Dive Time with Tim Grollimund

Barracuda, the torpedo of the reef

November 7, 2013 

The barracuda opens up for a cleaning session with a juvenile Spanish hogfish. (Photo by Tim Grollimund)

Last time I dove the Duane, we did a double dip. During our surface interval we watched a boat zip around between the Duane and the Bibb, spearfishing for barracuda.

It took the guy our entire surface interval to spear one barracuda. I realize they are used for bait, but wow, I thought that was a lot of effort for one fish, and the one he speared was not really very big.

Barracuda are another iconic charismatic species in the Keys. On one of my first trips to the Keys, in the late 1980s, my first experience with a school of barracuda was on a night dive. While heading back up the line to the boat, I was surrounded, as thick as the light could penetrate, with a wall of barracuda about two feet in length.

Not the biggest I’d seen, but the sheer numbers were impressive, and admittedly, a bit intimidating. I remember thinking “only one of these guys needs to get crazy and I’m toast.” But they were docile, and I always think of that incident when I see a school now. The largest schools I have seen were in Indonesia and the Philippines.

Other than under the life support buoy at Aquarius Reef Base, the most consistent place I see schools of barracuda are on the shallow southern end of Molasses Reef. More congregate there than on the Duane. Glad it’s within the protected area. And most of the time they are difficult to approach, unlike the schools overseas. I see a fair amount of them with hooks and lures hanging out of their jaws.

While I was poking around looking for some science about barracuda, I found an article on one of the fishing sites that said “Problem is, like many other fish, barracuda numbers seem to be dropping in areas with lots of fishing pressure, like the Florida Keys. There’s no mystery there; couple a lack of respect from many anglers with no bag and size limit, and you’ve got a recipe for scarcity. Or worse.” See the article, by Joe Richard, first posted in 2005, and reposted in May, here: http://www.floridasportsman.com/2013/05/16/barracuda-stocks-in-question/

That makes sense to me. I have noticed fewer cudas on the Duane than there used to be. I agree with his assessment, and to see if I could attach some support to what he said, I pulled sighting frequency data from the REEF.org database. I looked at the Key Largo area from 1997 to this year. He’s right, at least as far as sightings by survey divers go.

The trend is down, from 88 percent sighting barracuda during a survey in 1997 to a bottom of 64 percent in 2011, and a slight rebound to 68 percent in 2012.

This also tracks with NOAA’s Marine Recreational Information Program, although their geographic areas are larger. Data for both East Florida and West Florida show a similar downward trend in catch survey data. Both areas bottomed out in 2011, as did the REEF sightings data.

Average length per catch is also showing a downward trend, and is approaching the length of maturity for females in East Florida. The 2010 cold spell seemed to intensify the downward trend.

I was not able to find a lot of scientific research on their spawning practices or aggregations, but I did find some other information on growth and age.

Males are sexually mature at one to two years (minimum 18 inches in length) and females reach maturity at two to four years of age (about 23 inches). The flow of larvae from offshore reefs inward to the shallows peaks in late June to early July, with a second peak in late August to early September. This suggests a split spawning season for barracuda, in June and August. In the study I read from the Bulletin of Marine Science (see http://timgimages.com/PDF/BarracudaAgeandGrowth.pdf) “all female barracuda with developed, hydrated oocytes were collected on offshore wrecks in the Gulf of Mexico and Atlantic.”

So my question is, does fishing the wrecks and taking the cudas, particularly in the summer, have a significant effect on the population? I guess time will tell.

While most folks concede that barracuda look quite menacing, they actually have one of the least strong bite force measurements among apex predators. For example, barracuda rate 83 Newtons on the scale, while a hogfish rates 290, a striped burrfish rates 380, a blacktip shark 423, a bull shark 1,023 and a great hammerhead a whopping 2,432.

Lemon sharks are about the same as barracudas, at 79. I think this is a bit misleading, since it is the anterior measurement. The posterior measurement is quite a bit stronger, around 260 in a large cuda. Because of the shape of the elongated jaw in barracuda, there are significant differences in the anterior and posterior bite force. Their conclusion is a crunching bite force is not necessary for a species to be an apex predator, but other feeding strategies may be part of the story. See http://timgimages.com/PDF/BarracudaBiteForceHabegger.pdf from the Journal of Zoology.

It’s not the bite, it’s the bang. A barracuda is a torpedo, and the relative weakness of the bite force is more than offset by the speed to a prey item. It’s called ram feeding, and the shape of the jaw, the gape as a barracuda approaches a prey item and the speed at which the blow is delivered contribute to the overall efficiency of a barracuda strike. See http://timgimages.com/PDF/BarracudaRamFeeding.pdf for this study.

I have to wonder if, in the future, barracuda will become another species of concern if their numbers continue to decline.

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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