This isn't "rec", but it is "boats.electronics".

I am wondering how the weight of a catch on a fishing trawler could be
measured while the vessel is at sea. I'm thinking that the weight of the
whole vessel might need to be taken into account as there will be variables
such as fuel, water, etc.

Anyone know how this would be done?

Maybe rather than weighing while in the hold it would be weighed in the net
before dumping into the hold?

Thanks,

Dave

I would think after a few trips you could tell pretty close just by looking
in the hold. You would get a pretty good feel for how full it has been in
the past and what it weighted out to at the dock.

Some winches have load gauges on them but that doesn't take trash fish
(which can be a lot) into account.

--
Glenn Ashmore

I'm building a 45' cutter in strip/composite. Watch my progress (or lack
there of) at: http://www.rutuonline.com
Shameless Commercial Division: http://www.spade-anchor-us.com

"Dave Baker" wrote in message
...
This isn't "rec", but it is "boats.electronics".

I am wondering how the weight of a catch on a fishing trawler could be
measured while the vessel is at sea. I'm thinking that the weight of the
whole vessel might need to be taken into account as there will be
variables
such as fuel, water, etc.

Anyone know how this would be done?

Maybe rather than weighing while in the hold it would be weighed in the
net
before dumping into the hold?

Thanks,

Dave

In article ,
Dave Baker wrote:

This isn't "rec", but it is "boats.electronics".

I am wondering how the weight of a catch on a fishing trawler could be
measured while the vessel is at sea. I'm thinking that the weight of the
whole vessel might need to be taken into account as there will be variables
such as fuel, water, etc.

Anyone know how this would be done?

Maybe rather than weighing while in the hold it would be weighed in the net
before dumping into the hold?

Thanks,

Dave

In the North Pacific, the fish is sorted by specie into totes and then
weighed with hanging scales before it goes down to the hold on some
boats. On others, the fish isn't weighed untill it is off loaded to a
tender, and then weighed in hopper scales, or brailers. Most skippers
have a good idea how much fish is in the hold just by looking. Some
of them can guestimate to within a few hundred pounds.

Bruce in alaska
--
add a 2 before @

On 2005-11-24, Dave Baker wrote:
This isn't "rec", but it is "boats.electronics".

Maybe rather than weighing while in the hold it would be weighed in the net
before dumping into the hold?

I don't think so. they don't keep everything they net.

--

Bye.
Jasen

Hi:
Finally a topic that I can legitimately declare that I am an expert.

As an ex NMFS Fisheries Observer I spent several years in the 1980s and
early 90s calculating species composition, total catch weight, and a
bunch of other stuff on a variety of vessels and fisheries along the
west coast, North Pacific, and Bering Sea. I was basically a sea going
fish accountant.

So to answer your question ya gotta consider a few conditions:

Length of Vessel
Type of gear used (Longline, pot, midwater, drag, gillnet, purse,
trawl, troll, surimi MS etc...
Target species (salmon, pollock, Cod, hake, crab)

So how do you estimate catch size? Depends on a lot of factors. Are you
talking about 100 MT midwater bag of pollock sitting on the trawl deck
of a 360' factory trawler (F/T) bouncing around the Bering Sea on a
typical January day with 50 k wind and 30' seas or a 38 pound king
salmon getting landed on a sweet little 32' double ended salmon
troller built in 1932 and planked with Port Orford Cedar?

Chris

On 30 Nov 2005 09:29:26 -0800, wrote:

Hi:
Finally a topic that I can legitimately declare that I am an expert.

As an ex NMFS Fisheries Observer I spent several years in the 1980s and
early 90s calculating species composition, total catch weight, and a
bunch of other stuff on a variety of vessels and fisheries along the
west coast, North Pacific, and Bering Sea. I was basically a sea going
fish accountant.

So to answer your question ya gotta consider a few conditions:

Length of Vessel
Type of gear used (Longline, pot, midwater, drag, gillnet, purse,
trawl, troll, surimi MS etc...
Target species (salmon, pollock, Cod, hake, crab)

So how do you estimate catch size? Depends on a lot of factors. Are you
talking about 100 MT midwater bag of pollock sitting on the trawl deck
of a 360' factory trawler (F/T) bouncing around the Bering Sea on a
typical January day with 50 k wind and 30' seas or a 38 pound king
salmon getting landed on a sweet little 32' double ended salmon
troller built in 1932 and planked with Port Orford Cedar?

Thanks to everyone who has replied so far - the main thing everyone has made
me realise is that it's not as easily as I thought, and actually I didn't
think it would be easy anyway! :-)

For a bit more info, what we are trying to do is to automatically quantify
how much is being caught on the fishing boats, and to transmit that
information back along with position, speed, etc as part of Fisheries
monitoring.

This is in Asia, and there are some problems with vessels selling the fish to
other countries instead of locally, not to mention selling of their
subsidized diesel, so we can't really rely on information from the crew.

The vessels are maybe 30' to 40' wooden trawlers. Not sure what they catch,
but from looking at the sorting areas in port I believe they just take
everything they catch & don't do any sorting on board, nor throw anything
away (unless it's maybe a turtle or something big that they don't really
want). Undersize individual fish don't appear to be a problem either - seems
they are more prized actually!

Weather could be anything from dead calm to typhoon, though I'm guessing they
probably don't fish much in anything more than 2m of seas.

It actually sounds like a tricky task - weight on winch would probably be
highly inaccurate & too dependent on sea state & vessel speed. Hold weight?
Maybe also difficult to instrument? Especially as these are relatively cheap
hand-made wooden fishing boats that just go out with loads of ice to pack the
catch in & have no refrigeration or no standard size or position holds.

And then we have the problems of low bandwidth to transmit the information
back to shore, and the very high potential for sabotage..... :-(

Dave

Hi:

Actually counting fish is very easy. Just as long as a few facts are
known.
1) How do the fish get into the boat?
2) How big are the fish? Are you talking 0.25 Kg squid or a 200 Kg
tuna?

But even more important..... WHY do you want to know how to estimate
catch size on other people's boats?

Also who is going to use, and for what purpose, is the data being
collected? Are you a NGO, host nation, commercial fishing association,
or associated with a do-good save he the whales group?

By your inability to describe the situation I imagine you have no
commercial fishing experience and also do not understand basic
statistical sampling methods.

So help me out here. Why do you want to know how to estimate catch size
of someone else's boat. Do you have the owner/operator's
permission to do that?

Bob

On 4 Dec 2005 18:05:45 -0800, wrote:

Actually counting fish is very easy. Just as long as a few facts are
known.
1) How do the fish get into the boat?

Trawlers, so nets.

2) How big are the fish? Are you talking 0.25 Kg squid or a 200 Kg
tuna?

This is Asia - basically anything that gets into the net stays in the net,
and goes into the hold. From minnows to marlin. Sorting is done onshore when
the boat gets back to land. In general they are aiming for fish of 10kg
downwards.

But even more important..... WHY do you want to know how to estimate
catch size on other people's boats?

Because the government wants to know so they can stop their fishermen selling
their catch overseas.

Also who is going to use, and for what purpose, is the data being
collected? Are you a NGO, host nation, commercial fishing association,
or associated with a do-good save he the whales group?

Does this change the way it would be done?

By your inability to describe the situation I imagine you have no
commercial fishing experience and also do not understand basic
statistical sampling methods.

Apart from the fact that my father is a commercial fisherman, I agree that I
have little experience in this field. Which is why I am asking questions.

It's not so much of an inability to describe the situation, but a reluctance
to do so as this is a project which has certain sensitivities & even possibly
commercial considerations. I am happy to give information that is pertinent
to the technical problem at hand though.

So help me out here. Why do you want to know how to estimate catch size
of someone else's boat. Do you have the owner/operator's
permission to do that?

I am pretty sure I mentioned this before on a previous post. To stop the
fishermen selling their catch in neighbouring countries as they are using
subsidized fuel, and nobody wants to subsidize fishermen from one country to
have them sell their catch in another country.

Permission - Yes - by law.

Dave

Dave Baker wrote:
On 4 Dec 2005 18:05:45 -0800, wrote:

Actually counting fish is very easy. Just as long as a few facts are
known.
1) How do the fish get into the boat?

Trawlers, so nets.

2) How big are the fish? Are you talking 0.25 Kg squid or a 200 Kg
tuna?

This is Asia - basically anything that gets into the net stays in the net,
and goes into the hold. From minnows to marlin. Sorting is done onshore when
the boat gets back to land. In general they are aiming for fish of 10kg
downwards.

But even more important..... WHY do you want to know how to estimate
catch size on other people's boats?

Because the government wants to know so they can stop their fishermen selling
their catch overseas.

Also who is going to use, and for what purpose, is the data being
collected? Are you a NGO, host nation, commercial fishing association,
or associated with a do-good save he the whales group?

Does this change the way it would be done?

By your inability to describe the situation I imagine you have no
commercial fishing experience and also do not understand basic
statistical sampling methods.

Apart from the fact that my father is a commercial fisherman, I agree that I
have little experience in this field. Which is why I am asking questions.

It's not so much of an inability to describe the situation, but a reluctance
to do so as this is a project which has certain sensitivities & even possibly
commercial considerations. I am happy to give information that is pertinent
to the technical problem at hand though.

So help me out here. Why do you want to know how to estimate catch size
of someone else's boat. Do you have the owner/operator's
permission to do that?

I am pretty sure I mentioned this before on a previous post. To stop the
fishermen selling their catch in neighbouring countries as they are using
subsidized fuel, and nobody wants to subsidize fishermen from one country to
have them sell their catch in another country.

Permission - Yes - by law.

Dave

Hi Dave,
Okay now we're getting someplace.

First, try Mecca. These are the scientist:
http://www.afsc.noaa.gov/refm/observers/default.htm

Second, try the observer union. These are the people who actually do
the sampling on board and at shore based plants. They can tell you what
works and what doesn't:
http://www.apo-observers.org/Observe...o_homepage.htm

If you need methods to count fish and monitor vessel movement these are
the two places to go. If they do not have an answerer it don't exist.

Below are a few vague thoughts that came to mind that may help.

Do what the US does. License boats. Impose a miniscule "landing fee"
(tax/pound of fish). The tax pays the wages of the poor sole placed on
the boat to monitor movement and eye estimate catch size. Give the poor
sap a hand held gps. Bingo.

How about this. Put some black box gizmo (design left to the electronic
wizards here) that sends vessel position back to home base or easier
yet, simply records vessel movements for play back later. Hey, do they
make a cheep GPS that records course traveled? Stick it in a sealed box
with external antenna. If crew tampering is evident bust the boat for a
few Boks. No problem there except if your fishing boat is meeting a MS
for clandestine offloads.

So it sounds as though you simply want to make sure the boats bring
their catch home.
Problem one: how does the USA monitor vessel movement/location? USCG
uses planes and cutters. I think the 378' Morgenthau was patrolling the
East Pacific for a while. Does your host nation have a navy? Do not
forget onboard observers. There are electronic methods that cost less
than a C130 or a P3.

How much do you have to spend for the program? What resources are
available to deploy?

Oh, here is another way. Check out the December 2005 issue of National
Fisherman. Just got mine in the mail last week. On the back cover
you'll see an ad for some trawl technology that's pretty cool. Its
called ""trawl sonar." Been around since the mid 1980s It shows
what's going in the net and will "pop and egg" when certain
points in the codend (bag) are full. The sending units are called
"suit cases" by the guys who use it and "trawl information
systems" by the marketing people who sell it. It has a "third
wire" to transmit data to a screen in the wheel house. Here is a
little history. How do you tell if a boat is trawling? Yes, green over
white but......... Its also got two wires leading into the water over
the stern that is attached to a net that is flying along. Now this new
technology shows up in the 80s but nobody knows what to do with this
other wire that the trawl sonar uses to send the data back to the
house. Hey, lets hang it off the gantry and call it the ..........
Third Wire. The new stuff is of course wireless.

There are also non technical ways to insure compliance but would need
someone knowledgably with local cultural beliefs-values-attitudes and
morays. Maybe a cultural anthologist or ex Peace Corp Volunteer could
help. There may be a simple "cultural" answerer. So why do the
fishers feel compelled to sell their catch else where? Okay the
obvious........ better price or maybe? Gotta find the correct
Antecedent to that under the table Behavior. Then maybe you can add a
Consequence. Its as simple as (A-B-C).

The fish counting is not a problem. Just have the boats brail, dump,
suck, pike the buggers onto a scale on the dock. The real issue is
compliance to local law. Or in other words, how do you secure a border
and monitor vessel movement?

So my third question now is......How much do you have to spend?

Kinda like asking how much does a boat cost?

Bob.

Here are two others. Get a digital camera and morph it with a GPS. When
a photo is taken of the back deck every 5 minutes not only do you have
the date/time on each frame, you also have the lat and long. Put the
unit into a security housing and bolt it to the boat. The guys here
would have a better idea of cost per unit. Maybe $1000 each?

The National Marine Mammal Lab (NMML) people have used satellite
tracking technologies for about 25 years to get diving/movement data of
flippered beasts. Last I heard the units are about the size of a pack
of cigarettes, most likely smaller now. They record depth, duration,
water temp, location etc and when animal surfaces the unit burst dive
data to a satellite, then relayed to your office. Put it on a trawl
door or at the zipper end of the bag. Bruce Mate was the pioneer with
that stuff and worked out of OSU in Newport, OR. I think he's moved
on or retired now. Most likely you have seen his work featured on an
old Discovery Channel program.

Probably the most fun solution to your problem is to go to Seattle, WA
, walk into the NMFS Observer Program debriefing room (Sand Point Bldg.
5) and announce, "free beer for any observer who meets me at
Murphys/Buckeroo/Moon etc. You'll get lots a very bright young people
who'll brain storm you a cheep and fool proof solution for the price
a several pints.

Earlier in this thread you ask if it matters who is gathering the data.
It most certainly does. Also equally important is who will have access
to the data and for what purpose.
Might want ot read a book in the area of social and envionmental
economics. One of the best books I ever read was the history of Cod.
For example, how do you feed Europe when there is no industrial sized
protine source? Yep, 1392 Basks sailed the ocean blue in search of Cod.
In Cod We Trust. Which state flag had a Cod on it? Just another
thought. Why would a colony put a Cod on a coin? How about the more
recent Cod wars of Icland.