If you hang around online a lot (who doesn't now days), it won't take long to see a lot of negative comments from posters any time someone posts a video or picture of a bass hitting or lying on the boat carpeting. You'll see lots of claims from guaranteed death, to boat rash, and rubbing off of the slime coat. Even the booklet, "Keeping Bass Alive" states, "Swinging or flipping fish into the boat and onto the floor is a poor technique! 'Rugburn' can cause extensive damage to the mucus coat." It all seems to make a lot of sense from a practical standpoint, but is there any scientific basis for these assertions? Some recent research suggests these claims of harm might be misplaced.
Every fish has a layer of mucus covering its body, an epithelial layer, that provides a first barrier line of protection from things like bacterial and viral infections. Damage to this layer exposing the skin underneath can lead to these type of infections, and potentially even lead to death in severe cases. This study looked at what happens when a landed bass is allowed to lay on boat carpeting. They simulated this by placing caught fish in a plastic container lined with artificial outdoor carpeting, and then allowing that fish to do whatever it wanted (lay still, flop around, etc.) for 30 seconds unrestrained. They then used a compound called fluorescein to evaluate the damage.
Fluorescein reacts positively with epithelial damage via chemical reaction. The result is a glowing green light that can be captured easily via photography and analyzed for extent of damage using imaging software. It has been used successfully in other published research on similar skin damage in both northern pike and rainbow trout. What was the result with bass exposed to carpeting for this length of time? Basically, nothing.
There was no statistical difference in damage detected via this method when comparing those bass subjected to the carpeted box to those bass which weren't (controls). This brings up some interesting questions. Is there really no harm in letting your bass lie on the floor of your boat for a short period of time while you land it or cull through fish? The data would suggest no - it is one possibility. It is likely that different fish species have differences in their mucus layer, things like thickness and how well it holds up to external damage, intra- and inter-specific variation. Perhaps bass mucus layers are 'tougher' or more 'attached' or bound to the underlying skin, affording bass greater protection than other species. That would be a good thing.
Another possibility is that the fluorescein technique might simply not work well on bass for some reason, and the negative results from this study might not represent what is actually occurring in real life. Obviously, more research in this area is needed, including comparisons with other freshwater fish. So, while it is always good practice to limit the amount of external stress we place on our fish during angling, what is perceived to be a bad practice may not actually be harming our fish as much as we think. Lets hope that is the case.
- Evaluation of common angling-induced sources of epithelial damage for popular freshwater sport fish using fluorescein
Alison H. Colotelo, Steven J. Cooke