Once an overcapitalized fishery, shrimp fishing effort in the US Gulf of Mexico has considerably declined since the early 2000s. Current fishing mortality estimates are far below the overfishing limit; spawning biomass is at high levels and well above the limit that defines an overfished condition. Measures to reduce the bycatch of juvenile red snapper led to the mandated use of better performing bycatch reduction devices (BRDs) in federal waters. NOAA has implemented a fleet-wide turtle excluder device (TED) performance standards that requires an 88% TED effectiveness rate, which is monitored through tri-annual reviews of inspection records. The US shrimp fleet has improved TED compliance, meeting this performance standard during every 4-month monitoring period since mid-2014.
The current observer coverage in the fishery is not sufficient to adequately quantify and characterize bycatch across the entire fishery. Even with better performing bycatch reduction devices in place, there are 2.5 pounds discards for every 1 pound of harvested shrimp (a vast improvement from the baseline, but still high). There are limited data on the benthic impacts of shrimp trawling in the Gulf of Mexico (though most of the trawling does take place over resilient muddy and sandy bottoms).
Last updated on 12 December 2012
The condition of each shrimp stock is monitored annually. A new assessment model, Stock Synthesis (SS-3), was used to assess the Northern brown shrimp in 2011. This model is now considered the most appropriate choice for modeling gulf shrimp (Hart and Nance, 2012), and incorporates commercial fishing data (from 1984-2011) with fishery independent surveys (SEAMAP and Louisiana State Shrimp Surveys), deemed to greatly improving the precision of estimates (Hart, 2012).
Unlike previous assessments, where stock reproductive capacity and exploitation status (overfishing index) was estimated in terms of the number of surviving parents, output data is now generated in terms of spawning stock biomass and fishing mortality estimates (F) (Hart, 2012; Hart and Nance, 2012).
Last updated on 22 November 2014
In the past, NMFS scientists used to define overfishing for brown, pink, and white shrimp in the Gulf of Mexico in terms of spawning population size (parent stock size). However, with the recent revision of the assessment methodology, which presents outputs in terms of spawning stock biomass (SSB) and fishing mortality (F), there is a need to update the definitions of overfishing and overfished, so the comparison between the new model outputs (i.e. SSB and F) with these definitions is possible and the stock status effectively assessed. New definitions of overfishing and overfished in terms of F and SSB, respectively, have thus been recently proposed (Hart and Nance, 2012), but are yet to have been formally adopted.
Last updated on 22 Nov 2014
Proposed Amendment 15 to the Fishery Management Plan (see “Managers’ Decisions” section above) includes possible changes to stock status determination criteria. The potential new reference points in Amendment 15, “Overfishing” and “Overfished” thresholds, have been under discussion since 2011, and would bring fishery reference points in line with outputs of the newest stock assessments.
Amendment 15 presents the Council with three alternative approaches to setting these reference points (including not making any changes), and designates one of the three options as "preferred.’ For defining overfishing, the preferred method defines the maximum fishing mortality threshold (MFMT) as the maximum apical fishing mortality rate (F) computed for the fishing years 1984 to 2012 plus the 95% confidence limits. Species specific MFMT values will be recomputed during updated assessments, but only among the years 1984-2012. The values for each species will be updated every 5 years.
As for the preferred method of defining overfished status, the minimum sustainable stock threshold (MSST) is defined as the minimum total annual spawning biomass minus the 95% confidence limit for the fishing years 1984 to 2012. Species specific MSST values will be recomputed during the updated assessments, but only among the fishing years 1984-2012. The values for each species will be updated every 5 years.
Proposed (preferred) MFMT for Gulf of Mexico brown shrimp: 3.68
Proposed (preferred) MSST for Gulf of Mexico brown shrimp: 10,944 metric tons of tails (GMFMC, 2014).
Last updated on 13 December 2012
The stock of brown shrimp is healthy. Spawning stock biomass has been increasing since the early 2000s, and was estimated at c. 55,600 tonnes in 2011, well above the proposed overfished level (8,000 tonnes). Fishing mortality has been decreasing and currently is far below the overfishing limit (Hart, 2012; Hart and Nance, 2012).
Last updated on 13 Dec 2012
After a period of more than 10 years with fluctuations around the 15,000 tonnes, Spawning stock biomass (SSB) has been steadily increasing and is currently at high levels. For fishing mortality (F), a decreasing trend has been observed in both fishing fleets in the past decade, with current (2011) F´s of 0.63 and 1.14 for the offshore and inshore fishery, respectively. In terms of landings, despite the considerable inter-annual fluctuations, a decreasing trend since in the last decade is visible in the overall brown shrimp landings (Hart, 2012; Hart and Nance, 2012).
Last updated on 11 December 2012
White, brown, and pink shrimp species in the Gulf of Mexico are managed by the Gulf of Mexico Fishery Management Council under a federal Fishery Management Plan (FMP) that went into effect in 1981 (GMFMC, 1981). Further, the FMP is amended nearly annually with new controls to limit catch, access and bycatch. Effort is the primary control for the management of this fishery.
Proposed Amendment 15 to the FMP (GMFMC, 2014) is under consideration as of November 2014 (the Gulf of Mexico Fishery Management Council will vote on the measure after the public comment period ends). In addition to changing stock status determination criteria, the Amendment also defines the response to possible overfishing (if the fishing mortality rate exceeds the maximum threshold in two consecutive years, appropriate committees or panels are convened to review the situation, and may recommend fishing pressure reductions if excess fishing is determined to be a contributing factor).
Last updated on 11 Dec 2012
Last updated on 14 November 2014
Specific regulations are in place for shrimping in Texas state waters (≤ 9 nautical miles): e.g. closed seasons and areas, fishing gear restrictions, bycatch limits, use of TEDs and BRDs (TPWD, 2011).
Last updated on 22 November 2014
In order to acquire a federal commercial shrimp permit, Gulf shrimp fishermen must complete and submit a Gear Characterization form and report annual landings of shrimp and value by species. Permit holders must also participate in NMFS-sponsored electronic logbook reporting if selected.
Fishermen’s compliance with TED regulations is not currently a concern. In 2012, data emerged that suggested compliance with TEDs was lower than expected and the capture rate of sea turtles was higher than expected (NOAA, 2012b). In light of this information NOAA issued a TED performance standard that requires an 88% TED effectiveness rate (TEDs must be installed in compliance with regulations such that 88% of sea turtles encountered by the shrimp fleet can escape the nets) (NOAA, 2013). To monitor compliance NOAA reviews inspection records tri-annually (four month periods) to estimate compliance and effectiveness rates. If the TED effectiveness rate falls below 88% but remains at or above 84%, there will be an enforcement pulse and an increase in outreach to shrimpers to ensure their TEDs are properly installed. If TED effectiveness falls below 84% for two consecutive periods, there will be a minimum of 30-day shrimp fishery closure in the respective area, during which an enforcement pulse and increased outreach will help shrimpers to rectify the problems in TED installation (NOAA, 2016). When this system was first implemented, TED effectiveness consistently fell below the 88% threshold, and sometimes fell below the 84% threshold (NOAA, 2014). But since mid-2014 TED effectiveness per period has consistently remained above the 88% threshold (NOAA, 2016).
Last updated on 13 November 2014
The shrimp fishery is known to interact with several PET species, but the major concerns are over sea turtles (GMFMC, 2007). Turtle excluder devices (TEDs) have been required on shrimp otter trawls since 1990 and mandatory use of TEDs in both federal waters and some state waters has greatly reduced mortality (GMFMC, 2007). For skimmer trawls, pusher-head trawls (a type of push net) and wing nets (butterfly nets), the federal government provides an exemption to turtle excluder (TED) requirements. Vessels using these gears may employ alternative tow time restrictions in lieu of TEDs. The alternative tow time restrictions currently limit tow times to 55 minutes from April 1 through October 31, and 75 minutes from November 1 through March 31 (Statute §50 CFR 223.206 (d)(2)(i)).
Kemp’s ridley sea turtle population is rebuilding. Other populations are showing signs of increases but no definitive rebuilding is occurring yet (NOAA, 2012b).
The 2014 Endangered Species Act Section 7 Consultation and Biological Opinion found that continued operation of southeastern shrimp fishery under current regulations is not expected to cause appreciable reduction in the likelihood of survival and recovery of sea turtles, Atlantic sturgeon or smalltooth sawfish (NOAA, 2014).
Last updated on 5 December 2014
Federal fishery managers require mandatory observer coverage to monitor bycatch and sea turtle interactions. Observer coverage is low, at only about 2% of effort, but does generate information on the species and quantities of bycatch in the shrimp fishery. A recent study in 2012 characterized the Gulf of Mexico penaeid fishery based on data from the observer program from 2007-2010. Data indicated that grouped finfish accounted for 27% (9.4 kg/h) of the total catch, followed by Atlantic croaker at 16% (5.4 kg/h), brown shrimp at 14% (4.8 kg/h), white shrimp at 11% (3.7 kg/h), crustaceans at 7% (2.4 kg/h), seatrout at 6% (2.0 kg/h), invertebrates at 5% (1.8 kg/h), longspine porgy at 4% (1.4 kg/h), and pink shrimp at 4% (1.3 kg/h); all other species accounted for 6% (2.0 kg/h) of the total weight (Scott-Denton et al., 2012). In the same study ratios of bycatch to target catch were calculated: all bycatch to penaeid shrimp is 2.5:1; fish to penaeid shrimp: 2:1. These ratios for the Gulf of Mexico shrimp fishery are lower than previously estimated (4:1). The decrease can be explained, in part, by a decrease in percent composition of finfish species and in increase percent composition of shrimp because of higher shrimp catch per unit effort (almost double) than previously recorded.
Although not a main bycatch species, bycatch of juvenile red snapper in shrimp trawls (which accounts for less than 0.5% of total catch in the shrimp fishery) in the western Gulf of Mexico was found to be a key factor in the decline of this commercially valuable species (GMFMC, 2007). The Gulf of Mexico Fishery Management Council (GMFMC) established regulations to address the red snapper bycatch by the shrimp trawl fishery. The GMFMC believes that to end overfishing and rebuild the red snapper stock, large reductions in bycatch mortality from the shrimp fishery need to be achieved either through technological means such as Bycatch Reduction Devices (BRDs) and through a reduction in effort by the shrimp fishery. Electronic logbook data show that shrimp effort has decline (likely due to economic pressures) beyond the reduction target, thus no forced reductions in effort have been required.
To address bycatch the use of bycatch reduction devices (BRDs) has been required since 1998. Posteriorly, managers de-certified the use of several BRDs as part of the red snapper rebuilding plan (GMFMC, 2007) and required the use of BRDs that reduce finfish bycatch by at least 30%. However, in state waters only two Gulf states (Florida and Texas) require the use of BRDs (GMFMC, 2007).
In July 2014, a bycatch status study commissioned by the Florida Pink shrimp FIP, Texas Shrimp FIP, and Sustainable Fisheries Partnership was completed. This study used federal fishery observer data, the long-term fishery independent survey dataset of SEAMAP, biological information on the bycatch species, and shrimp fishery effort data to identify the main bycatch species of the Gulf of Mexico shrimp fishery, evaluate their status, and determine whether or not there is a correlation between shrimp fishery effort and the status of the byatch populations. The study showed that the only main bycatch species or species groups (comprising 5% or more of the catch by weight) in the Gulf of Mexico shrimp fishery are Atlantic croaker, longspine porgy, sea trouts, and inshore lizardfish. SEAMAP abundance data indicate that all of these populations are either stable or increasing, and comparison of the abundance data with shrimp fishery effort data suggest that only Atlantic croaker and sea trout population abundance appear to be correlated with shrimping effort. Both populations appear to have been increasing since shrimp effort decline in the early 2000s, and have demonstrated high resilience. While further studies, especially full-fledged stock assessments, on these populations would be helpful, this study indicates that the shrimp fishery does not pose a risk of serious or irreversible harm to the bycatch species or species groups (LGL, 2014).
Last updated on 12 December 2012
Benthic impacts of shrimp trawling in the Gulf of Mexico are not expected to be significant as most trawling is conducted over muddy and sandy bottoms, and valuable coral areas are closed to trawling (GMFMC, 2012). However, some studies also point out that the frequency and intensity of trawling in the Gulf is high and leads to more severe impacts on the bottom, despite the resiliency of the habitat. NRC identified Gulf as one of the most intensively trawled areas in the US.
Last updated on 12 Dec 2012
Sixteen marine reserves have been established within the jurisdiction of the Gulf of Mexico Fishery Management Council for various purposes and different fisheries. None relate directly to white shrimp concerns although two have shrimp conservation purposes. A cooperative Tortugas Shrimp Sanctuary is included as a reserve with the state of Florida to permanently close a shrimp nursery ground in the Florida Keys to the use of trawls and harvest or possession of shrimp. The Texas Closure of a nursery ground off Texas is cooperatively closed by the Gulf Council and the state of Texas for 45 to 60 days out to either 15 or 200 miles (GMFMC, 2006).
Other environmental sites of special interest relevant to penaeid shrimp and red snapper in the Gulf of Mexico include the seasonal closure of federal and state inshore waters to shrimping in Southwest Florida from November 1 through May 20 to protect juvenile stone crab and prevent loss of stone crab traps in trawls, over 4,051 square nautical miles; and the Central Florida shrimp/stone crab Separation Zones, which require closure of state and federal waters to either shrimping or crabbing from October 5 to May 203. Several small marine reserves exist to protect soft coral areas (GMFMC, 2006).