What material can be used as a binder that would slowly dissolve in sea water?

There is an on-going problem in the fishing industry concerning bait in the crab fishery. Bait is becoming almost as expensive as crab. At the same time, there are by products in the seafood industry that are just being wasted that would fulfill the required needs if it could be combined with a sea water soluble material that could be adjusted to dissolve within set periods of time such as 3, 5 or 7 days. Anyone have any ideas? No soap or any material that would disturb the natural balance of the environment would work. 

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Toga_Dan26 days ago

i haven't read every post here. Therefore might be redundant.

Lard as binder.

A bait cage with smaller holes.

Like wire screen.

seandogue27 days ago

Dry it and recombine by pressing into cakes.

I am curious to know, at what depth, the bait must be delivered, and also what shape the bait is.

I mean what I was thinking of was just turning the bait into a slurry, and delivering it through a pipe, as long as that pipe did not have to go too deep.

Although, I dunno, that might be too complicated. I do not have a clear picture of this bait delivery problem. For example if you need like hundreds of bait stations, then this probably means each individual bait station has to be cheap and disposable, or else you'd go broke trying to build and maintain all of them, and maybe dump a lot of plastic into the ocean too.

Regarding things that dissolve in salt water, you'll probably want to pick something cheap, and biodegradable, and biocompatable with the animals you're messing with.

The cheapest thing I can think of is ice, you know, cold solid water. If you cast your ice-bait chunk in the shape of a sphere, a shape with high (volume)/(surface area) ratio, that will help it last longer. That ratio also gets bigger with scale; i.e a large sphere has greater V/S ratio than a small one.

Also I have read rumors of a mixture of ice and sawdust that was long lasting in ocean water. It was some crazy story about someone who built a boat, or a raft, out of ice-sawdust mixture. Oh wait... Wikipedia is telling me this stuff really is a thing, here:


That makes me think: ice-sawdust mixture floats. Or at least it did in the story, I think. Dude wanted to build a boat out of it.

If ice-sawdust floats, you need something to weight it down with, because crabs live at the bottom. I think. Honestly, most of what I know about marine biology, I learned from watching Spongebob Squarepants.


Anyway, if you need to weight it down, I guess chain it to a rock, or make a mixture that includes rocks, or gravel, sand, etc.

Also frozen wet shredded paper might work too. Shredded paper has a lot in common sawdust, chemically speaking. Both have lots of cellulose and lignin, erm whatdotheycallit?


Oregonbythesea (author)  Jack A Lopez28 days ago

The ideas are getting better so I better relate the problem a little clearer. We have 500 pots fishing at all times while we can go through about half in daylight and all if we fish at night too. The pots are in anywhere from 8 fathoms to 80 fathoms. Right now we would normally take about 500 to 2,000 pounds of bait for a trip that could last a few days to a week. In the beginning of the season the crab are plentiful for the first month and then they start to thin out requiring a few days of soak time. If a storm should happen, then the pots could be untended for a week or more at a time and that is when a slow release bait would really be helpful. Even in the beginning, a slow release bait could mean $1,000's in profit. A cheap alternative to expensive clams, or fish, would be something like ground tuna carcases that are abundant during the summer months.

I think I have a better mental picture of this now.

First, I am going to re-cap, with a quick summary of what I have read.

I have read what's written here, what you wrote, what Downunder35m wrote.

Then I read the Wikipedia article, "Crab trap"

and one of its reference links,

Then I asked Google(r) Images to show me, "crab pots"

and I'll mention just a few of those links that looked interesting to me. One is from Oregon DFW,

and that might be relevant to you, since I am assuming you're in Oregon.

The other curious link I found via that image search, is link to a Youtube video, actually showing us some time-lapsed video, inside a submerged crab pot.

That's probably the best one.

Now I will tell you what I have learned, the parts that I think are relevant to your crab baiting problem.

First thing, the bait has to fit inside the bait box, which is this small cage/box, inside of the crab pot, which is itself a cage/box thing. These constraints give us some advantages and disadvantages, and I'll get to explaining what those are later.

The second thing is the word "dissolve" is an incomplete description of what is happening to your bait. You might think I'm arguing semantics. You know, "dissolves", "erodes", "gets eaten", "decomposes" "disappears", these are all truthful descriptions of what happens to the bait.

However, since your goal is to make the bait last longer, I think it will be helpful to consider what is really, in fact, happening to it.

I mean, "dissolves", is what happens when you stir a sugar cube into a cup of hot tea.

In contrast, what is happening to the bait in the bait trap is "decomposition"


You know, there's a combination of forces: chemical, biological, mechanical, and they're all working together to make the bait disappear.

The usual biology textbook examples of decomposition take place on land, probably because those examples are easier to study.

You know, like if you leave a dead cat on the side of the road, there are bacteria, in and on, the dead cat, working to change it from solid dead cat, into liquid dead cat, and gaseous dead cat. The liquids soak into the ground. The gases diffuse into the air.

But before the bacteria can even get started, there are other, much larger lifeforms, that show up: flies, ants, buzzards, and maybe even Wile E. Coyote, if he has a taste for carrion. These animals all work together to pick apart the dead cat, and carry it away in small pieces.

Wind and rain, are essentially mechanical forces, dispersing what is left of dead cat, blowing it away, washing it away.

I imagine there is an analogous process decomposing the bait in the bait box in a crab pot. There are tiny animals that show up to pick away at it. I mean, animals much smaller than the crabs you're trying to catch, like the marine environment equivalent of ants, and flies, and maggots.

In addition to the tiny animals, there are of course water currents, constantly moving to wash away any liquids, or solid pieces small enough to get washed away. I guess that's the marine environment equivalent of "wind".

And of course there are bacteria living on, and in, the bait, slowly changing its solid form into liquids and gases. But like in the terrestrial example, I am guessing the bacterial action is pretty slow compared to the the losses caused by the animals picking away at it.

Or it might be fast, because it's in water. Or it might be slow because it's cold water, without a lot of oxygen in it.

I guess all I'm saying is the process is a lot different than just a solid dissolving in a liquid.

That being said, I should get back to what I was going to say about the advantages, disadvantages, of the box-like bait box.

The main disadvantage is that it has a fixed volume. So if a full bait box lasts one day, and you want it to last seven day, you can't just use seven times as much bait, because that amount of bait will not physically fit in the bait box.

Unless you change its density... Is there a way to compress dead fish, or other meat, by a factor of like seven or ten?

Besides, ten times as much meat costs ten times as much money, in addition to the cost of compressing it.

I said the cage-like bait box had some advantages. The main one I can think of, is this box-inside-a-box, is that an insoluble, inedible thing, like a HDPE bottle, would probably stay put inside the bait box, and the only way to lose it, would be if the bottle were shattered, shredded, or if the entire crab pot itself were lost.

Anyway, consider this HDPE plastic bottle, like maybe the kind vitamins come in. Not clear plastic, like PET, but HDPE, with a sturdy screw on cap.

Now, as an example bordering on absurdity, consider what would happen with a sturdy HDPE bottle with a quantity of bait perfectly, hermetically sealed inside of it.

It might last underwater forever, since it is so well sealed, but at the same time it is useless as bait because no liquids, no smell, can diffuse out.

Next consider the same bottle, but with one tiny hole. A small amount of smelly liquid could escape, but not very much.

Next consider that there is a continuum between that bottle with one hole, two holes, three holes... and a bottle covered with holes, which is a net-like dispenser, kind of like what you've already discussed with Downunder35m.

You kind of dismissed what he said, as been-there-done-that, i.e. "we use all those methods and that is part of the problem", but to me that seems like a perfect method for controlling the rate at which bait can escape from the container.

I mean, I would not go to the trouble of 3D printing anything, especially not graceful, artsy, flowing net-like shapes. Instead I would go with an actual, ugly, HDPE plastic bottle, with just a few tiny, like (2mm, or 3/32 inch) holes drilled in it. Too many holes will weaken the bottle, make it vulnerable to breaking apart into plastic trash and washing away.

If you really want try bait-mixed-with-binder, I cannot think of anything better than what I mentioned previously, like cellulose, like newspaper, or ice, or ice-newspaper mixture.

Or maybe there is a way to make pure concentrated rotting meat smell, like cadaverine,


But at the same, you want it to be cheap. One of the links I attached earlier, this one,

mentioned offal like chicken necks and beef lips, so I guess meat raised on land works too.

Dry dog food is pretty cheap, in the 50 pound bag. That might be something to try.

I am not sure what kind of flavor the crabs are especially hungry for, but I am guessing any rotting, oily, meaty flavor will do.

There is plenty of material out there, from bags over nets to containers and 3D printing filament.
I gather you did not try a proper Google search?
For bait your main problem is sent and taste....
Don't what you mean by industry but if the industry you mean does not know what the hobby fisherman does than you guys lost contact to the real world ;)
Ever hear of using bigger containers with small holes on the bottom and a weight on top??
Works just fine for everyone using crap pots and nets around here....

Oregonbythesea (author)  Downunder35m28 days ago
First of all, I am not a hobby fisherman as I have been at it for more than 60 years now. As for your suggestion on containers, yes, we use all those methods and that is part of the problem. Bait in those containers will last about three day at most while hanging bait lasts about an hour or so. The solution is to use a hanging bait ground and mixed with some material that would dissolve slowly while retaining the effect of fresh hanging bait. Google search? If the answer was there, why post here?

Again from the hobby fisherman around the corner:
Use the hanging basket type but with holes only in the bottom part not all throughout the basket.
Fill it in layers of bait and insulator.
In our case the insulator is foil that dissolves in water.
Most basic type is simple gelantine as used for baking, available in sheets, rools or powder, the later can be mixed directly with bait too.
Using other plastic works too but needs testing for smell and taste first, some dissolve neutral while other often leave a bitter taste which turns fish off so I assume same is true for crabs..
Last but not least some folks also use mechanical devices similar to those pet feeders for when you go on holidays for a few days.
A spring loaded screw mechanism would be able to push your bait down to a relatively small hole, eliminating bigger fish to eat it all away in a hurry.

But if you constantly struggle to fill the traps and are left with no bait then your bait might just attract too much attention to the wrong species.
And if bait gets far too costly than we guys here take seafood platter cat food from the supermarket.
If bought in bulk a can is below 50 cents and work great to attract all sorts of sealife...

Oregonbythesea (author)  Downunder35m28 days ago
First of all, I am not a hobby fisherman as I have been at it for more than 60 years now. As for your suggestion on containers, yes, we use all those methods and that is part of the problem. Bait in those containers will last about three day at most while hanging bait lasts about an hour or so. The solution is to use a hanging bait ground and mixed with some material that would dissolve slowly while retaining the effect of fresh hanging bait. Google search? If the answer was there, why post here?