Tuesday, July 2, 2013

West Side

Current findings yield a fresh view of snook populations

The FWC commission met Wednesday, June 12 in Lakeland and determined, among other things, that snook are ready to open for harvest on Florida’s west coast.

 Recent history

It’s common knowledge to most of us that the winter of 2010 had quite an impact on Florida’s warm water fish, especially snook. The east coast population of snook came through relatively unharmed, but the west coast snook got hammered, especially way down south in the ‘glades and 10,000 Islands area.
The snook fishery across the entire state was shut down from harvest so biologists could assess just how hard the population was hit. After a year, it was determined that the east coast could handle an open season while the west coast still appeared to be quite sparse. Consequently, as we all know, the west coast had remained closed since 2010. The Commission has decided that the closure will expire this fall.  Old timers will tell you that a cold snap such as the 2010 winter occurs every decade or so. While this is true, this event was a singularity. “When this has happened in the past, the water temperatures might dip below 55 degrees (Fahrenheit) for two or three days, then climb back up. In 2010, there were areas where the temperature stayed below 55 for 14 straight days. That has never happened in the recorded history of Florida,” says Ron Taylor, senior snook biologist at FWRI (Florida’s Fish and Wildlife Research Institute). As it turns out, a cold spell that lasts that long had an additional impact on the surviving fish 
– it caused them to change habitats or locations where they normally occur. In other words, they abandoned their homes and moved. Sometimes maybe just down the same shoreline, or maybe across the bay. It doesn’t matter how far; the point is they weren’t where they used to be. Keep that thought in mind, it’s going to be an important part of the story.

Measuring Snook Stocks

The State of Florida uses a Spawning Potential Ratio (SPR) formula to determine the health of the snook fishery. SPR essentially measures the number of eggs that could be produced by a fish over its lifetime incorporating human fishing interaction against the number of eggs that would be produced if there was NO human fishing interaction. Essentially it boils down to a measurement of how much the overall population is impacted from fishing. What seems funny about SPR is that it doesn’t take natural occurring events into account, like red tide or cold kills. Consequently, the SPR on the west coast is a very robust 56% right now, well above the target of 40%.
Here’s one reason why SPR confuses some people (me included). If it measures the health of a fish population based solely on fishing, why isn’t the west coast SPR 100%? The season has been closed for 3 years! The answer makes sense when explained properly. Re-enter Ron Taylor: “You have to consider the fact that snook (on both coasts) live to be 21 years old. So while the season has been closed for 3 years, there are 15-20 year-classes (also called cohorts) of fish swimming in the water that were part of fishing harvest in the past.” In other words, SPR is not a snap-shot measurement. If the season were closed for 21 years, then the SPR could approach 100%. I’m leaving cryptic mortality out of the equation, but you get the point – SPR is a lifetime measurement and it takes the entire population into account. Or more technically, it is the contribution of the sum of mature female cohorts in the stock. 

Bottom line: Was the west coast really ready for an open harvest season?

Seems like the picture painted thus far might lead you to say no – longest cold snap in history, west coast was more impacted, etc. That sounds gloomy. But there are always two sides to every story.

A snook that was spawned right after the cold snap will be 3 years old this summer. A 3-year-old west coast female snook averages 28.3 inches long. That means that even if the west coast season had been open since 2010, none of the post-chill snook would have been legal to harvest anyhow. Further, giving a 3-year break from harvest to the bigger fish that survived the cold kill has had a very positive impact on the fishery.

Now is the time to recall the point I made earlier about snook moving down the block after the cold snap. Like I said, the surviving fish changed location. What that means is when FWRI biologists headed out to the random spots where they counted fish, there weren’t any. When snook guides cruised past their favorite snook holes, they probably didn’t see anything.
However over time, the bigger fish are coming back to their original stomping grounds. Ron Taylor explains, “In 2010, I went to my usual fixed sampling locations and collected very few - maybe 3 or 4 fish over 30 inches. In 2011 and 2012 I was sampling the same sites with the same effort and finding 35-50 snook. Those fish are older than 3. This tells us they survived the cold and disappeared for a while, but now are moving back into more traditional locations.”
That jives with catch rates reported in back country fishing tournaments in the Keys. In 2010, the entire fleet of theIslamorada Backcountry Fly Championship only caught 3 snook. That was right after the freeze. In 2013, they measured 27 snook and probably twice that many were caught overall. Each year the snook in that tournament average around 29 inches in length. That means they are cold snap survivors returning back to familiar spots. So two advantageous dynamics are at work simultaneously that have caused the west-coast snook stock to improve- the additional contribution that resulted from the harvest being closed PLUS the return of the survivors that had moved or changed their normal habitat.
  • West coast closed seasons: Jun 1- Aug 31; Dec 15 - Feb 28
  • West coast slot: 28-33 inches total length
  • East coast closed seasons: Jun 1- Aug 31; Dec 15 - Jan 31
  • East coast slot: 28-32 inches total length
  • More Info at the FWC site here, and get a peek at the snook stock presentation here.
The FWC report that was reviewed in Lakeland suggested that juvenile sized snook were hit the hardest. To me, this means that most surviving fish are already larger than the snook slot, and will be protected for the rest of their natural life from harvest whether there is a season or not. Those larger fish are the key to a robust fishery in the future, as studies clearly show that larger females produce healthier eggs, and plenty more of them to boot.
The FWC stock report concludes with the notion that the west coast population is in the process of recovery, and opening the season as scheduled won’t stop the population from growing. Ron Taylor says that there is no statistical or biological reason to keep the fishery closed.
Taylor also said there was another incentive for opening the season. “We have not been able to collect carcasses from anglers on the west coast for 3 years. We use those fish to age and sex the population.” This information is used measure the health of the population and to determine if harvest can be supported. “An open harvest allows us to start collecting that data once again.” You can compare that to your latest trip to the doctor where they drew blood. Watching someone poke into you to extract blood might seem counterintuitive to staying healthy. But that blood work (and by analogy, the data from an open harvest) often reveals a disease that can be addressed, or unveils an allergy you were previously unaware of, or one of a host of preventable health problems.
The Snook & Gamefish Foundation is confident that FWRI staff made the most informed recommendation possible. For one thing, they considered data that was provided directly from anglers via the Angler Action Program (AAP).
Florida anglers are extremely fortunate to have a commission that has proven to take public comment into consideration. They then balance that input with the information gathered from FWRI’s very dedicated staff of scientists and managers who work diligently to ensure we have the best possible understanding of snook and many other species of fish. So take advantage, make your voice heard.

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