be avoided and emphasis needs to be placed on where fishing takes place, how much fish is consumed and which species to target.
This will ensure a balance in numbers and will not create zones of depletion. Though open sea fishing is very regulated, most coastal efforts by fishermen go unregulated, especially in developing nations. This needs to be taken into account to develop a most secure system that will not deplete the genetic makeup of a species.