September 11, 2013
By Jeff Weakley
Haul seine net used in routine survey of snook.
The Florida Fish and Wildlife Conservation Commission (FWC) performs regular stock assessments of common snook, using information collected through a variety of sources. Management recommendations such as seasons and limits are proposed by FWC staff, with input from working groups composed of citizens, scientists, fishing guides and private advocacy groups such as the Snook & Gamefish Foundation. Draft recommendations are subject to public comment and final approval by the seven governor-appointed Commissioners. Generally, new regulations are published twice per year, but sometimes emergency measures are taken, as for snook following the cold kills in 2010.
Below are some important points from the recent snook stock assessment update, published June 5, 2013:
* Snook all around Florida got a good score in 2012, suggesting populations are bouncing back. The “score” in this case is a measure of the Spawning Potential Ratio. The SPR is basically an estimate of how successful the fish are at reproducing, given that a certain number from each year class are removed through fishing. The FWC aims for 40-percent SPR for snook. The SPR for the Atlantic stock in 2012 was 34 percent; the Gulf stock, 58 percent. (One expected byproduct of the 40-percent SPR goal is more trophy-size snook out there.)
* Anglers' catch rates for snook on both coasts are again rising. Figures for the Gulf, Atlantic and Everglades National Park showed a drop in catches in 2010 and 2011, following those back-to-back winters of exceptional cold. (Generally, sustained exposure to water temperatures below 60 degrees Fahrenheit may be lethal to snook.)
* Scientists also use haul seine nets to catch small snook, which can help determine “recruitment”—
how many fish are entering the population each year. These fishery independent monitoring data show increasing trends in the last few years, which is good. The surveys, like angler catches, had shown declines during the bad winters.
* Quick timeline of what happened:
- January 2010: Florida snook fishery closed by executive order, following widespread reports of snook dieoffs on all sides of the Florida
peninsula.
– Sept. 1, 2011: Atlantic coast snook fishery reopens under previous management rules, including Dec. 15-Jan. 31 and June 1-Aug. 31 season closures; 1-fish bag limit; 28- to 32-inch slot limit.
– Sept. 1, 2013: Gulf Coast and Monroe County snook fishery reopens until Dec. 1, with 1-fish bag; 28- to 33-inch slot limit.
How does the Angler Action Program figure into these calculations?
According to Dr. Luiz Barbieri, Program Administrator, Marine Fisheries Research for FWC, the AAP data helps fill in some gaps in catch models.
“The main piece of information we're getting from AAP is the size composition and magnitude of discards,” said Barbieri. [Discard being a formal, if slightly less friendly, way of saying “releases.”] “This is difficult to get through the regular survey processes.”
At present, there are three main kinds of survey processes: One, the fishery independent haul seines mentioned already. Two, creel surveys from Everglades National Park. And three, the federally administered Marine Recreational Information Program, or MRIP. The MRIP produces catch rate estimates through a two-step process: 1) Randomized surveys of citizens by telephone or mail, to estimate the number of fishing trips; and 2) estimates of what types and sizes of fish are being caught, based on shore intercept interviews—those field biologists you occasionally encounter at the dock.
In the case of snook, about 97 percent of the catches are released, which means shore intercepts reflect only “a miniscule portion of the total catch,” said Barbieri. “To have an idea of what people are actually catching and releasing, we need to have some idea of the discards.”
“Most of the stock assessment models are looking at co-horts—or year-class—of fish born in a certain year, and how they work through the fishery. We need to know the numbers born, how many survive this year, to the next, and so on. Then we need know the numbers being killed… for example, 5 to 10 percent of seatrout released have post-release mortality. Basically, the stock assessment guys come up with the total numbers of fish killed—if this many are estimated to have been harvested, add 5 percent of the number of fish released, to come up with the total actual kill.”
The recent snook closures shed some light on the importance of those kinds of figures. As Barbieri explained, the FWC took a precautionary approach when it closed the snook fisheries.
“When we looked at fisheries independent program, it looked like the smallest sizes were most impacted by the cold kill,” he said. “MRIP data was not that informative, showing more of a flat trend.”
In other words, angler catches seemed to remain steady, but field reports on both coasts suggested many adult snook had perished during the cold snaps. For the Atlantic coast, however, the FWC had one crucial piece of data—an acoustic tagging study in Palm Beach County revealed that adult snook moved away from the cold water and returned. “We were able to recommend keeping the east coast open, because we didn't see impacts comparable to what was over here [on the Gulf side],” said Barbieri.
Had the FWC had a more complete picture of the Gulf Coast snook population—including catches retained or released at all ages—a more targeted management decision may have emerged. And it's easy to imagine how future decisions might hinge on such data fields.
However—the AAP model has its own hiccups, including built-in biases. What if the majority of entries are provided by expert anglers and/or those periodically very lucky? Sort of a “Forum effect,” where fishing reports—while inspirational and useful on some level—may not provide an accurate sense of what's actually out there. I brought this up to Barbieri.
“At this point, we don't have a way to correct for that,” he replied. “But our need for discard information is so large, that even the sub-optimal information we get through volunteer angler programs is welcome and informative.”
Ron Taylor, Associate Research Scientist at FWRI, echoed Barbieri's comments regarding the utility of logbook reports for generating data on released fish. Taylor, resident snook guru at the institute, has been personally involved in helping design the format for the reports. He noted, too, that the federal National Marine Fisheries Service and state FWRI “have supported the AAP with the caveat that they develop a means to validate the reporting.”
Taylor and Barbieri said a study is slated to begin in spring 2014, specifically addressing the issue of correcting for biases in volunteer data. “We might be able to come up with some correction factor, or we might handle this in a different way, such as a panel picked randomly through some directory,” suggested Barbieri.
Angler reporting of catches is a tool still in its evolutionary stage, but it appears likely that state and federal fisheries researchers will wish to move forward with it. And if the popularity of Forums, Facebook, and personal logbook apps is any indication,
anglers seem eager to participate. FS
