I have a very important question to ask. Help me settle a bet with my fellow fisherpeople. Why do salmon jump? And do some salmon species jump more than others? Do they prefer jumping in certain temperatures? What’s the deal with all the jumping!?
Almost everyone in Alaska knows that salmon can jump. We can even see it from time to time around spawning seasons, where salmon will jump their way up waterfalls and fish ladders. Evolutionarily, salmon usually jump to get to where they’re going, for the sake of spawning. However, salmon can also be seen jumping in the open ocean. This is typically where a lot of debate and speculation comes in about why salmon are jumping.
A study published in 2017 offers us some insight into a few of the possibilities. According to Tlingit culture, salmon jump to better see their surroundings: both water and land (Fagen, 2017). Meaning a great leap out of the water could give them geographical orientation advantages. Salmon jumping has also been hypothesized as a form of play behavior. Dennis Dobson has been observing jumping salmon for decades in the wild and is able to describe their jumping behavior under the current scientific definition of play (Fagen, 2017). Perhaps this means that the salmon truly are jumping because they are happy.
Fagen (2017) also preludes to the fact that salmon could be jumping to dislodge sea lice. A scientific article published in 2018 confirms this. Their study looked at juvenile sockeye salmon Oncorhynchus nerka and sea lice, Caligus clemensi and Lepeophtheirus salmonis. They had two study groups: one where salmon were able to leap, and one where salmon were unable to leap. At the end of the three day study period, they found that the O. nerka salmon that were allowed to leap had 28% less sea lice than those that were prevented from jumping (Atkinson et al., 2018). Although more studies would help confirm this, it appears that salmon do, in fact, jump to get rid of sea lice.
Unfortunately, there are no studies out about the variability of jumping amongst the different salmon species. However, we do know some facts about their jumping habits. Salmon have been recorded jumping four feet, on average, while jumping over lower impediments. They have been recorded jumping as high as 12 feet when jumping over larger obstacles like a waterfall (Loesche, 2023). Generally, chinook, coho, and sockeye salmon jump around eight feet high, while chum and pink salmon jump around 3 feet high (“The 5 Species of Pacific Salmon Also a Steelhead and a Cutthroat,” n.d.).
Temperature can also play a role in the frequency of salmon jumps. Warm water means less oxygen and a faster salmon metabolism. This means their bodies are requiring more oxygen and more food, but there is less oxygen available. They either have to exert their bodies to find the food to sustain them or move somewhere cooler, both requiring lots of oxygen (CBC/Radio Canada, 2021). In addition, salmon are cold blooded and are unable to adjust their body temperature internally. They rely on external temperatures to regulate their system. Salmon do not do as well in warming waters. If it is a particularly warm year, and the surface temperature of the ocean is greater than that of the layers beneath it, then yes, salmon could be avoiding the surface, and therefore are not jumping.
Science is ever changing, and our understanding of how things work is continuously growing. Hopefully in the coming years there will be studies that give us clarification to some of the unanswered salmon questions that we have.
We are currently seeking more questions from the community. If you have a scientific related question, please email it to email@example.com.
The 5 species of Pacific Salmon. Also a Steelhead and a Cutthroat. (n.d.). Retrieved February 23, 2023, from https://www.lcsd.wednet.edu/cms/lib/WA01001184/Centricity/Domain/36/May%208%20The%205%20Species%20of%20Salmon.pdf
Atkinson, E. M., Bateman, A. W., Dill, L. M., Krkošek, M., Reynolds, J. D., & Godwin, S. C. (2018). Oust the louse: Leaping behaviour removes sea lice from wild juvenile sockeye salmon oncorhynchus nerka . Journal of Fish Biology, 93(2), 263–271. https://doi.org/10.1111/jfb.13684
CBC/Radio Canada. (2021, July 24). Salmon are getting cooked by climate change. here’s how they could be saved | CBC news. CBCnews. Retrieved February 23, 2023, from https://www.cbc.ca/news/science/salmon-climate-change-1.6114328
Fagen, R. M. (2017, May 30). Salmonid jumping and playing: Potential Cultural and Welfare Implications. Animals : an open access journal from MDPI. Retrieved February 23, 2023, from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5483605/#B39-animals-07-00042
Loesche, M. (2023, February 11). Why do salmon swim upstream? (fish facts explained). Strike and Catch. Retrieved February 23, 2023, from https://strikeandcatch.com/why-do-salmon-swim-upstream/