Recreationally caught AMG cobia. Photo © Eszter Keresztes
Cobia (Rachycentron canadum) are distributed worldwide in tropical and warm-temperature waters. They occur along the Atlantic coast from Nova Scotia to Argentina, and are most abundant in US waters from Chesapeake Bay south through the Gulf of Mexico. Two stocks are recognized in US waters, one along the Atlantic coast from Georgia north (Atlantic cobia) and the other along the east coast of Florida through the Gulf of Mexico. This stock definition was concluded through the Southeast Data, Assessment, and Review (SEDAR) 58 Stock Identification Process. Stock structure continues to be investigated through ongoing tagging studies to further identify and describe potential subcomponents of these populations.
Cobia typically reach sexual maturity by 3 years (generally 2.5 feet long, fork length), with males maturing earlier than females. Females grow to be larger than males, and may reach 6 feet and weigh up to 100 pounds. On the US Atlantic coast, cobia move into nearshore waters when water temperatures reach 20-25°C (68-77°F). While aggregated inshore, they spawn over a period of 4-6 weeks. Spawning is localized, with at least 2 genetically distinct spawning aggregations occurring within the Atlantic stock, one in Virginia and the other in South Carolina. The timing of local spawning progresses up the coast as temperatures warm, with peak spawning in May for South Carolina, June for North Carolina, and July for Virginia. Cobia are batch spawners, meaning a female may spawn several times (about every 4 to 6 days) during the spawning season.
Cobia make seasonal migrations, wintering in the south or offshore and moving north and inshore during the summer months. They are drawn to structure to feed and find shelter from predation. Juveniles and adults are often found around live bottom, wrecks, and buoys, as well as flotsam and seaweed mats. Their diet consists primarily of fish and crustaceans.
Enthusiastically pursued by recreational anglers, cobia support recreational fisheries throughout the South Atlantic and into the Mid-Atlantic region. Primary methods include bottom fishing with natural bait as well as sight-casting, which has gained popularity more recently. The annual recreational catch of Atlantic cobia has increased since the 1980s, with increases to numbers of fish recreationally harvested and those caught and released. In 2018, recreational anglers landed an estimated 113,939 cobia (number of fish) and released 367,129 cobia. Recreational harvest is managed through a one fish per person bag limit, 36” fork length minimum size limit, and state-specific seasons and vessel limits.
The commercial fishery is much smaller, landing 50,314 pounds in 2018. Primarily a bycatch fishery, it has been associated with the snapper/grouper hook and line fishery and troll fisheries for many South Atlantic species, although more directed fisheries have recently developed in some areas. Commercial harvest is managed through a coastwide two fish per person possession limit, 6 fish vessel limit, and a 33” fork length minimum size limit. States are able to make further restrictions to their respective fisheries, and some have instituted a 36” fork length commercial minimum size limit, matching the recreational fishery’s limit.
Two cobia stocks occur off the US Atlantic coast; the Atlantic Migratory Group (AMG cobia) and the Gulf of Mexico Migratory Group (Gulf cobia), which is found throughout the Gulf of Mexico and extends to Florida’s east coast. The 2020 SEDAR 58 Atlantic Cobia Benchmark Stock Assessment is the most recent assessment for Atlantic cobia. Stock status was determined by comparing spawning stock biomass (SSB) and fishing mortality rate (F) to reference point values based on F40%, or the fishing mortality rate that results in 40% of the stock’s maximum reproductive potential in the absence of fishing. SSB in 2017 was estimated at 4,212 metric tons (mt), above the SSBF40% (SSB at F40%) reference point of 2,979 mt, indicating the stock is not overfished. F in 2017 was estimated at 0.17, below the F40% reference point of 0.69, indicating overfishing is not occurring.
Atlantic cobia biomass has shown a pattern of rapid increase in strong recruitment years followed by years of decline. These strong year classes have maintained the stock above the overfished threshold through subsequent periods of biomass decline since the 1980s. Data from SEDAR 58 identified several of these notably strong year classes, the most recent of which occurred in 2010.
In 2017, the Commission approved Interstate Fishery Management Plan (FMP) for Atlantic Migratory Group Cobia, which began cooperative management of Atlantic cobia with the South Atlantic and Gulf of Mexico Fishery Management Councils and defined the management unit from Georgia through New York. In 2019, the Commission approved Amendment 1 to the FMP. Amendment 1 establishes management measures that transition the FMP from complementary management with the South Atlantic and Gulf of Mexico Fishery Management Councils to sole management by the Commission. Amendment 1 to the FMP was initiated in anticipation of the Councils’ Regulatory Amendment 31 to the Coastal Migratory Pelagics (CMP) FMP, which was also implemented in 2019 and removed Atlantic cobia from the Councils’ oversight.
Amendment 1 changed several portions of the Commission’s FMP that were previously dependent on the CMP FMP and institutes a long-term strategy for managing in the absence of a federal plan. Several of these changes established processes for the Commission to carry out management responsibilities previously performed by the SAFMC, including setting of harvest quotas and sector allocations, defining stock status criteria, and recommending management measures to be implemented by NOAA Fisheries in federal waters. Amendment 1 also transitioned responsibilities of monitoring and closing (if necessary) commercial harvest to the Commission. Finally, Amendment 1 established a de minimis status for the commercial sector that exempts states with small commercial harvests from in-season monitoring requirements. States are required to implement measures of Amendment 1 by July 1, 2020.
Moving forward, the Commission will recommend to NOAA Fisheries that fishing in federal waters be regulated according to a vessel’s declared state of landing. Regulations resulting from this recommendation would only apply in federal waters. Fishermen would still be required to follow state possession or landing limits in state waters.
Amendment 1 established a harvest specification process, which allows the Board to specify a limited set of management measures for up to 3 years. One of the measures that may be set through this process is a coastwide harvest quota. In February 2020, the Board specified the annual coastwide quota to be 80,112 fish for 2020-22, noting that status quo measures for the recreational fishery would remain in effect for 2020.
The commercial fishery is allocated 8% of the total quota, giving an annual coastwide commercial quota of 146,232 pounds. Non-de minimis states are required to monitor commercial landings. A trigger percentage of the commercial quota will be set based on past harvests. If commercial landings meet the trigger percentage, a coastwide commercial closure in state waters will occur at least 30 days later. States have the ability to be more conservative than Commission FMPs, if they choose.
The recreational fishery is allocated 92% of the total quota, giving an annual coastwide recreational quota of 73,703 fish. This quota is allocated into the state recreational harvest targets shown below. States may set their own seasons and vessel limits to achieve their respective targets. State harvests are periodically evaluated against the targets using rolling averages of up to the previous 3 years. If a state’s average exceeds the target, that state must alter its season or vessel limit to achieve the target in the future.