Where will tuna be in 30 years time? Or the impact of climate change - - PowerPoint PPT Presentation

Where will tuna be in 30 years’ time? Or the impact of climate change on tuna resources.

Valerie Allain, Pacific Community Patrick Lehodey, Inna Senina, CLS

TUNA 2018

15th INFOFISH world tuna trade conference

28-30 May 2018, Bangkok sustainpacfish.net

1. Importance of tuna in the WCPO 2. Climate impact 3. Model and climate scenario used 4. Impact on tuna 5. Impact on Pacific Islands

References: Lehodey, P., Senina, I., Calmettes, B., Dessert, M., Nicol, S., Hampton, J., Smith, N., et al. 2017. Modelling the impact of climate change including ocean acidification on Pacific yellowfin tuna. 13th Meeting of the Scientific Committee of the Western and Central Pacific Fisheries Commission, WCPFC-SC13, Rarotonga, Cook Islands, 9-17 August 2017, WCPFC-SC13-2017/EB-WP-01: 1–26. https://www.wcpfc.int/system/files/EB-WP-01%20SEAPODYM.pdf Senina, I., Lehodey, P., Calmettes, B., Nicol, S., Caillot, S., Hampton, J., and Williams, P. G. 2016. Predicting skipjack tuna dynamics and effects of climate change using SEAPODYM with fishing and tagging data. 12th Meeting of the Scientific Committee of the Western and Central Pacific Fisheries Commission, WCPFC-SC12, Bali, Indonesia, 3-11 August 2016, WCPFC-SC12-2016/EB WP-01: 1–71. https://www.wcpfc.int/system/files/EB-WP-01%20SEAPODYM%20SKJ%20Fixed.pdf

OUTLINE

1. Importance of tuna in the Western and Central Pacific Ocean

2.7 million tonnes of tuna 56% of the global tuna catch 5.3 billion USD 2016

1. Importance of tuna in the Western and Central Pacific Ocean

Status of stocks

2. Climate impact

Purse seine effort Transition Water >28.5°C La Niña El Niño

Impact on the ocean

2. Climate impact

2. Climate impact

Impact on the fish and its optimal habitat:

temperature and oxygen surface 500 m 100 m

Skipjack

Low oxygen High oxygen

Yellowfin Bigeye Albacore

depth Warm Cold prey and predators

3. Model and climate scenario used

SEAPODYM Model Tuna population (larvae, immature, adult) 6 forage groups Primary production fisheries Environmental constraints: temperature, currents,

• xygen, euphotic depth,
• cean acidification

Resolution 1° x month

RCP 8.5 - Business as usual, CO2 emissions keep increasing until 2100 IPCC scenarios RCP 6.0 – decline of CO2 emissions after 2080 RCP 4.5 – decline of CO2 emissions after 2040 RCP 2.6 – decline of CO2 emissions after 2020

3. Model and climate scenario used

4. Impact on tuna

Hu et al. 2015

4. Impact on tuna

Skipjack Yellowfin

2005 2050 2100

4. Impact on tuna

Bigeye Albacore

2005 2050 2100

4. Impact on tuna

5. Impact on Pacific Islands

Kiribati

80%

Papua New Guinea

4%

Tuvalu

52%

• Fed. States of Micronesia

40%

• Rep. of Marshall Islands

12%

Solomon Islands

9%

Proportion of tuna revenue in government revenue

5. Impact on Pacific Islands

Projected % changes in biomass in Pacific Island countries EEZs

CONCLUSION

• Models predict
• a decrease in tropical tuna biomasses in the Pacific
• a shift of the biomasses of tropical tuna towards the east, and towards the south for albacore
• a strong impact at the national level
• The main driver of changes is the warming temperature, ocean acidification is predicted to have a limited

impact

• Improving models to improve the accuracy and confidence of the forecast for better management and

adaptation

• Better observation of fisheries
• Better observation and understanding of the pelagic ecosystem
• Models can be used to project the impact of fishing

that remains the major external driver of the tuna population dynamics. Different fishing scenarios can be tested.