-Ziro Suzuki,
National Research Institute of Far Seas Fisheries-
Recently a scientific paper was issued, entitled “Is it good or bad to fish with FADs? What are the real impacts of the use of drifting FADs on pelagic marine ecosystems?” (Laurent Dagorn, Kim N. Holland, Victor Restrepo & Gala Moreno, 2012 Blackwell Publishing Ltd, FISH and FISHERIES,25pp).FADs is the abbreviation of Fish Aggregating Devices, a kind of floating fish reefs artificially made that have been in common use among the tuna purse seiners around the world due to their high efficiency to catch massive amount of tunas easily and securely. The widespread use of the FADs by the purse seiners increased tremendously the catch of target species such as skipjack and yellowfin. But, at the same time, bycatch of juveniles of bigeye always accompanies with the target species and the juvenile bigeye catches give a substantial negative impact to the bigeye stocks, As a result, how to limit the catch of juvenile bigeye by the purse seiners has become one of the serious issues to the Regional tuna Fisheries Management Organizations (RFMOs) in the world.
The said paper defends the use of FADs. Major points of the defending opinions are as followings: 1) There is no evidence that the use of FADs leads to overfishing of the tunas, 2) Taking juveniles tunas by FADs may not necessarily reduce the MSY if accounting the high natural mortality (M) of juveniles, 3) Bycatch in the FADs operations are much smaller compared with other fishing gears, 4) There is no unequivocal empirical evidence that the use of the FADs gives negative impacts to ecosystem and ecology of tunas, 5) Purse seine fishery is good for environment due to its low fuel consumption and low CO footprint. In addition, the paper postulates that banning the FADs is unlikely because, first, 6) it is very unlikely that industry will willingly abandon this efficient fishing tool and such a move would result in a drastic shortage of canned tuna that is the major source of affordable natural protein in the world, second, 7）banning the FADs operation could have unexpected negative consequences as any type of fishing invariably impacts an ecosystem. This paper does not defend limitless use of the FADs but proposes 8） FADs managements using satellite connected radio buoys attached to the FADs based on collected accurate real time information in use of the FADs.
While this paper is valuable one that reviews the newest information about FADs, there are several views expressed in this paper with which I do not agree or feel skeptical. I would like to express my frank view and concerns briefly about some of major points claimed in the paper.：As for 1), this paper puts too much attention to skipjack, while the more careful thoughts on the most critical bigeye stock is lacking. Although it is a fact that the bigeye stock had been reduced substantially before the current common use of the FADs by purse seiners, it is obvious from the scientific reports of the world RFMOs that the use of the FADs by purse seiners incurred additional very serious negative impacts to bigeye stocks. The paper seems to be optimistic about the future increase of the catch of skipjack but the Scientific Committee reports of the WCPFC (in responsible for managing the tuna stocks in the Western and Central Pacific) explicitly state that limiting the further increase of skipjack catch should be considered. One of the big issues that was not dealt in the paper is that the amount of bigeye catch by the purse seiners can not be accurately known. Due to difficulty in separating juvenile bigeye from yellowfin and small quantity of bigeye in the purse seine catch, bigeye catch recorded in the purse seine logbooks are likely to be underreported. To correct these biases, presently the amount of bigeye catch of the purse seine is adjusted using sampling on board of the ships and unloading sites. However, there remains possibility that the current adjusted catches of juvenile bigeye is still lower than the reality. Unfortunately, researches to improve the accuracy of juvenile bigeye catch by the purse seiners are not satisfactory. As for 2), it is demonstrated in the scientific report of the WCPFC, using higher natural mortalities on juvenile, that the bigeye MSY decreased significantly after the introduction of the FADs operations. As for 3), what I am concerned is oceanic white tip and silky sharks that are regarded as heavily overfished. Although the catch of those sharks by the FADs is smaller than longline case, the FADs operation areas are roughly overlapped with hot spot of nursery grounds of those species. It is not possible to ignore the FADs operation, along with the longliners, give additional detrimental impact to the decline of stock size for those two species In addition, the bycatch information on sharks are not good. Referring to 5) it is rather pointless to stress one or two good points for some specific gears as every fishing gears have merits and demerits more or less. As for 6), the paper seems to be overly reacting to the total ban of the FADs. Extension of FADs closure or other sensible ways could resolve the problems. For example, extension of FADs closure would not result in drastic decline of the tuna catch in the WCPFC area. Due to introduction of the FAD closure (3 months), some purse seine fleet like Japanese fleet that used to be heavily reliant of the FADs operation shifted to the operation mostly on the free swimming schools without decreasing the catch. Recognizing the reality that no practically applicable mitigation measures that do not reduce skipjack catch but selectively reduce bigeye catch are available now, it would be more sensible way to urge purse seine fleets still heavily depend on the FADs operations to shift from the FADs to the free swimming school operations. As for 7) the shift of operation mode from the FADs to free swimming schools would increase yellowfin catch. But, we have to identify urgency to be addressed and prioritize the problems to be resolved. I would consider the bigeye stock status has higher priority to be solved and ways to resolve yellowfin problem must be looked for per se. As yellowfin in the free swimming schools are mainly composed of large adults without bigeye and easily recognized the composition of the school before the setting nets, it is possible to avoid catching such schools if necessarily. Finally for 8), the WCPFC has regulatory measures to monitor, report and manage the FADs operation. However, it seems that no appreciable compliances to the measures have been made probably due to the complicated nature of the measures. The paper’s proposal would not be practical at this moment because the relevant information has high degree of confidentiality and not available in public so that it will take more time to become feasible as management measure.
Start of the FADs operation that lead to the current activities occurred in the mid-1970s in the Western equatorial Pacific by Japanese fishermen with a modest operation only relied on natural floating objects like drifting logs. Amazing increase of fishing efficiency of the FADs afterword is well documented in this paper. Although this high efficiency of catching all size of tunas is the largest merit of the purse seine fishing, due to its tremendous fishing power, much more strict control with higher transparency than other fisheries is required for this fishery to conserve and manage successfully the stock. Unfortunately, there is no progress in reduction of overcapacity of purse seine fishery. It should be noted that the use of modern FADs increased fishing capacity greatly. After reading the paper, I am rather convinced with the urgent need to control FADs operation more effectively.