Lemon Shark Update 2016

If you have been diving in the Jupiter area this year, you have probably bumped into a lemon shark or two, which is great, but, for the well-seasoned divers Florida divers, this is actually very worrying. Lemon sharks were seen in groups of 20, and sometimes up to 100, in these same areas back in the mid-2000’s, but, due to reasons not yet fully understood, this spectacle has not been seen in almost a decade.

As many of you may know, the Bimini Sharklab started tracking these adult lemons in 2007 using a technology called passive acoustic telemetry and ASC has contributed to this incredible project since 2011. Sharks are captured and implanted with tags that ping a unique ID code which can be detected on the hundreds of receivers anchored along the South East USA coastline. Over 140 lemon sharks have been tagged and our data has shown their annual north-south movements correlate very closely with the warm water temperatures, just like the human ‘snowbirds’ of Canada and NE USA. Lemons move up as far north as North Carolina and back to the Jupiter area each year. Unfortunately, the number of returning lemon shark detections has been declining pretty drastically in recent years. ,Sure, there are many reasons why we might not be hearing from these lemons, maybe they found better habitat elsewhere, maybe there is a longer-term movement pattern we haven’t yet determined, maybe the environmental conditions have change, some may have died from natural causes and some may have succumbed to fishing pressure.

The current knowledge of the life history of lemon sharks, mostly discovered by Bimini SharkLab’s Dr. Gruber and his team, shows they live fairly conservative lifestyles. They mature late in life (around age 12), they give birth to few pups (7-17 every two years) they grow slowly and live to a relatively old age (current maximum life-span is 37 years). These traits dictate how their populations respond to the pressures of fishing. If we take too many out of the population too quickly, the overall population declines. We are working hard to understand exactly what is happening with this population of lemon sharks. As we plug away at the science, we took a close look at the current fisheries regulations that might impact this species along the Atlantic Coast of the U.S. On a local level, we knew there was a localized aggregation of lemon sharks that peaked during the winter months so many were alarmed to hear that the Atlantic Commercial Shark Fishing season started on January 1st, allowing permitted vessels to target lemon sharks as part of the Large Coastal Shark management group (which includes species like tiger and bull sharks). This management group does have an annual quota and a total catch per day per vessel limit. Many Floridians were shocked to know that the U.S. has a commercial shark fishery that trades in the meat, skin and fins, however, In Florida, shark fins are the second most valuable seafood product behind stone crabs. The state of Florida was proactive and protected lemon sharks in state waters several years ago but that only extends 3 miles out on the Atlantic side. From our research, we know the lemon sharks venture across that state line frequently where they become fair catch in federal waters.

NOAA Fisheries’ Atlantic Highly Migratory Species Management Division (http://www.nmfs.noaa.gov/sfa/hms/) has the task of collating all available data on shark species and populations to set fishing regulations that meet the objectives of current laws, such as the Shark Conservation Act and the Magnuson-Stevens Act. Based on all of that, they determined that the fishing season would open in January with specific quotas and restrictions. Local citizens and divers raised concerns over whether the January opening date would unfairly endanger the highly publicized aggregation of lemon sharks. Unfortunately, many members of the public were unaware that the agency had posted the rule change and a request for public comments late in 2015. Most missed the opportunity to comment officially but were vocal online and on local media after the deadline. Behind the scenes, however, a group of academic, government and NGO scientists were able to discuss the findings from this research project in relation to the fishing policies. In March this year, the Highly Migratory Species Advisory Panel met in Washington, D.C. Here, NOAA Fisheries’ scientists and staff discuss topics that have been raised and allow for public comment and we were able to get the topic of the Jupiter lemon shark aggregation on the agenda.

At the HMS AP meeting on Wednesday, March 30th, 2016, the topic was discussed by NOAA Fisheries staff and the Advisory Panel, followed by comments from the public, including several collaborating scientists that have extensive experience studying the Atlantic lemon shark stock’s genetics, life history and movements.

Here is a summary of what was covered in the meeting and what the probable outcomes are:

  • Lemon shark Essential Fish Habitat (EFH) has been updated to include the area between Cape Canaveral and Palm Beach County, Florida;
  • The area from Boynton Inlet to Hobe Sound is under consideration for a Habitat Area of Particular Concern (HAPC) and is a strong candidate to receive this designation.  However, HAPC designation mainly protect the benthic habitat from activities such as dredging or destructive fishing methods such as bottom trawling;
  • Without additional data on a federal scale to indicate over-exploitation of lemon shark populations, they will not be a candidate for prohibition;
  • There is argument for the seasonal aggregations having considerable importance for the broader stock based on the movement and genetic data.  As such, it is possible that the area could be subject to a time area closure designation in the future.  At present the perceived threat is great enough to make this happen.
  • Commercial shark fishing representatives state they are uninterested in targeting lemons, most are more concerned with getting sandbars re-opened. An industry rep was present and worked with HMS permit holders this year to halt any attempts to target lemons in the aggregation region this season.  This seems to have been successful and this may be an additional avenue to protect the aggregation;
  • There is potential for incidental protection by pushing the importance of the area for the critically endangered smalltooth sawfish (given the recent sightings in the area).

The outcomes of these discussions, along with the continued collaboration of the public, our scientists and the policy-makers, are crucial to developing sustainable management strategies for the Atlantic population of lemon sharks. This information will help us determine the next feasible steps to conserving this valuable coastal shark species. Stay tuned as we move this process forward!

Any comments or questions – please email Hannah@AmericanSharkConservancy.org

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