Kotzebue Caribou decline 1976

[VernAK]

I have a huge stack of old Alaska magazines and the older Alaska Sportsman magazines that I peruse on these winter evenings. The November 1976 issue has a story regarding the caribou in the drainages of the Noatak, Kobuk and upper Koyukuk Rivers:

"Six years ago the Arctic Caribou Herd numbered about 240,000. Last April it appeared the herd had declined drastically to perhaps 100,000 animals, and at that time the board enacted token restrictions on hunting until ADFG could develop a more detailed census."

"After flying more than 400 hours and 40,000 air miles last spring five biologists involved have concluded that there are only about 50,000 caribou remaining in the herd."

more later

 

[Chumsnagger]

November 1976??, must have declined due to global cooling from that big hole in the ozone layer.

 

[arctichunting]

I have a huge stack of old Alaska magazines and the older Alaska Sportsman magazines that I peruse on these winter evenings. The November 1976 issue has a story regarding the caribou in the drainages of the Noatak, Kobuk and upper Koyukuk Rivers:

"Six years ago the Arctic Caribou Herd numbered about 240,000. Last April it appeared the herd had declined drastically to perhaps 100,000 animals, and at that time the board enacted token restrictions on hunting until ADFG could develop a more detailed census."

"After flying more than 400 hours and 40,000 air miles last spring five biologists involved have concluded that there are only about 50,000 caribou remaining in the herd."

more later

Mind taking a pic of that! I’d appreciate it


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[cubdriver84d]

Considering the recent decline, this is consistent with our general understanding that migratory caribou populations experience multi-decadal population cycles.

 

[VernAK]

Considering the recent decline, this is consistent with our general understanding that migratory caribou populations experience multi-decadal population cycles.

The more I study caribou herd fluctuations, the more it reminds me of snowshoe hare population changes.

 

[VernAK]

Hopefully this is legible.

 

[arctichunting]

Thanks Vern!


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[AKBC]

I notice the 1976 story you quoted uses the term "Arctic Caribou Herd" but we now recognize four of them. Makes me wonder if they were stating that the Western, Central, Teshekpuk, and Porcupine herds combined were 50,000 animals or if they were specifically referencing the Western herd.

 

[AKBC]

Notice the strong correlation between caribou population growth and increasing US CO2 emissions:



This is my reminder to be careful with "science".

 

[AKDoc]

Thanks for sharing the article with us Vern...it was an interesting read.

I'm sure I'm not alone saying this...Whenever I read herd numbers, I'm always reminding myself that the number I'm reading is an estimate based upon a specific methodology used to derive that estimate. It's certainly not an exact science. What always becomes interesting to me is the methodology used to reach an estimate. I'm curious the methodology used to derive the estimates in the 70's?.

In comparison to modern day herd estimates, it appears that ADFG uses the Rivest Population Estimation Method, which I read to be an inferential statistical analysis method using a small sample of radio-collared caribou and "photocensus". The Rivest method is described in the methodology section of the recently published paper below regarding an estimate of the Central Arctic Caribou Herd (CAH). I mention this to emphasize that even with modern day methodology, the statistical confidence range in the derived estimate is a broad numerical range. For example, in the recent article below they estimate the CAH to be around 50k, but the 95% confidence interval of that estimate is 50k +/- 10k. Thus, the true population size is statistically predicted to be somewhere between 40k to 60k...which is quite a range. BTW, I'm rounding those numbers.

caribou_2012_2022_unit_26b.pdf

Disclaimer: Wildlife biology is not my expertise, so I could be wrong in my interpretive assumptions of published methodologies. I also want to say that I greatly support the mission of the ADFG and its staff...some of which I know and are friends.

 

[actionshooter]

Very cool... just goes to show that history shouldn't be ignored

 

[VernAK]

Thanks for sharing the article with us Vern...it was an interesting read.

I'm sure I'm not alone saying this...Whenever I read herd numbers, I'm always reminding myself that the number I'm reading is an estimate based upon a specific methodology used to derive that estimate. It's certainly not an exact science. What always becomes interesting to me is the methodology used to reach an estimate. I'm curious the methodology used to derive the estimates in the 70's?.

In comparison to modern day herd estimates, it appears that ADFG uses the Rivest Population Estimation Method, which I read to be an inferential statistical analysis method using a small sample of radio-collared caribou and "photocensus". The Rivest method is described in the methodology section of the recently published paper below regarding an estimate of the Central Arctic Caribou Herd (CAH). I mention this to emphasize that even with modern day methodology, the statistical confidence range in the derived estimate is a broad numerical range. For example, in the recent article below they estimate the CAH to be around 50k, but the 95% confidence interval of that estimate is 50k +/- 10k. Thus, the true population size is statistically predicted to be somewhere between 40k to 60k...which is quite a range. BTW, I'm rounding those numbers.

caribou_2012_2022_unit_26b.pdf

Disclaimer: Wildlife biology is not my expertise, so I could be wrong in my interpretive assumptions of published methodologies. I also want to say that I greatly support the mission of the ADFG and its staff...some of which I know and are friends.

Doc,
You're certainly not wrong!

I've represented Delta on the 40 Mile Caribou Coalition for a couple decades and in that time, methods have improved dramatically. The use of GPS collars and digital aerial photography has improved the life of the biologists tremendously. Herd movement is now real-time and the biologist no longer has to cover a garage floor with black/white photos and spend weeks trying to identify caribou on the landscape.

Census methods are improving but I doubt if we'll ever see perfection. I put my trust in trend lines developed over multiple years.

As I read through some of these old magazines and books, I'm astounded as they tell of 500,000 caribou migrating through Isabel Pass or 300,000 migrating up the Delta River.

 

[AKDoc]

Doc,
You're certainly not wrong!

I've represented Delta on the 40 Mile Caribou Coalition for a couple decades and in that time, methods have improved dramatically. The use of GPS collars and digital aerial photography has improved the life of the biologists tremendously. Herd movement is now real-time and the biologist no longer has to cover a garage floor with black/white photos and spend weeks trying to identify caribou on the landscape.

Census methods are improving but I doubt if we'll ever see perfection. I put my trust in trend lines developed over multiple years.

As I read through some of these old magazines and books, I'm astounded as they tell of 500,000 caribou migrating through Isabel Pass or 300,000 migrating up the Delta River.

Well said Vern, and thank you for your many years of volunteer time you've devoted to Alaska wildlife management.

I'm aligned with you Vern. Your comment that census methodology has improved dramatically over the years, but will never be perfection is absolutely true...census perfection is not achievable nor should perfection be the goal IMO...greater predictive accuracy with doable labor output, yes. Also your interest in trend lines over the years...me too. Much more to say about that, but I'll stop there.

Again, thanks for sharing that interesting article from your personal reading archives...(said the one old man to the other ).