May 11

Bonefish Mortality – the good news

(This post was originally posted on Nov. 9, 2009.  I’m recycling it for my “Good C&R Week”.

After my bonefish vs. sharks (and cudas) post I put it up on a couple message boards and folks… well… they weren’t fans.

One guy even went so far as to suggest that pretty much any landed fish was going to die, specifically saltwater fish and in particular bonefish.  So, I had to go and find some more information.

The news was pretty positive.  Basically, if you limit your handling of the fish and limit the fish’s exposure to air, they are going to do well.  The good folks at Carlton University, again, had the goods.

In one study, out of 12 fish caught and tagged with gastric implanted acoustic transmitters one was killed quickly, one transmitter was found two days later and the 10 remaining  tags were still swimming around (in their bonefish hosts) at least 13 days later.

Here’s the study.

Ah… well… that’s nice to know.

Here are the conclusions reached as it pertains to how anglers, guides and fisheries management folks could help improve the survival rates of bonefish post-release.


The results of our study suggest that there are opportunities for anglers, guides, resource managers and conservationists to enhance the sustainability of recreational bonefish angling. …(1) Our first recommendation would be for anglers to land fish as quickly as possible and to minimize air exposure during the hook removal and release phase. A cooler or live-well aboard boats may provide an appropriate holding unit to minimize air exposure for this procedure. In fact, we recommend allowing all captured fish to recover for 2–3 min in a cooler or live-well prior to release. Fish that are returned to the water without losing their equilibrium should be better able to avoid predators and resume normal activities more rapidly. Because the likelihood that a bonefish will survive after release is substantially reduced in regions where sharks are abundant, distracting a shark by splashing may be helpful, but will not prevent all predation. (2) We also recommend, that when sharks are in the immediate vicinity of release, anglers hold their bonefish in a cooler or live-well and transport it to an alternate release location. This action may not be possible for anglers that are wading. If sharks are present and the likelihood that a shark will attack either angled or released fish is high, we encourage anglers and guides to relocate to an alternate location. If a captured bonefish is bleeding, we recommend that it be held in a live-well/cooler for 2 min to allow clotting before release or moved to an area with complex cover such as mangroves. The conservation of bonefish will depend upon anglers using strategies to release fish in good condition, such that they can avoid predators.  Educational material related to proper fish handling needs to be  disseminated to stakeholders around the globe that are involved in catch-and-release bonefish angling, or management of these fisheries resources.

I think in a subsequent study the idea of releasing the fish near mangroves turned out not to be effective as bones seem to head to deeper water (where lemon sharks are known to lurk), not the mangroves.

One of the researchers, Dr. Cooke.

Nov 09

Bonefish vs. Sharks (and cudas)

On the rather long list of stuff I didn’t know about you can add the growing body of knowledge regarding bonefish catch and release mortality.

It turns out that, depending on what is lurking nearby and how long it took to take that picture, mortality of bonefish in the R part of the C&R equation can be up to 40%.  FORTY PERCENT! Holy $h1t!

(UPDATE: the study referenced here the mortality rate for bonefish that had lost equilibrium was about 30%, another study pointed toward 40%)

Forty percent… as a trout C&R angler, I’m used to thinking of that number more like 3-5%.  40% just seems totally unacceptable and I hope if you are reading this, you’d find it unacceptable as well.

How this came about… scientists, anglers, the Bahamas, bonefish… an intriguing mix that yielded some really interesting and important findings.

Whether a bonefish had or had not lost equilibrium was a significant predictor of predation, with bonefish losing equilibrium being over six times more likely to suffer predation than those that did not lose equilibrium (sciency stuff removed here). All other variables measured during the study (total length, angling time, handling time, air exposure time, bleeding, and water temperature) were not directly related to predation risk.

Fish that were preyed upon did not spend significantly more time further from mangroves than fish that were not preyed upon. In fact, following release 17 (20%) bonefish were observed swimming into open water (N2.5 m deep) rather than staying in close proximity to the shore line or in shallow water.
Longer air exposure and overall handling times were significant predictors of the loss of equilibrium in angled bonefish. Angling time, total length, water temperature, and bleeding at the  hooking site were not significant predictors of equilibrium loss.

If you want to read it straight from the abstract, you can find it here, courtesy of Cooke Lab at Carlton University (Canadian).  (Thanks Steve for the hook up on this study.)

So, what does this all mean?  It means dropping the Hero Shot is a really, really good idea if you care about that particular fish living.  If you can take a pic of that fish in the water, great… but if you do what I did on my last trip and take the fish out of the water (or have the guide take the fish out of the water) for an extensive photo shoot… well… it won’t go well for the fish and it may only have a couple of minutes left to live.

If the fish is unable to right itself when you put it back in the water, that fish is in trouble.  It could even be that these stressed fish even leave a trail of chemicals  behind them that predators like Lemon Sharks zero in on.

Jason Lozano, one of the anglers involved in the study had this to say…

With 15 seconds of air exposure 80% of the fish we released in one day were killed by lemons or cudas within 2 mins. If the fished avoided contact with the predator longer than 2 mins their chances increased substantially.

Jason pointed out that some flats clearly had more predators than others.  If you are fishing a flat with more cudas or sharks and you take that fish out for the glory/hero shot to the point it loses equilibrium when it is released, well, that fish will likely die soon.

So, to review… don’t take the fish out of the water.  It’s a bad idea if you want the fish to survive.

UPDATE: In the study referenced above, bonefish that had lost equilibrium had a mortality rate of 30%, while bonefish that did not lose equilibrium had a mortality rate of about 4%.

Bad Idea…

Bad idea

Knowing what I know now, I wouldn’t have taken this picture.

Good idea…