Fall Alaska king crab harvest canceled

[Metlakatla]

NOAA just released a report that confirms that the main reason for the snow crab decline in the Bering is climate change (they starved).

https://www.fisheries.noaa.gov/featu...2FChris%20Long.

[Northrick]

It was definitely hot in Alaska in 2018. And, it is obvious to see how that would warm ocean water near the surface. But warm water is less dense than cold water (except around freezing) so one would think the water warmed by unusually high air temperatures would stay near the top of the water column. Crab live on the bottom, hundreds of feet down and I would think water temps down there would be resistant to change.


It would be nice if an article included some more pertinent data. In other words, sea water temperatures at 600ft, where the crab live, was an average of X degrees before 2018 and was an average of Y degrees between 2018 and 2021. Most of what I see is sea surface temperatures. That's not where crab live.

[Metlakatla]

Originally Posted by Northrick

It was definitely hot in Alaska in 2018. And, it is obvious to see how that would warm ocean water near the surface. But warm water is less dense than cold water (except around freezing) so one would think the water warmed by unusually high air temperatures would stay near the top of the water column. Crab live on the bottom, hundreds of feet down and I would think water temps down there would be resistant to change.


It would be nice if an article included some more pertinent data. In other words, sea water temperatures at 600ft, where the crab live, was an average of X degrees before 2018 and was an average of Y degrees between 2018 and 2021. Most of what I see is sea surface temperatures. That's not where crab live.

I really don't think the fisheries scientists at NOAA are that dumb.

I didn't see anything in the NOAA article that mentioned surface temperatures.

On the other hand, NOAA takes the temperature of the water on the seafloor every year during something called a bottom trawl survey, and that's where they got their temperature data.

[HodgePodge]

Originally Posted by Northrick

It was definitely hot in Alaska in 2018. And, it is obvious to see how that would warm ocean water near the surface. But warm water is less dense than cold water (except around freezing) so one would think the water warmed by unusually high air temperatures would stay near the top of the water column. Crab live on the bottom, hundreds of feet down and I would think water temps down there would be resistant to change.


It would be nice if an article included some more pertinent data. In other words, sea water temperatures at 600ft, where the crab live, was an average of X degrees before 2018 and was an average of Y degrees between 2018 and 2021. Most of what I see is sea surface temperatures. That's not where crab live.

I'm sure the change in temperatures is like a cascade effect. A chain reaction in the food chain that eventually works it's way to the crab. Think about the intricacy of the food chain from photoplanton to zooplanton... etc. The little fish who dine on them, etc etc.

Whether it be destroying the prey that the crab rely on... or the temps moving them somewhere else.

Though I doubt it's just temps that are destroying the crab. Overfishing, habitat destruction and higher temps combine to drastically damage the fishery.

[Metlakatla]

During the marine heatwave, something called the "cold pool" — where juvenile snow crab (and other bottom-dwelling species) live — disappeared on the seafloor. The cold pool is formed every year as the sea ice melts. Data collected by the bottom trawl surveys mentioned by NOAA includes seafloor temperatures, degree of salinity, and the area covered by that year's cold pool.

NOAA's marine scientists are pretty good at what they do.

[Northrick]

Originally Posted by Metlakatla

I really don't think the fisheries scientists at NOAA are that dumb.

I didn't see anything in the NOAA article that mentioned surface temperatures.

On the other hand, NOAA takes the temperature of the water on the seafloor every year during something called a bottom trawl survey, and that's where they got their temperature data.

I wasn't trying to say the scientists don't know what they are doing. Not at all. What I was trying to say is that I wish articles on these investigations included more specific information.

[Metlakatla]

I think NOAA's most recent article did a pretty good job, but it's basically only an outline of a study that's many pages long, as it's meant to be.

Originally Posted by Northrick

It would be nice if an article included some more pertinent data. In other words, sea water temperatures at 600ft, where the crab live, was an average of X degrees before 2018 and was an average of Y degrees between 2018 and 2021. Most of what I see is sea surface temperatures. That's not where crab live.

Here's where it explained how they got their temperature data:

NOAA Fisheries scientists have observed ocean temperatures over the 40-year history of their annual bottom trawl survey of the eastern Bering Sea.

Btw, juvenile snow crab populations were at record levels just several years ago.