Endangered orcas compete with seals, sea lions for salmon

Discussion in 'Conservation, Fishery Politics and Management.' started by Whole in the Water, Nov 20, 2017.

  1. Whole in the Water

    Whole in the Water Well-Known Member

    [​IMG]
    In this Sept. 2017, photo made with a drone, a young resident killer whale chases a chinook salmon in the Salish Sea near San Juan Island, Wash. The photo, made under a National Marine Fisheries Service (NMFS) permit, which gives researchers permission to approach the animals, was made in collaboration with NOAA Fisheries/Southwest Fisheries Science Center, SR3 Sealife Response, Rehabilitation, and Research and the Vancouver Aquarium's Coastal Ocean Research Institute. Endangered Puget Sound orcas that feed on chinook salmon face more competition from seals, sea lions and other killer whales than from commercial and recreational fishermen, a new study finds. (John Durban/NOAA Fisheries/Southwest Fisheries Science Center via AP)

    SEATTLE — Harbour seals, sea lions and some fish-eating killer whales have been rebounding along the Northeast Pacific Ocean in recent decades. But that boom has come with a trade-off: They're devouring more of the salmon prized by a unique but fragile population of endangered orcas.

    Competition with other marine mammals for the same food may be a bigger problem than fishing, at least in recent years, for southern resident killer whales that spend time in Washington state's Puget Sound, a new study suggests.

    Researchers used models to estimate that from 1975 to 2015, marine mammals along the U.S. West Coast ate dramatically more chinook salmon - from 6,100 metric tons to 15,200 metric tons, according to a study published Monday in the journal Scientific Reports.

    In the same period, salmon caught by commercial and recreational fishing from Northern California to Alaska declined from 16,400 to 9,600 metric tons.

    "This really quantifies yet another pressure on recovering the salmon population," said co-author Isaac Kaplan, a research fishery biologist with the Northwest Fisheries Science Center, part of NOAA Fisheries. Other threats to salmon include habitat damage, dams and pollution.

    The emphasis typically has been on managing how fishing affects salmon. But this study brings the rest of the ecosystem, including predators, into the picture, Kaplan said.

    Researchers have known marine mammals gorge on salmon in certain hotspots, including the Columbia River between Oregon and Washington. But the predators may be eating even more in the ocean than thought.

    The authors estimated how much salmon in different life stages four marine mammals ate based on a number of assumptions, including their weight, diet and size. The species included California sea lions, Stellar sea lions, harbour seals and fish-eating killer whales.

    The study does a very good job of accounting for who eats chinook salmon during its various life stages, said Andrew Trites, professor and director of the marine mammal research unit at the University of British Columbia. He was not involved in the study. "They've identified some of the major players, but they haven't identified them all," such as other fish, marine birds and porpoises, he said.

    The study found killer whales, which increased from 292 to 644, ate the most salmon in terms of biomass, or weight, while harbour seals ate the greatest numbers of salmon, mostly juvenile fish.

    Scientists also found certain populations of fish-eating resident killer whales in southeast Alaska and Canada waters ate a lot more salmon. But the orcas that spend time in Puget Sound ate about the same volume they did 40 years ago, mostly because their numbers have been relatively constant.

    Puget Sound orcas, also known as southern resident killer whales, face greater challenges than their orca counterparts farther north because they have a narrower menu of fish stocks and fewer available fish compared with what they need, Kaplan said.

    These whales have struggled due to lack of food, pollution and impacts from boats since they were listed as endangered in Canada in 2003 and 2005 in the U.S. There are now just 76, down from a high of 140 decades ago.

    Marine mammal protection efforts including the Marine Mammal Protection Act in 1972 have meant good news for other populations. Harbor seals, for example, increased 210,000 to 355,000.

    Puget Sound orcas consume adult chinook salmon - also called king salmon because they're the largest - that migrate back to Puget Sound waters.

    "Every other one of those predators has a chance to eat that salmon before. They're the last ones to sit at the table and get a chance to eat," said Brandon Chasco, lead author of the study and an Oregon State University postdoctoral student.

    Meanwhile, harbour seals feast on millions of smaller, juvenile salmon as they migrate to the ocean from local rivers.

    "They're first in line to eat the prey before they become adults," Chasco said. "The question is whether those fish would have died in the ocean, or if they're taking prey out of the mouths of predators farther downstream."

    The authors say efforts to restore threatened salmon runs may be masked by the increasing numbers eaten by these marine mammals.

    The study was paid for by the Pacific Salmon Commission, which was formed by the governments of Canada and the United States in 1985.
     
  2. OldBlackDog

    OldBlackDog Well-Known Member

    We know that the seal population has grown dramatically, yet the greens don’t want to deal with this fact.

    They kill hundreds of thousands of salmon, science has shown this.

    The answer is obvious, cull the seals and sea lions and save the killer whales.

    This science must be brought to the table whenever they talk about saving the whales.
     
  3. Whole in the Water

    Whole in the Water Well-Known Member

    Couldn't agree more!
     
  4. agentaqua

    agentaqua Well-Known Member

    chromatose007 likes this.
  5. SpringVelocity

    SpringVelocity Well-Known Member

    ?? Greens aren't driving it. Its the NGO groups that dont want to deal with it. Our MLA isn't pushing a fishing closure.
     
  6. OldBlackDog

    OldBlackDog Well-Known Member

    NGOs?


     
  7. agentaqua

    agentaqua Well-Known Member

    Non-Governmental Organizations. E.g.: DSF, Watershed Watch, GSA, Pacific Marine Conservation Caucus, orca salmon alliance, orca watch, orca network, etc. The ones that show-up for these meetings, and submit to the consultation process, and get their views in the newspapers...
     
  8. OldBlackDog

    OldBlackDog Well-Known Member

    Yup, greens.

    Wonder how they will like it when they start killing seals to save whales?


     
  9. OldBlackDog

    OldBlackDog Well-Known Member

    Remember this when you discuss with people.



    Harbour seals, sea lions and some fish-eating killer whales have been rebounding along the Northeast Pacific Ocean in recent decades.

    But that boom has come with a trade-off: they're devouring more of the salmon prized by a unique but fragile population of endangered orcas.

    Competition with other marine mammals for the same food may be a bigger problem than fishing, at least in recent years, for southern resident killer whales that spend time in Washington state's Puget Sound, a new study suggests.

    Researchers used models to estimate that from 1975 to 2015, marine mammals along the U.S. West Coast ate dramatically more chinook salmon - from 6,100 metric tons to 15,200 metric tons, according to a study published Monday in the journal Scientific Reports.

    In the same period, salmon caught by commercial and recreational fishing from Northern California to Alaska declined from 16,400 to 9,600 metric tons.
     
  10. tigerprawn

    tigerprawn Member

    This is a must read on the pinniped problem up and down the coast.
    I know this is a repost but is a huge issue. This fall I counted over 30 sea lions at the mouth of sooke harbour and 10 years ago maybe 2 or 3.
    Time to push on this issue now before it’s to late

    https://assets.documentcloud.org/documents/4254787/Chasco-Et-Al.pdf
     
    Last edited: Nov 21, 2017
    tincan and littlechucky like this.
  11. littlechucky

    littlechucky Active Member

    Great piece. Thank you.
     
  12. fogged in

    fogged in Well-Known Member

    If I am reading the chart below correctly, it is not unprecedented for the Southern Resident Orca population to rise and fall.
    In 1976 the total of J K and L pod which make up the Southern Residence family was 71
    The number in 2017 was 76
    There have been several peaks and valleys in population during the years in between 1976 and 2017
    The most frequent reason for the recent decline in population is lack adequate numbers of Chinook Salmon
    Could these population gains and losses over the years be the sole result of the decline Chinook returns?
    https://www.whaleresearch.com/orca-population
    chart.gif
     
    Last edited: Dec 17, 2017
  13. wildmanyeah

    wildmanyeah Well-Known Member

    As I recall reading it’s not the total number they are concerned about but the amount of birthing females and also how many males are being born.

    Not sure the other peaks and valleys are related to food.
     
  14. tincan

    tincan Well-Known Member

    The other thing to note about this graph is that the starting point (1975 or so) was about the time we stopped capturing SRKW from the wild to place them in captivity. There were around 40-50 whales from the SRKW population that were captured in the previous decade or so. Either way, it is true that the SRKW population has gone up and down and it's not like the current population of 76 is the lowest ever or is alarmingly low in and of itself. As @wildmanyeah says the number of breeding females, males, etc are also important factors in ensuring they have sustainable populations. Andrew Trites gave a good summary of this a few weeks back. I think it's on youtube.



     
  15. wildmanyeah

    wildmanyeah Well-Known Member

    There is without a doubt pain coming the the Fraser and Columbia River fisheries....


    "The team compared their hormone data to records of Chinook salmon runs in the Columbia and Fraser rivers, the two most significant sources of Chinook in the southern residents’ natural range. They saw that large runs at those watersheds coincided with periods of lower nutritional stress in the orcas. But in years with poor runs at either site, signs of nutritional stress were higher. Boosting Columbia River and Fraser River salmon runs could help the killer whales recover, Wasser said."

    “As it stands now, the orca numbers just keep declining with no signs of recovery,” said Wasser. “We’re losing a valuable resource here.”

    http://www.washington.edu/news/2017...-nutritional-stress-and-low-salmon-abundance/
     
  16. wildmanyeah

    wildmanyeah Well-Known Member

    "Wilhelmson says immediate measures discussed by experts in attendance included closing chinook salmon fisheries, and reducing tanker traffic along the Salish Sea."

    "We don't know what the long term impacts of a [chinook fishery] closure will be, but we'll never know to what extent it will benefit the species unless we do it."

    "We all have to be courageous if we say we really value the species."

    http://www.cbc.ca/news/canada/british-columbia/bc-orca-symposium-1.4350859
     
  17. wildmanyeah

    wildmanyeah Well-Known Member

    The fish farm thread is a gift that just keeps on giving. Here is another example of the need to end the Chinook fishery in BC.

    "Curtail Chinook Fisheries

    Right off the top, let me say that I think it is not that far fetched that DFO will curtail the sport fishery for chinook on the grounds they feed orcas and there are not enough of them. Brian Riddell, PSF, may have a more informed opinion on this as he led a recent several-day meeting on orca issues."

    http://onfishingdcreid.blogspot.com/2017/11/laws-and-policies-to-do-with-pacific.html

    Thanks Megabite
     

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