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Florida’s Sharks: a shifting baseline?

Written by

Mission Blue

Published on

July 23, 2012

By Samantha Whitcraft, Shark Savers International
Photo: Mary O’Malley, Shark Savers

Florida is one of those places that like South Africa and Australia, is synonymous with sharks. The good news is that the State of Florida has listed 25 species of elasmobranchs as completely protected from harvest, on their ‘Protected Species’ list. The Florida Fish and Wildlife Conservation Commission (FWC) defines this protected status as prohibiting the harvest, possession, landing, purchase or sale of these species or any part of them. The complete list includes not only some of the most charismatic species like white sharks and whale sharks but also species that are more rare like sawfish and basking sharks. And in the past three years alone, a united coalition of local conservation organizations, scientists, catch-and-release fishermen and concerned citizens have rallied to add several more species to that list.

First, in February 2010, to protect a unique, local aggregation that is popular with both local and visiting divers, lemon sharks were added to the list. Then, more recently, in November 2011, the FWC added three species of hammerheads — great, scalloped and smooth, and tiger sharks to the list; becoming the first place to specifically protect the much-maligned tiger shark.
Additionally, as FWC explains, “Sharks have been strictly regulated in Florida since 1992, with a one-shark-per-person, two-sharks-per-vessel daily bag limit for all recreational and commercial harvesters and a ban on shark finning. Roughly two-dozen overfished, vulnerable or rare shark species are catch-and-release only in Florida waters.”
There is no doubt that these are important measures for shark conservation and our ocean ecosystem, given their often key ecological roles as apex predators. However, there remains a gap in their protection in that many of these same species don’t have similar protections in Federal waters. This means that they can be harvested, within the limits of federal laws, beyond the 3 nautical miles offshore in the Atlantic and the 9 nautical miles offshore in the Gulf of Mexico that encompasses state waters.
Photo: Mary O’Malley, Shark Savers

But why are both state and federal protections so vital? If Florida is, indeed, synonymous with sharks, aren’t there plenty around? The answer to that question depends on the species and on the time frame referenced, and on whom you ask. Scientists estimate that between between 1981 and 2005 hammerheads suffered more than a 90% decline in the northwest Atlantic and the Gulf of Mexico. Meanwhile, Florida divers report seeing nurse sharks fairly regularly but rarely a tiger shark or hammerhead of any species, besides bonnetheads. But that wasn’t always the case; even as little as 30 years ago, local Florida divers remember regularly seeing lots of big sharks at select dive spots. Today, however, many of those sites are now either devoid of these amazing animals or seeing one is a happy surprise. More experienced, long-time divers recount their memories of a time when they saw sharks regularly including large schools of bull sharks and migrating hammerheads; but now, they rarely do.

In the Shark Savers’ short film, “Now, More Than Ever, Sharks Count,” * a few of Florida’s first and most experienced shark divers share their individual experiences of witnessing a ‘shifting baseline’ in the number of sharks in their waters, over the past several decades. What is a ‘shifting baseline’? The term was first coined by fisheries biologist Daniel Pauley in 1995, and today the concept is more broadly applied to the gradual shift over time in each new generations’ expectations of what any healthy ecosystem looks or functions like. In other words, a new diver today might see a few nurse sharks and a reef shark on a dive down in the Florida Keys and think that represents an expected, average ‘baseline’ of sharks for that reef ecosystem. But a historical look back over the 20th century might suggest otherwise.

“Now, More Than Ever, Sharks Count” Executive Producer, Samantha Whitcraft

In the 1920’s and 30’s there were at least two significant shark processing factories on Florida’s coasts – one in Port Salerno, Martin County and the other on Big Pine Key in the Florida Keys. By 1946, at the height of its production, the factory in Martin County used 12 boats to catch and processed 25,000+ ‘tigers of the sea’ per year. Meanwhile, the factory in the Keys used six boats and reportedly landed 100 sharks per day, on average. These larger factories eventually went out of business, because cheaper sources of vitamin A came on the market, but the sharks were likely also fished out of the area. Today, in some of these same waters, it can take days for researchers to find one large tiger shark or even a known aggregation of lemon sharks.

However, today, Florida is still associated with sharks, especially, in the press when the rare bite of a surfers’ ankle or a bloody catch and kill tournament, or rare sightings of a white shark gets much of the attention. But the real story is that Florida’s rich coral reefs and dense coastal mangroves were once far richer in sharks than they are now. Divers today hope to one day see what these ecosystems may have looked like before the baseline shifted; how much more healthy our coastal waters might be when vital apex predator populations rebound. That is why Florida needs to continue to lead the way in shark conservation.
Shark Savers was founded in 2007 by six long-time divers driven by a shared passion – to save the world’s dwindling shark and manta populations. Today, more than 25,000 members from 99 nations share that passion. Shark Savers’ programs result in more protections for sharks and rays, both locally and globally.


* Official Selection and Finalist (Digital Interactive Campaign category), Blue Ocean Film Festival – 2012



References:
M.R. Heithaus, Burkholder, D., Hueter, R.E., Heithaus, L.I., Pratt, Jr., H.L., and Carrier, J.C. 2007. Spatial and temporal variation in shark communities of the lower Florida Keys and evidence for historical population declines. Canadian Journal of Fisheries and Aquatic Sciences, 64: 1302-1313.