Among the “way too many” interests I have in fisheries science (besides management, MCS, labour and climate change), one that I have been very keen on is eFADs and “effort creep”… I wrote a lot about it, but basically, it changed tuna purse seining during my lifetime. My skills 25 years ago would be obsolete now if I had not jumped in the FAD wagon… in fact, I’ll say that the catch and size of the fleet we have today are only possible because of FADs. (and that can be seen as a bit creepy)
definitivelly a before and after in Purse seine with FADs
I see it blatantly during FAD closure, where it takes at least twice the time for a vessel to catch enough to come to port, the logarithmic growth of the eFADs tech providers and the fact they enlist carriers to deploy them on their behalf.
One of the “obscure” consequences of eFADs and other technologies (like remote oceanographic sensing, specialised drone technology, and whatever else facilitates finding fish) is what is called “effort creep”, so I’m a sucker for any publications on the topic, and as the Scientific Committee meeting of the WCPFC gets closer, the excellent crew of SPC always produce a good paper on this topic that is worth reading Examining Indicators of Effort Creep in the WCPO Purse Seine Fishery (and I recommend you do that)
I quote some aspects I find key to it, and the summary below (for the lazy of you)!
Introduction
Fisheries management controls that are based on limiting effort require ongoing monitoring to track how effectively the unit of effort continues to constrain the fishing mortality. The effectiveness of a unit of effort in catching fish can change over time due to the adoption of new technologies, gear modifications, fisher skill, enhanced communication/networking among skippers and/or access to other information such as oceanographic data that helps locate fish.
Changes in the effectiveness of fishing effort can potentially alter the expected relationship between effort and fishing mortality compared to that when the effort limits were initially established, and this may undermine the achievement of management objectives.
Gradual or abrupt change in fishing effectiveness, within an effort-based management framework, is generally referred to as “effort creep”. While effort creep can be positive for a fishing industry when it reduces the cost and environmental impacts of harvesting fish, management systems that rely on effort controls may need to consider adjusting effort limits over time to account for effort creep. Finally, industry adaption to effort based management can also lead to sub-optimal investment in operational aspects, such as technology, whereby the effectiveness of harvesting fish may increase but the cost required to harvest them increases disproportionately.
Effort creep can be difficult to quantify because it is composed of both direct and indirect components.
The direct components relate to nominal fishing effort (e.g. vessel fishing days, number of net hauls, sets or hook deployments etc.), while the indirect components may relate to factors related to technology uptake (‘technology creep’), slight gear modifications, increased information and networking, increased knowledge and skills of individual fishers. These aspects may not influence the amount of nominal fish effort, but they can influence the effectiveness of each unit of effort, i.e., the effectiveness of a purse seine net set to catch a certain volume of fish. While the direct components of effort are relatively easy to measure and track, the influence of indirect components on fishing effectiveness are challenging to quantify.
For the pacific island countries parties to PNA, the effort management unit is ‘the vessel day’, which refers to any day that is related to harvesting fish, and thus includes days in which nets are deployed and days when searching is conducted but a net is not necessarily deployed. Under the VDS system, most days when a vessel is within a member EEZ will initially be counted and charged as vessel days, but the days can be reduced through a process of claiming for non-fishing days according to specific criteria. Purse seine fishing outside of PNA member EEZs and archipelagic waters is managed by flag specific limits on catch or effort as specified in the Tropical Tuna Conservation and Management Measure CMM 2021-01. Further effort in archipelagic waters of some countries that are members of the PNA may not be managed under the VDS (i.e. Papua New Guinea and Solomon Islands).
FAD dynamics and implications
Using fishery data combined with FAD tracking information, it was estimated that at the scale of the WCPOthere were 31,000 FAD buoy deployments in 2016 and approximately 34,500 in 2017, 39,500 in 2018 and 33,400 in 2019. If these estimates are reliable this means the number of FAD buoys deployed per year issimilar to the number of FAD sets per year. The median number of active buoys monitored per vessel per day ranged from 45 to 75 depending on the year, well below the current management limit of 350. It remains unclear how close the number of FAD buoy deployments is to the number of actual FAD rafts deployed, as raft theft and buoy change over is considered a common occurrence. More work is required to better estimate the number of FAD raft deployments to account for theft and exchange of buoys, and any trends in these activities. FAD density may influence catch rates along with FAD technologies (e.g., sonar-equipped FADs)and these factors could both influence changes in fishing strategies and catch rates. Integration of FAD information is a continued priority for future work to increase understanding of the indirect and difficult to measure drivers of effort creep.
Summary
Understanding effort creep as it relates to effort-based management requires coupling changes in nominal effort indicators, in this case purse seine sets, with changes in the effectiveness of nominal fishing effort, in this case the effectiveness of purse seine sets in catching tuna. This paper presents simple aggregated annual estimates of indicators of nominal effort creep in terms of numbers of purse seine sets per year and per fishing day, and the effectiveness of nominal effort in terms of catch rates per set. For both types of indicators there were no long-term trends since the implementation of the VDS system, either for the PNA waters under the management of the VDS or non PNA waters where the fishery is managed under flag specific catch or fishing day limits. The lack of trend in catch rates per set was also consistent for associated and unassociated set types. While there was considerable interannual variability in the indicators, the lack of sustained increasing trends suggest that despite the implementation of an effort based management systems based on fishing days, there was not an overall increase in the amount of nominal effort realised within the fishing day effort unit.
We do note however that at the introduction of the VDS there was a major increase in the total number of sets each year for PNA waters, largely driven by an increase in the number of unassociated sets. This step change may be a result of the change in the management system, but is not indicative of effort creep. In fact this change is entirely consistent with an increase in the number of fishing days from 2009 to 2010, and there is no notable increase in sets/day over the same period. We note that the aggregated nature of the data presented does not preclude that nominal and effective effort creep could be occurring for specific flags and EEZs. A more detailed analysis at flag and EEZ level is required to explore this possibility. Finally, it is clear that increases in effectiveness of associated sets did occur prior to the VDS implementation that appeared related to the transition to dominant use of drifting FADs facilitated by the availability of affordable satellite tracking buoys.
Despite the increased use of technologies such as acoustic sensors on FAD bouys, we did not see any sustained increase in catch rates per set for associated sets since the VDS was implemented. This is a somewhat surprising result in light of industry perceptions that FAD technologies have been a major contributor to improving their effectiveness. It may be that the FAD technologies have improved the efficiency and economics of fishing operations (i.e. time and travel) to the extent that employing these technologies improves profitability but that they have not been so effective in increasing catch rates per set or capacity for higher setting rates per day.
The lack of positive trends in catch rates per set is, however, not entirely conclusive that no efficiency creep is occurring. If increased efficiency at catching fish is occurring against a backdrop of stock decline, it could result in stable catch rates per set (i.e., the effort/efficiency creep compensates for declining stock abundance/availability). Furthermore, even if efficiency creep is not occurring the highly selective nature of purse seine fishing (both associated and unassociated modes) can result in hyperstable catch rates per set even when the stock may be declining or even increasing. The strong potential for hyperstability in purse seine catch rates presents an issue when interpreting how these data indicate both stock trends and effort creep. The catchability proxy included in this analysis considers daily catch rates in relation to biomass estimates. In a scenario where harvest efficiency is stable, catch rates would be expected to decline as biomass declines. The increasing trend in the catchability proxy for purse seine skipjack suggests that increased capture efficiency may be offsetting the recent estimated decline in biomass from the 2022 stock assessment. This may be influencing the stability in the catch rate indicators.
Effort creep can have implications for the performance of the VDS in relation to meeting stock conservation objectives and economic returns to PNA members. Increased efficiency could have at least three implications:
i) if vessels can catch more fish in one day they may not need to purchase as many days,
ii) if fishers can catch more fish in one day without incurring significant additional cost, the value of a day could be higher, and
iii) if fishers can catch more fish in one day this could undermine the ability of the VDS to constrain fishing mortality to the expected level.
The aggregated data presented in this study suggest the variation in catches per day is dominated by interannual variation that is likely difficult to predict.
However, it is possible that different EEZs and or flags may show different patterns and or sustained trends in catch rates per set or sets per day that could be of interest to individual PNA members for optimizing economic returns from their allocations of VDS days. These higher resolution type analyses are beyond the scope of this paper but could be considered in future work, subject to data confidentiality and SPC staff time. The indicators presented do not suggest that overall effort creep is undermining the VDS control on fishing mortality compared to when it was implemented. In this analysis, we have examined catch and effort indicators independently from vessel characteristic indicators ( e.g., vessel length, GRT, well capacity); further analyzing changes in catch rates with respect to changes in vessel characteristics or technologies employed may improve our ability to assess effort creep. Continued research into the development of suitable effort creep indicators should focus on these integrated analyses, including improved understanding of changes in operational decision making and fishing strategies influenced by advances in technology. This would require closer collaboration with industry which has proven difficult. We would encourage enhanced data collection or reporting of technology and information sources used by purse seine fishing operations. We also note the importance of enhanced data collection from the fishery, including the wide array of drifting FADs throughout the Pacific. Building a more complete and accessible database with information on the location, movement, and characteristics of FADs should enhance these analyses. In addition, Vessel Monitoring System (VMS) data will become increasingly important as we investigate changes in fisher behaviour over time.
SPC looks forward to continuing to work with the PNA on effort creep in the purse fishery.
The present at my feet