A musky with an injury possibly caused by a lip-gripping device. (Credit: John Aschenbrenner)

Research: Lip-Gripping Devices May Injure Fish

By Jordan Weeks, Research Editor

My love/hate relationship with social media continues … at least it provides some good article ideas! If you want some entertainment just post a strong position on either side, sit back and watch what happens when you mention lip-gripping devices.

Sometimes scientific literature is devoid of research on fishing-related topics. However, in 2008 researchers Andy Danylchuk, Aaron Adams, Steven Cooke and Cory Suski evaluated injury and short-term survival of bonefish as influenced by mechanical lip-gripping devices used by recreational anglers.

Like muskellunge, bonefish are rarely harvested (95 percent-plus catch and release). Therefore, proper handling and release is important to anglers passionate about these saltwater white sucker look-alikes. Correct handling minimizes injury to the fish and angler, allows easy hook removal, and decreases time out of water for the fish. “Damage from handling (e.g., scale loss, bruising, slime loss) coupled with the stress from an angling event can lead to opportunistic pathogen infections that have the potential to kill the fish. Furthermore, the handling event itself can induce physiological disturbances, e.g., through air exposure (Ferguson and Tufts 1992, Cooke et al. 2001), that ultimately leads to post release mortality (Danylchuk et al 2007 a,b),” researchers wrote.

There are several brands of lip-gripping devices on the market. The intent of this article is not to call out any, but to shed light onto the impacts of using them. The devices researched in this article are characterized by opposing metal pieces designed to hold the mouth of the fish. It secures the fish by clamping both inside and outside the jaw. These devices maintain the grip as long as pressure is applied against the fish.

“These tools presumably allow the fish to be restrained by the anglers using one hand, leaving a second hand free to hold a fishing rod or remove the hook, allowing anglers to avoid touching the fish with their hands,” researchers wrote. The overarching idea is to reduce handling and therefore reduce stress and injury to the fish, increasing post-catch survival. However, this premise has never been investigated.

If you spend any time on social media, you will certainly see that mechanical lip-gripping devices continue to be advocated for as a proper way to handle fish. “The goal of this study was to evaluate a commonly used mechanical lip-gripping device and assess its use on the injury, behavior, and survival of bonefish. Bonefish were selected because they are a common popular saltwater recreational sportfish for which catch and release rates approach 100 percent as a result of strong conservation ethic among its specialized angling group (Cooke et. al. 2006). Furthermore, the bonefish angling community has a particular interest in this device, because it has the potential to reduce slime loss during handling, which is a concern for this group of fishes (Cooke and Phillip, 2007),” the study stated. The same can be said for muskellunge and musky anglers!


Fish were collected via seine. After initial collection, fish were kept at the location of capture in net pens and observed for normal swimming patterns. Once normal activity was observed, fish were transported to a research facility in coolers. During transport, water was exchanged up to six times, aeration was added, and each cooler contained no more than four fish.

Following a resting period in the lab, each fish was exercised for a period of one minute (to mimic an angling capture) and randomly assigned one of three treatment groups. Treatment groups were as follows: “1. Handling using a lip-gripping device with the fish horizontal in the water; 2. Handling while using a lip-gripping device with the fish held vertically out of the water; and 3. Restrained by hand while submerged, without the use of a device (control).” Each fish was handled for 30 seconds and each treatment included 10 individuals. After treatment fish were held for 48 hours.


“Bonefish in this study ranged in size from 14.9 inches to 21.3 inches. No fish died during handling or the 48-hour holding period,” researchers wrote.

Only one of the control fish (not lip-gripped) showed any signs of injury. Eighteen of 20 treatment fish (both groups) received injuries to the lower jaw. All bonefish held vertically received injuries (four had serious injuries). Seven of 10 fish had perforations in the soft tissue between the mandible and the isthmus (small piece of skin on the belly between the gills and the body). Perforations ranged in size from 5 mm to 28 mm. Perforations ranged from small circular holes to long tears. Two of the bonefish with perforations suffered a broken mandible. Two fish had tongue injuries (tongue separated from the mouth). Three other fish had less severe, non-perforated injuries. Six of 10 fish had multiple injuries. Eighty percent of the bonefish held horizontally received injuries. Four received perforated wounds. Two bonefish had a broken mandible (these injuries were more severe than the treatment fish held vertically). Four fish had their tongue separated from the base of the mouth. Two had non-perforated injuries. Three of eight fish in this treatment had multiple injuries.

This research showed a significant difference regarding injuries between treatment and control groups! The occurrence and size of perforated wounds was not significantly different between the two treatment groups. “In addition, there was no significant difference in the body size of bonefish that received perforated wounds verses those that received non-perforated wounds,” the researchers said.


While I realize this study was not performed on muskellunge, in my opinion, several very important things can be taken from it. First, using a lip-gripping device on a large fish like musky, will most certainly cause injury to the fish. Second, it didn’t seem to matter if the fish was lifted or held in the water. This device still caused injury in over 80 percent of fish. Third, while none of the study fish died after 48 hours post treatment, we do not know if the injuries involved increased mortality after that time. It’s hard for this biologist to believe it did not have an adverse effect. Lastly, I think there may be a time and place for these products…If you have exhausted all other means of hook removal and as a last resort.

We all must assume some delayed mortality when we release muskies. However, minimizing post-catch mortality is in everyone’s best interest. “Systematically examining the influence of specific elements of the angling event is critical for the development of scientifically based best practices that can act as guidelines for recreational anglers,” the study said. This is my main goal.


Danylchuk, A.J., A. Adams, S.J. Cooke, and C.D. Suski. 2008. An Evaluation of the injury and short-term survival of bonefish as influenced by a mechanical lip-gripping device used by recreational anglers. Fisheries Research 93, 248-252.

Cooke, et. al., 2006. Is catch-and-release recreational fishing compatible with no-take marine protected areas? Ocean Cost. Manage. 49, 342-354.

Cooke et. al., 2001. The influence of terminal tackle on physical injury, handing time and cardiac disturbance of rock bass. N. Am. Journal of Fisheries Management, 21, 265-274.

Cooke, S.J., and D.P., Phillip, 2007. Improving the sustainability of catch-and-release bonefish fisheries: insights for anglers, guides and fisheries managers. In: Alt J. (Ed), Biology and Management of the World Tarpon and Bonefish Fisheries. CRC Press, Boca Raton Florida, pp. 359-381.

Danylchuk et. al., 2007a. Post release mortality of bonefish, exposed to different handling practices during catch-and-release angling in Eleuthera, The Bahamas. Fish. Manage. Ecol. 14, 149-154.

Danylchuk et. al., 2007b. Effects of recreational angling on the post release behavior and predation of bonefish on tidal flats in Eleuthera, The Bahamas: the role of equilibrium status at time of release. J. Exp. Mar. Biol. Ecol. 346, 127-133.

Ferguson, R.A., and B.L., Tufts. 1992. Physiological effects of brief air exposure in exhaustivity exercised rainbow trout: implications for catch and release fisheries. Can. J. of Fish. Aquatic Sci. 49, 1157-1162.

Gregg Thomas

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