As the WCPFC Scientific Committee Meeting approaches, a barrage of fascinating papers that I wish I had the time to read becomes available on the webpage. As I cannot follow everything, I have some topics of personal interest, among them Effort Creep, which I have written about in the past.
I’ve spent more than a few hours talking to Paul Hamer (the lead author) about these fascinating aspects, and I’m always keen to know where we are in the region.
The summary of the paper follows, but as always, read the original if you have the time.
The paper examines indicators of effort creep in the Western Central Pacific Ocean purse-seine fishery, focusing on the impacts of management strategies and technological advancements on fishing efficiency and sustainability.
Evolution of the WCPO Purse Seine Fishery
The industrial tuna purse-seine fishery in the WCPO has undergone significant changes since its rapid development in the 1980s-1990s, particularly in management and technology. The implementation of the PNA VDS and advancements in fishing technology have influenced fishing efficiency and effectiveness.
Technologies like FAD buoys, sonar, and bird radar have enhanced fishing operations.
Understanding Effort Creep in Fisheries
Effort creep refers to the increase in fishing efficiency and effectiveness within an effort-managed fishery, which can undermine management objectives. Monitoring effort creep is crucial to ensure that fishing mortality remains within sustainable limits.
Effort creep can lead to increased fishing efficiency and effectiveness.
It poses risks to stock management by eroding the effectiveness of effort limits.
Monitoring is essential to adjust total allowable effort as needed.
Indicators of Effort Creep in the WCPO
This paper updates indicators of effort creep in the WCPO purse seine fishery, focusing on trends in catch and effort levels since the VDS implementation from 2007/2008 to 2023, with partial data for 2024.
The analysis aims to inform fishery managers about trends relevant to sustainable management.
Trends in Fishing Days and Sets
The analysis reveals that the number of sets per fishing day has remained stable, with no clear increasing trend since the VDS implementation. The use of Vessel Monitoring Systems (VMS) has provided more accurate estimates of fishing days.
The number of sets per fishing day is consistently below 1.0 for PNA waters.
No increasing trend in sets per day has been observed since the VDS was implemented.
VMS-derived fishing days are more representative than logbook estimates.
Catch Rates and Effectiveness of Purse Seine Sets
Catch rates per set have shown stability, indicating that the effectiveness of purse seine sets has not increased significantly since the VDS implementation. Associated sets have higher catch rates than unassociated sets, but overall trends remain consistent.
Catch rates per set have remained stable since the VDS implementation.
Associated sets consistently produce higher catch rates than unassociated sets.
No long-term trends in catch rates for either set type have been observed.
Implications of Management and Policy Changes
Management and policy changes introduced by the PNA and WCPFC have influenced fishing practices and effectiveness. The balance between FAD and free school fishing remains roughly equal, suggesting external disincentives to shifting towards FAD-dependent fishing.
Management changes have impacted fishing practices and effectiveness.
The purse seine catch remains approximately 50% FAD and 50% free school fishing.
External disincentives may prevent a shift to a majority FAD-dependent fishery.
Recommendations for Future Monitoring and Analysis
The paper emphasizes the need for ongoing monitoring of effort creep indicators and improving the accuracy of logbook reporting. Future analyses should include additional metrics and refine methods for estimating fishing activities.
Continued monitoring of effort creep indicators is essential for management.
Improving logbook reporting accuracy is necessary to correct historical data biases.
Future reports should include indicators for FAD deployments and monitoring per vessel.
Overview of Fishing Effort and Trends
The analysis evaluates fishing effort and catch rates in the Western and Central Pacific Fisheries Commission (WCPFC) area from 2007 to 2023, focusing on purse seine fishing dynamics. It highlights the impact of management strategies like the Vessel Day Scheme (VDS) on fishing practices and efficiency.
Purse Seine Effort Inside and Outside PNA EEZs
The fishing days in the WCPO purse seine fishery are regulated by the PNA VDS, with associated sets targeting fish around floating objects and unassociated sets targeting free schools.
Total raised sets in PNA waters increased from 24,800 in 2007 to 44,200 in 2014, with a major rise from 27,800 in 2009 to 39,900 in 2010.
In 2023, the total raised sets were 31,726 in PNA waters and 6,119 in non-PNA waters.
Associated sets fluctuated between 9,200 (2010) and 15,630 (2015), with 11,917 in 2023.
Unassociated sets increased from 9,160 to 15,635 from 2009 to 2010, with 19,800 in 2023.
Non-PNA waters saw associated sets rise from 660 in 2010 to 2,641 in 2023, while unassociated sets remained stable.
Disaggregated Sets Per Day: Observer Data
Observer data indicates the behavior of individual vessels and their operational efficiency over time.
Approximately 20-25% of fishing days in PNA waters involved more than one set, while non-PNA waters had 5-15%.
Increases in multiple sets per day were noted in 2015 and 2019, possibly due to El Niño conditions.
The motivation for multiple sets is likely to increase harvest rather than compensate for lower catches.
Purse Seine CPUE Inside and Outside PNA EEZs
Catch per unit effort (CPUE) trends show variations in catch rates per set and per fishing day.
CPUE inside PNA waters has been lower than outside, with average catch rates per day being similar.
From 2020-21 to 2022-23, CPUE decreased by 2% for mt/set and increased by 4% for mt/day in PNA waters.
No long-term trends in catch rates per set were observed for both associated and unassociated sets.
FAD Dynamics and Implications
The use of FADs has evolved with technology, impacting fishing efficiency and strategies.
The reliance on manufactured FADs has increased, with drifting logs dominating associated sets before 2000.
Approximately 50% of the catch now comes from manufactured drifting FADs, despite 70% of sets being on free-swimming schools.
The effectiveness of FAD technology may not be fully realised due to management policies and accessibility issues.
Aggregate Purse Seine Catches Inside and Outside PNA Waters
Total tuna catch trends indicate fluctuations in catch rates and species composition.
In PNA waters, total tuna catch decreased by 1% while skipjack catch increased by 2% from 2020-21 to 2022-23.
Outside PNA waters, total tuna catch decreased by 5% and skipjack catch by 11%.
The catch composition remains dominated by skipjack, with FAD sets catching a higher proportion of bigeye tuna.
Changes in Vessel, Gear, and Technological Characteristics
Vessel characteristics and technological advancements are crucial indicators of fishing effort and efficiency.
Vessel metrics show changes of +1% to +11% from 2020-21 to 2022-23, with longer-term trends showing stability since 2007.
Technological advancements, such as FAD-mounted echo-sounders, are perceived as important for improving catch rates.
Increased reliance on information technology is noted, with a need for better data on technology use in fishing operations.
Understanding Effort Creep and Management Implications
Effort creep relates to changes in fishing effort and effectiveness, impacting management strategies like the VDS.
No clear long-term trends in catch rates per set suggest that nominal effort has not increased significantly since VDS implementation.
The analysis indicates that while efficiency may be stable, it does not necessarily imply increased fishing mortality.
Future research should focus on integrating vessel characteristics with catch rates to better assess effort creep and its implications for management.