Albacore tuna

The albacore stock in the Indian Ocean is abundant and not subject to overfishing.This stock is managed and assessed by the Indian Ocean Tuna Commission (IOTC). The last stock assessment was carried out in 2022, using data up to 2020. The next stock assessment is expected in 2025.Indian Ocean albacore has been caught since the 1950s. Catches peaked at around 45,000 tonnes in 2010 and have stayed at relatively high levels, at around 39,000t.Spawning biomass (SB) has declined since the 1980s, but it remains above target levels (Maximum Sustainable Yield, MSY). In 2020 it was 156% of SBMSY, indicating that the stock is not in an overfished state.Fishing mortality (F) in 2020 was 68% of FMSY, and so the stock is subject to overfishing. This is a significant improvement on previous figures from 2019, which showed that F was 135% of FMSY and approaching the upper limit set for the fishery.There is some uncertainty in this assessment, particularly relating to recent biomass trends. Catch estimates may also be unreliable as reporting in the Indian Ocean is poor from some countries. Better data is needed for a more reliable assessment. The report notes that changes in Catch per Unit Effort have influenced the results, but the assessment does not account for changes in catchability, e.g. through improved efficiency of fishing gear. Projections on the future of the stock are somewhat uncertain, and are influenced by recent recruitment of young tuna into the stock, which has been poor. They indicate that catches at 2020 levels (41,051 tonnes) would have a low probability (1% or lower) of causing the stock to fall below BMSY or above FMSY. Catches at this level would be below the estimated Maximum Sustainable Yield, which is 45,000t.This is again very different from the 2019 assessment, which indicated that catches of 38,000t would cause the biomass to fall below MSY. Maximum Sustainable Yield in that assessment was estimated to be 35,700t.

Few appropriate management measures are in place for Indian Ocean albacore. There are no catch limits or quotas to prevent overfishing. There are some uncertainties in the catch data, and monitoring and enforcement needs to be improved.Tuna, marlin, and swordfish are highly migratory species, found on the high seas and in numerous countries' waters. This makes harmonised and effective management challenging. Regional Fisheries Management Organisations (RFMOs) are responsible for monitoring and managing these stocks on behalf of the countries that access them. However, the degree to which management is implemented, monitored and enforced by each country varies significantly.This stock is managed and assessed by the Indian Ocean Tuna Commission (IOTC). There is no catch limit, but there are targets to keep fishing mortality (F) and spawning biomass (B) at the levels which would produce Maximum Sustainable Yield (MSY). There are also limit reference points (0.4 BMSY and 1.4 FMSY) which would indicate the need for further management actions, if the stock reached them. Harvest control rules (HCRs) are needed to ensure that fishing pressure is appropriately managed if and when the stock declines, and these have not been developed for albacore. Without catch limits or HCRs, appropriate management measures are not in place for this stock.Stock assessments are carried out regularly for this stock, including an estimation of Maximum Sustainable Yield and predictions of the likelihood of the stock meeting its targets. The 2022 stock assessment indicated that MSY is 45,000 tonnes. Provisional catch in 2021 was 14,051t and the 2016-2020 average is 39,397t. Catches at current levels are expected to maintain the stock in a healthy state. However, the previous assessment in 2019 indicated that catches at previous levels posed a threat to the stock, and no measures were taken to reduce them. Management is not, therefore, responding to scientific advice or ensuring adequate protections for the stock.The main management measure for Indian Ocean albacore is a freeze on the capacity of the fishing fleet to 2003 levels, to prevent the fleet from growing. This legislation is very generic, applying across all fleets, and would be better replaced by spatial and temporal closures and quota allocation. There also appear to be concerns that the freeze has not been well enforced thus far.Monitoring and compliance with management measures in the IOTC region is generally poor. Some countries repeatedly fail to report catch data to the commission. In 2018 IOTC introduced a new measure aimed at improving reporting on catch and bycatch, including prohibiting a country from retaining a species if they fail to report catches for it. However, in 2021 the commission noted that data reporting issues persist. Mandatory observer coverage is very low, at just 5% for all vessels over 24m or under 24m and fishing outside of their Exclusive Economic Zone (EEZ). A number of countries fail to meet the 5% threshold. In general, 20% is scientifically recommended to ensure adequate monitoring of catch and bycatch. In 2019 a proposal was put forward to increase coverage to at least 20%, but consensus could not be reached.Other IOTC conservation and management measures of note include:To help address Illegal, Unregulated, and Unreported fishing (IUU), the IOTC maintains an active vessel register and an IUU Vessel List. In 2021, all transhipments at sea were banned, except for large scale tuna longliners, which must be pre-approved, monitored by an observer and the vessel uses a Vessel Monitoring System (VMS).In 2012 IOTC banned the use of driftnets on the high seas. In 2022 this will be extended to the entire IOTC area (i.e. including countries' EEZs).Using aircraft and unmanned aerial vehicles as fishing aids, which significantly contribute to fishing effort by helping to detect fish, is banned.Using artificial lights to attract tuna and tuna-like species beyond territorial waters is banned.

Most albacore catches from the Indian Ocean are by longline. While longlining is unlikely to have habitat impacts, it can have a bycatch of highly vulnerable species such as sharks, turtles, and seabirds.Around 90% of the albacore catch in the Indian Ocean is taken in pelagic and coastal longline fisheries. Most of the rest is by handlines and trolls, which are very selective and low-impact. A small amount of the catch is by gillnet, which would receive a default red rating from MCS owing to the very high levels of cetacean and turtle bycatch.A number of Endangered and Critically Endangered species are caught as bycatch in Indian Ocean longline fisheries, but scientifically recommended gear modifications to reduce impacts have not been implemented. Several countries have failed to implement national plans of action (NPOAs) for sharks, seabirds and turtles as required. Monitoring and reporting of bycatch in fisheries managed by IOTC is poor. Most data come from scientific observers on vessels. Scientific recommendations are that 20% of a fishery should be observed for accurate data. IOTC only requires coverage of 5%. Many fleets are not reaching this level. This makes it difficult to assess the impact of these fisheries on vulnerable species.Longlining for swordfish and albacore tuna takes place closer to the surface than in other fisheries. This increases the bycatch risk, as animals such as sharks and seabirds are more easily attracted to the bait.The IOTC reports that flatback, green, hawksbill, leatherback, loggerhead and olive ridley turtles are caught in its fisheries. Of these, hawksbills, southwest Indian Ocean leatherbacks, and northwest Indian Ocean loggerheads are critically endangered. Data on interactions is not regularly submitted, so the extent of bycatch is unknown. Gillnetting is the biggest concern for turtles, with estimates ranging from 11,000-52,000 individuals being caught annually. Longlining is estimated to catch around 3,500 turtles annually. In the southwest, longlining could be threatening local populations. Turtles can also be entangled by Fish Aggregating Devices used by purse seiners, and around 250 turtles are estimated to be caught by purse seiners annually. An estimated 75% of turtles are released alive from longliners and purse seiners. The scientific committee advises that maintaining or increasing fishing effort in the Indian Ocean without appropriate measures in place will likely result in further population declines. Current mitigation measures include requirements to release turtles wherever possible. Longliners must carry cutters or de-hookers to aid with this but scientifically recommended gear modification, such as circle hooks, is not required.Seabirds caught in IOTC fisheries include a number of endangered albatrosses, including the critically endangered Tristan albatross. Albatrosses and large petrels are amongst the most threatened groups of birds in the world, due in a large part to the impacts of bycatch in longline fisheries. Data on interactions is not regularly submitted, so the full extent of bycatch is unknown. Available information suggests higher sea bird bycatch at higher latitudes, and in coastal areas in the southern Indian Ocean. Impacts have been assessed in more detail in areas south of 25 degrees, and very high seabird bycatch rates have been recorded. This coincides with the greatest densities of albatrosses and large petrels. The scientific committee notes that the available evidence indicates considerable risk from longline fishing to the status of seabirds in the Indian Ocean. A recent assessment estimated that approximately 30,000-40,000 seabirds were killed by longlining in the Southern Hemisphere (including south Indian Ocean) between 2012 and 2016. The required longline mitigation measures, which only apply to areas south of 25 degrees S, do not follow recommended best practice. IOTC requires two measures from a set list of options, including weighted hooks, bird scaring lines and night setting. ACAP (the Agreement on the Conservation of Albatrosses and Petrels) recommends the simultaneous use of all three, or hook-shielding or underwater bait setting devices.Most bycatch of cetaceans is by gillnetting, but interactions with longliners have been recorded. Cetaceans such as pilot whales, Risso's dolphins and killer whales can be attracted by the fish caught on the line. These interactions are not well recorded and the scale of impact by longlining is unclear. There are no mitigation measures for longline. The IOTC scientific committee notes that maintaining or increasing fishing effort in the Indian Ocean without appropriate mitigation measures in place may result in further declines in a number of cetacean species.In 2020, around 82,000t of sharks were caught, with rays totalling around 1,800t. Gillnets are responsible for around 40% of the catch, followed by longline, handline, and trolling. It is estimated that around 30,000t is blue shark, which is not overfished or subject to overfishing. Most of the rest was not reported to species, so data on interactions is poor. However, species such as the critically endangered oceanic whitetip and scalloped hammerhead, and the endangered shortfin mako and pelagic thresher are known to be caught at significant levels in the Indian Ocean. The available evidence indicates considerable risk to these species. Mobulid rays are also bycaught and are declining across the Indian Ocean.There are some mitigation measures, such as restrictions on finning, and bans on retaining some species. Most thresher sharks die after being hooked, even if released. Therefore the ban on retaining them is probably not effective at protecting them. There are no gear-specific measures, in spite of evidence that this could reduce impacts. In the Atlantic, the use of circle hooks has been shown to increase survival of shortfin mako, blue marlin and swordfish if accidentally caught.