Intrinsic rates of increase are unknown. Most Penaeid Shrimp species reach sexual maturity within 12 months and have a maximum life span of 24 months (GMFMC 2005; SAFMC 2004; Garcia 1985).

Most commercial fishing for shrimp occurs within several miles of the coast and concentrates effort on adult shrimp which have migrated from the estuaries and congregate offshore for spawning (Muncy 1984). Since various species of shrimp enter the spawning grounds at different times during the year, several fisheries may successfully operate throughout the year (Larson et al. 1989).

Broad-scale environmental changes, such as El Nino events, can influence Penaeid shrimp populations. During the 1998 El Nino, the commercial shrimp fishery in Ecuador collapsed (U.S. Department of State 1999). In Bangladesh, annual catch rates for all Penaeid Shrimp species reflect year to year fluctuations (FAO 1997). El Nino events can also influence shrimp populations positively; dramatic increases in rainfall during the 1982-83 El Nino in Ecuador and Peru resulted in flooded coastal estuaries and record-setting increases in shrimp production (NOAA 2006; Forrester 1997).

Penaeid Shrimp species, which dominate imported shrimp catches are highly fecund (SAFMC 2004; FAO 2001). This enables populations under favorable environmental conditions to rebound from very low abundance in one year to high abundances in the next (SAFMC 2004).

Although individual shrimp species exhibit varying distributions throughout the world, commercially important Penaeid Shrimp inhabit temperate and tropical regions throughout the world. The Giant Tiger Prawn, a Penaeid shrimp of considerable commercial importance in Indonesia, Thailand, and Bangladesh, inhabits coastal waters throughout the Indo-West Pacific (including Southeast Asia), East and Southeast Africa, and Pakistan to Japan (FAO 2005). In other exporting countries, up to fifteen different species inhabit coastal waters and support important tropical shrimp trawl fisheries (FAO 2001; 1997).

Because of their short-lived nature (they are essentially annual crops), BMSY, and similar proxies, are difficult to apply to shrimp populations (Leard, pers. comm. 2006). Few, if any, surveys of shrimp abundance have been conducted among tropical shrimp trawl fisheries (FAO 2001; FAO 1997).

Although overall information on shrimp abundances are lacking, fishery scientists have observed decreases in shrimp populations in the offshore waters of Bangladesh which are said to possess the largest shrimping grounds among the South Asian nations. Fishery biologists relate the decreases to increased competition in commercial Tiger Shrimp trawling (FAO 1997). Moreover, the destructive practice of shrimp fry collection (used to seed shrimp farms) throughout many exporting nations removes large amounts of juvenile shrimp and finfish and threatens the abundance of future shrimp populations (EJF 2004).

Age, size and sex distribution among Penaeid Shrimps is functionally normal (GMFMC 2005; SAFMC 2004; Muncy 1984; Bielsa et al. 1983).

Although commercial fishers use a variety of gear to capture shrimp, the otter trawl remains the dominant gear used in the fishery (FAO 2001). A pair of wooden 'otter' boards inside the otter trawl holds the mouth of the net open by exerting a downward and outward force at towing speed. A heavy mesh bag with 'wings' on each side funnels shrimp and other captured organisms into the codend, or tail, of the net (GMFMC 2005; FAO 2001). To maximize efficiency, fishers typically operate two to four 40-foot trawls, which are pulled from each of two firmly constructed outriggers located on the port and starboard side of the vessel (FAO 1997).

Since trawling nets, and their attachments, are designed to maximize contact with the seafloor, shrimp trawling can modify benthic, or seafloor, habitats and affect benthic fauna, diversity and community structure (FAO 2004; Morgan and Chuenpagdee 2003). Shrimp trawling can inflict substantial damage to the seafloor by crushing, burying and exposing marine organisms. Additionally, by disturbing and re-suspending sediment, shrimp trawling releases nutrients into the water column, increasing the occurrence of algal blooms and decreasing seagrass production (SAFMC 2004). Shrimp trawling frequently occurs in shallow coastal areas, which serve as nursery grounds for commercially important fish species, and destroys the structural diversity critical for a large array of marine life. Additionally, shrimp trawling typically occurs over the same areas every year, leaving benthic environments little opportunity to recover (FAO 2001; Watling and Norse 1998).

Worldwide, mangrove forests are under intensive pressure from harmful fishing practices and deliberate destruction for aquaculture, namely shrimp farming (Islam and Hague 2004; Cardenal 1997). The introduction and expansion of shrimp farming has severely impacted coastal resources around the world, degrading wide coastal areas, mangroves forests and other wetlands. Shrimp farming destroys critical habitat for commercially important fish and shellfish, including shrimp (Naylor et al. 1998). Shrimp farms directly pollute coastal ecosystems by releasing biological wastes and pollutants (EJF 2004; Naylor et al. 1998).

Worldwide, shrimp farming has resulted in the loss of approximately 2.5 million acres of mangroves, particularly in Thailand and Ecuador, which lead the world in farmed shrimp production (EJF 2004; Cardenal 1997). Since mangroves provide critical nursery habitat for developing fish and shrimp, direct relationships between declining mangroves and declining fish catches exist (Cardenal 1997). In Bangladesh, the destructive loss of mangroves has been linked to continued decline in artisanal fishery catches (Islam and Hague 2004) and similar correlations have been observed in Australia, Indonesia, Malaysia, and the Philippines (EJF 2004). Since mangroves serve as natural filters for terrestrial pollutants and sediments, widespread mangrove loss can increase erosion, sedimentation and pollution, which can spread to coral reef and seagrass habitats (EJF 2004). Since approximately 99% of farmed shrimp production occurs in developing nations (EJF 2004), increased proliferation of shrimp farms throughout the developing world can severely impact coastal ecosystems and critical wild shrimp habitat (EJF 2004; Cardenal 1997).

Information on critical habitat protection within tropical shrimp trawl fisheries is limited. In Bangladesh, although managers established a closed season to facilitate the breeding of shrimp and other species, the restrictions are not enforced and the result is indiscriminate shrimp trawling throughout the year leading to the depletion of spawning adults (FAO 1997).

According to recent analyses, a serious lack of information exists on the effect of shrimp trawling on living marine resources (FAO 2001; FAO 1997). Basic information, such as the presence of benthic organisms and potential damaging effects done to them by trawling in many regions is lacking, and has not been collected (FAO 1997). Furthermore, lack of proper surveillance and management in many exporting countries may enhance the adverse effects of shrimp trawling on habitat and marine resources (FAO 1997).

In many tropical shrimp trawling countries, fishers add heavy chains known as tickler chains, which attach to the bottom line of the mouth of the trawl net and are dragged over the seafloor to drive shrimp into the trawl nets. Tickler chains destroy shellfish, sponges, sea urchins and other bottom-dwelling organisms (FAO 1997).

Twelve exporting countries, including Indonesia, the Philippines, Venezuela and Mexico, currently participate in a project funded by the Global Environmental Facility and implemented by the Food and Agriculture Organization of the United Nations to reduce environmental impact from tropical shrimp trawling (FAO 2006). However, since these countries contribute only a small percentage of shrimp to the United States (NMFS 2006), we chose to subtract for this factor.

Gear effects of shrimp trawl on habitat can vary within and among shrimp trawl fisheries. In Indonesia, fishing area conditions range from sandy and muddy mixtures to hard bottom, mangrove-rich regions (FAO 2001), while in other regions, fishing areas may include vulnerable reefs and seagrass beds (FAO 1997). Although shrimp trawling can severely impact hard-bottom communities, its effects on soft bottom habitats are less severe and often minimal (FAO 2004).

Since the habitats and sediment types over which shrimp trawling occurs vary widely between exporting nations, we chose to neither add nor subtract for this factor.

The United States leads the world in global imports of shrimp; approximately 88% of all shrimp sold in the U.S. is imported (Josupeit 2004). Tropical shrimp trawl fisheries in Thailand, Indonesia, Ecuador, China, Vietnam, India, Mexico, and Bangladesh supply the majority of shrimp exported to the United States (NMFS 2006).

Adequate information on management within tropical shrimp trawl fisheries is lacking. Regulatory measures and their enforcement can vary considerably between exporting countries, which include numerous underdeveloped countries which lack adequate funding for enforcement (FAO 2004; 2001). In Indonesia, fishery managers require licenses for all shrimp trawl vessels and prohibit trawling without the use of Turtle Excluder Devices (TEDs) or Bycatch Reduction Devices (BRDs), although monitoring and control of implementation remains low (FAO 2001). In the Philippines, fishery managers require licenses for all shrimp vessels and implement a minimum mesh size of 25mm and partial or complete closures of certain trawl areas to counter declining catch rates (FAO 2001).

Given the limited knowledge of management within the tropical shrimp fisheries, we chose to award a score of 1.00 for this factor.

Very few studies assessing the catch composition, population status, fishing effort and catch levels of tropical shrimp fisheries exist (FAO 2004; FAO 2001; FAO 1997). The few studies which have been conducted conclude that serious problems of insufficient monitoring exist within the fishery (FAO 2001; FAO 1997).

Increased exploitation of shrimp by trawling has resulted in a noticeable change in predator-prey relationships and catch composition in Bangladesh waters. Declines in populations of long-living commercially important fish species such as Red Snappers, Groupers, and large Croakers have been linked to the large, unregulated catch of juveniles by shrimp trawlers (FAO 1997). Additionally, the destructive practice of shrimp fry collection (used to seed shrimp farms) throughout many exporting nations removes large amounts of juvenile shrimp and finfish (EJF 2004). Wild shrimp fry collection can significantly impact wild shrimp populations, which can have serious impacts on coastal biodiversity and commercial fishing practices (EJF 2004).

Information on the number of vessels in commercial shrimp trawl fisheries is limited. In several exporting nations, fishing effort (ie. number of vessels) in the shrimp fishery has substantially increased, despite catch per unit effort (CPUE) remaining stable (FAO 2001).

Given the lack of adequate information, we chose to neither subtract nor add for this factor.

No recovery plan is needed.

Worldwide, shrimp trawl fisheries generate approximately 2% of the world's catch of fish in weight, but result in more than one third of the global bycatch total (Hall et al. 2000). Tropical shrimp trawl fisheries alone have the highest discard rate of all fisheries and account for over 27% of estimated global bycatch totals (FAO 2004). Shrimp trawls produce bycatch/catch ratios (weight discarded per weight landed) between 3:1 and 15:1 (Hall et al. 2000). In Indonesia - one the leading exporters of shrimp to the U.S. ¨C bycatch/catch ratios range from 8:1 to 15:1 (FAO 2001).

Finfish dominates the majority of the catch in many shrimp fisheries. Throughout the world, shrimp trawl fisheries routinely capture catfish, anchovy, herring, menhaden, shad, eel, flounder, snappers, groupers, mackerels, croakers, and jacks ¨C many of which are commercially important (FAO 2001). Since shrimp in tropical shrimp fisheries overlap in size with many juvenile fish species, the size of fish caught in the fishery are generally small (20 cm) and often of similar size to the shrimp (FAO 2001). Discards of undersized fish, are particularly problematic in having a negative impact on the health and future condition of marine resources (FAO 1997).

In many tropical shrimp trawl fisheries, bycatch which was formerly discarded is now being utilized (Zeller and Pauly 2005; FAO 2001). Since many tropical shrimp trawl fisheries occur adjacent to low-income, food deficient countries, local governments do not discourage the amount of bycatch being caught, but rather encourage its use once it is caught (FAO 2001). Most of the 1.8 million tones of bycatch produced by the Chinese shrimp trawl fishery, for example, provide feed for the Chinese aquaculture industry (FAO 2001). In Southeast Asia ¨C where exports supply the majority of shrimp to the U.S. - government agencies offer assistance in the move towards the use of bycatch species for the production of traditional food products and aquaculture feeds (FAO 2001). Although shrimp trawl fisheries in Indonesia retain more and more edible fish, the discard rates of juvenile fish remains high (FAO 2001), and in Bangladesh, discard rates of up to 80% have been estimated (FAO 1997). Recent analyses also suggest a trend of increased utilization of bycatch amongst Central America and Caribbean countries. In Belize, Colombia, Costa Rica and Nicaragua, between 20 to 30% of bycatch produced by shrimp trawl fisheries is now being utilized (FAO 2001).

Shrimp trawling has long been recognized as a significant source of sea turtle bycatch and mortality throughout the world. Six species of sea turtle (Leatherback, Green, Loggerhead, Kemp's Ridley, Hawksbill, Olive Ridley) appear on IUCN's Red List of Threatened Species as either 'endangered' or 'vulnerable', due largely to interaction with fisheries (IUCN 2006; Lewison et al. 2004; Crowder 2001; Hall et al. 2000).

Beginning in 1978, the U.S. National Marine Fisheries Service began developing Turtle Excluder Devices (TEDs) to reduce the mortality of sea turtles in the Gulf of Mexico and South Atlantic trawl fisheries (GMFMC 2005; SAFMC 2004). A TED is a grid-like structure which directs turtles, and other large organisms, out of trawl nets through a hole above the grid (GMFMC 2005; SAFMC 2004; Crowder 2001; Salz 1998). TEDs have been largely successful in reducing sea turtle bycatch in the U.S. Shrimp trawl fishery (Brewer et al. 2006; GMFMC 2005; SAFMC 2004; Crowder 2001). Recent analysis of Australia's Northern Prawn trawl fishery indicates that nets equipped with a TED resulted in a 99% reduction in sea turtle bycatch (Brewer et al. 2006).

In other exporting countries such as Indonesia and Bangladesh, fishery managers require shrimp trawls to use a Turtle Excluder Device (TED) or Bycatch Reduction Device (BRD) (FAO 2001; FAO 1997), however these restrictions remain largely unenforced (FAO 1997). Many fishers argue that TEDs and BRDs allow large commercially important fish to escape from the net and fishers are reluctant to use them (FAO 2001; FAO 1997).

Despite the introduction of these devices, the mortality of sea turtles in association with shrimp trawling continues (Epperly and Teas 2002). Current TED openings do not allow larger turtles, such as Leatherbacks and adult Loggerheads, to escape the net, decreasing overall TED effectiveness for Loggerheads in the Gulf of Mexico to only 25% (Epperly et al. 2002). Since haul duration of tropical shrimp trawls typically range from 2 to 5 hours (FAO 2001), even trawl nets equipped with TEDs may continue to capture and interact with endangered and threatened sea turtles (Epperly and Teas, Epperly 2002).

In 1989, the United States began prohibiting the importation of shrimp from countries whose sea turtle protections were not compatible with those in the U.S. (Salz 1998). As of May 2006, the U.S. Department of State certified 38 nations as meeting the requirements for continued importation of shrimp into the U.S., including the use of TEDs or having fishing environments that do not pose a danger to sea turtles (U.S. Department of State 2006). Chief exporting Caribbean nations including Belize, Ecuador, Honduras, Mexico, Panama, Suriname, and Venezuela require TEDs and have received certification (U.S. Department of State 2006).

For these reasons, we chose to neither add nor subtract for this factor.

Shrimp trawling in tropical regions around the world continues to capture significant numbers of non-targeted species (FAO 2001). Bycatch Reduction Devices (BRDs) allow the escape of commercially important species of finfish and can significantly reduce the incidental capture of non-targeted species (FAO 2001). BRDs, such as the Nordmore grate, reduce bycatch levels by seperating actively swimming fish, which will swim out of the net to avoid passing through the grate, from passive shrimp which continue into the net (FAO 2001).

The use of BRDs in temperate shrimp trawl fisheries has considerably reduced bycatch levels without substantial reduction in the catch of shrimp (FAO 2001). Despite their success in temperate shrimp fisheries, the use of BRDs in tropical shrimp trawl fisheries is not as effective since shrimp in these fisheries overlap in size with juvenile fish which need to be excluded from the net (FAO 2001). Continuing work involving the use of grids and other devices mounted into the top panel of tropical shrimp trawls show some promise but remains incomplete (FAO 2001). Additionally, increased utilization of bycatch in many countries has reduced the demand for BRDs to those which exclude only the smallest of non-targeted species (Zeller and Pauly 2005; FAO 2001).

The practice of collecting wild shrimp fry (juveniles) to 'seed' shrimp farms has the potential to severely impact shrimp and finfish populations. In Bangladesh, the removal of more than 2 billion Giant Tiger Prawn larvae results in approximately 200 billion other organisms, including other shrimp, finfish, and zooplankton. Here, shrimp fry fisheries remove up to 90% of the Giant Tiger Prawn population (EJF 2004). Shrimp fry fisheries, and the enormous bycatch they generate, threaten future populations of shrimp and finfish and can severely impact coastal biodiversity and commercial fisheries (EJF 2004).