Some comments were made that using a Catcher's Mitt might be bad when you plan on releasing a fish because of the slime it removes. So I did some research and reached out to William E. Kelso, Ph.D. He is Associate Director and Graduate Coordinator, F.O. Bateman Professor of Renewable Natural Resources, School of Renewable Natural Resources, Louisiana State University Agricultural Center.
Q: There has always been a concern that when you handle fish, you remove some of their slime and this can lead to a higher mortality of the fish. There has been much talk and study of this over the years especially with Large Mouth Bass.
A: There are no definitive studies on handling, mucus removal, and harm to fishes.
Q: The slimier the fish the more people hate touching them and the more they like my product. Spotted Sea Trout (specks) are high on the list for sliminess. I think that peoples fear of hurting specks by removing some of the slime while handling them before release, is a little bit unwarranted. I think specks make mucous for a living and replace any you knock off in a matter of minutes. So, my first question is how fast do fish replenish lost slime. Especially specks, reds, bass, crappie, and catfish.
A: Fish have their slime removed all the time when they swim through grass, rub up against the bottom and brush structure. I don't know about replacing in minutes, but they are capable of replacing it within an hour.
A few studies on salmonids indicate minimal problems with rapid return to the water. Landing nets probably do more damage to fins and skin abrasion than anything else, but again, handling mortality studies typically indicate single digit loss rates, and most of these are probably due to extended handling, blood loss from sensitive hooking locations, etc. I think the advantages of being able to securely grab a fish, unhook it, and quickly get it back into the water outweigh problems with mucus loss, as you said, that’s what fish do.
Q: I have heard all my life that if you plan on releasing a fish you should wet your hands before handling. I have not been able to find any research to back that up. But if it is true, the mitt on the Catcher’s Mitt is very textured and stays wet for a long time. So, I am thinking it would be very good in that respect for releasing fish.
A: I think a wet Mitt would be about as safe for a fish as you can get. Many studies have focused on stress responses, with blood samples taken for periods of time after capture looking at corticosteroids and other hormones, but these studies are not targeting the mucus aspects of handling.
Good luck with the Mitt, I like the idea of being able to secure the fish quickly, if you can minimize the use of nets, dropping the fish, etc., that will likely have the greatest benefits regarding handling stress and mortality.