Sweet Release?

Species of game fish react differently to being hooked; understanding those differences can help anglers reduce mortality of the fish they release

shark release

shark release

Doug Olander

(This editorial appears in the May 2014 issue of Sport Fishing.)

All those teeth and bad reputation notwithstanding, some sharks aren’t all that tough. In fact, in terms of how they hold up after a battle at the end of a line, some are downright wimps.

That is, in part, the finding of a new study with the hefty title of "Physiological stress response, reflex impairment, and survival of five sympatric shark species following experimental capture and release," published in Marine Ecology Progress Series, Volume 496. ("Sympatric," by the way, just means they're found in the same general waters.)

Scientists fought and caught five species of sharks on hook and line using standardized techniques for comparison purposes. While the authors note limitations of this initial study, calling for further research, they did form some interesting conclusions with applicability to sport fishermen.

It seems that the five species reacted differently to the stress of fighting on a line. From this study, tiger sharks qualify as tough customers, with nearly 100 percent of those tracked up to four weeks after release doing just fine. The study lists lemon sharks as being nearly as hardy, based on lactic acid levels and other parameters measured, since post-release survival studies were not conducted on lemons.

Bull sharks fared pretty well after release, with 74 percent surviving. Somewhat less hardy were blacktip sharks. But the most susceptible of all to the rigors of a long struggle when hooked were hammerheads, with more than half suffering mortality during the weeks after their release.

This makes me wonder what sort of differences in post-release mortality there might be among other closely related game fishes. Anyone who fishes for redfish and trout knows that reds can stand a bit of quick handling before release, but even minimal handling can leave a seatrout too weak to swim. I know that among deepwater rockfishes along the Pacific Coast, some species are too barotraumatized ("blown up") to swim back down if pulled from 50 or 60 feet of water, while other species can be taken from 100 to 150 feet or so and usually swim back down with no trouble.

The Atlantic’s popular black sea bass readily show signs of barotrauma, such as the stomach being everted from the mouth thanks to expanded swim-bladder gases. Anglers probably wonder — as did scientists — how many of these “inflated” fish could survive, even those that managed to swim down. Turns out, from a very recent study, most of them; long-term survival of fish studied was 90 percent.

Lots of anglers release fish pretty regularly. Clearly, we want them to survive. The more we know about how species react, the more successful we can be at minimizing release mortality. Information like that cited above can help us. So will a visit to fishsmart.org, a site dedicated to helping anglers follow known best practices in releasing fish.

Before closing, I must offer what I've come to consider the obligatory disclaimer. Neither I nor Sport Fishing has any sentiments whatsoever in any way, shape or form against keeping fish to eat. I find that something of "release backlash" has formed among some fellow fishermen, so any talk of releasing is construed as some sneaky PC way of saying that keeping any fish, ever, is wrong. No one (on this website) is saying that — only suggesting that knowledge of how fish do and do not survive after anglers let 'em go is a good thing: It's in all of our best interests to maximize survival of fish we release.