collapse

Author Topic: The CDFW methodology for North Coast abalone counts  (Read 5484 times)

Offline MATT MATTISON

  • Dreaming of the day abalone is re-opened
  • Administrator
  • Member
  • *
  • Posts: 8603
  • Diving My HAPPY PLACE
    • http://norcalunderwaterhunters.com/forum/MGalleryItem.php?id=1815
The CDFW methodology for North Coast abalone counts
« on: April 28, 2016, 07:13:33 AM »
 The California Department of Fish and Wildlife's methodology for North Coast abalone assessment and management.
North Coast Abalone Management (CDFW)


Marine Invertebrate Survey and Assessment Project
https://www.wildlife.ca.gov/Conservation/Marine/Invertebrates/Survey-Assessment-Project
CHECK OUT MY YOU TUBE CHANNEL AT:
https://www.youtube.com/user/mattmattison/videos

THANK YOU TO MY AWESOME SPONSORS

Offline Marco Mazza

  • Member
  • *
  • Posts: 123
Re: The CDFW methodology for North Coast abalone counts
« Reply #1 on: April 28, 2016, 12:51:53 PM »
Hello all,
It's been quite a while since I've posted in NCUWH, college and work have had me pretty tied up... plus i moved to socal for the time being ::)
but something about this post really stood out to me:

Skip to 4:10 of the video. They're only counting abalone one meter out from their survey line that "can be seen without the aid of a flashlight or turning over rocks. Therefore, emergence survey data typically does not include counts of very small abalone that occur deep in crevices and under boulders"

ANYONE SEE A PROBLEM WITH THIS^^^

They're literally not counting any abs in the holes and crevices, a good number of spots hold the majority of their abs in holes/crevices! Think about how many big tabletop rocks they're swimming over that are loaded with abs, only to count the one or two on top rather than the 10 or 12 beneath it.

Also, "small abs that occur deep in crevices or under boulders"... I'm sure any trophy ab diver will agree that some of their biggest abalone have come from within the deep holes and crevices.

"Dive surveys require a tremendous amount of planning, coordination, and organization. Survey participants are certified scientific divers trained in transit methods of species identification, and are well briefed to insure that the data collected is precise."
BUT YOU DONT LOOK UNDER ROCKS

Please tell me its not just myself who sees a problem with this type of survey method.

That being said, I do have to say that I appreciate the time and effort of the DFW and the divers included in trying to help manage our abalone fishery off the Northern California coast.

Offline MATT MATTISON

  • Dreaming of the day abalone is re-opened
  • Administrator
  • Member
  • *
  • Posts: 8603
  • Diving My HAPPY PLACE
    • http://norcalunderwaterhunters.com/forum/MGalleryItem.php?id=1815
Re: The CDFW methodology for North Coast abalone counts
« Reply #2 on: April 28, 2016, 01:00:49 PM »
I have been saying this for years Marko, but I was told these are to non intrusive, and when you start flipping over rocks looking in holes with lights it is now an intrusive survey. Someone please correct me if I am wrong, will not be the first time I would be wrong hahahaha
CHECK OUT MY YOU TUBE CHANNEL AT:
https://www.youtube.com/user/mattmattison/videos

THANK YOU TO MY AWESOME SPONSORS

Offline Marco Mazza

  • Member
  • *
  • Posts: 123
Re: The CDFW methodology for North Coast abalone counts
« Reply #3 on: April 28, 2016, 01:32:07 PM »
I definitely understand that! But looking into holes being intrusive? I can definitely understand flipping over rocks and hurting fragile marine life, but a flashlight is so minor I would not call that intrusive!

Offline Duckfoot

  • Member
  • *
  • Posts: 988
    • Jack Shaw Sculpture
Re: The CDFW methodology for North Coast abalone counts
« Reply #4 on: April 28, 2016, 01:44:10 PM »
I don't know to what degree this has been tested, but apparently, and this surprises me, there isn't a huge difference in results with or without flashlights. For one thing, divers are on SCUBA so bottom time is a different issue. And when on SCUBA your eyes have time to adjust to the darkness.  It is interesting that PISCO uses lights and DFW doesn't but lighting isn't the larger problem. DFG transects are sometimes placed where you won't find abs and that data is incorporated into the survey results anyway. Apparently the department is working on that.
If you want to build a ship, don't drum up people to collect wood and don't assign them tasks and work, but rather teach them to long for the endless immensity of the sea.  –Antoine de Saint-Exupéry

Offline Chaw III

  • Member
  • *
  • Posts: 22
Re: The CDFW methodology for North Coast abalone counts
« Reply #5 on: April 28, 2016, 02:09:38 PM »
I've wondered the same thing about them not looking in the cracks. At the 6:30 mark they do mention that they do sometimes conduct invasive surveys where they'll look in all the nooks and crannies. They probably get a ratio by conducting the two types of surveys in the same location, the compare the numbers. So later they can just count the easy ones, then do the math in order to try to make an inference of the total numbers of abs. If this were the case it would seem pretty unreliable though. I've dove places without a cave for an abalone to hide, but other locations I would have only seen one out of the 60-70 abs that day without a light.

These are all just my guesses though. I'm only two semesters in my marine fisheries major, I'll get back with a definite answer in a couple of years.

Offline Joshua R.

  • Member
  • *
  • Posts: 2581
Re: The CDFW methodology for North Coast abalone counts
« Reply #6 on: April 28, 2016, 02:22:52 PM »
These methods and how the data is used will be revised during the FMP process. 

Offline lazyhook

  • Member
  • *
  • Posts: 128
Re: The CDFW methodology for North Coast abalone counts
« Reply #7 on: April 28, 2016, 05:19:03 PM »
I don't know that a precise count of every single animal is necessarily the goal.  I would think the more important issue is the general trend.

If a particular transect area has a certain number of abalone that are visible without turning over rocks or looking in deep holes, then that might be it's "normal" condition for a baseline.  As long as all the subsequent transects in that area use the same general method, then any potential trends can be noted.

My bigger fear over the current transect method is that the baseline assumptions for healthy or "normal" densities may have been set too high in some cases.  Then, even if follow-on surveys show a "normal" density, that false comparison or trend can cause all the alarms.

Just as I don't pay attention to what one person thinks they remember about the kelp density 3 years ago in August vs. what they see this year at the beginning April.  Their baseline comparison is off.

Offline moon

  • Member
  • *
  • Posts: 21
Re: The CDFW methodology for North Coast abalone counts
« Reply #8 on: May 07, 2016, 06:54:32 AM »
I think Lazyhook has it right, and before making assumptions one needs to go to the website given in the video and read the complete report, if it's like any other report it's dry, complicated  and probably boring. I would not criticize nor praise methodology based on a promotional video aimed at the general population.
I used to do research dives in college some were good, and some  were way off.

Sent from my SCH-I545 using Tapatalk

moon

 

noob spearo podcast

THE SPEAR Spearfishing Podcast

Support the NCUWH Website

Help support the NorCal Underwater Hunters Website by donating today.

Your decision to contribute is strictly voluntary. If you see value in this website: meeting new dive buddies, posting dive reports, a place to post your pictures, sharing great fish stories, plan out of town hunting trips, etc..., then please contribute. All proceeds go towards supporting the costs to host and maintain this awesome website.

If you prefer to send a check or money order, please PM me, MATT MATTISON, for the address.

Thanks!
Matt