Research technician Erin Voigt, measures a juvenile shark, as part of the University of North Carolina Coastal Shark Survey Cruise, Morehead City, NC. Photo credit: Mike Waine.
Sharks belong to the class Chondrichthyes (cartilaginous fish) that also includes rays, skates, and deepwater chimaeras (ratfishes). Relative to other marine fish, sharks have a very low reproductive potential. The low reproductive rate is due to sharks slow growth, late sexual maturity, one to two-year reproductive cycles, a small number of young per brood, and specific requirements for nursery areas. These biological factors leave many species of sharks vulnerable to overfishing.
Sharks have internal fertilization and the embryo of most species spend their entire developmental period protected within their mother's body, although some species lay eggs. Females produce a small number (2 - 25) of large pups, which have an increased chance of survival due to their size. Adults usually congregate in specific areas to mate and females travel to specific nursery areas to pup. These nursery areas are discrete geographic areas, usually in waters shallower than those inhabited by the adults. Frequently, the nursery areas are in highly productive coastal or estuarine waters where abundant small fish and crustaceans provide food for the growing pups. These shallow areas have fewer large predators than deeper waters, thus enhancing the chances of survival of the young sharks.
Sharks are a vital part of ocean ecosystems all over the world. Scientists consider them to be a keystone species because they generally reside at the top of the food chain having a strong impact on other species either directly or indirectly. Removing or reducing shark populations in an area can cause an imbalance in the food chain and produce far reaching negative impacts. Because of this, the health of shark populations in an ecosystem is often an accurate indicator of the overall health of the system.
The commercial shark fishery, which uses bottom longlines and gillnets, is generally concentrated in the Southeastern U.S. and Gulf of Mexico. The Atlantic fishery targets both large coastal shark (LCS) and small coastal shark (SCS) species with bottom longline as the primary commercial gear. An Atlantic bottom longline is, on average, 3.4 miles in length and contains about 300 hooks. Skates, other sharks, or various finfish are used as bait. The gear typically consists of a heavy monofilament mainline with lighter weight monofilament gangions, or branch lines, coming off the main line. The Southeast shark gillnet fishery is comprised of several vessels based primarily out of ports in northern Florida. Vessels typically use nets ranging from 456 to 2,280 meters long and 6.1 to 15.2 meters deep, with about 5.2 inches of stretched mesh.
In 2014, the top commercially harvested sharks included smooth dogfish, blacktip, Atlantic sharpnose, shortfin mako, and the common thresher shark. LCS landings were approximately 503,594 pounds dressed weight (dw), a 14% increase from 2013, and SCS landings were approximately 269,252 pounds dw, a 3% increase from 2013. Total U.S. landings of Atlantic pelagic species were 358,549 pounds dw in 2014, nearly double 2013 landings. This is largely attributed to increased landings of thresher shark as well as blue, porbeagle, and shortfin mako.
The recreational fishery for Atlantic sharks occurs in federal and state waters from New England to the Gulf of Mexico and Caribbean Sea. Once called “the poor man’s marlin,” recreational shark fishing is now a popular sport at all social and economic levels, largely due to accessibility to the resource. Sharks can be caught by rod and reel virtually anywhere in saltwater, with even large specimens available to surf anglers or small boaters in the nearshore area. Most recreational fishing takes place from small to medium-size vessels. SCS species such as Atlantic sharpnose, bonnethead, and finetooth comprise the majority of the recreational harvest. Short-fin mako and common thresher sharks are generally accessible only to those aboard ocean-going vessels.
Approximately 102,000 sharks were recreationally harvested in 2014 in the Atlantic region, compared to 70,000 sharks in 2013. The SCS complex largely dominated the catch with approximately 91,627 fish harvested in 2014; the largest harvest of the SCS complex since 2009. Sharpnose sharks represented 61% of the this harvest. The LCS complex, including hammerheads, had an estimated 10,785 fish harvested in 2014.
Stock status is assessed by species or by species complex if there is not enough data for an individual assessment. In summary, fourteen species have been assessed domestically, three species have been assessed internationally, and the rest have not yet been assessed. The accompanying table outlines the stock status and associated assessment process for each species or species group.
In 2015, a benchmark stock assessment (SEDAR 39) was conducted for the smoothhound complex, including smooth dogfish, the only species of smoothhound occurring in the Atlantic. The assessment indicates smooth dogfish is not overfished and not experiencing overfishing.
The North Atlantic blue shark (Prionace glauca) stock was assessed by ICCAT SCRS in 2015. The assessment indicated the stock is not overfished and not experiencing overfishing, as was also concluded in the 2008 stock assessment. However, scientists acknowledge there is a high level of uncertainty in the data inputs and model structural assumptions; therefore, the assessment results should be interpreted with caution.
SEDAR 34 (2013) assessed the Atlantic sharpnose (Rhizoprionodon terraenovae) and bonnethead (Sphyrna tiburo) sharks. The Atlantic sharpnose stock is not overfished and not experiencing overfishing. The stock status of bonnethead shark stocks (Atlantic and Gulf of Mexico) is unknown. It is recommended that a benchmark assessment for both stocks be undertaken.
The North Atlantic shortfin mako shark (Isurus oxyrinchus) stock was assessed by ICCAT SCRS. According to the 2012 assessment, current levels of catch may be considered sustainable as potential indicators of overfishing identified in the prior assessment have diminished. The stock is not overfished nor experiencing overfishing.
SEDAR 11 (2006) assessed the LCS complex and blacktip sharks (Carcharhinus limbatus). The LCS assessment suggested that it is inappropriate to assess the LCS complex as a whole due to the variation in life history parameters, population dynamics, and catch and abundance data among the LCS species. Based on these results, NOAA Fisheries changed the status of the LCS complex from overfished to unknown. As part of SEDAR 11, blacktip sharks were assessed for the first time as two separate populations — Gulf of Mexico and Atlantic. The results indicated that the Gulf of Mexico stock is not overfished and not experiencing overfishing, while the current status of blacktip sharks in the Atlantic region is unknown.
A 2011 benchmark assessment (SEDAR 21) of dusky (Carcharhinus obscures), sandbar (Carcharhinus plumbeus), and blacknose (Carcharhinus acrontus) sharks indicates that both dusky and blacknose sharks are overfished and experiencing overfishing. Sandbar sharks continued to be overfished. As described in the Magnuson-Stevens Act, NOAA Fisheries must establish a rebuilding plan for an overfished stock. As such, the rebuilding date for dusky sharks is 2108, sandbar sharks is 2070, and blacknose sharks is 2043. The Commission's Coastal Sharks Management Board approved the assessment for management use in 2012, and NOAA Fisheries’ Highly Migratory Species Division (HMS) is incorporating the assessment results as part of Amendment 5a and 5b to its FMP. Amendment 5a addresses sandbar and blacknose sharks, as well as scalloped hammerhead and Gulf of Mexico blacktip. Amendment 5b addresses dusky sharks.
Porbeagle sharks (Lamna nasus) were assessed by ICCAT SCRS in 2009. The assessment found while the Northwest Atlantic stock is increasing in biomass, the stock is considered to be overfished with overfishing not occurring. NOAA Fisheries established a 100-year rebuilding plan for porbeagle sharks; the expected rebuilding date is 2108.
A 2009 stock assessment for the Northwest Atlantic and Gulf of Mexico populations of scalloped hammerhead sharks (Sphyrna lewini) indicated the stock is overfished and experiencing overfishing. This assessment was reviewed by NOAA Fisheries and deemed appropriate to serve as the basis for U.S. management decision. In response to the assessment findings, NOAA Fisheries established a scalloped hammerhead rebuilding plan that will end in 2023.
In 2007, SEDAR 13 assessed a number of species including the SCS complex and finetooth (Carcharhinus isodon) sharks. The peer reviewers considered the data to be the ‘best available at the time’ and determined the status of the SCS complex to be ‘adequate.’ Finetooth sharks were found to be not overfished and not experiencing overfishing.
In the mid-1980s, sharks were considered an underutilized resource and fishermen were encouraged to fish for them. Over the next few years, fishing effort increased considerably and the impact of unregulated harvest was beginning to take its toll on some shark species. In the early 1990s, the National Marine Fisheries Service (NMFS) implemented a Fishery Management Plan (FMP) for Sharks of the Atlantic Ocean to rebuild depleted stocks and protect healthy stocks from overfishing. In May 2008, the Atlantic States Marine Fisheries Commission adopted an Interstate Fishery Management Plan for Atlantic Coastal Sharks (August 2008) to complement federal management actions and increase protection of pregnant females and juveniles in inshore nursery areas. The FMP regulates 40 different species of coastal sharks found on the Atlantic coast (see table under Commercial and Recreational Fisheries).
State-shares of Smoothhound Sharks Coastwide Quota
Addendum I, approved in 2009, modified recreational possession limits for smoothhound dogfish and other species, allowed at-sea processing of smooth dogfish from March - June, and removed the two-hour net check requirements, which was determined to be ineffective at reducing bycatch. Addendum II and Addendum III (2013) addressed changes in the federal management of coastal sharks. Addendum II allocated state-shares of the smoothhound dogfish coastwide quota, and modified the maximum fin-to-carcass ratio, consistent with the Shark Conservation Act of 2010. Addendum III created two new species groups (Hammerhead and Blacknose) and increased the recreational size limit for hammerheads.
Amendment 9 to the Highly Migratory Species FMP was published as a final rule in 2015, it brings smoothhound sharks under federal management starting on March 15, 2016. The Board approved a smoothhound 2016 coastwide quota of 1201.7 mt dressed weight. Pursuant to the provisions of Addendum II the coastwide quota will be allocated into state shares, as shown in the accompanying table. At the February 2016 Board meeting, Addendum IV was initiated to address inconsistencies between state and federal management (as a result of Amendment 9) related to a catch composition requirement in order to remove the fins of smoothhounds at sea. The Commission is accepting public comment on Draft Addendum IV until July 11, 2016. For the 2016 fishing season, the Board approved a fishery opening date of January 1 and a variable possession limit. As of April 2, 2016 the possession limit for those species within the aggregated large coastal sharks (LCS) species group (silky, tiger, blacktip, spinner, bull, lemon, nurse) and the hammerhead species group (scalloped hammerhead, great hammerhead, and smooth hammerhead sharks) is 25 sharks per vessel per trip. ASMFC will follow NMFS for inseason changes in the possession limit.