Dive Time with Tim Grollimund

Snook recover after 2010 cold snap

September 27, 2013 

A snook is framed by a school of minnows on French Reef. (Photo by Tim Grollimund)

TIM GROLLIMUND

Snook seem to be a popular topic these days. They are a Florida icon, and underwater I would consider them part of the charismatic fauna we have here.

They can be very shy, and they like to hide under ledges and in swim-through areas on the reef. They stay pretty much on the bottom. They seem peaceful and don’t seem to mind divers if approached cautiously.

I usually make sure they see me, and approach them in a slow, deliberate fashion. I don’t think I have ever seen one move very fast, but as I said, I approach them with no sudden movements. I think they like to find a spot and hangout, like a couch potato (where’s my remote?).

This year I’ve seen a lot of snook on French Reef and in several spots on Molasses Reef. They were there in numbers a couple months ago when the massive minnow schools were on French Reef. The groupers and snappers were zipping all around, and the snook were lethargically sliding in and out of the minnow caves.

I have seen more this year than ever — but my first winter was the 2009-2010 cold snap. Scientists say that about one third of the snook stock did not survive that cold spell, and the effect was the most devastating on the juvenile population, which are a bit less tolerant to chilly water.

Snook have a long history of recreational fishing, and are an important part of the flats fishing effort. A lot of guides get a lot of paychecks from helping anglers catch snook. After three years as a catch-and-release scenario, folks can take them this year. New fishing rules allow one per day per person within specific size ranges.

The importance of the flats fishery to our economy is huge. According to the recent Bonefish and Tarpon Trust report, in 2012, well over $400 million in economic impact was generated from flats fishing. Although snook fishing is not broken out as an individual species in the report, it is included in the “Other inshore” category with redfish, sharks and barracuda. This segment accounted for 45 percent of the total expenditures. You can see this report here: http://blog.bonefishtarpontrust.org/?p=1378. Open the link and see Table 19 on page 22.

From what I have read in other articles and reports, there are still some scientists and guides that think it’s too soon to take any snook, and they should be catch-and-release for at least another year. One of the concerns is a large part of an entire age cohort is missing from the population. Juveniles in the shallows were the hardest hit, which leaves a gaping hole in the age continuum. It’s sort of like a college that has a recent graduating class about half the size of a normal graduating class. There’s a bunch of folks missing.

How will that cold-shortened graduating class affect the breeding stock in the next few years? They have made a great comeback, no doubt about it, but perhaps that is one of the concerns of the folks that want to keep them as a catch-and-release species for a while longer.

What a great example of the resilience of a species when protective measures are implemented. Now we have more on the reef, and some in the pan.

Another interesting aspect of the snook population is documented in the telemetry study from the FWC Fish and Wildlife Research Institute. They acoustically tagged 30 snook in the 9-square mile Banana River No-Take Reserve near Kennedy Space Center. This is one of the oldest no-take reserves in the country. They looked at the movement of snook within protected waters and beyond.

They examined the no-take reserve as a spatial approach to fisheries management, with the export of targeted species over time — spillover — as a primary component of the observation data assembled. They found that after a year and a half into the study, none of the larger fish that left (spilled over) returned to the reserve. One was found about 118 miles away by a fisherman, who returned the acoustic transmitter.

On the down side, they found that smaller individuals were less likely to migrate. This had a severe effect during the cold snap, as movements of tagged fish in the reserve stopped, suggesting they had not survived the cold.

According to the FWC website, “The current investigation illustrates how such extreme events can severely deplete the population of a singular no-take reserve. To be effective as fisheries management tools, multiple no-take reserves may need to be spread throughout the range of the focal species.” See http://myfwc.com/research/saltwater/fish/snook/telemetry/ for the detailed information.

In another article on the Snook Foundation site (http://snookfoundation.org), Ron Taylor is quite specific on the habitat and life-cycle needs of a healthy snook population. The article is called “The Developmental Stages (Ontogeny) and Associated Habitats of Common Snook.” This is a good read, as it details the entire life cycle of snook, and spells out the critical importance of healthy mangroves and upland rivers to juvenile development and recruitment into the adult population. I loaded a pdf version on my web site for easy access: http://timgimages.com/PDF/Developmental_Stages_of_Snook.pdf

All in all, snook demonstrate a great comeback for an iconic species with some protection in place, the positive effect of spillover from protection as a fishery management technique, and the importance of protecting diverse habitats to ensure the transition of juveniles to the adult population.

There is a great lesson here for ecosystem protection initiatives.

Tim Grollimund is a freelance photographer and PADI divemaster based in Key Largo. He can be reached at tim@timgimages.com or through his web site at www.timgimages.com.

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