As most of you know the issue of dFADs (I call them eFADs, because of their e-capabilities) is of real interest to me, they touch pretty much every aspect of fisheries I’m interested in. Harvest technology, policy, management, bycatch, MCS, science, operations, subsidies and so on. No doubt (and by far) there the biggest impacting development in Purse seine fisheries in the last decade.
just a small sample
They are controversial and polarising, while some focus on their elimination (which is something I personally doubt would be possible), I like to know as much as I can about it… and with that understanding try to manage their negative impacts (plenty written about them) and see if they are positives from them…
What do I mean with positives? Back in the last century when working in fisheries research and stock assessment (differentiation of reproductive stocks in hake was my thing) we started harnessing the power of biomass determinations by using sonars… monstrous things at the time… that required regular calibration… the number of times that we had with a colleague to walk the vessel sides on fair weather holding marked lines with a copper ball at the mid-distance to find the transducer and calibrate that thing at different depths was pathetic… anyway… it was a game-changer.
Today we have at any time 20 to 40000 of these mini sonars deployed every year in the WCPO… if there was a way to harness all that data we could (to a certain extent only) almost have a version of real-time biomass assessment which could hugely beneficial for stock assessments and therefore management and policy.
I know… perhaps unsurmountable issues around the property of data (its all own by the buoy owner) and well as the capacity to harness and make productive use of that data…
But then… as I said in a recent interview… “If I wasn’t obstinately optimistic… I don’t think I’ll be alive today. I cling to any positive news I can, and see if the model that got us to that positive news can be adapted somewhere elsewhere we have a problem"
(Don't worry I’m tacking eFAD as MARPOL in the next blog)
Anyway…. 20 to 40000 deployments a year is a huge range (and add to the ones there are already!) but how we know that number?
Here is where my really clever colleagues from SPC come in… as part of their work as science providers for stock assessment, the “effort creep” associated with eFADs is a key part.
Their latest efforts have been published in this very interesting and innovative paper, where they explain how they estimated the use of dFADs in the WCPO through a novel combination of four fisheries datasets over the 2011–2019 period: at-sea observers’ data, vessel logbook reports, Vessel Monitoring System (VMS) data, and trajectories from the satellite buoys on dFADs.
I can only imagine the hurdles and complications around using these data, which are often privacy and commercially sensitive and confidential, but kudos to them as they are seen as secure partners by all players in the fishery.
The key finding is that between 20,000 and 40,000 dFADs are deployed per year. This corresponds to every purse seine vessel monitoring on average between 45 and 75 dFADs each day. A striking result was also the relatively stable trend in terms of dFAD deployment detected over the last decade, which is different from the increasing trends seen in other oceans that rely more heavily on dFADs.
I recommend you read the original I just going to quote the Recommendations for improved dFAD monitoring they propose, which are key to my interest.
While current levels of dFAD use remain challenging to determine with high certainty worldwide, the long-term management of dFADs could benefit from a better understanding of the optimum number of dFADs to maximize profitability while limiting impacts on tuna stocks and ecosystems. Results from this study could provide baseline data to monitor dFAD use and impact in the WCPO, with application of these methods in other oceans.
However, to improve the ability to estimate potential dFAD levels (e.g. deployments, dFAD density, active buoys), the collection of additional information is suggested. For example, to better understand the total number of dFADs in the water and the number of dFADs used per vessel, the provision of: (i) the number of new dFADs deployed per year per vessel or fleet; (ii) the average daily or total number of active dFADs per vessel per month; and iii) the number of deactivated dFADs per month, would enhance these efforts. Some of these data are already being collected by some Regional Fisheries Management Organisations (Báez et al., 2020). This could also be achieved through complete submission of dFAD trajectories, which in turn will be a key addition to scientific studies on dFAD density (Restrepo and Justel-Rubio, 2018); impacts on catch rates, and tuna behaviour (Scutt Phillips et al., 2019b).
The PNA FAD tracking database, through the compilation of local dFAD density will allow for such additional studies on the impacts of dFADs on tuna ecology to be performed. New FAD logsheets have been launched in 2020 in the WCPO by the PNA and will require captains to fill in any dFAD related information, including the unique buoy identification number, which will improve some of the issues with the data currently collected. In addition, given the connectivity between the WCPO and the EPO and the general westward trend in currents, collaboration between scientists working in both these Pacific regions should be encouraged. Additional data sources could also be considered (e.g. dFAD marking with fishery-independent autonomous satellite devices; data collection of dFADs reaching coastal areas).
This could help to better assess other environmental impacts, such as dFAD loss, marine pollution, and beaching, or to follow individual dFADs instead of the satellite buoy attached to it which may be swapped several times. Overall, the compilation of these data would allow better scientific analyses and advice on the optimum management strategies for sustainable use of dFADs by the purse seine fleets in the WCPO and other ocean basins.
