Hold Me Tender: Looking After the Fish We Catch

Hold Me Tender: Looking After the Fish We Catch

Some recent research has confirmed what many anglers have suspected for some time – holding fish vertically can cause them damage.

To anyone who hasn’t used them, lip grippers are a handy little tool that use a pincer-like gripping movement to hold onto the lip of a captured fish. This can make it easy to remove a hook with minimal fuss prior to release, and can also reduce the need to have the fish come in contact with other surfaces (which can help protect their slime coating, scales and skin). So effective are these devices at holding fish securely, that some anglers have taken to using them as a handle; lifting their fish up by the lip to bring it into the boat and take photos, before release.

cod on boga

Figure 1. Pic courtesy of Jamin Forbes

Figure 2 Lip grippers can be a great way of handling big fish safely when used correctly (Pic courtesy of Jamin Forbes)

Figure 2. Lip grippers can be a great way of handling big fish safely when used correctly (Pic courtesy of Jamin Forbes)

 

A little while back, a fisheries researcher from the Northern Territory, Alf Hogan, was moving barramundi broodstock between tanks, lifting each one by its lower jaw as he did so. He was later concerned to note that all of the broodstock lifted in this manner subsequently died. A detailed follow up study was later conducted by some researchers from the (now) Department of Primary Industries, Fisheries and Resources in the NT, to look more closely at the effect of lifting barramundi using ‘lip grippers’.

The researchers ‘exercised’ barramundi (basically, chased around a tank until they were tired) to simulate capture with rod and line, before attaching a lip gripper to the lower jaw of 21 fish. Ten of those fish were then held out of the water using just the lip gripper for 20 seconds. The remaining 11 fish were lifted with the lip gripper, but with a hand supporting the fish at its midsection in a horizontal position. They then compared the survival and injury levels between these fish, and another 10 barramundi which had been held out of the water in a landing net for the same length of time (with no handling using lip grippers). Whilst only 2 fish died (it doesn’t look like these deaths were related to the different handling approaches), X-rays showed that lifting fish with lip grippers shifted the alignment of the fishes’ vertebrae, which did not return to normal after three weeks.

Figure 3 X-ray of a barramundi showing the natural curvature of the first four vertebrae and the locations where distances between vertebrae were measured (source: Gould and Grace 2009)

Figure 3. X-ray of a barramundi showing the natural curvature of the first four vertebrae and the locations where distances between vertebrae were measured (source: Gould and Grace 2009)

The researchers suggested that the injuries received by fish being lifted using lip grippers might have resulted in deaths if they had used larger fish (the fish they used were between 53cm and 102cm in size). It is also possible that the shift in spinal alignment may have resulted in reduced health issues which played out beyond the duration of the study.

Figure 4 Holding fish using lip grippers whilst still in the water is a great way to keep them calm and healthy, maximising their chance of survival (Pic courtesy of Jamin Forbes)

Figure 4. Holding fish using lip grippers whilst still in the water is a great way to keep them calm and healthy, maximising their chance of survival (Pic courtesy of Jamin Forbes)

Whilst this study focused on barramundi, it is likely that other species like Murray cod, big threadfin salmon and jewfish, also don’t handle being lifted up by their jaw (would you!?).  What’s more, these findings also raise some concerns at potential impacts of grabbing fish by their tail and lifting them up (which anglers do from time to time with tunas, mackerels and a host of other species).

So in short, if you’re using a lip gripper, keep the fish in the water if possible (through look out for crocs up north!). If you must take the fish out of the water, make sure you give it plenty of support at the fish’s mid-section. This will help to minimise the stress on its operculum and spine, and make sure it swims away to fight again another day.

Fact Box:

For more information on the latest science relating to recreational fishing, visit the Recfishing Research website. Recfishing Research is a national group established to improve investment and the return on investment in recreational fishing research, development and extension at a national scale.

If you would like to be kept informed on important research developments relating to recreational fishing, contact Recfishing Research’s Extension Manager on matt.barwick(at)recfishingeresearch.org.

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Matt Barwick
Matt is Program Coordinator for Recfishing Research, a national Subprogram under the Fisheries Research and Development Corporation which plans and manages research, development and extension activities to deliver benefit to Australia’s recreational fishing community. Matt has delivered projects in Australia and overseas, in both marine and freshwater systems, working closely with recreational, commercial and indigenous fishing sectors.
Matt Barwick

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