Tuesday, June 14, 2016

LIft the Ban on Harvest of Atlantic Goliath Grouper? by Cantley Krafft

Atlantic Goliath Grouper (Epinephelus itajara) are, as the name implies, giant groupers that can be found in shallow waters along tropical coasts from Florida to Brazil. Due to their outstanding size and schooling behavior, these grouper were once vulnerable and highly sought after by commercial fishermen and divers. In 1990 the population was estimated to be approximately 5% of the original abundance (Shideler 2014). This devastation in the population was a result of poor water management practices and overfishing. Thus, in 1990, the Atlantic Goliath Grouper was listed as a critically endangered species by the IUCN, and a harvest ban was initiated (Koenig 2014). However, Goliath grouper populations have since seen a significant recovery, and now fisheries managers are facing pressure by anglers, divers, and other members of the Floridian community to lift the harvest ban in the United States (Shideler 2014). After studying the current ecological and human factors that influence the grouper populations, lifting the harvest ban on Goliath grouper would most likely threaten the population significantly and should not be done.
Goliath Grouper. Photo by W. Stearns is licensed under Ocean Research and Conservation Association
            Fisheries managers have studied the ecological influences on Goliath grouper for a long time now, and have found that these grouper have a large dependence on mangroves. Goliath grouper depend on mangroves largely for spawning and nursery grounds, as well as recruitment areas for adulthood. Mangroves provide a habitat for the juvenile groupers to obtain nutrients and protection before they reach adulthood and head out to coral reefs or sunken ships nearby (Frias-Torres 2006; Koenig et al. 2007). Koenig (2014) states “in the 1900s, before the harvest ban, poor water management in South Florida initiated the [population] decline by reducing the quality and coverage of mangrove habitat.” Without stable sanctuary for the juveniles, they were not likely to survive and grow. On top of that, immense amount of fishing pressure on the grouper enhanced the steady population decline before the harvest ban. Now with the lack of heavy fishing pressure, the species has recovered significantly (Koenig 2014) by finding safeguard in the few quality areas of mangrove habitat such as the Ten Thousand Islands and the Everglades off of the Florida coast. However, much of the mangrove that is available is largely threatened or declining due to industrial and agricultural development and pollutions. Therefore, if the mangrove habitat is not effectively managed and conserved, lifting the harvest ban will likely have negative repercussions and promote a decline in Goliath grouper population.

            It’s critical to recognize that the current abundance and stability of mangroves could result in a large decline of Goliath grouper if the harvest ban is lifted. The low abundance of mangroves is a direct result of the channelization to redirect freshwater flow from the Everglades to industrial areas, mosquito control in the tropical regions, and of course the industrial, agricultural, and residential developments (FSUCML 2014). According to the Florida Department of Environmental Protection (FDEP), a large loss of mangrove acreage is attributed to human activities; Tampa Bay has lost over 44 percent of its coastal wetlands acreage (which includes both mangroves and salt marshes), Charlotte Harbor has lost 59 percent of its original mangrove habitat, Lake Worth has lost 87 percent of its mangrove acreage, and lastly 76 percent of the existing mangrove acreage in St. Lucie Inlet is not productive to the fishery due to mosquito impoundments (FDEP 2015). With the great dependence that Goliath grouper have on mangroves, fisheries managers and the FDEP must take mangrove habitat conservation into account before considering the potential lift on the harvest ban. Without the appropriate abundance of quality mangrove environments, lifting the ban could severely harm the Goliath grouper populations.

            Many anglers, divers, and other members of the Floridian community claim the Goliath grouper are dominating the area and that the harvest ban should be lifted. Divers have established this belief due to the large amount of recorded encounters with large abundances of these fish while diving, which is likely a result of the schooling behavior in the grouper. Moreover, fishermen have witnessed Goliath grouper stalk and ambush a fishermen’s catch right off their fishing line. This has resulted in the common belief that Goliath groupers are “eating all the fish” because occasionally a Goliath grouper will come and devour a vulnerable fish that’s struggling on the end of a fishing line. Rather, goliath groupers are simply opportunity seekers, and will seize an opportunity at an easy meal if one presents itself, such as a struggling fishing on the end of a fishing line. It’s actually rare for these fish to consume prey other than crabs and crustaceans (FFWCC 2016). While Goliath grouper populations have increased significantly since the harvest ban, lifting the ban now could result in an over-exploitation of the fish and lead to a large decline in the population. 
Juvenile Goliath Grouper  Source
With or without the harvest ban, Goliath groupers are one of the largest big game fish on the planet, and are sought after by anglers around the world. Before the ban, the populations were heavily pressured and over-exploited by fishermen, and as a result, the population dropped significantly. They were extremely vulnerable to overfishing due to their lack of fear for humans, their large size, and schooling behavior (Riggs 2009). With the harvest ban in place, fishermen are still able to pursue these goliaths as long as they are “returned to the water free, alive, and unharmed” (FFWCC 2016) after being caught. With these circumstances in place, the Goliath grouper population has seen significant growth and recovery; the harvest ban has assisted the recovery of Goliath grouper significantly. If the harvest ban is lifted, it is likely that people will harvest the growing population right back down due to the value of Goliath grouper as a superior big game fish.

            In conclusion, there are many environmental and human factors to consider when considering a potential lift on the harvest ban of Goliath groupers in the United States. Given the instability and threats to the species’ habitat and lifestyle, the harvest ban should not be lifted. If the harvest ban is lifted under the current circumstances, this could produce a double negative that could drive the Goliath grouper abundance down significantly. Until there is a substantial increase in the abundance and quality of mangrove for the Goliath grouper to thrive throughout, and other influential factors can be deemed stable, the harvest ban should remain closed.
FDEP (Florida Department of Environmental Protection). “Mangroves ‘Walking Trees.’” Florida Department of Environmental Protection http://www.dep.state.fl.us/coastal/habitats/mangroves.htm (accessed April 14, 2016).
FFWCC (Florida Fish and Wildlife Conservation Commission). “Goliath Grouper: Epinephalus itajara.” Florida Fish and Wildlife Conservation Commission http://myfwc.com/fishing/saltwater/recreational/goliath-grouper/ (accessed April 15, 2016).
Frias-Torres, Sarah. 2006. Habitat use of juvenile goliath grouper Epinephelus itajara in the Florida Keys, USA. Endangered Species Research 2:1-6
FSUCML (Florida State University Coastal and Marine Laboratory). “Global Threats to Goliath Grouper.” FSU Coastal and Marine Laboratory https://www.marinelab.fsu.edu/labs/ck/grouper-ecology/goliath/threats (accessed March 17, 2016).          
Koenig, Christopher. “Back from the brink: Atlantic Goliath Grouper recovery in the southeastern United States.” FSU Coastal and Marine Laboratory https://www.marinelab.fsu.edu/labs/ck/grouper-ecology/goliath/ (accessed April 12, 2016)
Koenig, C. C., F. C. Coleman, A.-M. Eklund, J. Schull, and J. Ueland. 2007. Mangroves as Essential Nursery Habitat for Goliath Grouper (Epinephelus itajara). Bulletin of Marine Science 80(3):567-585.
Riggs, M. 2009. Scaling of Feeding Behavior and Performance in the Goliath Grouper, Epinephelusitajara.  Honors College Thesis project, Western Kentucky University,  Bowling Green, Kentucky.
Shideler, G.S. 2014. Lifting the Goliath Grouper harvest ban: Angler perspectives and willingness to pay. Fisheries Research 161:156-165

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