Researcher Tom Reimchen states the trout adipose fin acts as a mechano-sensory organ.
Hatchery salmon disadvantaged by fin clipping: study
A new study suggests that the common practice of clipping the adipose fin of hatchery salmon may be damaging their swimming ability and survival rate. The adipose fin, found on a fish’s back behind its dorsal fin, was until now considered vestigial rather than functional and is typically cut off from millions of hatchery fish for identification purposes when they are caught.
But it turns out the practice is harming fish more than previously thought, according to a study co-authored by University of Victoria biologist Tom Reimchen and published recently in Proceedings of the Royal Society.
The study shows advanced microscopic techniques which reveal that adipose fins in brown trout, which belongs to the salmon family, hold a network of nerves linked with star-shaped cells similar to those in the brain.
“This strongly suggests that the fin acts as a mechano-sensory organ that relays positional information to the fish,” said Reimchen.
He noted that this is particularly vital when the fish is traversing turbulent waters, as the adipose fin plays an important role in the fish’s swimming abilities. In the past, Reimchen had found that removing the small fin forced the fish to use more energy to keep up speed and position, which would likely put the fish at a disadvantage in the ocean, where salmon brave survival challenges ranging from climate change to predators.
The researchers found that the adipose fin acts like a complex feeling device, allowing the fish to detect water flow and make up for it as necessary, reports The Globe and Mail.
“While the removal of the adipose fin may be less damaging than the removal of any other fin, our results suggest that we should be rethinking the removal of a vital sensory device, especially when these fish are already subjected to considerable demographic and environmental stresses,” Reimchen continued.
"The practical issue emerging from our study is: what is the result of the increased loss of their swimming ability and their reduced competitive performance and do they come back at a lower rate than fish with an adipose fin?" he asked, reports The Times Colonist.
The adipose fins serve as markers when the fish is caught. The data is then sent to the Department of Fisheries and Oceans Canada (DFO) to help it gauge stock assessment and trends in salmon abundance and survival.
Update to educators on April fuel spill into Goldstream River
From Don Lowen (firstname.lastname@example.org) South Vancouver Island Education Coordinator
I have received a number of requests from teachers for information concerning the tragic fuel spill upon the lower reaches of the Goldstream watershed on April 16th. Here are a couple of notes sent to me:
“Just read an article in the paper about the devastating effect of the accident in Goldstream on the fish and am very concerned. I'm sure my students will be too. If you have information I can share with them or any ideas about how we can help, please pass them onto me. Or links, people my class can write to, maybe even fundraising? Our classroom salmon are big and healthy and almost ready to go into the Cowichan River. They seem even more precious than ever. This is not a project just for fun or education. Is there any more we could be doing??? Thanks for listening, I'm sure you are busy but the thought of those beautiful wild fry being killed like that touches my heart with sadness.” (Shauna Curtis, Maple Bay School)
“We are so sad to hear about the tanker crash and subsequent oil spill into the river. What bad news! The students are all very concerned about the salmon and the ecosystem as a whole and they have asked me to ask you if there is anything they can do to help??” (Christine Munro, Maria Montessori School)
For information, please read Peter McCully’s attached detailed update..
Some of you have also asked what you or your class can do to help, and here are some of my thoughts.
- Writing letters to media and politicians will help to keep this disaster on the radar, reminding all that, drunk driver or no, there is no separation in Nature between our ways of living and the health of the planet that sustains us. That truck rolled through the Goldstream watershed that day because there is a demand for its payload. The challenge is not to remove drunk drivers from the road; the challenge is to find ways to reduce or remove the need to transport toxic payloads through any watershed.
- You already understand that a fuel spill affects nature inclusively. No organisms are spared, so let’s remember that this spill also landed on the aspirations of humans who are also part of the Goldstream community – First Nations, volunteer stewards, and children, to name a few. With the support of Fisheries and Oceans Canada, the Tsawout First Nation has worked closely with Goldstream Hatchery volunteers on past restoration projects, and will do so in the future. Close to 1,400 students were poised to release a total of 11,000 salmon fry from classroom projects into Goldstream River, and many of these projects started with visits to the Nature House on the estuary. These students planned and dreamed all year of the experience of giving life back to the Goldstream. How do you put that into words that government will understand? How do you convince government that the cost of its investment in stewardship through public involvement (Volunteer restoration and education) will never match the cost of mitigation and enforcement? If you can find a way, please let me know.
- It occurs to me that an interesting secondary level research project would be to compare the total cleanup cost of one event - the April 16th spill into the Goldstream - to the annual cost of public involvement programming across the Pacific Region.
Hope this helps, and thanks for all your kind thoughts.
Don Lowen, Managing Director
3731 Winston Crescent
Victoria, BC V8X 1S2
Phone (250) 388-4756
Cel (250) 213-8582
Director General of DFO Science for the Pacific region was put on the stand at the Cohen Commission to answer questions
On March 17 the Director General of DFO Science for the Pacific region was put on the stand at the Cohen Commission to answer questions about a Ministerial memo regarding a virus that may be killing large numbers of Fraser sockeye. The transcripts will eventually be available from the Cohen Commission website, but in the meantime here are my notes. http://alexandramorton.typepad.com/
It was a disheartening display of avoidance behavior following in the footsteps that brought us the east coast cod collapse.
I am deeply grateful to Greg McDade and Lisa Glowacki, the lawyers that represent me at the Commission. I am also thankful to First Nations lawyer, Brenda Gaertner who brought a powerful sense of outrage that DFO has not informed First Nations on this potentially very serious virus.
We have a long way to go, but these lawyers were a storm over passive waters.
From humble beginnings when the Steelhead Society of BC (Comox Valley Branch) under the direction of Father Charles Brandt wondered why the Tsolum River was not rebounding after the devastation of the clear cut logging from the turn of the century to the 1950's. The Tsolum River Restoration Society now boasts the completion of a complete covering of the minesite that was discovered as the cause.
It is agreed that historical logging (that left no tree standing on the southern slopes of Mt. Washington and all along the Tsolum River) destroyed so much habitat for salmon that historical levels of production were decimated! It is also agreed that after great efforts on the part of the community and DFO stocks still did not rebound.
It was not until 1985 that the toxic runoff created by a short-lived copper mine (1964 - 1967) was discovered.
As we now approach the end of this toxiciity we can see our way to restoring this once incredibly productive watershed.
We invite you to share with us this journey of ecological restoration in action as we tackle the next most serious problems and struggle with human use of the land in order to ensure long-term protection for the essential ecological features.
We see a day when we will again have a sports fishery in the river bringing tourists from all over the world to "play" with a huge steelhead or cutty. We also see the day where the Tsolum River will again take its rightful place in the production of chum, pink and coho salmon to support a commercial fishery. But more than anything else we see a wonderful community amenity providing an experince with nature with a functioning ecosystem, the miracle of spawning salmon and a balanced and healthy place for animals and humans.
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