Abundant Jellyfish Disrupt Commercial Salmon Fishery

Observation: We were fishing for salmon at Red Bluff, on the east side of Popof Island, on the Pacific Maid (Figure 1.), a 58-foot limit seiner. Pulled in the nets and got a huge catch of jellies. I have been fishing in this area my whole life, and we have never seen so many that we could not fish there anymore. They were fouling the nets and even causing a danger to the boat.

This type was not as "hot" (stinging) as some others we normally see, and they were huge, some weighing as much as 10 lbs. They are also really dense and clog up the scupper holes and prevent the deck from draining. This is what makes them dangerous for the boats. What type of jellies are these? Why are they here? Is this about the currents changing? Is this one of the reasons why we had such a poor pink salmon season? Did their current go somewhere else? We did notice that the water was warmer last summer. We think that may be why we didn't get the salmon we usually get.

LEO says: There was another observation about the size of the jellyfish in Sand Point last year. See attached. The post has been added to the LEO Jellyfish Project and the LEO Blob Project. It has also been shared with ADF&G and Auke Bay Lab. Please seen contributions below.

Alaska Department of Fish and Game Consult: (2017-04-12) Elisabeth Fox, Fishery Biologist III, "This is the first I’ve heard of an unusually high abundance of jellyfish from the 2016 season – I’m curious as to where the jellyfish were thickest and if there was a specific time that there was the highest concentration. As far as pink and jellyfish interactions/correlations, that’s a tough one to sort out. There is a correlation between huge pink years followed by poor pink years, as we saw in the 2015 (one of the largest on record) and 2016 (one of the poorest on record) seasons. The reports about pinks and the harvest information both support that although few pink salmon returned in 2016, the fish that did return were on average much larger than other years." Source: Commercial Fisheries Division, ADF&G

Auke Bay Laboratories Consult: (2017-04-12) Kristin Cieciel, Marine Research Institute Staff, writes "The jellyfish in the photo are Chrysaora melanaster, the northern sea nettle. They will have periods of high abundance and their distribution can be quite patchy if this photo (Figure 2.) was from the end of August-October that is when they typically start to slow down and begin the die off. People will start reporting them washed up on beaches around the end of October through November. As they are dying off they also tend to be found floating around more in the upper part of the water column." Source: Alaska Fisheries Science Center, NOAA Fisheries

Update: (2017-04-13) Kristin Cieciel provides additional information about: (Chrysaora melanaster) is found in waters all over the state of Alaska and along the west coast to at least British Colombia, it is a northern Pacific species. During some years they can be quite thick or abundant in certain areas, that is not an indication of climate change or unusual to find a large patch of them in any particular location in any year around Alaska. It would need to be repeated encounters or lack thereof and changes in numbers that would signal something is occurring in the environment. I have been monitoring this species in the Bering for 13 years and 6 years in the Gulf of Alaska. We have been seeing recent declines in overall numbers in the Bering Sea where it has been dominant for the last decade and variation in species composition in both locations over the last 2 years, meaning more kinds of different gelatinous species are present. Whether this has to do with climate change, I cannot say but I will say the number and location of jellyfish does not seem to track to a specific cold year or warm year temperature pattern, something else or many things are likely the factors that are causing these fluctuations in jellyfish populations." Source: Alaska Fisheries Science Center, NOAA Fisheries

Resources

Arctic Ocean Diversity (ArcOD) – *Sea Nettle: Chrysaora melanaster Brandt, 1838 - "The Chrysaora melanaster is the largest jellyfish in the Arctic. Benthic form has not been observed in the Arctic, suggesting the species may be seasonally imported from the subarctic. Diet includes copepods, larvaceans, other jellies, larger zooplankton and small fish. Tentacles can produce a nasty sting to humans" Source: ArcOD Census of Marine Life (August 2010)