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Author Topic: It's time to stop tinkering and just ban crabbing for one year  (Read 32017 times)
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« Reply #120 on: May 24, 2014, 07:50:26 PM »

thbub61 you are so right. Recreational crabbers do not have to report there catch day in and day out. Multiply that by the chesapeake witch is about 200 miles long and about 20 to 30 miles wide and that is what is draining the bay way down. there is alot of 16 ft. boats during the week and many on the weekend taking bushels of crabs from the bay without being reported. Not so much the chesapeake but also the wye river chester river and also all the tributaries. Recreational crabbers must report there catch somehow when they come in from crabbing. Hopefully a solutation can be worked out to tell how many crabs are coming out of the maryland and virginia waters.
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« Reply #121 on: May 24, 2014, 08:09:07 PM »

the winter dredge survey is a joke, has anyone read the methodology?  The pull the dredge at 1500 random spots in the bay, for 1 minute, at 3 knts, multiply the size of the dredge by how far they pulled it, then average all the numbers, and multiply that by how many sq meters are in the bay...and then they check so see if it's a cold winter, or mild winter, and MAKE UP a number for winter mortality.  I believe this year is was 30%. 

The first problem with this is a dredge is not going to catch 100% of the crabs that it goes over, especially small crabs, or on hard botom.  Then just make up a mortality number??? That survey can be manipulated to say anything they want it to say.
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« Reply #122 on: May 26, 2014, 05:07:51 PM »

the winter dredge survey is a joke, has anyone read the methodology?  The pull the dredge at 1500 random spots in the bay, for 1 minute, at 3 knts, multiply the size of the dredge by how far they pulled it, then average all the numbers, and multiply that by how many sq meters are in the bay...and then they check so see if it's a cold winter, or mild winter, and MAKE UP a number for winter mortality.  I believe this year is was 30%. 

The first problem with this is a dredge is not going to catch 100% of the crabs that it goes over, especially small crabs, or on hard botom.  Then just make up a mortality number??? That survey can be manipulated to say anything they want it to say.

DUH!  It would be funny if it wasn't so sad....
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« Reply #123 on: May 26, 2014, 10:34:47 PM »

^^^^ pretty sure we got the hint the first 3 times ..
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« Reply #124 on: May 27, 2014, 06:32:24 AM »

Move the size limit up for all and you will see a difference no  2s and 3s just ones and Jumbos and your fishery would flourish. Also like Maryland no pots just long lining. Something has to be done where I live you can walk across pot bouyes they keep the smallest crabs in the early and complain when they can't catch crabs in the summer.

Go away. Roll Eyes
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« Reply #125 on: October 11, 2014, 05:22:48 PM »

This may not be news to any of you, but some put the decline at 65% over the last 15 years. But more telling is that the population of females dropped by a whopping 85% in just a ten year period. I am guessing the rock fish do not discriminate between gender when they feed on crab.

But the regulations do allow for more harvesting of females. I understand their logic for doing so, however it may have proved to be flawed.

Females only mate once in their lifetime. Remove a single sally and you prevent millions of eggs from being released.

So I suspect as the harvest yields dropped, the sally's fell under increasing pressure. But you guys are hands on, you may have a better sense if that really happened over a 15 or 20 year span. Personally I don't believe any females should be harvested with wild stock populations so low, not just in the Chesapeake, but the mid-Atlantic coast.

It is possible for pollution or disease to stratify effects by gender. And the migration of females in the Bay is different than males. I really think the drop in females is a telling clue.

Annotation: I checked on this, and the claim that females only produce eggs once is dated information that has been demonstrably refuted with crabs in captivity. Some have reported them producing sponges 3 or 4 times. -My bad!
« Last Edit: October 13, 2014, 10:11:41 PM by Jennifer » Logged

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« Reply #126 on: October 11, 2014, 08:05:52 PM »

Females have been regulated and restricted up and down the whole Bay.........And things have got worse...Do you really think more regs will make a difference?........Until the Water pollution is controlled and runoff is stopped and building along the Bay Shores is stopped there will be problems...
Why do crabs want to migrate in water filled with pollution and poisons of all kinds??....JMO...
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« Reply #127 on: October 11, 2014, 08:31:06 PM »

Just looked at some simple math on the data someone provided in an earlier post on harvest totals from 1990 to present. It provides a non-normal distribution (unnatural) that appears skewed. Also the variance is so large (a standard deviation of 200 million), that mathematical predictions don't give very much practical insight. The charts imply that there are assignable causes. Individual / Moving Range charts are robust enough for non-normal data evaluation, so I produced them for you all in this thread. Upper and Lower Control Limits (UCL, LCL) predict maximum and minimum expected values based on the variation observed. The average is shown on both charts. A moving range is simply the difference between each years catch, expressed as a positive value (absolute value). I'm not certain if the data is in millions of crabs or millions of pounds of crabs.

No points fell outside the expected limits. The chance of any one point falling below the average is 50%. The chance of two consecutive points below average is .50 x .50 or 25%. The chance of 7 consecutive points below average is less than 1%, and considered significant. So we see a run begin in 1998. By 2004 it is statistically significant on the chart, if not already realized by the industry. But it existed for 12 years. The probability of that happening due to chance alone is .5 to the 12th power, or .000244, or .02%. It shows up on the moving range chart as 11 points from 1999 to 2009 Something happened, called an assignable cause.  There was no data offered to correlate with the harvest amounts, or to test for statistical significance.

From the practical standpoint, the bay is too large, and too diverse to draw meaningful correlations even if the data were presented. And since the crabs migrate up and down the bay, the timing of data collection will affect the statistics. From the mathematical standpoint, the below average run skews the data. Normal practice is to remove it, add data for at least 30 data points, and recalculate the control limits and averages. Practically, since each data point is a whole year, thirty years covers too much time, too many natural changes, and too many anthropomorphic changes.

From what I see in just this simple data, the drop in catch this year is not excessive or to be unexpected. There is a 12.5% chance that next years harvest will also be below average. The problem seems more centered around heightened expectations from the winter count. A series of winter counts could be plotted in the same fashion, to show what is expected, and what is actually an instance with an assignable cause.  (and then evaluated for correlation with the actual harvest) As I see it, as long as the last winter count was within predictable ranges, this year's harvest is more of a perception problem than the performance of restocking efforts, or pollution control efforts, or such. I would so much like to see UMD data and their analysis.

Note, the 12 year run lowers the average and changes the calculated limits, so there was no reason to test the distribution of the points for comparison to probability (i.e. 2/3 of the points should be in the inner 1/3 of the chart, etc if the data points were normally distributed).
« Last Edit: October 13, 2014, 02:38:06 PM by Jennifer » Logged

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« Reply #128 on: October 11, 2014, 08:45:27 PM »

The problem with all that data is.......  Nobody knows how many bushels are harvested each year by Rec's.  Undecided
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« Reply #129 on: October 11, 2014, 10:20:17 PM »

I hear you. If all the pieces of the puzzle were available, I am certain the minds at the University of Maryland would be able to make sense of it all.

What ever data I come across, I try to listen to what the data is telling me, much like a waterman listens to nature at a cool crisp sunrise. Most people just hear the sounds, but some individuals know there is information in the color of the sunrise, the sound of the birds, or the sounds of bait fish jumping. I just wanted to share what I considered to be the information in that simple data set, that might not be so obvious to many.
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« Reply #130 on: October 12, 2014, 05:41:15 AM »

You can "Toss" all past Data out the window...DNR Don't even believe the past Data,unless of course it works to help themselves...Watermen have been afraid of Catch shares and limits for years now...So they Pumped their landing numbers up "Just In case" the State would start the Catch Share Program...Thats coming down the road in the near future...When the Crabbers have to send DNR a text message before they leave to go crabbing and another text to DNR when they plan to return to a specific dock at a time were DNR can meet them and check their catch numbers...Then DNR might get an idea of how low the catch shares need to be..........
If you check back a few years, Maryland talked Va. into banning Crab Dredging at the lower part of the Bay...This was going to make crabs abundant thoughout the whole Bay....Guess what?  It didn't help any..Instead it put hundreds or thousands of people out of work.....I don't know of any proof of any sook restrictions have helped....
DNR catch even control it's own Budget from year to year ......Do you really think they can save the CRABS??
....
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« Reply #131 on: October 13, 2014, 11:59:19 AM »

Personally, I believe in critical thinking. So please understand that I am not personally attacking you or any individual, but offering a perspective that might not be apparent or obvious.

There are some questionable ethics that have evolved from necessity in the industry, and in the marketing of crabs. Here you cite the falsification of official documents made by watermen due to fear (not necessity), but criticize the institution that is relying on that data in efforts to improve conditions. That is defensive posturing, presumably because you feel threatened.

What it takes to achieve positive results is an unknown. Any attempt, be it trial and error, or scientific based, or regulatory, will incur unequal costs on groups with disparity. It is those inequities that require cooperation at a minimum, and will most likely produce sacrifice.

Sacrifice is only justified in this issue, where current situations (including costs) are unsustainable. Current and future sacrifices must take into account past sacrifices and traditions.

This is but one meager opinion. And it is one of an outsider. My only bias is that of a love of the bay and all it can offer. Actually, I don't even eat crabs or most seafood for that matter.
« Last Edit: October 13, 2014, 12:21:07 PM by Jennifer » Logged

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« Reply #132 on: October 13, 2014, 02:10:46 PM »

Blue crabs are obviously an unlimited resource that will never run out no matter how many people harvest them. We should abolish commercial licensing and let the Chinese come in and harvest them too since they can never run out.
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« Reply #133 on: October 13, 2014, 03:38:39 PM »

If I were Queen of the Bay, and had to make choices based only on this data - which would be so obviously foolish - I would look at it in two different ways:

1. Reducing Variation. While attempting to have an effect on complex systems, variation is the foe. The more stable a complex system is, the better the chances are to measure the effectiveness of isolated and intentional changes.

In the chart, it is apparent that the low harvest years showed the least variations (from year to year), and were more stable. This might imply that those lower levels are more sustainable under the environmental conditions (weather) that existed at the time.

If harvest levels were capped to some algorithm of what is sustainable (based on environmental cues), then everyone would have their chance to catch, up until that limit were reached. That would eliminate the threat of individual catch quotas but it would be an annual repeating moratorium.

2. Climate Change. If we compare these harvest figures, to climate change reports, there is a striking coincidence. As Global warming and changing weather patters became noticeable reality, the harvest stayed below average. About 2008 the oceans were deemed to be acting as more of a "heat sink" than was previously calculated or predicted. On the chart, 2008 shows the beginning of an upward trend, followed by and end to the below average run. It suggests recovery and a lag time which would be logical.

The timing, direction, and duration of seasonal storms have great influence on whether crab eggs or crab larvae are blown from sea to shore where juveniles have a better chance for survival. So where some report storms "washing out" the bay bottom of grasses, in fact wind and sea currents can have a beneficial impact on wild stock populations. What I presume is that the winter count implied a high population, but a lack of bottom vegetation made that population vulnerable to predators. (that reasoning does not explain the drop being skewed by gender, but the harvest specifics of the preceding year might have)
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« Reply #134 on: October 13, 2014, 03:45:41 PM »

2. Climate Change. If we compare these harvest figures, to climate change reports, there is a striking coincidence. As Global warming and changing weather patters became noticeable reality, the harvest stayed below average. About 2008 the oceans were deemed to be acting as more of a "heat sink" than was previously calculated or predicted. On the chart, 2008 shows the beginning of an upward trend, followed by and end to the below average run. It suggests recovery and a lag time which would be logical.
laugh laugh laugh laugh laugh laugh laugh laugh laugh
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« Reply #135 on: October 13, 2014, 03:54:51 PM »

10 years of no ocean warming so it must be global warming!  laugh Roll Eyes
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« Reply #136 on: October 13, 2014, 04:19:53 PM »

It appears the chart applies a linear regression to force a single trend over the time period. One could equally apply a polynomial regression, which would not be flat (or add a year or two or subtract a year or two to the data set). I presume this data represents something scientists derive as an average ocean temperature. Obviously, an average of such a large mass, even tiny changes are drastic in consequence. While ocean depth, water density, and stratification all play major roles in your global data, we are talking about the bay here, not 25,000 feet of ocean waters spread across the globe.

What I was referring to was the storms generated by the global warming, and the impact of those storms on the bays crab population. Those storms are driven by the global information you reached for. It is obvious, even to a layperson, that modern storms during 99-08 routinely covered 1/2 to 2/3 of the continental US. They are obviously much larger, and the larger ones were more frequent. But scientists cannot adequately explain or model the shift that began about 2008. The best reasoning at the moment is that the oceans absorbed more heat than the models predicted. If they did, it is not understood why. Also it is just since that time that scientists discovered there is more non-liquid water than in all the oceans combined, locked up in rocks below the mantel. But that is the beauty of science. It always self-corrects and advances, unlike a political view.
« Last Edit: October 13, 2014, 04:29:35 PM by Jennifer » Logged

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« Reply #137 on: October 13, 2014, 04:26:40 PM »

Some people are just too smart to figure out Crabs, Not busting any balls here...But thats what my 85 year old great grandfather told me when i was about 12 years old....He also said the more these "Smart People" study crabs the more they find out they don't know much about the crabs...He never fathomed people making Hundreds of thousands of dollars a year studying crabs...
He worked on the Chesapeke Bay and it's rivers all his life and couldn't figure crabs and fish out...But he was able to admit he didn't know....


People with "Smarts" will never admit that!... Wink
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« Reply #138 on: October 13, 2014, 04:40:21 PM »

Jennifer is way above my pay grade.
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« Reply #139 on: October 13, 2014, 05:05:01 PM »

My father was head of Engineering over 9 manufacturing plants across the country. He loved talking to people on the Chesapeake; people probably very much like you described your Grandfather to be. Good people of good common sense. Engineering, after all, is the practical application of theory - it requires common sense.

I on the other hand only went with Dad fishing, so that he would take me water skiing afterwards. That was our little deal -lol. Personally, I think fishing with a hook is cruel to animals, but the overwhelming vast majority of people think far differently. But that is why I actually enjoyed when he went crabbing instead of fishing. At least in crabbing, you catch the prey alive, intact, and unstressed (not injured). I just stayed away when they cooked the catch, and declined to eat them, partially for that reason.

I (as you said both your Grandfather and those "smart people" you referred to, do), know very little about crabs. It is just in the last two months that I have been reading everything I can find on the subject. I am just relating what I have read to the conversations here, as best as can be expected.

What I found out today, from a nice gentleman from the University of Maryland, is that some of the contradictions in what I have read are due to the progression of knowledge. While you may keep a more pragmatic view of crab and remain justified in that view, I for one am glad to see knowledge progress. I am not particularly well educated in the formal sense; I am what is called intellectually curious. I simply find something that interests me, and learn as much as I can, to see if I can accomplish anything worthwhile, and make some contribution.  
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