Workshop on the Use of Biodegradable Fish Aggregating Devices (FADs)

Abstract

A workshop on the use of biodegradable FADs, or FADs made with natural materials, was organized by ISSF the 3 rd and 4 th of November of 2016 in the Aquarium of San Sebastian (Spain). This workshop was organized in order to propose solutions to reduce the amount of plastic and other non-natural materials used in FADs to avoid pollution of the oceans when FADs sink or beach in coastal areas. A recent research conducted in the Indian Ocean, using information from the trajectories of the buoys utilized to geo-locate FADs, showed that 10% of the deployed FADs ended up in stranding events (Maufroy et al 2015) 1. Nowadays FADs are made using as main components petroleum products as plastic, PVC, nylon nets, etc., that degrade slowly, causing a growing accumulation of these products in coastal areas year on year. The impacts associated to FAD beaching events are damages in coral reefs, marine pollution as well as ghost fishing. Scientists working on FAD research as well as fishing industry, well aware of the impacts that FAD beaching events can cause in reefs and coastal ecosystems, have been working since 2007 to develop FAD structures that minimize this impact. Among other experiments, trials with FADs made of diverse materials from natural origin were conducted in real fishing conditions. One of the main difficulties detected during the trials at sea was the lack of sufficient observations during the life of experimental biodegradable FADs. Due to the complex fishing strategy with drifting FADs, a high percentage of FADs deployed by a given vessel is usually fished and retrieved by other vessels, which makes difficult to revisit and get information on how the biodegradable structure evolves as well as on its lifetime.

Full text

Workshop on the Use of Biodegradable
Fish Aggregating Devices (FADs)
Gala Moreno, Victor Restrepo, Laurent Dagorn, Martin Hall, Jefferson
Murua, Igor Sancristobal, Maitane Grande, Sarah Le Couls, Josu Santiago
A workshop on the use of biodegradable FADs, or FADs made with natural
materials, was organized by ISSF the 3rd and 4th of November of 2016 in the
Aquarium of San Sebastian (Spain). This workshop was organized in order to
propose solutions to reduce the amount of plastic and other non-natural materials
used in FADs to avoid pollution of the oceans when FADs sink or beach in coastal
areas. A recent research conducted in the Indian Ocean, using information from the
trajectories of the buoys utilized to geo-locate FADs, showed that 10% of the
deployed FADs ended up in stranding events (Maufroy et al 2015)1. Nowadays
FADs are made using as main components petroleum products as plastic, PVC,
nylon nets, etc., that degrade slowly, causing a growing accumulation of these
products in coastal areas year on year. The impacts associated to FAD beaching
events are damages in coral reefs, marine pollution as well as ghost fishing.
Scientists working on FAD research as well as fishing industry, well aware of the
impacts that FAD beaching events can cause in reefs and coastal ecosystems, have
been working since 2007 to develop FAD structures that minimize this impact.
Among other experiments, trials with FADs made of diverse materials from natural
origin were conducted in real fishing conditions. One of the main difficulties
detected during the trials at sea was the lack of sufficient observations during the
life of experimental biodegradable FADs. Due to the complex fishing strategy with
drifting FADs, a high percentage of FADs deployed by a given vessel is usually
fished and retrieved by other vessels, which makes difficult to revisit and get
information on how the biodegradable structure evolves as well as on its lifetime.
1 Maufroy A, Chassot E, Joo R, Kaplan DM (2015) Large-Scale Examination of Spatio-Temporal
Patterns of Drifting Fish Aggregating Devices (dFADs) from Tropical Tuna Fisheries of the Indian
and Atlantic Oceans. PLoS ONE 10(5): e0128023. doi: 10.1371/journal.pone.0128023
ISSF Technical Report 2016-18A
1. Background
Suggested citation: Moreno, G., V. Restrepo, L. Dagorn, M. Hall, J. Murua, I. Sancristobal, M. Grande,
S. Le Couls, J. Santiago 2016. Workshop on the use of biodegradable fish aggregating devices (FAD).
ISSF Technical Report 2016-18A. International Seafood Sustainability Foundation, Washington, D.C.,
USA.
International Seafood Sustainability Foundation
601 New Jersey Ave NW Suite 220
Washington DC 20001
www.ISS-Foundation.org

2
Recently AZTI, ISSF and IATTC have been conducting experiments under
controlled conditions to study the behavior of some of the materials from natural
origin available in the market, as sisal, cotton and coco fiber configured as ropes,
canvas and fabrics of various thicknesses. These experiments which some are still
ongoing, measure the breaking strength of the different ropes in time, the amount
of biofouling adhered, as well as monitor if fishes are feeding on them. So far, these
under-controlled trials have allowed discarding those ropes not suitable due to
their low resistance as well as knowing the degradation in time for other materials.
However, trials in real fishing conditions are necessary to obtain conclusive results
on the capacity of biodegradable FADs to aggregate tunas as well as to discern the
most appropriate biodegradable materials to be used. ISSF organized the
workshop in response to these necessities as well as to involve the fleets from
different oceans in the search for solutions. During the workshop, discussions were
driven to find an appropriate FAD structure to be tested with biodegradable
materials available nowadays, as well as to find the best strategy to test those FADs
with the collaboration of the different fleets operating in Indian, Atlantic and
Pacific Oceans.
2. Objectives of the workshop
The objective of the workshop was to join efforts, through collaboration of
scientists and fishers, to find solutions to reduce the environmental impacts of
FADs sinking in the ocean or beaching in coastal areas.
Specific objectives, in accordance with the development of biodegradable FADs
were:
1. To determine the structural features needed for a FAD to be productive.
2. To determine the lifetime required for a FAD to be used as an efficient
fishing tool in the different oceans.
3. To review the different alternatives available in the market, tested through
experiments: from natural origins (biodegradables) and other alternatives
from non-natural origin.
4. To design new biodegradable FAD structures for the different oceans.
5. To define the protocol (or strategy) to test biodegradable FADs in real
fishing conditions through the cooperation of the fleets in the 3 oceans.
3. Results
3.1 Structural features needed for a FAD to be productive
A review was conducted to determine the structural features needed for future
biodegradable FADs to efficiently aggregate tunas.

3
First of all, fishers agreed to say that any type of floating object can be efficient if it
is located in the good place at the good time. Location and time is therefore the key
issue for successful tuna attraction. Therefore, the structure of the FAD should be
designed so that it will drift to good areas at the good time. The drift of the FAD is
the main variable to control in order to aggregate tunas. There are regions where
the FAD needs to drift slowly to effectively aggregate tunas. In such regions, a deep
FAD structure is needed to anchor it in deep waters. For other regions, the drift
needs to be driven by surface currents. In such contexts, the FAD structure should
be shallow. Thus, two types of FAD structures need to be addressed, a shallow one
and a deep one, basically in relation to the oceanographic conditions of the area
and probably to other factors such as the vertical distribution of tuna prey.
The shadow produced by the floating structure of the FAD as well as the strings
and flags that are usually added to the shallow part of the submerged structure,
were considered necessary to attract those species that occupy the space close to
the FAD, named intranatans
2
(Lobotes surinamensis, Abudefduf saxatilis, etc.).
Intranatant species in turn, may play the role of attractors of other species that
occupy the space at greater distances from the FAD, such as tunas. It may be that
once the FAD is colonized by intranatant species, the structure of the FAD (color,
shadow, etc.) loses importance on the ability to attract tunas, as intranatant
species once present at FADs, may serve as a more powerful attractor than the FAD
structure itself. Although visual and hearing abilities of tunas are not well known
yet, it is likely that the noise, odor and movement of intranatant and extranatant
(Aluterus monoceros, Kyphosus cinerascens, Caranx sp., etc.) species at FADs could
be detected further away than stimuli produced by the FAD itself, unless there is
an element of the structure which produces noise, as it has been mentioned for the
case of anchored FADs with the anchoring chain.
Finally, the importance of the depth of the FAD structure was attributed solely to
achieve the desired drift.
3.2 Lifetime of a biodegradable FAD to be useful for fishing
Given the complexity of FAD fishing strategy, and the particularities of each ocean
on the way FADs are deployed, maturation time and fishing, the required lifetime
for a FAD was specified by ocean:
-Eastern Pacific Ocean: From 6 months to 1 year
-Western Pacific Ocean: 1 year
-Indian Ocean: 1 year
- Atlantic Ocean: From 5 months to 1 year
2
Those species that move within 2 m range from the FAD. Parin, N.V., and Fedoryako, B.I. 1999.Pelagic
fish communities around floating objects in the open ocean. Fishing for Tunas associated with floating
Objects, International workshop. Inter-American Tropical Tuna Commission (11): 447-458

4
It was considered that a FAD is not usually used beyond the times specified above.
Thus, FADs older than these thresholds should be able to degrade as fast as
possible.
3.3 Review of the different biodegradable materials tested by scientists and
fishers
During the meeting, a review of the different experiments conducted by both,
scientists and fishers was done. The behavior, resistance, bio-fouling, price and
other issues were discussed for materials from natural origin as well as for other
alternatives that come from non-natural origin. The following items were
discussed and agreed from the results of this review:
The concept of biodegradable
 Although the definition of biodegradable is “capable of being broken down
(decomposed) by the action of microorganisms”, the time required for this
biodegradation is an important issue here. The challenge for the current
objective is to design a biodegradable FAD that aggregates fish and can last
up to the above thresholds (from 5 months to 1 year, depending on the
ocean) and capable of biodegrading as fast as possible after this time.
 Other alternatives from non-natural origin as plastics, metal, oxo-
biodegradable plastics were discarded. Although these materials could have
a lesser impact in the manufacturing and transportation stages of their life
cycle compared to that of materials from natural origin, their slow
degradation and durability and the end of their life cycle can have such an
impact on coastal ecosystems that they were not considered as options.
Submerged structure of the FAD
 Some of the materials from natural origin were discarded due to their
fragility and short lifetime, as coco fiber and jute in fabric configuration as
fish ended up feeding the fabric.
 Nowadays ropes made of cotton are the ones that have shown higher
breaking strengths and durability in time. There are 2 types of cotton ropes
that have been tested, one with the capability of adhering bio-fouling
(similar to those used to grow mussels in ropes) and the ones that do not
allow the bio-fouling (Fig 1). The latter would allow the structure of the
FAD to be more stable over time while the ones that adhere bio-fouling will
aggregate incrusting organisms that will decrease the floatability of the
structure with time. However, the latter could be helpful in the first stages
of the colonization process of the FAD (this hypothesis has not been tested).
Other ropes have not been tested yet as tencel ropes available in the market
made of eucalyptus.

5
Fig. 1. Different rope types from natural origin analyzed during the
workshop.
 Canvas made of cotton used for activities that require high resistance, as
military activities, were identified as a good alternative to be used as flags
attached to the main structure of the FAD, both to create more volume as a
“drifting reef” as well as to use them as drift anchors to make the FAD drift
slower (Fig 2). First prototypes of FADs using this canvas as drift anchor
have recently been deployed at sea. These canvas have different numbering
in relation to their thickness, one of the thickest (number 12) was the
preferred one for the fleet that is testing them.
Fig. 2. Biodegradable canvas of various thicknesses made of cotton

6
Surface structure of the FAD
 One of the most critical parts of constructing a FAD is the buoyancy of the
structure. Their lifetime depends in many cases on the adequate
assessment of the buoyancy needed for a given structure. Thus, it is
necessary to precisely calculate the buoyancy for the FAD to be active
during the required time. Nowadays the biodegradable alternatives for
current floating materials used in FADs, as PVC pipes, purse seine net corks,
plastic buoys, containers or drums, are scarce. One of the few alternatives
presented during the workshop was the balsa wood (Ochroma pyramidale)
(Fig 3 and 4). This wood that is well known for its great buoyancy could be
the biodegradable alternative for the floats of FADs. Tests at sea using this
wood together with bamboo canes as floats are in progress. Hopefully
results for these first FADs will soon be available (Fig 5).
Fig 3. Fisher evaluating the balsa wood
Fig 4. Detail of the balsa wood

7
Fig 5. First prototypes deployed at sea using as floats balsa wood and
bamboo canes.
 Bamboo canes have been used for many years to build FADs. One of the
main difficulties with bamboo is that they lose buoyancy with time due to
seeping of water inside cane´s air chambers, eventually making the FAD
sink. Fishers prefer green canes or recently-cut canes due to their higher
lifetime. However, they still need to add plastic floatation to prevent the
FAD from sinking. Another alternative worth exploring are natural oils,
waxes or other treatments that are already used in some countries to
enhance the lifetime of bamboo canes. Perhaps an appropriate treatment of
bamboo canes would extend their lifetime up to the required time (a
maximum of one year would be required).
 The potential use of coconuts as an additional floatation to bamboo canes
was presented during the workshop.
 Although there have not been tested yet at FADs, current research with new
polymers from natural origin (potatoes, algae, etc.) to manufacture
containers, open up a series of alternatives to be used as floatation at FADs
in the near future.
 Canvas made of cotton described before, were also identified as a good
alternative to cover the raft in order to provide consistency to the structure
and shadow to attract fish. A range of colors are available for the needs of
fishers, as for instance in dark colors to decrease the likelihood of being
detected by other vessels that are looking for FADs.
 It was also considered the use of a hydrostatic release unit for the buoy that
is used to geo-locate FADs. This unit would allow releasing the buoy before
it sinks together with the FAD structure. This way the buoy could be
retrieved reducing pollution at sea. Some of the issues to be solved will be

8
retrieving the buoys as well as making them not being accounted as an
active FAD in oceans where there is a limit on FAD numbers per vessel.
3.4 Biodegradable FAD designs to be tested in different oceans
One of the main objectives of the workshop was to design biodegradable FADs that
could be tested at sea in the near future, using materials available nowadays in the
market. Mixed groups of fishers and scientists were formed to propose FAD
designs.
Selected materials for the different FAD designs were:
 Balsa wood (buoyancy)
 Bamboo canes (buoyancy and submerged structure)
 Pinewood (surface structure)
 Cotton canvas (cover of the raft, submerged flags and drift anchor)
 Cotton rope with loops (submerged structure)
 Cotton rope without loops (submerged structure and to assemble canes and
balsa wood for the raft)
 Tencel ropes (eucalyptus)
 Stone (weight )
 Sand (weight)
 Hydrostatic release (to release the buoy when the FAD sinks)
 Buoys or purse seine corks
3
In total, 7 biodegradable FADs were designed (Figs. 6-12). The deepest structures
reached 60-80 m, with one design of 40 m and were mainly designed for the
Atlantic Ocean. Very shallow FADs were designed for the Indian Ocean, with only 2
m depth. Such shallow FADs could also be effective in the Pacific and in the Atlantic
oceans where tunas are feeding in surface, as in Peru and Gabon waters. From the
7 FADs designed, 5 were using biodegradable structures and plastic buoys as floats
(to avoid FADs sinking during the first trials) while 2 were 100% biodegradable.
3
Although buoys or purse seine corks are not biodegradable, they were considered necessary during the
trials to get data from the diverse biodegradable materials in test. Some of the experiments at sea failed
because all the FADs sank and no data was retrieved. The buoyancy needed for a given structure needs to
be tested by monitoring the bio-fouling adhered to the different parts of the FAD. To avoid the potential
sink of experimental FADs during the first trials, plastic buoys could be added to obtain extra buoyancy
and assure data is gathered for this experimental FADs.

9
Fig. 6. Biodegradable FAD designed during the workshop for the Atlantic Ocean.

10
Fig. 7. Biodegradable FAD designed during the workshop for the Atlantic Ocean.

11
Fig. 8. Biodegradable FAD designed during the workshop for the Pacific Ocean.

12
Fig. 9. Biodegradable FADs designed during the workshop for the Pacific Ocean.

13
Fig. 10. Biodegradable FAD designed during the workshop for the Indian Ocean.

14
Fig. 11. Biodegradable FAD designed during the workshop for the Indian Ocean.

15
Fig. 12. Biodegradable FAD designed during the workshop for the Indian Ocean
(shallow structure).

16
3.5 Strategy to test biodegradable FADs during fishing operations
Once the different biodegradable FADs were designed, discussions were driven to
define an effective strategy to test them in real fishing conditions. Until now the
experiments to test new designs at sea have been conducted by individual
companies deploying a reduced number of FADs. This strategy was not successful
as stated earlier in this document, due basically to the difficulty of revisiting and
getting information on the experimental FADs. Frequently, a single FAD has
different owners in its lifetime which makes difficult to monitor the FAD structure
over time. It is thus necessary to be able to monitor a FAD in a coordinated way.
Moreover, the different owners add or repair some elements of the structure that
have degraded so that the FAD can be different from the first deployment to future
visits. Thus, it was clear that the collaboration of the different fleets and purse
seine companies was necessary to achieve an efficient monitoring of the evolution
of the FAD structure over time. Hence, for the success of the trials with
biodegradable FADs the following protocol was proposed:
 Fleets should collaborate by deploying FADs and providing information on
the time evolution of biodegradable FADs encountered at sea.
 Fleets deploy a given number of biodegradable FADs per vessel (e.g. 10-20
FADs per vessel to reach a significant large number of FADs). These
numbers should be determined during the meetings with the different
fleets (fleet-owners and fishers).
 In order to get a meaningful result, 3 to 4 standardized designs maximum
per ocean should be tested, so that enough data is retrieved per design type.
Ideally experimental FADs should be built in port and deployed in the same
area as traditional FADs, so their effectiveness could be compared with that
of the traditional FADs for the same spatial and temporal strata.
 Since the objective is to monitor the time evolution of biodegradable
materials and assess the buoyancy of the FAD, non-biodegradable floatation
could be added at the beginning to guarantee that the FAD does not sink
and that data will be collected.
 Deployment site, type of biodegradable design and the code of the geo-
locating buoy should be registered. Every FAD should be well identified so
that data can be retrieved and followed by the different owners.
 If a biodegradable FAD is encountered at sea, the following data should be
registered: the catch (if any), the condition of the FAD and the new code for
the buoy if the original has been replaced.
 Having access to the trajectories and sounder of the buoys attached to
biodegradable FADs, would allow assessing the capability of biodegradable
FADs to aggregate tunas even if they are not visited or fished by purse
seiners, as well as following their lifetime if they are not retrieved.
 Data should not be collected in real time but with a given time delay and
should be subject to a confidentiality agreement.
 An entity should be in charge of collecting and analyzing the data. It was
suggested that ISSF could fulfill this role.

17
3.6 Retrieving FADs
Even if biodegradable FADs will considerably reduce the impacts on the
ecosystems, it will not completely eliminate all impacts. Retrieving FADs that
beached in critical areas of particular vulnerability, as coral reefs, was discussed.
4. Conclusion
First of all, the workshop showed the importance of involving the different
stakeholders of the fishery, e.g. fishers and scientists, to find practical solutions to
reduce impacts that FADs have on the ecosystem. The combination of empirical
knowledge of fishers and scientific knowledge by scientists was of great value.
The participants in the workshop agreed that biodegradable FADs would be as
productive as traditional FADs, as long as they drift to the good places at the good
time, which also means that they must last long enough. Different designs of FADs
have been proposed, depending on the oceanic regions. The main challenge is to
find a successful biodegradable alternative to the floats (purse seine corks, buoys,
etc.). Fishers were keen to collaborate at sea to collectively test new materials and
new designs of FADs.

18
Annex I. Participants
Fishing industry
Abel Pinaud (Fishing master of CFTO, Atlantic Ocean)
Alfredo Eres (Fishing master of Nirsa, Eastern Pacific Ocean)
George Cañarte (Fishing master, Eastern Pacific Ocean)
Gotzon Goikoetxea (Fishing master of Albacora, Indian Ocean)
Jagoba Codina (Fishing master of Garavilla, Pacific Ocean)
Javi Alarcia (Fishing master of Albacora, Atlantic Ocean)
Maitane Grande (Marine biologist from Albacora company)
Patrick Helies (Fishing master of CFTO, Indian Ocean)
Sarah Le Couls (Responsible of Fleet strategy in CFTO)
Scientists
Gala Moreno (ISSF, USA)(chair)
Igor Sancristobal (AZTI, Spain)
Jefferson Murua (AZTI, Spain)
Josu Santiago (AZTI, Spain)
Laurent Dagorn (IRD , France)
Martin Hall (IATTC, USA)
Víctor Restrepo (ISSF, USA)

19
Annex II. Graphical material