Estimates of r are available for two of the four species most commonly consumed in the United States, Blacktip and Sandbar Sharks. Mean values for these two species are 0.12 and 0.19, respectively (Cortes 2002b).

Estimates of age at maturity are as follows: 15-16 years (Sandbar Shark); 5-5.8 years (Common Thresher)(Carrier et al. 2004); 3-8 years (Blacktip Shark)(Fishbase 12/8/04). No estimate of age at maturity for Shortfin Mako Shark is reported.

Growth rates (k) are reported for the following species: 0.124-0.184 (Common Thresher Shark); 0.039-0.087 (Sandbar Shark); (Carrier et al. 2004).

Most sharks have relatively long life spans. Maximum ages reported are as follows: 22 years (Common Thresher Shark); 18-25 years (Sandbar Shark) (Carrier et al. 2004); 18 years (Blacktip Shark); 28 years (Shortfin Mako Shark) (Fishbase 12/8/04)

To account for the fact that many of these parameters fall within the low point category, we awarded a score of 1 here.

Many shark species require pupping or nursery grounds. Heupel and Hueter (2002) found that while many studies have suggested that nursery areas are most important to sharks for predator avoidance and food abundance, for Blacktip Sharks, predator avoidance may be the more important use for juvenile Blacktips.

Pupping or nursery areas may be inshore, offshore, or in estuarine areas where vulnerability to fishing pressure and habitat alteration may be higher than in the open sea. For example, Sandbar Sharks in the Western North Atlantic utilize shallow bays and estuaries of the east-central USA for pupping. Many shark species also tend to aggregate by age, sex, and reproductive stage, making them more vulnerable to fisheries (Camhi et al. 1998). Sandbar Sharks, for example, travel in large schools as they migrate southward in winter along the Western North Atlantic seaboard. And Blacktip Sharks occur in large schools in surface waters (IUCN 2000).

Many sharks are long-lived species, with life history strategies that have evolved with few predators. Sharks have low reproductive potential, with reproductive strategies that are more closely related to cetaceans, sea turtles, large land mammals and birds than other teleost fishes (Camhi et al. 1998). For example, Sandbar Sharks reach sexual maturity between 15 and 29 years of age and on average produce 8.4 pups per litter. Sandbar Sharks also have a litter only once every two years (Sminkey and Musick 1996).

Many sharks species have populations that are distributed throughout several ocean basins. Shortfin Mako Sharks, for example, are found worldwide in tropical, sub-tropical, and temperate waters (Camhi et al. 1998).

Information on abundance is available for Sandbar, Blacktip, Thresher, and Mako Sharks (species targeted in directed shark fisheries in the U.S. and are known to be consumed in the U.S. for their meat) as well as large and small coastal sharks in the U.S. Atlantic and Gulf of Mexico. Estimates are listed below. To account for the range in abundance we awarded a medium score here.

U.S. Atlantic and Gulf of Mexico:

Sandbar Sharks: .000325% to 222% of the number needed to produce MSY (NMFS 2003). The wide range in estimates shows that data on Sandbar Sharks are very uninformative. There is little information on true abundance (Babcock, pers. comm. 2003).

Blacktip Sharks: 79% to 166% of the number needed to achieve MSY (NMFS 2003).

U.S West Coast:

Common Thresher: population is at the level needed to produce MSY (~1.0 BMSY) (PFMC 2002). Because Common Thresher sharks are a coastal species, estimates of abundance for that species are considered to be relatively accurate. Still, a portion of the population that is caught off the U.S. West coast migrates into Mexican waters, where fisheries target sharks and where stocks are not assessed (Au, pers. comm. 2003).

Shortfin Mako: Biomass is approximately 60% of unfished biomass and is close to the biomass needed to produce MSY. Estimates of abundance of mako sharks are not precise, however, because as widely distributed oceanic species, makos caught in the gillnet fishery represent only a small portion of the total population (Au, pers. comm. 2003).

CPUE trends indicate that common Thresher Sharks off the U.S. West Coast are increasing in abundance. The rise in CPUE in some areas is due to decreasing effort in the California drift gillnet fishery and the fact that fishing permits are not being re-issued. Mako sharks off the U.S. West coast appear to be declining (PFMC 2002). In the Atlantic and U.S. Gulf of Mexico, Sandbar Sharks began showing increasing trends in 1993 until 1998. From 1998 to 2001, trends were a combination of mostly flat or slightly increasing. For Blacktip Sharks, there has been no clear trend over the past few decades. Both slightly increasing and slightly decreasing trends were observed in recent years (1998-2001) (NMFS 2003). To account for this variation in trends among species, no points were added or subtracted here.

Age and sex distribution of Thresher Sharks off the U.S. West Coast is likely to be healthy. The targeted gillnet fishery catches Thresher Sharks of all ages and of both sexes. Little is known about the age and sex distribution of Shortfin Mako sharks off the U.S. West Coast (Au, pers. Comm, 2003). In the U.S. Atlantic and Gulf of Mexico, there is little information available on the age or sex distribution of shark populations. For example, the age-structured models used in the stock assessment do not produce any outputs on age distribution (Cortes, Pers. Comm 6/3/03). No points were added or subtracted here to account for lack of information on most species.

Sharks caught in commercial fisheries are mostly targeted with longlines (both surface and bottom) and gillnets. Thresher and Mako Sharks off the U.S. West coast are caught in the California-Oregon drift gillnet fisheries. In the U.S. Atlantic and Gulf of Mexico, most sharks are caught by bottom longlines, drift gillnets, and rod and reel (including commercial, recreational, and charter/headboats). Gillnetting is done both by drifting (one vessel, with gillnet set in a straight line that fishes passively) and strikenetting (set rapidly around a school of sharks, or set behind the wake of a shrimp vessel when it begins haulback) (NMFS 2003).

Coastal and inshore areas are important nursery habitat for sharks, and consequently are critical to shark productivity. The amount of suitable nursery habitat available is recognized as a limiting factor on shark populations. For juvenile sharks, inshore areas provide lower predation rates and high forage abundance (PFMC 2002). Although there is research in progress to identify important shark habitat areas, no measures are in place in the Atlantic to protect shark habitat (Fordham and Camhi, 2003).

The Shark Finning Prohibition Act of 2000 changed the nature of many U.S. shark fisheries substantially. The law prohibits any U.S.-based fisher (in state or federal waters) from engaging in shark finning (the practice of cutting of a shark’s fins and discarding the carcass overboard), possessing shark fins harvested on board a U.S. vessel without the corresponding carcass, or landing shark fins without the corresponding carcasses. The U.S. Secretary of Commerce published the Final Rule on the Act in February 2002 (Federal Register Vol. 67, no. 28, 2002). In states that had very large shark fisheries, the ban had a substantial impact. Hawaii, for example, had the highest shark landings among Pacific sharks prior to the ban, with landing totaling 6.2 million pounds in 1998 (Camhi 1999). Fins landed in Hawaii were exported to Asia to supply the market for shark-fin soup. Now, sharks caught in Hawaii are mostly incidental catch in longline fisheries targeting more valuable species such as tunas (Ikehara, Pers. Comm 2003). In 2001, landings of sharks in Hawaii totaled only 320,902 pounds (NMFS 2003a). However, outside of U.S. federal waters, shark finning is legal and continues to supply markets for shark fin soup.

In the U.S. Atlantic and Gulf of Mexico, shark fisheries operating in federal waters are managed by the National Marine Fisheries Service, Highly Migratory Species division. While sharks are included in the Fishery Management Plan for Highly Migratory Species (NMFS 1999), the shark fisheries are now being managed under an Emergency Rule. Quotas for Sandbar and blacktip sharks are in place in the U.S. Atlantic. Catches of some shark species are prohibited and the list of prohibited species was recently expanded. Minimum sizes in the commercial fisheries are not in place under the Emergency Rule.There is also a limited access program and seasonal restrictions. Although not overfished, overfishing of sandbar sharks is still occurring. Rebuilding targets have not yet been met (NMFS 2003). Blacktip sharks are not overfished, overfishing is not occurring, and the population is considered rebuilt (NMFS 2003).

The major shark fishery off the U.S. west coast—the targeted gillnet fishery for thresher and mako sharks—is managed by the states of California and Oregon. A Fishery Management Plan (FMP) for fisheries targeting Highly Migratory Species (HMS) in federal waters of the U.S. Pacific is expected to be implemented in 2004. The new plan is expected to include harvest guidelines, which are not in place under current management. Current management measures include time/area closures to protect thresher sharks during pupping season, a limited entry program, and seasonal restrictions. Thresher and mako sharks are not considered overfished. Overfishing is not occurring for Thresher Sharks and is probably not occurring for Mako Sharks (Au, pers. comm. 2003).

Overall, there is management in place for the important fisheries for Thresher and Mako sharks of the U.S. West Coast and for Sandbar and Blacktip Sharks in the U.S. Atlantic and Gulf of Mexico. The improved status of these species indicates that for the most part, sustainability goals are being met.

Although catch monitoring is currently taking place, the quality of historical catch data is very low (NMFS 2003). As a result, most of the shark stock assessment predictions about population size relative to virgin population size are characterized by high uncertainty (Apostolaki, Pers. Comm., 2004). However, we have not subtracted points here to account for efforts to improve monitoring.

U.S. Atlantic:

Rebuilding programs are in place for Ridgeback and non-Ridgeback Large Coastal Sharks. Precautionary measures are in place for pelagic and Small Coastal Sharks (NMFS 2003).

U.S. Pacific:

The state of California implemented time/area closures specifically to protect common thresher sharks during the pupping season. This measure has contributed to the rebuilding of thresher sharks off the U.S. West Coast (Crooke, pers. comm. 2003).

The U.S. shark fishery is not overcapitalized. Before shark finning became illegal, landings in Hawaii totaled 6.2 million pounds in 1998 (Camhi 1999). In 2001, landings were only 320,902, because sharks are now taken mostly as incidental catch in more lucrative fisheries (NMFS 2003a; Ikehara, pers. comm 2003). Thus, we do not consider this fishery to be overcapitalized.

Bycatch is problematic in U.S.-based targeted shark fisheries, although the nature of the bycatch varies according to fishery. In the drift gillnet fishery targeting Thresher Sharks off the U.S. West Coast, catches of Blue Sharks are high: catches are 2-3 times the number of thresher and mako sharks (Crooke, pers. Comm. 2003). However, interactions with protected species are no longer considered very serious in this fishery. Closed seasons and closed areas to protect sea turtles, mandatory use of acoustic pingers to deter marine mammals, and regulations requiring that nets be set 6 fathoms below the surface to avoid marine mammal entanglements have been implemented and bycatch has since been reduced (Price, 2003, personal communication).

In the targeted bottom longline fisheries in the U.S. Atlantic and Gulf of Mexico, bycatch of sea turtles is problematic. Expected annual capture of sea turtles in shark bottom longline fisheries is 2 Leatherbacks, 12 Loggerheads, 2 Green, 2 Hawksbill, and 2 Kemps’ Ridley turtles (NMFS 2003). The South Atlantic strikenet fishery, however, is a more targeted fishery. In the 2002 right whale calving season, 99.3 percent of catches (numbers caught) were sharks. Of the shark catch, 99.3% were Blacktip Sharks. The remaining 0.7 percent of the catch was comprised of teleosts and rays (Great Barracuda, Cownose Ray, and houndfish). No sea turtles or marine mammals were caught. In 2002, outside of the right whale calving season, there was no bycatch: no teleosts, sea turtles, or marine mammals were caught. Shark catches were comprised of Blacktip and Blacknose sharks (NMFS 2003).

A low score was awarded here to account for the bycatch of protected species in the bottom longline fisheries and the high bycatch of Blue Sharks in the U.S. West Coast gillnet fishery.

In the U.S. Atlantic, sharks are taken as bycatch in other fisheries. For example, there is substantial bycatch of Small Coastal Sharks in shrimp trawl fisheries and in the Gulf Menhaden purse seine fishery (Fordham and Camhi 2003). No measures are in place specifically to reduce bycatch of sharks (Fordham and Camhi 2003). However, areas closed to pelagic longlining and areas designated as closed under the Atlantic Large Whale Take Reduction Team, apply to fisheries for sharks (Brewster-Geisz, pers. comm. 2003).

In the California drift gillnet fishery, there is bycatch of sharks as in the Atlantic. Efforts to reduce bycatch in this fishery have focused on sea turtles and marine mammals.

Management has taken significant action to reduce bycatch of protected species in the drift gillnet fishery off the U.S. West Coast. There are closed seasons and closed areas to protect sea turtles, mandatory use of acoustic pingers to deter marine mammals, and regulations requiring that nets be set 6 fathoms below the surface to avoid marine mammal entanglements. Skipper and operator workshops are also conducted (Price, 2003, personal communication). As a result of these measures, bycatch has been significantly reduced. Marine mammal takes have been very low. For example, no short finned pilot whales have been taken, and takes of northern common right whale dolphins have been below the amount that is considered problematic for the population. No marine mammal species listed under the Endangered Species Act have been taken since 2000. Since 2001, when the time area closures were implemented to protect sea turtles, no leatherback sea turtles have been taken. One loggerhead was taken in 2001 (Price, 2003, personal communication). There have also been no records or observations of interactions between the fishery and seabirds such as Short-Tailed Albatross, Bald Eagles, California Least Terns, or California Clapper Terns or salmon and Cutthroat Trout (PFMC 2002).

In the U.S. Atlantic, there are areas closed to longlining to protect sea turtles and areas designated as closed under the Atlantic Large Whale Take Reduction Team, which apply to sharks (Brewster-Geisz, pers. comm. 2003).