Featured Research

from universities, journals, and other organizations

Melanin pigmentation in salmon fillets: Causes, risk factors

Date:
October 23, 2013
Source:
Norwegian School of Veterinary Science
Summary:
A PhD project has examined the unwanted discoloration, or melanin "black spots", of muscle fillets from farmed salmon. The cause of these spots was previously believed to be due to the use of vaccines with oil-based adjuvants, but this study shows that spots with similar characteristics can also occur in unvaccinated salmon. The search for the cause of this phenomenon must therefore focus on other areas.

At the time of slaughter, up to 10-30% of the salmon can show signs of black spots in their muscle fillets. This phenomenon is caused by chronic inflammation sites in the muscles, where cells containing melanin accumulate and give rise to black discoloration.
Credit: Norwegian School of Veterinary Science

A PhD project carried out at the Norwegian School of Veterinary Science has examined the unwanted discoloration, or melanin "black spots," of muscle fillets from farmed salmon. The cause of these spots was previously believed to be due to the use of vaccines with oil-based adjuvants, but this study shows that spots with similar characteristics can also occur in unvaccinated salmon. The search for the cause of this phenomenon must therefore focus on other areas.

Farming of Atlantic salmon in Norway contributes to make the country the world's second largest producer and exporter of fish. Norwegian aquaculture generates a great deal of revenue. However, the downgrading of salmon fillets due to melanin spots leads to losses of several hundred million kroners per year. At the time of slaughter, up to 10-30% of the salmon can show signs of black spots in their muscle fillets. This phenomenon is caused by chronic inflammation sites in the muscles, where cells containing melanin accumulate and give rise to black discoloration. The cause of these spots was thought to be linked to the use of vaccines containing oil adjuvants, but other factors such as environmental conditions, genetics and disease also appear to play a role.

Hilde Fagerland's thesis is a study of pathological melanin pigmentation in farmed salmon. Her analyses showed that the melanin probably arises as a result of chronic inflammations and scar tissue formation. Fagerland used data obtained from vaccinated fish to analyse equivalent spots in unvaccinated fish -- both diploid and triploid fish and spring and autumn smolt (juvenile salmon). The formation of the black spots in unvaccinated fish resembled those found in the vaccinated fish, irrespective of ploidy or production season (spring or autumn). Fagerland found just as many individuals with fillet pigmentation amongst unvaccinated fish as amongst vaccinated fish. However, triploid fish were found to be more likely to develop black spots than diploid fish.

One particularly interesting finding was the combination of vaccination and temperature/photoperiod smolt production (autumn smolt), which resulted in a larger number of affected fish compared to fish that are vaccinated and then undergo simulated natural smoltification (spring smolt). This may point to a possible cumulative effect of, or interaction between, raised temperatures and vaccination. This temperature-related effect was corroborated by the results of a cell experiment (SHK-1), where the synthesis of melanin appeared to be affected by the temperature.

Analyses of pathological pigmentation in the hearts of fish suffering from cardiomyopathy syndrome (CMS) also found a link between black discoloration and processes of repair and scar tissue formation in the fish.

In short, the findings of this project indicate that melanin is formed as a support to the defense and repair processes that occur following chronic inflammation.


Story Source:

The above story is based on materials provided by Norwegian School of Veterinary Science. Note: Materials may be edited for content and length.


Cite This Page:

Norwegian School of Veterinary Science. "Melanin pigmentation in salmon fillets: Causes, risk factors." ScienceDaily. ScienceDaily, 23 October 2013. <www.sciencedaily.com/releases/2013/10/131023090534.htm>.
Norwegian School of Veterinary Science. (2013, October 23). Melanin pigmentation in salmon fillets: Causes, risk factors. ScienceDaily. Retrieved September 22, 2014 from www.sciencedaily.com/releases/2013/10/131023090534.htm
Norwegian School of Veterinary Science. "Melanin pigmentation in salmon fillets: Causes, risk factors." ScienceDaily. www.sciencedaily.com/releases/2013/10/131023090534.htm (accessed September 22, 2014).

Share This



More Plants & Animals News

Monday, September 22, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Raw: San Diego Zoo Welcomes Cheetah Cubs

Raw: San Diego Zoo Welcomes Cheetah Cubs

AP (Sep. 20, 2014) The San Diego Zoo has welcomed two Cheetah cubs to its Safari Park. The nearly three-week-old female cubs are being hand fed and are receiving around the clock care. (Sept. 20) Video provided by AP
Powered by NewsLook.com
Chocolate Museum Opens in Brussels

Chocolate Museum Opens in Brussels

AFP (Sep. 19, 2014) Considered a "national heritage" in Belgium, chocolate now has a new museum in Brussels. In a former chocolate factory, visitors to the permanent exhibition spaces, workshops and tastings can discover derivatives of the cocoa bean. Duration: 01:00 Video provided by AFP
Powered by NewsLook.com
Could Grief Affect The Immune Systems Of Senior Citizens?

Could Grief Affect The Immune Systems Of Senior Citizens?

Newsy (Sep. 19, 2014) The study found elderly people are much more likely to become susceptible to infection than younger adults going though a similar situation. Video provided by Newsy
Powered by NewsLook.com
Jury Delivers Verdict in Salmonella Trial

Jury Delivers Verdict in Salmonella Trial

AP (Sep. 19, 2014) A federal jury has convicted three people in connection with an outbreak of salmonella poisoning five years ago that sickened hundreds of people and was linked to a number of deaths. (Sept. 19) Video provided by AP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins