Grayling post release mortality

[Hardrar]

I’m more interested in the considerations around heart-failure of fish than hook punctures or tearing. I guess because I don’t have a zoological background I struggle with questions of fish-mouths healing, pain-receptors and so on. I can grasp the idea of a fish becoming exhausted and overheating in warmer water though.

Grayling tend not to frequent waters that’s are prone to warming in Summer and tend to be laying low and less likely to be caught in warmer conditions. Our local rivers are spring fed, so water temperatures don’t fluctuate that much at all, from season to season.
The Chalkstream that runs across the bottom of our garden, will have water in it now, that fell between 5 months and 20 years ago, as it’s nearly all aquifer groundwater fed . These streams and rivers are called Winterbournes as they are often quite high in Summer and low in Winter, due to the delay in water percolating through the bed rock.
This keeps water temperature in a very narrow band- ideal for Wild Trout and Grayling. I have carried a water thermometer on my vest for decades and it’s interesting how cold the water is, even after a very hot prolonged period.
In July and August your legs can get really cold still after prolonged deep wading and daft as this sounds some members wear thermal leg warmers under their chest waders even in mid summer.
Small shallow stillwaters tend to suffer more, but Grayling don’t frequent them.
My local Stillwater is chalk stream fed, and has some Klonking Grayling in it as a result, They are hard to catch but always recover well as the water is naturally cold and well oxygenated.
It’s not the temperature persay that harms them, but the lack of oxygen dissolved in it, as warm water carries much less oxygen than cold can.

 

[bobmiddlepoint]

Grayling once settled and calm can sometimes surprise you, especially the bigger ones... I keep them in the net/water to unhook and then the bigger ones I always leave in the net just to make sure they have recovered... then get the camera ready and drop the net away and have them cradled in the hand still in the water but raised just a little bit so you can see them better... sometimes they’ll sit like that until my hand gets so cold you have to leave them to it, other times they kick and disappear the moment the net is dropped out the way... if you are on your own and it’s a large fish then it is the only safe way to photo them
i reckon it’s 50:50 whether you end up with a photo of the fish or just a blur of silver and some water splashing over the camera

I'm not having a pop here, I'm thinking aloud and asking a question...
If you have been holding a fish until your hand is very cold where has all that heat gone? Obviously most of it has gone into the river but some of the heat from the palm of your hand must have gone into the fish. Now this is going to be more of a cold water/winter thing but how does the heat from your hand affect the fish?


Andy

 

[albacore]

Thanks, that clarifies the relationship between water temperature and oxygen for me. I’m pretty sure it’s never going to be perfect; as in 100% survivability of all fish caught and released. Ultimately, I think it’s the individual’s choice and right, if it’s within the rules of where they are fishing, to retain fish or not. There’s more discomfort, for me, about the releasing of fish, a proportion of which are going to die, as opposed to purposely killing one or a few to eat. It’s kind of ironic though, the more skilful the angler, the more often they come up against the dilemma.

 

[bobmiddlepoint]

Thanks, that clarifies the relationship between water temperature and oxygen for me. I’m pretty sure it’s never going to be perfect; as in 100% survivability of all fish caught and released. Ultimately, I think it’s the individual’s choice and right, if it’s within the rules of where they are fishing, to retain fish or not. There’s more discomfort, for me, about the releasing of fish, a proportion of which are going to die, as opposed to purposely killing one or a few to eat. It’s kind of ironic though, the more skilful the angler, the more often they come up against the dilemma.

The more skilful angler always has the option of stopping if he feels he might be doing harm.


Andy

 

[BobP]

Yes a lot of that was to result in the development of circle hooks, rather than traditional J hooks, I’ve noticed with the short point curved shank Tiemco and Hanak hooks, that I use, they don’t hook deeply, which makes unhooking very easy. Our local Stillwater has been c n r since 1980 with a “Sport only” ticket.

I think you'll find that circle hooks were used in long line fishing at sea long before they arrived in freshwater fishing. Certainly as far as fly fishing was concerned they never caught on. John Goddard wrote an article on their use at least 15 years ago if not longer.

 

[boisker]

I'm not having a pop here, I'm thinking aloud and asking a question...
If you have been holding a fish until your hand is very cold where has all that heat gone? Obviously most of it has gone into the river but some of the heat from the palm of your hand must have gone into the fish. Now this is going to be more of a cold water/winter thing but how does the heat from your hand affect the fish?


Andy

I would say the heat from the hand disappears / is stripped pretty much immediately... blood supply to the extremities / skin will shut down, if you looked at a heat map of your body your hands would be blue... certainly for winter Grayling fishing

 

[loxie]

Thanks, that clarifies the relationship between water temperature and oxygen for me. I’m pretty sure it’s never going to be perfect; as in 100% survivability of all fish caught and released. Ultimately, I think it’s the individual’s choice and right, if it’s within the rules of where they are fishing, to retain fish or not. There’s more discomfort, for me, about the releasing of fish, a proportion of which are going to die, as opposed to purposely killing one or a few to eat. It’s kind of ironic though, the more skilful the angler, the more often they come up against the dilemma.

The purpose of fishing is to catch fish for food. The purpose of angling is to catch fish for fun. The less angling is fishing the less comfortable I am with the morality of it. It's incredibly difficult to find a rational justification for harming animals solely for fun.

 

[Hardrar]

I'm not having a pop here, I'm thinking aloud and asking a question...
If you have been holding a fish until your hand is very cold where has all that heat gone? Obviously most of it has gone into the river but some of the heat from the palm of your hand must have gone into the fish. Now this is going to be more of a cold water/winter thing but how does the heat from your hand affect the fish?


Andy

I don’t handle them, release in the net with a Ketchum or a good pair of long forceps.