Carcharhinus obscurus is taken as both bycatch and target in commercial shark fisheries using, set nets, longlines, hook and line and trawls (Cramer 1995, Compagno in prep.) in many areas of its range. The species has among the most sought after fins for shark fin soup because of their large size and high fin needle content (ceratotrichia) (TRAFFIC 1996, R. Hudson pers. comm.). Because of its high-value fin, dusky sharks caught incidentally in tuna and swordfish fisheries are now regularly landed rather than released. Carcharhinus obscurus was found to represent at least 1.2-1.7% of the fins auctioned in Hong Kong, the world's largest shark fin trading center (Clarke et al. 2006a). It is estimated that between 144,000 and 767,000 Dusky Sharks are represented in the shark fin trade each year or, in biomass, 6,000 to 30,000 mt (Clarke et al. 2006b). The very low intrinsic rate of increase of the Dusky Shark renders this species among the most vulnerable of all vertebrates (including great whales and sea turtles) to man-induced mortality (Compagno et al. 2005, Musick 1999). Furthermore, Compagno et al. (2005) report that the species is difficult to manage or protect because it is taken in mixed species fisheries, and has a high mortality rate when taken as bycatch.

Further threats to C. obscurus are from beach meshing programs in Australia and South Africa and from recreational fishing. Beach meshing in Australia (Queensland and News South Wales) undoubtedly catches C. obscurus, however, species-specific data are not available. Between 1972 and 1990, the New South Wales programme caught a total of 765 whaler sharks (Reid and Krough 1992), of which Stevens (1984) reported the capture of larger juvenile and adult C. obscurus by recreational fishers off the east coast of Australia. Dusky sharks were one of the most important species in the trophy shark tournaments held in Florida, USA, until the stock collapsed (Heuter 1994).

Northwest and Western Central Atlantic
The initial decline of C. obscurus in the Northwest and Western Central Atlantic was caused by a targeted recreational fishery that developed in the late-1970s and by bycatch in the pelagic swordfish longline fishery (Musick et al. 1993). A rapid expansion of the directed commercial shark fishery in the US in the late 1980s was fuelled in large part by the demand for shark fins in the markets of Asia (Cook 1990). Although Dusky Shark meat is used domestically in the US, the very high value of the fins suggests that the decline in this dusky shark population over past decades has been, and continues to be, driven by international trade in shark fins. There is little reason to believe that the demand for dusky shark products will lessen, especially as other fishery resources become increasingly depleted. In the Gulf of Mexico during the late 1980s, the dusky shark was the fourth most abundant species in the tuna longline bycatch, where medium to large dusky sharks were often shot, finned and discarded (Russell 1993).

Declining catch rates for Dusky Sharks in this area have been a cause for concern. Off North America the proportion of C. obscurus in the catch decreased, while fishing for more abundant species continued (Musick et al. 1993). Carcharhinus obscurus was put on the protected list in 2000, requiring all individuals captured in the longline fishery to be released. Even though the mortality of small juveniles on the longline was as high as 50% (lower for larger juveniles and adults) (Romine 2004), the juveniles have shown an increase of about 30% from the lowest point in the time series to 2005 in the Virginia Institute of Marine Science (VIMS) survey, and continue to rise. This increase was not apparent in the stock assessment, which analysed catch data and multiple fisheries-independent and fisheries-dependent time series data sets in the western Atlantic (NMFS 2006). This assessment led to estimated declines of 62-92% between 1974 and 2003. These declines are of the same magnitude as those found in analyses of the VIMS survey data (Musick et al. 1993, Romine 2004, Ha 2006), but in these studies the low point in Dusky Shark abundance occurred in the early-1990s. The NMFS (2006) assessment, which did not include the 2004-2006 VIMS survey data (which shows a further increase in juveniles) may not have detected the recent increase of juveniles because it was heavily influenced by pelagic data sets collected in deep water where juveniles are absent. The other long-term shark targeted survey in this region, which has been conducted off Cape Lookout, North Carolina through the University of North Carolina annually between 1972 and 2005 (data available to 2003) has captured 1,036 Dusky Sharks. This survey series shows a large, statistically significant decline of 98.8% (95%CI: 97.5-99.6%) and found evidence of no increase in recent years (Myers et al. in prep.).

A new analysis of observer data from the U.S. Atlantic pelagic longline fishery from 1992-2005 (which combined catches of Dusky, Silky, and Night Sharks because of identification problems) suggests that this species complex has declined significantly, by 70% (95% CI: 54-81%) during this recent time period (Baum et al. in prep.). The observer data shows a steeper decline when Dusky Shark is analysed alone, but this analysis ignores species identification problems, and hence is not considered reliable (Baum et al. in prep.). For the Gulf of Mexico, an analysis of data from U.S. pelagic longline research surveys conducted in the mid-1950s and U.S. pelagic longline observer data from the late-1990s estimated that dusky sharks declined by 79% over this forty-year period (Baum and Myers 2004), which is less than the three generation period for this species. Thus, recent management actions in the US may have led to an increase in the numbers of juvenile Dusky Sharks, however adults still appear to be declining.

Southwest Atlantic
This species is taken both incidentally and as a target species in longline and artisanal fisheries throughout Brazilian waters and elsewhere in the South Atlantic. It is taken by longline off Santos where it is retained as "other sharks" (Arfelli and Amorim 1994). The species has also been recorded from artisanal fisheries off Rio de Janeiro State (Sant'Anna and Siqueira 2000) and from southern Sao Paulo State (Motta et al. 1997, Bertozzi et al. 2000, Gadig et al. 2000). From July 1996 to February 1997 the species made up 1.12% of the catch (Motta et al. 1997) and 5.61% of the total catch from 1996 to 1999, which consisted mostly of juveniles, most frequently caught in June and August (Gadig et al. 2000). A number of countries operate longline fleets targeting tuna and swordfish in the high seas areas of the Southwest Atlantic region. In addition to the coastal nations of the Southwest Atlantic, nations including Taiwan, Korea, Japan, Spain, Bolivia, Cape Verde, United Kingdom, China and Barbados also operate vessels here. Tuna and swordfish longline fisheries now also target sharks due to increasing demand for shark products and the value of their fins (Bonfil et al. 2005, Mejuto et al. 2005).

Mediterranean Sea
The main threats in the Mediterranean Sea are commercial fisheries. This species is caught sporadically in longline, setline, gillnet and sometimes by tuna trap ("Tonnara - Tonnarella") fisheries, principally off North African and rather less frequently by surface longlines, artisanal setlines and possibly trawlers in the Sicilian Channel. Carcharhinid sharks have been caught as target or bycatch in historical fisheries in this region, where fishing pressure is high, however there are few species-specific records from which to elucidate population trends. Carcharhinus obscurus is rarely observed on fishmarkets in the Mediterranean, but is easily mistaken for other "grey" requiem shark carcasses, such as C. plumbeus. This species is utilised for human consumption in several areas of the Mediterranean, including Sicily, Malta and Libya, although the meat is considered of low commercial value.

Australia
The fishery for C. obscurus off southwestern Australia developed in the 1940s, but rapidly increased in the late 1970s to produce annual catches of 500-600 t. The fishery uses demersal gillnets (16.5 to 17.8 cm stretched mesh) to target neonates in the nursery area and the selectivity of the nets results in very few individuals over three years of age being captured. The flesh of the young C. obscurus is highly regarded and fetches a good price on local markets. Fins are also sold. Current estimates are that 18-28% of neonates are caught in their first year. An assessment using demographic models indicated that the fishery was sustainable at the then level of catch provided the fishing mortality of animals larger than two metres was less than 4% (Simpfendorfer 1999). However, a more recent assessment (McAuley et al. 2005) found that the stock was less productive than previously thought, and that mortality of older dusky sharks in wetline fisheries outside the target fisheries was leading to a decline in recruitment. This assessment also estimated that the catch per unit effort (CPUE) of Dusky Sharks declined by more than 75% between the early 1970s and 2004, and that the decline was continuing. In 2006 additional management measures were introduced to the fishery (see below), including a maximum size limit for Dusky Shark. These management measures should arrest further declines, but continued monitoring and assessment will be essential to monitor the stock, and the effectiveness of these measures.

South Africa
Off South Africa, there is a pelagic tuna longline fishery that may take some as bycatch but this is unconfirmed. There is a small commercial line fishery taking juvenile C. obscurus, and there is a recreational line fishery that targets juvenile C. obscurus but most are released (they were not released a decade ago) and there is the beach meshing operation that catches juveniles, adolescents and adults. Carcharhinus obscurus would have been a significant component in the beach meshing program off KwaZulu-Natal, South Africa, between 1978 and 1999, when the mean annual catch of was 256 individuals (range 129-571, Dudley et al. 2005). There was no trend in either catch or catch rate. A subsequent update by Dudley and Simpfendorfer (2006) showed no trend in either catch rate or size over the period 1978-2003. The large mesh size of the nets used in these programs means that many of the C. obscurus taken are sub-adults and adults, but juveniles are also caught. The occurrence of sub-adult and adult C. obscurus off KwaZulu-Natal is affected by an annual winter influx of sardines Sardinops sagax and shark catches are influenced by attempts to remove the nets in advance of the arrival of the sardine shoals (Dudley et al. 2005). Reports of C. obscurus in recreational fisheries are limited. Van der Elst (1979) reported that large numbers of juvenile C. obscurus were taken by recreational shore anglers in South Africa and Govender and Birnie (1997) have expressed concerns about the high rate of instantaneous fishing mortality in this fishery, although there is an increasing tendency to release the sharks.