Orcas Running Out of Food

cabezon

Sculpin Enterprises
#31
There is increasing evidence: genetic, ecological, and morphological that there are clear distinctions among populations of killer whales that may indicate the evolution of unique population, or subspecies, or even distinctive species (see http://www.nmfs.noaa.gov/pr/species/mammals/whales/killer-whale.html) around the world. In some cases, the degree of divergence has led some scientists to propose that distinctive populations deserve recognition as unique species (see https://www.sciencenews.org/blog/deleted-scenes/one-ocean-four-or-more-killer-whale-species). And there are regions where distinctive foraging habits may be leading to future speciation (see http://www.sciencemag.org/news/2013/08/north-atlantic-killer-whales-may-be-branching-two-species).

Locally, we have transient killer whales that feed on marine mammals and resident killer whales that feed on salmon, especially chinook salmon. Transients do not switch to salmon just because salmon are abundant in the summer, not will residents switch to marine mammals just because salmon populations are tanking. Transients killer whales travel in small groups and vocalize less when hunting while residents form large social groups and actively vocalize while cooperatively hunting salmon.

These southern resident killer whales are distinctive in several ways from both transient killer whales and other populations of fish-eating resident killer whales to the north. Their numbers are much reduced, especially after exploitation for marine parks in the 1960s. Their numbers have not rebounded after capture for marine parks was outlawed. They face multiple threats including lethal and sublethal impacts of hazardous chemicals that they bioaccumulate from their food, interference in feeding and social behavior by whale-watching, and a decline in their preferred food. As a result, the southern resident killer whales are on the endangered species list.

These resident killer whales support a valuable whale-watching industry and are part of the fabric of what makes life in the Pacific Northwest special. Our lives would be poorer if we no longer could experience a pod of resident killer whales ranging from the San Juans to the Nisqually delta following schools of salmon in the summer and fall. This reduction in quality of life can be translated into monetary value.

Steve
 
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cabezon

Sculpin Enterprises
#32
At the same time, Balcomb, as is his want, is making an advocates' argument in his King 5 interview (http://www.king5.com/article/tech/s...es-that-are-running-out-of-food/281-506640529), ignoring evidence that does not fit his narrative. For example, he makes big deal that there are less than 30 (out of 76 individuals in the southern resident killer whale population) individuals capable of reproduction. At an absolute level, having only 30 reproducing individuals is of concern; the implication is that this is too close to zero = extinction. [And the complications that result from inbreeding and limited genetic diversity raise their head -> extinction vortex (https://conservationbytes.com/2008/08/25/the-extinction-vortex/)].

But to have less than half of any population as non-reproducing is not unusual (with one semi-unique wrinkle for killer whales). These 46+ non-reproducing individuals include a) menopausal females, b) sexually-immature individuals, and c) males.

Killer whales are one of the few species where older females enter menopause and cease reproduction; a few of the 46 non-reproducing individuals would appear to be females in this age group. A hypothesis to explain the presence of menopausal females is they provide aid through their accumulated experience that increases the reproductive success of their daughters that remain in their natal pods.

Some of those 46 non-reproductive individuals are juveniles who are not yet sexually mature; they have the potential to reproduce in the future. Just about all long-lived species will have a block of immature individuals [Dwarf surf perch are an exception; the males are ready to rock at birth....]. The presence of large percentage of immature individuals in a population may indicate that a population is ready to increase rapidly once these individuals mature (demographic lag). Or it could indicate that there are environmental challenges that lead to high mortality as individuals transition into sexual maturity. While the Center for Whale Research has high quality data on birth, deaths, and age for individuals among the three pods of southern resident killer whales (see https://simplebooklet.com/publish.php?wpKey=HiPDDCYGTuXh2pyNPxHwB6#page=0), I have not seen a technical life-history analysis that identifies where the demographic bottlenecks lie in this population (but I have not looked very hard for one because I do not have access to this literature).

Finally, because male killer whales do not appear to make a major contribution to raising juvenile killer whales and one male can fertilize many females, males, beyond a minimum, are not considered as individuals that determine the future growth of the population. Males are likely to form the majority 46 non-reproductive individuals; most species have a 50:50 sex ratio. Therefore, in calculating the reproductive potential of a population, males are typically ignored and the key value is the number of reproductive females. [Phalaropes, a group of three species of shorebirds, are the exception that proves the rule. The males incubate the eggs and raise the chicks; females mate with multiple males sequentially during the breeding season (see https://en.wikipedia.org/wiki/Phalarope). If one were quantifying population growth in phalaropes, the number of males would be the key variable, not the number of females beyond a minimum number]

Steve
 
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jwg

Active Member
#33
This thread has focused on the Orcas.
And seals have been mentioned.
And the title mentions food.

Regarding the last two, new research clarifies that seals do not exist entirely, or even primarily on salmon, their diet is much more varied.

https://www.hakaimagazine.com/news/behind-the-blubber/

So before some one says to cull the seals so that the salmon are saved, and available to resident killer whales ( and man), thought I would get that knowledge posted.

J

"
Preliminary DNA tests of the scat samples show that salmon represent just 2.5 percent of the diet of non-estuary seals in springtime; while gadids, such as hake and walleye, make up 61 percent; and forage fish, mainly herring, comprise 24 percent.

In the fall, those numbers change, with the proportion of salmon (mostly chum) rising to 10 percent, while gadids drop to 42 percent, and forage fish hold steady at 23 percent.

These findings suggest that one cannot simply extrapolate the diet of estuary seals across the greater seal population in the Strait of Georgia.

Scat samples of estuary seals in spring showed their diets comprised of three percent salmon, 46 percent gadids, and 38 percent forage fish.

In the fall, estuary-dwelling harbor seals’ salmon consumption does soar, rising to 35 percent. But even here, it was predominately chum salmon, with only a small proportion of chinook and coho.
 

cabezon

Sculpin Enterprises
#34
Finally, I do not understand Balcomb's focus on the Snake River dams if one is interested in the survival of the southern resident killer whales. Yes, removing those dams will open up a large area of habit for salmon populations that are part of the Columbia River system. This may increase these Columbia River populations (though all those hungry sea lions at Bonneville might eat any surplus). But when would the southern resident killer whales profit from these salmon? From summer to late fall, these killer whales range through the Salish Sea, from the mid-Strait of Juan de Fuca, Gulf Islands, San Juan Islands, and to Southern Puget Sound. It is my understanding that Columbia River salmon do not enter the Salish Sea, except perhaps for a look-in by Neah Bay. So, for most of the year, the range of these salmon and the whales do not overlap. How would increasing Snake River / Columbia salmon populations feed southern resident killer whales?

The $64,000 question is where do the resident killer whales go in the winter, what do they do, and how important is this time period for their overall survival and reproduction. In winter, they have been observed as far south as Central California and as far north as the Queen Charlottes (Haida Gwai). NOAA is slowly learning more about their movements in winter via satellite tracking (see https://www.nwfsc.noaa.gov/research/divisions/cb/ecosystem/marinemammal/satellite_tagging/index.cfm), but observing what they are doing and what they are eating is a huge challenge in winter (see https://www.nwfsc.noaa.gov/news/blogs/display_blogentry.cfm?blogid=5).

So, let's assume that resident killer whales are feeding salmon when they are not in the Salish Sea. Where are those Columbia River salmon that Balcolm wants them to eat? They are farther north in Southeast Alaska and the Alaskan gyre. Again, no overlap between predator and potential prey.

So, while there are ecological arguments for removing the Snake River dams, helping resident killer whale populations seems like a long shot. If I had studied these whales all my life and were concerned that a major threat is a lack of food, I would be focused on the challenges impacting known sources of food: chinook (and chum salmon) from the Fraser River, the S Rivers, the Puyallup River, and the Nisqually River. I would be advocating for reducing the commercial and recreational catch in Southeast Alaska, British Columbia, and off the Washington coast that intercept returning salmon before they are available to resident killer whales. I would be advocating for improving habitat and restoring the important estuarine transition areas for chinook smolts. I would be advocating for reduction in the release of pollutants that may impact the survival and reproduction of killer whales. His focus on the Snake River dams is curious, to say the least.

Steve
 
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mbowers

Active Member
#37
I don't think we know if all killer whales can eat seal meat. Just like humans can have a severe fish or peanut allergy that means starving is better than eating fish, it's conceivable that the fish eating orcas could have a mammal meat allergy and therefore really can not eat seal..

Sent from my Moto Z2 Play using Tapatalk
 

Salmo_g

Well-Known Member
#38
I think concerns about saving southern resident orcas from starvation due to lack of salmon is little more than hand wringing. It's fairly well established that unlike the transients, the southern residents are fish eaters that cannot or will not adapt to a different diet. And despite Representative Blake's lame attempt to boost hatchery salmon production (Blake exists in the hip pocket of lower Columbia River, Willapa Bay, and Grays Harbor gillnetters) to feed the orcas comes at a time when the WA Legislature has been repeatedly and systematically cutting the General Fund appropriation to WDFW for over a decade. Hatchery salmon production in Puget Sound probably helped feed resident orcas, but that production has been significantly reduced, partly in the effort to recovery wild Chinook salmon production - that hasn't, isn't, and won't work, at least not well enough to nourish killer whales.

The story that isn't being told is that the southern residents may have already dropped below the threshold of long term survival, let alone any recovery. Given that PS Chinook are not going to recover (yeah I know the official policy is that recovery is an achievable goal) and hatchery salmon production is not going to be increased in the kind of way that would be necessary to maintain a healthy orca population, and that our society is more about high quality lip service than it is about making the very real sacrifices that would be necessary to secure survival and or recovery, then accepting the extinction of the southern residents in the coming decades is the most likely and realistic option. At some point people are going to catch on to the notion that trashing the environment has consequences. Of course it won't matter then because it will be too late. Oh, is that an extinction level meteor that's about to hit us?
 

cabezon

Sculpin Enterprises
#39
The story that isn't being told is that the southern residents may have already dropped below the threshold of long term survival, let alone any recovery. Given that PS Chinook are not going to recover (yeah I know the official policy is that recovery is an achievable goal) and hatchery salmon production is not going to be increased in the kind of way that would be necessary to maintain a healthy orca population, and that our society is more about high quality lip service than it is about making the very real sacrifices that would be necessary to secure survival and or recovery, then accepting the extinction of the southern residents in the coming decades is the most likely and realistic option. At some point people are going to catch on to the notion that trashing the environment has consequences. Of course it won't matter then because it will be too late. Oh, is that an extinction level meteor that's about to hit us?
Sadly, this is likely true. But the law can be a powerful lever to turn government lip service into action (see McCleary suite). If food is truly in short supply, this killer whale population is at risk of extinction because the salmon that they require are being commercially and recreational harvested. Will some conservation group, like the Center for Whale Research, sue the Federal Government for not using all the power available under the Endangered Species Act? If I were a whale advocate, I would argue in court that the feds should to stop ALL interception of Puget Sound chinook: off SE Alaska. and off Washington. And the same pressure could be applied in Canada via their analogous laws as the Southern Resident Killer Whales range into Canadian waters too (see http://www.sararegistry.gc.ca/document/default_e.cfm?documentID=1341). And one could even press for renegotiation of the Pacific Salmon Treaty (see http://www.psc.org/about-us/history-purpose/pacific-salmon-treaty/) between the U.S. and the Canadian governments to reduce / end the interception of these salmon off the west coast of Vancouver Island before the killer whales have an opportunity for lunch.

Steve
 
#40
Just wanted to thank @cabezon for his extremely informative posts here and elsewhere on this site.

Your ability to present unbiased, factual information in a manner that even a simple minded individual like my self can follow and understand is a rare gift that I at least appreciate greatly. Your posts also avoid going down the political road which is just as great.

So thank you very much sir!
 
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Klickrolf

Active Member
#41
I refuse to buy into any of this. If some populations of killer whales have decided to reside in Puget Sound and become salmon only feeders then they've made a mistake. They've become dependent on something that is not dependable and never has been dependable. Populations of this and that fail regularly in nature and either adapt or are replaced with something more adaptable. I think you guys are wanting to make PS Orcas something special while they are demonstrating they are dependents and therefore not special at all. It's all about survival and if they cannot adapt they will certainly become extinct.
 

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