Sonar-style cod study gains State House Support

[Bottom-Dweller]

http://www.gloucestertimes.com/fishi...-House-support

[CaptainAlex]

Time for a seal season:

http://boatinglocal.com/news/seals-b...-recovery.html

[amarshall]

Time for a seal season:

http://boatinglocal.com/news/seals-b...-recovery.html

[aloop]

Attachment 211700

Many Warranties voided that day!

[LadyB]

I don't know how you can club one of those things let alone when it is looking right at you !

[bobbysea]

Getting back to using sonar for cod surveys, what the hell were they looking at on the ff in order to make a set? In fairness, were they using some prevously used locations were they had caught before to keep the study honest? Why would you need to appropriate more funds to do a sonar survey, when you can make a set on what your seeing in the sonar? I'm confused as hell. Can somebody square me away?

[Bottom-Dweller]

I believe the purpose of researching / investing in this new sonar technology is to augment the trawl method in order to more accurately calculate cod biomass. As you may know it is difficult to discriminate bottom fish species from a sonar readout. Imagine if this new sonar could be tweaked enough to discriminate cod from haddock or sand shark. The trawl would still be required to get samples for age, weight & health of the fish, but this sonar method would cover significantly more area than any trawl could ever accomplish.

Of course, NOAA wants nothing to do with it, they prefer doing their fuzzy math based solely on the limitations of their trawl surveys. At least Massachusetts is taking the lead and with any luck they will be successful in proving the technology. Personally I applaud Massachusetts for stepping up to the plate, this is money well spent!

If Mass proves the technology, then it becomes political, NOAA will be forced into looking at the technology and perhaps they can lay off a few statisticians.

[twofinbluna]

I believe the purpose of researching / investing in this new sonar technology is to augment the trawl method in order to more accurately calculate cod biomass. As you may know it is difficult to discriminate bottom fish species from a sonar readout. Imagine if this new sonar could be tweaked enough to discriminate cod from haddock or sand shark. The trawl would still be required to get samples for age, weight & health of the fish, but this sonar method would cover significantly more area than any trawl could ever accomplish...

BD- They are a LONG ways from ever being able to use sonar to tell the difference between a cod and a haddock on a sonar. The same goes for differentiating just about any species. Take herring for example- even the most trained eye will never be able to look at something on a sonar and tell you for sure if it is herring, mackerel, turd pollock, or even krill or something like that.

The only way you can use sonar to assess correctly is to do a whole lot of sampling while you are surveying with the sonar. The same boat that is using the sonar will have trawl gear and will sample whatever it is they are seeing to know for sure what it is. The bottom line is you would not want them trying to assess using sonar without heavy sampling because it can really skew the results. If you are hoping for a better cod assessment that will show more cod than what the basic survey is showing, what if they are seeing cod but they do not think that is what it is? Or what if during the herring survey (which they already do) they are in an area with a ton of krill and they assume it is herring? Then the assessment swings the other way and shows too much of something than is actually there. There have been examples in the past of people trying to do sonar studies and not sampling enough and it has led to some seriously bad data, as you can imagine.

I would have to assume that any future sonar surveys that may spring up (including the one MA wants to have happen) would have a lot of sampling built in. If not it would be troubling. Like I said, you do not want any technicians/researchers on those boats trying to look at a sonar read out and be guessing what they are seeing. And you will still want those normal trawl surveys too since it is good to have multiple sources of data.

[twofinbluna]

Meant to add that they actually do an acoustic survey already for herring as a compliment to the trawl surveys and other indices. It is an offshore survey, but they cover a decent amount of what some would call inshore. (There are also some studies in the works to do more of an inshore survey.) Some people blame the over-optimistic assessments that brought in the pair trawlers on those older surveys. Either way they realized a while ago that sampling effectively is important. To be honest, I am not convinced they do enough even now but my guess is it is a lot better now than it used to be.

The bottom line is that any additional data that you can get is good and can help give you a better idea of what is out there. But make sure whenever you support something like this you make clear that you want to see a lot of sampling!

[Bottom-Dweller]

Twofin, I completely agree with what you are saying, I don’t think the sonar is going to be an easy challenge and trawl sampling will always be a must. I think this sonar method is kind of like taking a census of the human population using satellites and then breaking the data down into ethnicity, seemingly an impossible task! But you have to start somewhere in order to create a check and balance and not rely solely on the trawl because it has been proven to be ineffective and open to interpretation. Something is needed to augment the trawl and this is a step in the right direction.

Definition of Insanity: Doing the same thing over and over again and expecting different results.