Blue crab population said to fall again

[BILL H]

NOAA report presented in today's Baltimore Sun gives more bad news, or at least confirms the bad news that we already knew. Notes that winter dredge survey is reported to be 90% accurate (whatever that means statistically).

[paxfish]

It means a whole lot. The WDS has accurately predicted the harvest for nearly 20 years.

When they made the new regs in May, they used the preliminary findings. Now they are published, and it was as bad as they thought. 120 million crabs. Something like 220 million is considered to be the minimum for a healthy stock. And there were over 400 million in the 1990 survey. A fairly steady decline since then (with a few good years and lots of bad years.)

Hopefully, this winter's WDS shows improvement with the new regs.

[BILL H]

It means a whole lot. The WDS has accurately predicted the harvest for nearly 20 years.

When they made the new regs in May, they used the preliminary findings. Now they are published, and it was as bad as they thought. 120 million crabs. Something like 220 million is considered to be the minimum for a healthy stock. And there were over 400 million in the 1990 survey. A fairly steady decline since then (with a few good years and lots of bad years.)

Hopefully, this winter's WDS shows improvement with the new regs.

Pax, although I believe the WDS is an excellent tool, and uses a robust statistical approach, a statement like "90% accurate" means nothing in statistical terms. There is more information that is needed. Something like "the methodology should estimate the population within plus or minus 5%, 90% of the time (substitute correct number for the 5%)". If the number is 50% instead of 5%, then it is not a very good methodology.

Newspapers, and newspaper reporters, are not generally renowned for their statistical sophistication, so I am 90% (plus or minus 3%) sure that the fault is in the reporting, not in the WDS.

[Scott McGuire]

BillH,

The winter dredge survey has been used as a tool to predict the following years harvest. I don't think it was intended to be used as a predictor, but since it has matured it has gotten within 10% of the harvest of the following year's harvest. I think this is what they mean by 90% accurate. I'm not defending their choice of words, but I'm sure it was just an effort to make it easier to understand for the average fisherman/crabber.

[BILL H]

Thanks Crow,
Just feeling a bit "crabby" this morning.

[Scott McGuire]

slough it off man...

[paxfish]

Gotcha Bill. I concur.

I read too much into your "whatever that means" statement.

[crabby and son]

I'm sure that with the new restrictions that this winter's survey will be better. How much?....not too much I'm afraid. They waited too long to do something and what they did isn't much. but it is a step in the right direction. It didn't get bad in one year and it won't get better in one year. Gary

[paxfish]

They are pretty resilient - I am hopeful (hope is not a plan, I know). Remember, at 200 million total population, the wise men claim we can take 46% and stay at that level. Remarkably prolific, them crabs. So they are cutting to something like 37% with the new regs.

And, the harvest in October and November has been millions of migrating females. All pregnant. They will be protected in most of October and all of November. And no dredging of females down in Virginny.

We shall see. We must remain vigilant that the new regs don't get overturned. I know there's at least one lawsuit in Virginia disputing the new regs....

We shall see.

[ohbeone]

Like Lynn said during one of the meetings and I'll quote her, "They're like cockroaches."