I've read a number of papers where the predation rate of released bonefish is studied, most loses being to cudas or sharks. However none of these studies have clarified what the predation rate would be if there wasn't the influence of the fisherman. Obviously cudas and sharks eat bonefish whether they've previously been released or not - I believe they preferentially target released fish because it takes less energy to run one down. But this does not mean that the overall predation rate is higher though, just that they target weakened fish. Or have I got this all wrong?
James
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Predation on the flats
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Predation on the flats
Hi JamesJames9118 wrote: However none of these studies have clarified what the predation rate would be if there wasn't the influence of the fisherman. Obviously cudas and sharks eat bonefish whether they've previously been released or not - I believe they preferentially target released fish because it takes less energy to run one down. But this does not mean that the overall predation rate is higher though, just that they target weakened fish. Or have I got this all wrong?
I'm not sure what you are trying to clarify but I agree that a C&R'd bonefish is more vulnerable to predation. For how long after release and until full recovery I don't know. I say this because I watched a reef shark run down and eat a bone I had released on CXI. It didn't make my day.
Absent any angling I don't know how often bonefish get eaten on the flats by cudas, sharks or GT's for that matter so I don't have a baseline rate and I struggle to imagine how we would get one. Does that let us off the hook, so to speak?
I can surmise that at the least C&R may skew predation toward the fish we catch and since we don't fish blind we tend to target the larger fish. Can't see much good coming from that but I have no idea how much harm we do.
It's another example of the unavoidable and unintended consequences of angling pressure.
Cheers
Mark
"The line of beauty is the result of perfect economy." R. W. Emerson.
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Bernd Ziesche
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Predation on the flats
Hi Mark,Geenomad wrote:I say this because I watched a reef shark run down and eat a bone I had released on CXI. It didn't make my day.
I agree with James. I have also seen cudas (several times) taking fish (bones included) off my line. It is the unnatural movement of the fish being hooked making the cudas curios. I think cudas notice every unnatural movement easily.
But I also have seen cudas running into a school of Bonefish (none hooked or released) several times. I remember a bay on Acklins Island (Bahamian Islands) where a huge cuda was into Bonefish on every start of low tide when the first Bones came back into the channel. It did not seem like he was looking for the released Bone there but just naturally feeding on the schools of Bones.
It of course would be necessary to first of all research for a percentage of natural feeding behaviour for the cudas. And that will change from spot to spot, I think. Difficult though.
I know that I have released a lot of Bones while having a cuda not far away and the cuda did not grab the Bone as far as I could see it.
In the end I think the cuda eats as much as he eats - doesn't matter how many Bones are released around him.
I would want to ask the researcher if the cuda wasn't finished for the day after having eat a released Bone. And if that didn't safe another Bones life...
Cheers
Bernd
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Predation on the flats
Hi Bernd
I don't disagree with James either because I don't know what the predation rate on bones would be by cudas or sharks or GTs etc in the complete absence of angling. No baseline in other words. But the absence of proof and the absence of causation aren't the same thing.
In the particular instance (yeah I know one fish does not a PhD thesis make
) I was fishing a little area about 2/3 the size of an olympic swimming pool. I caught and released several bones from the same pool. A shark came in, chased down a bone and ate half of it. Other predators and scavengers came out of the deeper water and went back out when the commotion died down. The guide waded over and picked up the head of the bone that got eaten. The mouth had a fresh hook wound in it.
From this experience I surmise that catching a bone and releasing it makes it more vulnerable to getting eaten than other bones and maybe many other fish as well, at least until it recovers. Again I don't know for how long.
Speaking of unnatural movement attracting predatory attention... Back when I spearfished I remember taking a long shot at a fish swimming with a whole bunch of other fish (mixed species) in behind a bommie (Australian term for a little column of reef often standing separately). No sign of aggression. Everyone just chilling in the current to pass the time of day sort of atmosphere. The spear clipped the target in the head and killed it instantly without pinning it on the spear. So it was just swimming along happily, clunk, and it was spiralling down. The other fish were on it like piranhas before it had fallen more than a couple of feet in the water column.
My thinking was, and still is, that what gets eaten is the softest target - no mercy or beg pardons. Fish feed when they feed so I'm not saying the newly released bones will always get eaten, like you aren't saying they will never be eaten, but I do think we anglers can bias the target selection. It doesn't take much to be picked out. That's the predation business for you. And here's a happy thought, I think humans have the same instinctive capacity for target selection. Usage rates vary.
Cheers
Mark
I don't disagree with James either because I don't know what the predation rate on bones would be by cudas or sharks or GTs etc in the complete absence of angling. No baseline in other words. But the absence of proof and the absence of causation aren't the same thing.
In the particular instance (yeah I know one fish does not a PhD thesis make
) I was fishing a little area about 2/3 the size of an olympic swimming pool. I caught and released several bones from the same pool. A shark came in, chased down a bone and ate half of it. Other predators and scavengers came out of the deeper water and went back out when the commotion died down. The guide waded over and picked up the head of the bone that got eaten. The mouth had a fresh hook wound in it.From this experience I surmise that catching a bone and releasing it makes it more vulnerable to getting eaten than other bones and maybe many other fish as well, at least until it recovers. Again I don't know for how long.
Speaking of unnatural movement attracting predatory attention... Back when I spearfished I remember taking a long shot at a fish swimming with a whole bunch of other fish (mixed species) in behind a bommie (Australian term for a little column of reef often standing separately). No sign of aggression. Everyone just chilling in the current to pass the time of day sort of atmosphere. The spear clipped the target in the head and killed it instantly without pinning it on the spear. So it was just swimming along happily, clunk, and it was spiralling down. The other fish were on it like piranhas before it had fallen more than a couple of feet in the water column.
My thinking was, and still is, that what gets eaten is the softest target - no mercy or beg pardons. Fish feed when they feed so I'm not saying the newly released bones will always get eaten, like you aren't saying they will never be eaten, but I do think we anglers can bias the target selection. It doesn't take much to be picked out. That's the predation business for you.
And here's a happy thought, I think humans have the same instinctive capacity for target selection. Usage rates vary.Cheers
Mark
"The line of beauty is the result of perfect economy." R. W. Emerson.
https://thecuriousflycaster.com
https://thecuriousflycaster.com
Predation on the flats
Over the years I have caught several thousand bonefish. I can only remember one that was eaten by a shark on release.
This was in the Keys and I was fishing with a very experienced guide. The shark hit the bonefish almost as soon as it was released. As if it was waiting. My guide was extremely upset and blamed himself that he did not see the shark first. It is a shame as it was a 12lb fish.
I have had a lot of sharks chasing hooked fish but have up to now never lost one. Barracudas are a different matter they will hit a fish that is hooked very quickly.
On one occasion in the Bahamas I found a school of bones about the size of a football field. There were many thousand fish in the school. It was surrounded by barracudas, You could cast into the school hook a fish and the barracudas would compete for it. Even if the fish was in the middle of the school they would only hit the hooked fish. After loosing a couple of fish we moved of and surprisingly enough some barracudas went with us. They were obviously keyed into the idea -where there is a boat there is lunch.
Coming back to the original point. I don't think that anglers releasing fish make a big difference to the predation rate. They must make some difference, obviously, but I think it is pretty small. Bonefish go onto the flats when then water is low to feed. This is because the water is not deep enough for larger predators. They feel safe. When the water is deeper it's a different story. The fish are more wary. I always think that if the water is above your knees then it is too deep.
This was in the Keys and I was fishing with a very experienced guide. The shark hit the bonefish almost as soon as it was released. As if it was waiting. My guide was extremely upset and blamed himself that he did not see the shark first. It is a shame as it was a 12lb fish.
I have had a lot of sharks chasing hooked fish but have up to now never lost one. Barracudas are a different matter they will hit a fish that is hooked very quickly.
On one occasion in the Bahamas I found a school of bones about the size of a football field. There were many thousand fish in the school. It was surrounded by barracudas, You could cast into the school hook a fish and the barracudas would compete for it. Even if the fish was in the middle of the school they would only hit the hooked fish. After loosing a couple of fish we moved of and surprisingly enough some barracudas went with us. They were obviously keyed into the idea -where there is a boat there is lunch.
Coming back to the original point. I don't think that anglers releasing fish make a big difference to the predation rate. They must make some difference, obviously, but I think it is pretty small. Bonefish go onto the flats when then water is low to feed. This is because the water is not deep enough for larger predators. They feel safe. When the water is deeper it's a different story. The fish are more wary. I always think that if the water is above your knees then it is too deep.
IANACI
Predation on the flats
When working out in the Bahamas in the 90s we certainly noticed a predator build up on flats that where fished hard, we tried to mix it up as much as possible but sometimes wind and tide made some flats more fished and therefore more fish released.
The number of reef sharks and cuda definitely increased after a few days, nurse shark and ray numbers where pretty constant.
TK
The number of reef sharks and cuda definitely increased after a few days, nurse shark and ray numbers where pretty constant.
TK