Roy Marlow’s assertion that anglers’ baits are responsible for ‘... up to 40 per cent of fish deaths’ is probably correct. Maybe not directly, but it doesn’t take a genius to know that much of the degradation of water quality in massively-overstocked commercial fisheries is down to excessive use of baits with protein levels higher than fishes' digestive systems can cope with. That increases bacteria, which use oxygen, depleting levels to a point where fish that may already be suffering from a disease, such as KHV, cannot cope.
This appears to be a price that fishery owners and many anglers are prepared to pay.
The baits mainly under Roy’s microscope are high-oil/protein pellets and many fish-farmers will tell you they cause no problems at all. They would be right because they are used under strict control and fed in carefully calibrated quantities.
I’ve seen, at Sparsholt College, the results of fish being overfed in identical conditions. Those fed the correct amount of feed for their growth and well-being were in pristine condition, in clear water. They were active and looked shiny and a picture of health, rapidly disposing of any feed introduced. Those in the next door tank, in identical water from the same filter, were being fed twice as much. They were sluggish, the water was murky and they grudgingly munched a few pellets that had lain on the bottom for some time.
I know that many fishery managers’ approach to bigger catches is to introduce more fish. Sounds logical, doesn’t it? However, what would definitely be a better idea is to reduce the amount of feed the resident fish are subjected to which, in turn, would make them hungrier. It would improve water quality and, as a result, fish would live longer, happier and healthier lives.
Of course using low-oil pellets and feeds, produced for cyprinids rather than trout, halibut or salmon (those pellets don’t contain those species, they are designed to feed them!) will have a huge influence, especially where animal protein is combined with fish protein to aid digestion.
Angling doesn’t know how lucky it is to have escaped the Animal Welfare Act legislation. If it hadn’t, there would be far fewer fisheries, containing a lot fewer fish, than we currently are blessed/cursed with.
If anglers aren’t prepared to accept sensible bait limits ¬ and fishery managers aren’t prepared to put them in place ¬ I am certain that Roy’s statement will inevitably be borne out in the future ¬ not that distant a future either.