DVL quarry

BAROTRAUMA takes toll at DVL winter tournaments…

UPDATED, 3-26–For those regulars fishing Diamond Valley Lake this past winter where tournament limits were reduced to three fish per boat for a DFW study of barotrauma, you should know the results will soon be published, according fishery biologist Quinn Granfors.

Having seen the report, all I can say is, if there was a bright spot in the data, it was that, “deflation significantly reduced mortalities.” But as the insurance commercial says, “Everybody knows that.”

Here’s a brief synopsis. A portion of all the fish–specifically those showing some signs of barotrauma taken from eight winter tournaments–was divided into two groups. Of those 214 bass in the study, 107 were deflated while the other 107 received no such treatment.

And here’s how it shook out. Of the 107 that were not deflated, 32 percent died. Of the other group of 107 that were deflated, 14 percent died. In both cases, this mortality occurred within 36 hours of the event. In other words, among those fish in some distress, deflating increased survival.

Likewise, from those fish that showed no external signs of barotrauma (“positive buoyancy or abnormal swimming, external hemorraging, bulging eyes or gas-bladder distention”) they not only looked better, they were better. The study showed just 2 percent of those fish succumbed.

But here’s what detractors will bring up. The study entailed a total of 655 total bass. Of those, more than one third of all those showed signs of trauma (including DOA’s) and if all were treated and survived the same rate as those in that group in the study, the losses would have been 30 bass even after decompression, plus 28 that were deceased by the time of the weigh-in, plus 4 that might die though they looked fine. Put those together, you get just under 10 percent loss in a live release event.

Clearly, the three-fish limit probably helped the cause, but the question will surely come up: are these acceptable losses?

The report concludes, “Further study is needed to evaluate how immediate or delayed deflation, the two artificial deflation methods [needle or crating], shortened tournament duration, or a reduced bag limit affect FLMB [Florida largemouth] mortality to provide sound scientific recommendations to fisheries managers.”

So, any suggestions before regulations inevitably come our way?

BTW: You can find a pdf of the entire study here. From there find “Barotrauma related mortality” and click to download.




One Response to “Barotrauma results at DVL unveiled”

by Jason Prewitt

Hey George, I’ve read that journal article and it is an excellent publish. Quinn did a fantastic job on shedding light on barotrauma and the effectiveness of proper and responsible needling and catch and release technique. His methods were sound and his calculations were very significant. It’s a great read. I hope everyone gets a chance to study that paper. I would say be ready for a 3 bag limit every winter at DVL… Don’t quote me but that may be coming.