Improving the biological status of BSC stocks

 Palk Bay Fishery Assessment  

‍Fisheries Inspectors (FIs) from the Department of Fisheries & Aquatic Resources’ (DFAR) District Fisheries Offices (DFOs) in Jaffna, Kilinochchi and Mannar conducted the 9th annual assessment of the BSC fishery. The assessment was completed over a period of 27 days between 15th February and 31st May 2023. FIs measured and checked the maturity of 5,969 female crabs from 14 landing centres in the three districts. Fishing communities, agents and seafood manufacturers notably Taprobane Seafood Group, assisted the FIs to collect data from the Palk Bay fishery. 

‍Stock Status (Biomass) The spawning potential (SP) of the stock was estimated by pelagikos using an application available in the Barefoot Ecologist’s Toolbox. The following life history ratios and parameters were used M/K = 1.37 | Linf/Lm50 = 0.55 | Linf = 189mm | Lm50 = 104mm | Lm95 = 124mm for the analysis. The spawning potential of the fished population (44%) strongly suggests that the status of the BSC stock in the Palk Bay was sustainable in 2023. The spawning potential was above the Upper Target Reference Point (SP = 40%) associated with fisheries operating at maximum sustainable yield. This indicates that the Palk Bay stock was underfished in 2023.

 Impact of Fishing (Mortality) No indication of growth overfishing was observed in the Palk Bay fishery in 2023. The percentage of immature crabs observed in the catch was 2% in 2023, compared to 3% in 2022 and 2021. The average length (size) of crabs caught (136mm ≈ 170 grams) was above the estimated Optimum Length (Lopt = 130 mm ≈ 146 grams). 56% of the crabs sampled were caught at the length that would produce MSY (117 – 143 mm ≈ 104 – 190 grams). Old, large female crabs (> 143 mm ≈ 190 grams) made up 33% of the sampled catch. No indication of recruitment overfishing was observed in the Palk Bay fishery in 2023. 

Gulf of Mannar Fishery Assessment 

FIs from the DFAR’s DFOs in Puttalam and Mannar conducted the 9th annual assessment of the BSC fishery in the Gulf of Mannar. FIs measured and checked the maturity of 5,057 female crabs over a period of 33 days between 8th February and 28th June 2023. FIs collected monthly data from seven landing centres and four collections centres in the two districts. Data collection was supported by fishing communities, agents and seafood manufacturers, notably Taprobane Seafood Group and Alpex Marine. 

Stock Status (Biomass) 

The spawning potential (SP) of the stock was estimated by pelagikos using an application available in the Barefoot Ecologist’s Toolbox. The following life history ratios and parameters were used M/K = 1.37 | Linf/Lm50 = 0.55 | Linf = 189mm | Lm50 = 104mm | Lm95 = 124mm for the anlaysis. The spawning potential of the fished population (39%) suggests that the status of the BSC stock in the Gulf of Mannar was sustainable in 2023. The spawning potential was above the Target Reference Point (SP = 30%) associated with a BSC fishery operating at maximum sustainable yield. The estimated spawning potential was well above the Limit Reference Point proposed for the fishery (SP = 20%); the point at which recruitment to the stock is likely to be become reduced and the fishery would become unsustainable. 

Impact of Fishing (Mortality) 
No indication of growth overfishing was observed in the Gulf of Mannar fishery in 2023. The percentage of immature crabs observed in the catch was 1% in 2023, compared to 4% in 2022 and 13% in 2021. The average length (size) of crabs caught (136 mm ≈ 170 grams) was above the estimated Optimum Length (Lopt = 130 mm ≈ 146 grams). 63% of the crabs measured were caught at the length that would produce MSY (117 – 143 mm ≈ 104 – 190 grams). Old, large female crabs (> 143 mm ≈ 190 grams) made up 29% of the sampled catch. No indication of recruitment overfishing was observed in the Gulf of Mannar fishery in 2023. 

Improving the ecological status of the BSC fisheries 

Ecological impacts on non-target species 
The FIP continued to implement two new activities with BSC fishing communities and the Department of Wildlife Conservation (DWC) throughout the first six months of 2023, to reduce the ecological impact of BSC fishing on turltes in the Palk Bay and the Gulf of Mannar. 

(1) Live-release of turtles caught by fishing gears in the Gulf of Mannar fishery 
A preliminary analysis of 126 observations reported by field assistants in four fishing villages revealed that 275 turtles were entangled in fishing nets during the period of December 2022 to May 2023. 74% of entanglements were due to ray nets (67%) and nets set for silver pomfret (17%). Turtles also become entangled in nets set for shark, BSC, Indian mackerel, nine ply nets, minnel nets and shrimp nets (see right). 81% of turtles entangled in fishermen’s nets were released alive. 52 turtles died before they could be released. All of the dead turtles were accidentally entangled in ray nets (94%) or silver pomfret nets (6%). The nine turtles entangled in BSC nets were released alive by fishermen. 

Ray and pomfret nets: The mesh size of nets used by fishermen to catch rays in the Gulf of Mannar ranges from 5” to 21”. The twine used ranges from 9 to 36 ply. 18” mesh nets with 21, 30 or 36 ply are the most common nets used to catch whiptail stingrays, devil rays, spotted eagle rays, cow-nosed rays and honeycomb rays weighing up to 200kg, including. Silver pomfret weighing up to 4kg are caught using 7” mesh nets with 7 ply twine. 

Turtles: Four species of turtles - olive ridley (Lepidochelys olivacea), green (Chelonia mydas), hawksbill (Eretmochelys imbricata) and loggerhead (Caretta caretta) - were observed in fishermen’s nets. Olive ridleys were the commonest turtle entangled in fishing nets (77%). The map (see left) shows turtle entanglements and the outcome (alive or dead) with different types of fishing gears in the Gulf of Mannar fishery. 

Live-release programme: 74 BSC fishermen in the four fishing villages have so far been given equipment to enable them to live-release turtles entangled in their nets. More equipment and data will be added to the analysis in the second semester of 2023. BSC Fishermen use 4½” nets with 4 or 6 ply twine to harvest blue swimming crab weighing up to 400g. 

(2) Community outreach programmes and support to the Department of Wildlife Conservation 
The FIP continued to mobilise fishing communities in support of turtle conservation in the first half of 2023. Community outreach programmes were successfully completed with fishing communities in Pookulam, Baththalangunduwa, Palugahathurai and Thilayadi in the Gulf of Mannar fishery. Two outreach programmes were successfully completed (Nallayan and Koutharimunai). Two outreach programmes are ongoing (Anppuram and Kiranchi) in the Palk Bay fishery. 

In May the FIP received an investment from Direct Source Seafood to co-finance five community outreach programmes in collaboratoin with the DWC’s Beat Office at Illanthadiya in the Gulf of Mannar fishery. Preliminary consultations with five communities have been completed by DWC and the FIP . Five community outreach programmes will be implemented by the FIP using funds made available by Direct Source Seafood before the end of 2023. 

The FIP continued to provide technical assistance and financial support to strengthen the capacity of DWC officers and offices in the Gulf of Mannar fishery. Turtle nesting data collected by DWC officers since 2020 was analysed by pelagikos staff. A summary report was prepared on behalf of the Illanthadiya Beat Office. Field equipment was provided or repaired, including improvements to the DWC Dolphin Watching Ticket Office. A new boundary fence was constructed for the Kandakuliya Field Office. New data collection formats were also prepared for DWC officers to record turtle interactions with fishing gears on the Kalpitiya peninsular. 


The two new FIP activities seek to address concerns raised by the MBA’s Seafood Watch programme about the threat posed by bottom-set crab nets to turtles in the two fisheries. The fisheries’ scored 1.73 (AVOID) for Criterion 2 in MBA SW’s re-assessment in 2022. Concerns about the impact of BSC fishing on turtle populations in the Gulf of Mannar and the Palk Bay are the last remaining barrier preventing the fisheries from achieving a BEST CHOICE eco-recommendations in 2024. 

Ecological impacts on marine habitats 
No new information or data were collected or analysed to improve (i.e. reduce) the impact of BSC fisheries on marine habitats in the Palk Bay or the Gulf of Mannar in the first semester of 2023. The fisheries scored 3.00 GOOD ALTERNATIVE in MBA SW’s re-assessment in 2022. The new regulation for BSC fishery management prohibits dredging or damaging the sea bottom while conducting fishing operations for BSC. 

Improving BSC fisheries management 

‍Fishery Specific Management System 
‍The DFAR’s DFOs offices in Jaffna (3), Kilinochchi (1) and Mannar (5) successfully completed nine Fisheries Management Committee meetings during the first semester of 2023. Items on the agendas included the DFAR’s proposal to declare district-level Fisheries Management Areas (FMA) for Jaffna, Kilinochchi and Mannar districts; the number and location of Fisheries Management Committees to be established under each FMA; the results of the 2022 Palk Bay and the Gulf of Mannar BSC fisheries assessment; the blue swimming crab fisheries management regulations (No. 2277/04 of 2022); the Sri Lankan blue swimming crab bulletin No. 18; the results of the 2022 Palk Bay giant mud crab fishery assessment; the Compliance Survey to be conducted by the DFAR with Fisheries Cooperative Societies in 2023 and any other fisheries management issues in the relevant Fisheries Inspector Divisions under the Fisheries Management Committee. The minutes of each meeting were recorded in Tamil and translated into English. The meeting minutes in Tamil will be presented by the Fisheries Inspectors at the District Fisheries Committee meeting to be held in second semester of 2023.

Improving economic equity and social responsibility in supply chains 

Equity and Social Responsibility: Neither fishermen nor local manufacturers have gained any economic benefit from becoming South and South East Asia’s only eco-recommended BSC fisheries since 2018. No actions were implemented to improve social responsibility in supply chains for Sri Lankan BSC products during the first semester of 2023. 

‍Impact of COVID19 and April22: The average beach price (US$) paid to fishermen in the Palk Bay fishery fell by 63% in April 2020 (due to COVID19) according to data collected by the Poonaryn Fishermen’s Cooperative Societies’ Union (see right). Beach prices recovered to -27% by December 2020. 2021 was a better year for fishermen with the average beach price ending the year +114% (YoY). Sri Lanka’s default on domestic and international debt, the depreciation of the rupee and hyperinflation meant that the gains made in 2021 were lost in 2022. The average beach price in December 2022 was down 47% compared to December 2021.