A system dynamics perspective on a global fishing enterprise:
The case of tuna ranching in Mexico
Submitted to the The 25th International Conference of the System Dynamics Society
Boston, Massachusetts, July 29 — August 2, 2007
Donald D. Robadue, Jr.
Coastal Resources Center, University of Rhode Island
Department of Informatics, University at Albany
220 South Ferry Road, Narragansett, Rhode Island 02882
401.787.8665
robadue@gso.uri.edu, don@robadue.com
Raul del Moral Simanek
Universidad Autonoma Baja California,
Apdo. Postal 453
Ensenada, Baja California,
C.P. 22800, México
R1319@prodigy.net.mx
Abstract
Tuna ranching is a value-added economic activity along the coast of Baja California in Mexico
involving the live capture and transport of migrating juvenile tuna to pens located near shore,
where they are fed for a period of months then harvested and shipped fresh to Japan for the high-
end sushi market. It is nested within the global business of tuna fishing and processing for the
fresh seafood, in particular sushi market, centered in Japan but expanding elsewhere. This is turn
is nested in the entire fishery and global business of tuna. Little is known outside the industry
about the functioning of Mexican tuna ranching, however it differs in important ways compared
to its Australian and controversial Mediterranean competitors that indicate relative stability, most
notably that it does not involve the harvest of reproducing age animals. Our analysis and
exploratory modeling exercise reveals no cause for complacency however. There are several
factors and issues, most of which are not the typical concerns found in popular descriptions of
tuna ranching world wide, that a system dynamics model suggests examining more closely in
helping determine whether Mexican ranching activities have the potential to become sustainable.
Background
Fin and shellfish aquaculture is a major and growing use of the world's coastal and marine zones,
with species cultivated to meet protein needs for local populations including the poor, for export
to global mass markets (salmon, shrimp) as well as species such as bluefin tuna, highly prized
fish for sashimi in Japan and other Asian countries. “Aquaculture, probably the fastest growing
food-producing sector, now accounts for almost 50 percent of the world’s food fish and is
perceived as having the greatest potential to meet the growing demand for aquatic food.”
(United Nations Food and Agriculture Organization, State of World Aquaculture, 2006)
A recent NY Times article covering the United Nations Food and Agriculture (FAO) report
"State of World Aquaculture 2006" notes: “Fish farms are close to matching fishing fleets in
supplying seafood to expanding global markets... The main impediments to aquaculture are a
lack of sufficient investment capital in poorer countries, limited land and fresh water and
concerns about environmental impact.” (Revkin, 2006) Bluefin tuna is a prized fresh fish in
Japan, fetching a wholesale price of nearly $17 per kg in 2006.
2004 l 2005 l 2006 |
ALL SOURCES ]
Fresh Bluefin tuna
Metric tonnes 9,966 9,882 7,395
Million Yen 21,163 19,209 14,945
Million US Dollars 201.5 164.1 125.5
Frozen Bluefin tuna
Metric tonnes 6,626 4,220 5,355
Million Yen 10,782 7,632 11,143
Million US Dollars 102.6 65.2 93.6
Exchange rate 105 117 119
Table 1 Japanese imports of fresh and frozen Bluefin tuna, all species from all sources, Source: Sonu, 2007
The demand for seafood is expected to outstrip supply from wild and aquaculture sources. The
lead author of the FAO report, Rohana Subasinghe (2006), states: “It is apparent that the
aquaculture sector continues to intensify and diversify, is continuing to use new species and is
modifying its systems and practices. This is being achieved with the growing awareness that the
resources upon which it and society in general depend must be used responsibly. Effective
regulation is only possible with an effective information system."
Is bluefin tuna ranching in Mexico sustainable? Does the Mexican industry and government
have all the policy tools and levers at its disposal to insure this? What kind of information
system could be helpful in contributing to adequate planning, regulation and monitoring of
mariculture so it can provide sustained benefits? Marine and coastal mariculture is diverse and
complex in terms of the species utilized, technology employed, locations selected, ecosystems
affected, governmental authorities potentially involved and markets served. We are presently
developing a policy modeling approach based upon system dynamics methods for one particular
type of a rapidly increasing form of mariculture: ranching or fattening of marine finfish, in
particular the relatively small but rapidly increasing practice of fattening Bluefin tuna. This case
is on its face simple enough, and of strong current interest, to allow for developing and validating
a policy level model drawing upon the mental models of a variety of actors presently engaged
from a business and public policy viewpoints.
Bluefin tuna ranching is practiced at a larger scale in the Meditteranean, especially in Spain and
Morocco, and Australia in the Port Lincoln region. In effect there are three separate global
stocks (Thunnus thynnus, or the Atlantic Bluefin Tuna; Thunnus maccoyii, the Southern Bluefin
Tuna, and Thunnus thynnus orientalis,the Pacific Bluefin Tuna, which are managed under
different legal regimes, but all serving the Japanese fresh and frozen sushi grade tuna market.
Year 2003 2004 2005 Jan-Nov Jan-Nov
2005 2006
Metric tonnes of Fresh 2769 3849 4097 3318 2359
Pacific Bluefin Tuna
imported from Mexico
by Japan
Table 2 Reported annual production of fresh tuna from offshore "ranches" in Mexico, Source: FISH
INFOnetwork (2007)
Assembling accurate, consistent data on sale volume and price of Mexican ranched tuna is not
straightforward, nor is a steady horizon of increasingly high production guaranteed, since many
factors influence output, as described below. As Table 3 indicates as an example, the wholesale
price (equivalent to the price received at the Mexican border before transshipment to Japan) for a
lot of 38 fresh tuna from the ranches averaged $22.74 kg and ranged from $20.66 to $25.61 per
kg on January 18, 2007. This compared to a price of $39.66 for a wild caught Atlantic bluefin
caught off the coast of North Carolina. (Source: Sonu, 2007).
WHOLESALE PRICES AT TOKYO CENTRAL
WHOLESALE MARKET BLUEFIN TUNA, fresh
Date of sale | Sales Origin High Average | Low
volume yen/US | yen/USD | yen/USD
D per kg per kg
per kg
01/18/2007 | 38 fish Mexico 3,100 | 2,752 2,500
$25.61 | $22.74 $20.66
01/18/2007 | 5 fish New York 7,500 | 5,250 4,300
$61.98 | $43.38 $35.53
01/18/2007 | 4 fish North
Carolina $39.66 Wild
118-121 yen = U.S.$1.00
07/19/2007 | 24 fish Mexico
$20.32
121-123 yen = U.S.$1.00 Captured
Source: Southwest Regional Office, National Marine Fisheries Service
http://swr.nmfs.noaa.gov/fmd/sunee/twprice/twp51807.htm
Table 3 Market Prices of Wild and Ranched Bluefin Tuna
The industry in Mexico was inspired in part by the early experience in Australia, and in turn may
be affected in a variety of ways by developments in both regions. Globally there is a high level
of concern over the status and sustainability of the wild tuna stocks and the activity of tuna
ranching. Greenpeace (2005) and the WWF (Tudela and Garcia, 2004; ATRT, 2006) among
many other critiques have decried the ineffectiveness of fishing quotas and tuna export
restrictions in preventing the imminent collapse of both the ranching industry and the Atlantic
Bluefin fishery itself. The Australian tuna fishery was on the verge of collapse in the early
1990s, with tuna ranching introduced and now tightly regulated as part of overall Australian
initiative to maintain sustainable fisheries and fish export businesses. (PIRSA Aquaculture,
2003).
Popular articles on tuna ranching sometimes take a skeptical perspective, conjuring up the
exaggerated imagery of a lawless maritime Wild West with ranchers, fishers, and the
government embroiled in rough-and-tumble conflict. (Montgomery, M. 2005). Such a metaphor
widely misses the mark when applied to Mexican tuna ranching in our view, although perhaps
the use of purse seines to capture juvenile tuna and transport them to pens close to the coast has
something in common with a "round-up", and perhaps the divers who inspect and collect the
fattened tuna are "wranglers". In fact, the Discovery Channel broadcast a two part series in
August, 2007, on the Australian tuna ranching industry titled "Tuna Wranglers".
Sasha Issenberg's recent journalist account of world trade in fish for raw consumption "The
Sushi Economy" (Issenberg, 2007), offers a different metaphor, placing tuna ranching at the
center of the global fishing industry. In describing Australian tuna ranching he points out: "The
most successful of Port Lincoln’s (Australia) ranchers have made their money by identifying the
optimal level of investment. They need to know when to stop feeding and to kill, the point at
which they have created the highest value fish (per weight) as possible, and their investment
begins to exceed the return." (Issenberg, 2007). The results of our work to date also suggest that
tuna ranching is a sophisticated and well organized economic activity, and tuna ranching in
Mexico also contains an element of maquila, the value-added production of goods with technical
and material inputs from foreign investors, in this case principally the Japanese, with some local
economic benefit, but organized mainly to serve the needs of the investing nation.
Anthropologist Theodore Bestor's multifaceted study of Tokyo's Tsukiji fish market, broadens
the perspective of Japan's system for providing fish to its population even further: "The structure
of a commodity chain — the links, stages, phases, and hands through which a particular product
passes...is a highly contingent social formation....Tsukiji serves as a central node—a command
and control center--- for this global trade, and the market’s activities have wide influence..."
(Bestor, 2004).
Key Questions
The core question from a policy perspective is whether and at what level is tuna ranching in
Mexico is sustainable, and from a methodological perspective, can a policy level SD modeling
serve as a bridge between scientific assessments and policy dialogue among stakeholders? Is
Mexican tuna ranching utilizing Pacific Bluefin uniquely resilient, compared to the highly
criticized Mediterranean based on Atlantic stocks, and higher-cost Australian ranching based on
southern Pacific stocks? What policies are suggested when all aspects of the value chain of the
industry are taken into account, including variability in migrating stock, limitations on coastal
siting, alternative technologies, local economic impacts? How vulnerable are management
decisions to information flow problems within the ranching industry, and what might be the
advantages of more transparent information practices?
Approach
The story presented in this paper is the result of an ongoing collaboration between an
environmental planner/ intermediate level system dynamics modeler with no previous contact or
awareness with the tuna fishing industry, and a scientist with considerable experience in fishing,
fisheries business investment and with confidential contacts within the tuna ranching industry in
Mexico. It combines the elicitation, simulation and refinement of the evolving mental model of
the scientist with content analysis of the limited literature on the Mexican case, and generalized
data that is used to calibrate and validate the various builds of the model. In this sense, a
modeling exercise can be viewed within the framework of action research.
Analysis of available literature also provides useful input and raises important questions about
dynamics of parts of the value chain that require interviews with key actors to verify, as well as
interaction with the project team, representatives of the tuna industry, as well as government and
NGO actors to specify and test model scenarios. For example, one environmentalist warns that
tuna ranching is unsustainable because of the risk of overproduction driving prices lower, which
has happened in both shrimp and salmon farming. (Dalton, 2004) By contrast, an interview with
the largest tuna rancher in Mexico addresses this price fluctuation as well, noting that it occurred
early on during the emergence of tuna ranching, threatening the financial feasibility of the new
business. (Panorama Acuicola, 2005).However, the issue related to price that each stakeholder is
concemed with differs. The environmentalist is interested in slowing the growth of new sites
and seeks to avoid higher levels of tuna fishing, while the businessman is concerned about
having a stable regulatory climate, few new restrictions, and getting all Bluefin tuna allocated to
the ranching industry.
In the following sections the exposition begins with a comparison of textbook and mental model
versions of Mexican tuna ranching. It is followed by a brief comparison of variations on the
basic textbook model that appear through content analysis of the few popularly available
descriptions of the industry. A formal simulation model was then developed, based on both
these sources, and is presently undergoing continuous revision as the quest for information to
calibrate and validate earlier build of the model leads to hypothesized and confirmed aspects of
structure and behavior that need to be included. We have tried to preserve the iterative,
detective-like nature of this exploration in the narrative.
What is tuna ranching in Mexico?
This investigation begins with a simple question that was told in story-like form and recorded in
the following causal loop diagram shown in Figure 1. Tuna ranching nests within other, larger
fisheries and economic activities, including the overall tuna fishing industry and the sardine
fisheries. To begin with, Bluefin tuna are merely visitors to the northern Pacific coast of Mexico
and the western United States. They travel in schools as juveniles from the stock located off the
Japanese coast, arriving around May and departing Mexican waters in August. Coincidently
there is a sardine population that overlaps the area occupied by the Bluefin tuna, making it easy
and economical to feed the captured tuna fresh sardines. The object of tuna ranching is fairly
straightforward: capture, hold and feed tuna for several months until they increase the
proportion of fat to the preference of the Japanese buyers, in other words, a marbled effect, so
that a higher price can be obtained.
Since Mexican tuna ranching occurs around the City of Ensenada, less than two hours from the
U.S. border city of San Diego, it is quite feasible to select, kill, process, pack and ship fresh
chilled tuna to Los Angeles, where it boards an air cargo flight to Japan. Fresh Bluefin tuna is
also available from wild fisheries and to some degree from the Atlantic, Australian and
Mediterranean fisheries. Current freezing technology is so efficient that it allows for
comparatively good prices for frozen Bluefin tuna, although the Japanese market offers a price
premium for fresh.
Western Pacific
bluefin tuna stock ~
Processed fresh and
* bluefin tuna to market
Blue fin tuna Fattened juvenile
B1 Decreasing Tuna Stock © caught and ——> tuna
placed in pens a
Sardines fed to price
Blue fin tuna entering Sens #
juvenile tuna
Mexican waters K
Decisions on tt) 7 7 +
Blue fin tuna leaving fishing effort ; : 2
Mexican waters : R1 Increasing Tuna Ranching profit from sale of
cp _—Dlue fin tuna
Capacity to fatten eer
blue fin tuna
X i Demand for
Blue fin tuna bluefin tuna
ranches
Figure 1 Simple mental model overview of tuna ranching in Mexico
The expert view of tuna ranching
A more elaborate conceptual model of tuna ranching is depicted using stock and flow notation in
Figure 2, drawn from a content analysis of a recently published comprehensive text book on
aquaculture (Pillay and Kutty, 2006) This concept map elaborates considerably on a few key
aspects of the simple mental model, and it is also notable for treating tuna ranching as a supply
chain with no explicit feed back loops, however several are implied. This and subsequent model
diagrams and simulations were created using Vensim DSS.
Moving from left to right in Figure 2, Pillay and Kutty imply there is a feedback loop between
catching juvenile tuna and the need for fishing quotas, although in the case of Mexico, tuna is a
migrating stock from the western Pacific, in particular Japan. In practice, Australia also closely
manages the southern Bluefin tuna stock. Fishing for tuna is done using purse seines, and the
fish are transferred and carefully towed to fish pens located in open water near the coast. A
number of practical issues come into play in terms of finding schools of tuna, the towing process,
the siting of ranches, which are comprises of collections of pens near shore. It is also at this
point that research on closed cycle tuna ranching is noted, which would substitute wild caught
tuna with juveniles spawned in captivity. Once placed in pens, the tuna must be fed continuously
in order to gain the fat content that increases their value in the fish market, for example with
fresh or frozen sardines. Managers then determine when to begin selecting tuna to be processed,
packed and shipped by air freight in the case of fresh tuna, or by ship in the case of frozen, not
unlike wild caught tuna. Since both are important, the conceptual framework of Pillay and Kutty
addresses issues unique to each.
Critiques of tuna ranching
By way of comparison, and to indicate the potential of modeling exercises which incorporate
detailed analysis of document content, John Volpe wrote a highly critical piece in BioScience.
(Volpe, 2005) This is depicted in Figure 3 as an annotated version of the stock and flow diagram
extracted from Kutty and Pillay. Volpe's major critiques are shown moving from right to left on
the diagram in the form of major feedback loops linking the notion that a high price differential
between ranched and wild caught tuna is required to make the operation viable. Price drops from
oversupply of ranched tuna will lead to an industry collapse. A second major feedback loop
following from price drops relates to Volpe's claim that a concentration of firms in tuna ranching
will lead to weaker regulation and low compliance. He draws from the example of the Atlantic
Bluefin tuna to highlight problems with poor documentation of catch, known as [UU or " illegal,
unreported, unregulated" tuna fishing, which has plagued Mediterranean tuna ranching and the
fishery in general. This criticism is echoed strongly by Greenpeace and WWF. More broadly
the stock assessment study group of the International Commission for the Conservation of
Atlantic Tuna (ICCAT) found recently that:
the available information strengthens the opinion held by the Group that harvests of
bluefin tuna from the eastern Atlantic and Mediterranean have been seriously under
reported in recent years, particularly those from the Mediterranean. The volume of catch
taken in recent years likely significantly exceeds the current TAC (total allowable catch)
and is likely close to the levels reported in the mid-1990s, i.e. about 50,000 t in the East
Atlantic and Mediterranean. (ICCAT, 2006)
Noting that accurate catch data is essential for managing the bluefin fishery, "our inability to
obtain reliable information on catch and catch at age seriously undermines the credibility of
conducting analytical evaluations of stock status which rely on this information." The ICCAT
researchers also point out that fishing technology is changing rapidly in the Mediterranean as a
consequence of Bluefin tuna ranching, in particular the modernization of fleets using purse
seines for live capture of juvenile tuna. "This worrying development in a context of
overexploitation potential has further led to a tremendous spatial expansion of the PS fleets in the
Mediterranean, ...Consequently, the Mediterranean nowadays supports BFT (Bluefin tuna)
fishing over its entire surface; a situation that has never been encountered in the past and that is
of high concern since there appears to no longer exist any refuge for BFT in the Mediterranean
during the spawning season."
GENERIC TUNA RANCHING MODEL INTERPRETED FROM PILLAY AND KUTTY, 2006
HANDLING AND
‘SELLING FRESH TUNA
Shes for ies approved PATTENING AN FROM PENS
coae: or cages HARVESTING TUNA IN
Zs Fresh tund Fresh
type of cage——__, constructing PENS from una sol
BLUE FIN TUNA investment in cages ait Ea cages selling fresh [to marke fresh tuna
fishing boats * ‘on tuna in cage una ransported to
STOCK ENTERING "SG PUTTING TUNA investment in | handling fresh Bit Js, token
WATERS INTO PENS cages \ tuna quality of freshdemand for PIC® 10" marker
t harvesting tuna fresh tuna
tuna in
me] = fim _ =
— fishing bluefin caught! towing |_cages funa placed in) °*9°S incages i | from cagestreezing | cages to market! frozen tuna
aetias caught cages td tuna T selling ‘transported to
juna in Mexico juvenies ' AA fish feed 4 frozen tuna nutket
2k fa \ research on cage research on harvestin:
Total Bluefin Tuna Quota *\ towing | towing cost per | loss of tuna 2 facilities for 4
| \ distance \ km breedingand larvae fromstressof = SNS techniues ‘freezing price For frozen” comand for
| A grow out of tuna towing ‘ama frozen tuna
f fishing towing speed quality of _»
quota approved by enforcement fart RESEARCH ON TUNA frozen tuna
government effort ‘ond RANCHING
tcheries \
FISHING FOR TUNA research on TECHNIQUES
breeding and larvae
Environmentalist noe FREEZING AND
SHIPPING FROZEN
concerns
RESEARCH ON CLOSED TUNA
CYCLE FARMING OF
TUNA
Figure 2 Generic tuna ranching conceptual model extracted from content analysis of Pillay and Kutty, 2006.
VOLPE'S FEEDBACK BASED CRITIQUE OF TUNA RANCHING
(Volpe, 2005)
HANDLING AND
SELLING FRESH TUNA
Sites for ites approved RBS ae FROM PENS
cages for cages HARVESTING TUNA IN
PENS |Fresh tun Fresh
type of cage—__y jfeonstructing ‘rom tuna sol a
BLUE FIN TUNA ee cages Neeeres ee coges selling fresh fo market fresh tuna
stock ENTERING fshng PUTTING TUNA investment in| handling fresh, Pd cg forte ee
warers INTO PENS cages | tuna "|" quality of freshdemand for PRC® TOP Fresh marke
\ aii Yuna fresh tuna
tuna in
Tuvenke vente Tune ; Tuna Frozen a
Bluefin Tuna| as Tu towed to| Tum e feeding tung |Tuna ae cages harvested {Tuna fro! tuna sold] 2)
ae row inc cages una placed in| 99° in cages ia ‘rom cage: ro market
Stack | sringbtuefn [ag | tema L_coges naplaced oe fromcagesfreezing |_cages fo market frozen tuna
gb caught cages { tuna 1, selling transported to
ajuvemiles fish feed 4 \,_ frozen tuna market
gor te La facilities for f
fishing Wi biosecty Bz, | vas FISH USED freezing demand for
Total Bluefin effort ak apes Va pies eae price for frozen —froven tuna
Tura Quota | " quality of una
J bec Tuna if frozen tuna
} enforcement 4, indstry 4
| effort FISHING FOR . SS cojfapse
| c TUNA i, V2 PROFIT FROM
quota opproved Ve impor teed pine iy
sh
by government | V1: suBsiDY FROM
| 1 Industry \ V3 INDUSTRY CONTRACTION NATURE'S INPUTS
concentration \ (FROM PROFIT DROP DUE TO
Environmentalist yg CONCENTRATION OF increases ‘OVERSUPPLY OF TUNA) FREEZING AND
‘SHIPPING FROZEN
concerns
FIRMS (LEADS To \__ fishing effort /
a
TUNA
Figure 3 Critique of Tuna Ranching by Volpe, 2005, in stock and flow format. Red arrows and variables in italic san serif font indicate areas of
criticism,
Notes to Figure 3:
Balancing Loop | "Mediterranean ranches are flooding world markets, resulting in a decline in
value of ranch tuna by 50 percent from 2003 to 2004. Tuna ranching is viable only as long as the
premium price of its product is protected, which in turn demands scarcity of supply. The industry
is showing every sign of becoming a victim of its own success. If present rates of growth are
maintained, an industry wide collapse is imminent."
Reinforcing Loop | "As companies approach collapse, motivation to offload production costs
will grow, resulting in more violations of the emaciated regulation regime. This is sure to make
the current bad situation worse. From the ashes, a handful of large multinational players will
most likely emerge to supply markets in an OPEC-like quota supply model."
Balancing Loop 2 "Ranched tuna eat a lot of fish—so much, in fact, that the local environment
can rarely keep pace, necessitating the import of feed fish from other regions... this potentially
opens a Pandora’s box of epidemiological problems."
Variables added to Pillay and Kutty generic tuna ranching model
V1 Subsidy from nature's inputs
V2 Profit from frozen tuna
V3 Industry contraction (from profit drop due to oversupply of tuna)
V4 Fish used for feeding
V5 Imported feed fish
V6 Local food fish stocks
V7 Biosecurity Risk
V8 Concentration of firms (leads to weakened regulation)
Source: Volpe, 2005.
To what extent do the global concerns about Bluefin tuna ranching
serve as a guide to the Mexican case?
Fisheries management perspective
In sharp contrast to the Mediterranean and Australian cases, very little is written or disseminated
about the Mexican tuna ranching industry. This is first of all reflected in official publications of
the Mexican government itself. The Mexican Diario Oficial (August 25, 2006) publishes the
policies and analyses of the Instituto Nacional de Pesca. Tuna aquaculture receives barely two
pages, with a simple bar graph acknowledging the growth of Bluefin tuna capacity to 11 ranches
and production increasing from virtually nothing in 1997 to nearly 3000 tonnes in 2003. The
document also notes that there are no regulations for tuna aquaculture, and that at some point it
might be useful to have an official guideline published on the correct treatment of the live tuna
fishery. The two main issues requiring research are the need for a "balanced" feed to supplement
natural foods (such as sardines) and sanitation, for example parasites and infections. In terms of
10
management policies, the national policy notes that it might be good in the future to separate out
the management of yellow fin from Bluefin tuna, given that the latter are an extremely small
fishery. Also, the tuna fishing fleet in general should not be allowed to increase. Finally, the
bluefin tuna stocks are categorized as "overexploited".
Leon and Ruiz (2006) add little to this discussion except to suggest that it might be worthwhile
to require that all Bluefin tuna be assigned exclusively to tuna ranching, since "using the
captured Bluefin tuna in any other process would be to lose its economic potential, especially
given its scarcity".
The OECD (2006) conducted a comprehensive study of Mexico's fisheries policies including
marine, aquaculture and inland, striking the theme of the globalization of fisheries and its impact
on Mexico. Tuna ranching does not figure very large in the overall set of reforms required to
place Mexican fisheries on the path to sustainability, greater political visibility and a range of
administrative reforms to strength enforcement, cooperation and research, and reduce unhelpful
subsidies and overinvestment on the other. The OECD points out that "there is very little work
done in Mexico on the economic and social aspects of fisheries management policies and the
literature in this area is very small" (2006:230). It goes on to note that "the interest in these
studies at the policy level appears slight, yet it is these types of studies which will provide
essential information on the socio-economic impacts of fisheries policy changes".
A new general fisheries law was in fact adopted in Mexico in 2006 and Mexico has been actively
engaged in international discussions, including the effort to create a code of responsible fisheries.
It also successfully negotiated a trade agreement with Japan in 2005, including the reduction of
tariffs for fresh tuna imports among many other products. An article at the time quoted Philippe
Charat, the largest tuna rancher, as saying "Sure, if Japan removes tariffs on it (Bluefin tuna), we
will export 50% more" (Asia Pacific News, 2004).
Among the specific concerns, the OECD found that "there is limited information on the
economic profitability of commercial fisheries" (2006:312) As part of creating greater certainty
in the aquaculture sector, the study recommends "maintenance of long term concessions for
aquaculture and tuna ranching", which are transferable. Overall, the OECD urges Mexico to
create longer term plans for fisheries, and draw on concepts of self-regulation and market
mechanisms, including individual transferable quotas rather than limited entry schemes that
allow for over-exploitation through "technological creep". The OECD concludes that "...it is
important to recall that fisheries are a dynamic system with many integrated components.
Changing one component of the system will have consequences for other parts of the system;
some consequences will be anticipated and well understood, while others will be unexpected"
(2006:318).
A modeling approach to understanding Mexican tuna ranching issues
and policy discussions
This section begins with a description of the first stock and flow working model that emerged in
November 2006 during a work session with the authors, and its structure preceded the
11
preparation of the graphical representations of Pillay and Kutty, and Volpe shown in Figures 2
and 3.
A glimpse of the core structure of the Mexico tuna ranching value chain model developed so far
is presented in Figure 4. This is consistent with the aquaculture literature on tuna ranching, as
represented by Pillay and Kutty in Figure 2, but without reference to closing the biological cycle
and spawning Bluefin tuna, nor to freezing the fattened tuna, since Mexico mainly produces
fresh bluefin. While the critic Volpe (Figure 3) uses feedback thinking by discussing larger
feedback loops that he believes pose a challenge to the tuna ranching industry, these extended
loops are not yet included in the running model. A simple price feedback loop influences the
rate of processing, since market prices do vary (in a way described by Bestor (2004) that is far
more complex than represented here) as well as influences ranch size.
The working stock and flow model captures the basic value adding production chain of tuna
ranching within the Mexican context, and appears to have a measure of face validity. It
simplifies various aspects of each stage, since it is not the goal at the outset to simulate the
activities and financial situations of the constituent firms rather to prepare an aggregate model
that captures overall behavior and dynamics of importance to industry sustainability.
The boundaries of the working model are set at the stock of the Pacific Bluefin tuna Thunnus
thynnus orientalis, that in this version is assumed to be in equilibrium and unaffected by fishing
in Mexico and the Pacific. It is also limited at the sardine fishery, which is assumed to be
unaffected by fishing or sales of sardine to the tuna ranches. The economics and support
industry, as well as financial transactions and pricing of the tuna, are not incorporated in this
version. All of these components and possible additions are discussed in more detail below and
will be added and extended in future versions as the ideas, parameters and scenarios suggested
by project team members are identified and incorporated.
The core scenario and basic parameters are drawn from the known and estimated characteristics
of the industry in Mexico, however the model runs shown here illustrate the functionally and
plausibility of the structure and emphasize creative inquiry as to the sustainability of the activity
from economic, social and environmental perspectives. Calibration and more detailed validation
remains to be carried out.
Key uncertainties exist about the tonnage of tuna actually captured and transferred to pens, the
number of pens put into operation each year, the amount of juvenile tuna in pens, the feeding rate
practices of different ranchers, the conversion factor for transforming a kg of sardines into added
fat. The amount of tuna fattened in ranches and sold and exported from Mexico is accurately
tracked by the supply chain but real data for model validation on the exact production levels is
not consistent with information obtained to date on the fattening process. The base case
presented here runs use general parameters suggested by key informants, but which require
verification and validation, as small changes in some of these parameters cause large behavior
changes in the model output. The assumed goal of tuna ranching is to add enough fat to tuna to
maximize market value of the processed product.
12
Additional key assumptions in the scenarios shown below include: each ranch has 10 pens, each
pen holds 40-80 tonnes of tuna, and all pens are filled each year, with the implication that nine
fully operating tuna ranchers seek to acquire 3600-7200 tonnes of juvenile tuna. The shows as a
look up graph an approximation of the Mexico ranch construction history, tracing information on
the number of ranches put into operation since 2001, up to 9 total ranches.
A second set of key assumptions are feeding and food conversion rates. It is assumed that each
pen in operation requires (40 or 80 tonnes fish/pen x 80kg/ton/day) =3.2 to 6.4 tonnes of
sardines per day per pen, or 96 to 192 tonnes per pen per month or 15552 to 31104 tonnes of
sardines per season for 54 pens. The runs assumes that one tonne of sardines is 5 % efficient in
adding fat to tuna, that is per month each tonne of juvenile tuna gains 120 kg of fat from eating
2.4 tonnes of sardines.
Overall, just doing simple spreadsheet math, if tuna ranchers had purchased 4320 tonnes of tuna
in a given season, and fed their tuna on average for three months before harvesting, they would
have been able to ship 5875 tonnes of fresh tuna to Japan, having operated 54 pens for 3 months.
The value added as determined by fat content gained would be 1555 tonnes or 35%. The amount
shipped should also be corrected to account for the weight loss from removing gills and guts.
In discussions during model structure design and formulation of reference modes, it was assumed
that the tuna would be in pens continuously for three months, then harvesting and processing
would begin. The current structure attempts to capture this by allowing tuna to be harvested in
less than three months as well as much longer than three months.
In sum, this first build of the model, derived mainly from co-author Simanek's mental model of
the industry, generates plausible results for key aspects of the Mexico portion of the Pacific
bluefin tuna supply chain.
13
Sardines fed to
2 Bluefin tuna juvenile tuna
on entering
Western Pacific Mexican ri
bluefin tuna stock waters *’
#
on Bluefin tuna Fattened Processed fresh
caught a =. ; — -P = bluefin tuna to
S placed in pens * juvenile tuna + market
- +
B1 Decreasing Tuna Stock effect of
price onrate
of processing I
Bluefin tuna leaving fener ed rice
Mexican waters Sing eon
* R1 Increasing Tuna Ranching
Capacity to fatten
bluefin tuna in pens ” Demand for
+
. bluefin tuna
Bluefin tuna effect of price on tuna
ranch pen capacity
ranches
Figure 4 Overview of initial build of Mexico Tuna Ranching model
hes
Bleefin Tuna Renching Inductry in Mexico Overview
rection of juvenile bluefin fiehed locally in Western Pas
4Enee roa
33 Accumdated sardines
Capacity Per Pes
sero teectan of engin Juveate ado jae
fio ‘} of
Pena Per Ranch a J hes
froctien juvente Bioefin fished on their way to WP
—!
(ie
Fishing Searen Length 12 Camdate rain | bate Precenes
Expected MismenReqared WesksinPen | "maple gageed | SuttedTunaPer
\ Pm 1 eer a
NOISE SEED TUNA |
aise Seeded Dosetin
Neise Correlation Time
4 |
ant Taga Orares TS ‘Seam Mara Te Coenen
Figure 5 View of the control panel of the Mexican Tuna Ranch Model
The following three graphs show some of the basic behaviors tracked in the model. The model
catches, moves, tracks and fattens Bluefin tuna. The weight of processed tuna includes the added
fat minus the removed components such as gills and guts.
Catching, Moving, Fattening Bluefin Tuna
200 week
2,000 tonnes
100 week
1,000 tonnes
0 week
0 tonnes
470 480 490 500 510 520
Time (week)
Catching Juvenile Tuna week
Moving tuna to Fixed Pens week
Cumulative tuna in mobile cages tonnes
Cumulative Processed Gutted Tuna Per Season tonnes
Figure 6 Catching, moving and processing tuna
15
The model also tracks the deployment and removal of pens at the end of the season, in part as a
possible way to monitor activity in the ranches.
Pens Filled, Pens Removed
4 pens/week
40 pens
2 pens/week
20 pens
0 pens/week
0 pens
470 480 490 500 510 520
Time (week)
Putting Pens into Operation ————————————_ pens/week
Removing Pens from Operation. ———————————_ pens/week
Tuna Pens in Water pens
Figure 7 Deploying and removing tuna pens
Finally, as Figure 8 indicates, the model feeds, fattens and then processes tuna, with noise used
to introduce variation in pricing that affects exact harvest timing. However, this graph also
suggests problems in the model structure and parameters, since it implies that tuna keep fattening
when feeding has largely stopped, and that some tuna (those processed in the last part of the
season) are starved.
Feeding, Fattening and Processing Tuna
600
300
417 425 433 441 449 457 465
Time (week)
Actual Tuna Processed ——————————————_ tonnes/week
Perceived Adding Fat ———————————————_ tonnes/week
Sardines Required tonnes/week
Figure 8 Feeding, fattening and processing tuna
16
BLUEFIN TUNA JUVENILES IN MEXICO WATERS
fishing Western Pacific
Equilibrium “juvenile stock-
juvenile stock Oo
Western Pacific Juvenile [|X
srereosig J Best Tung Stock Bluefin Juveniles Returning
“Bluefin Tuna Stock —
Bn /estern Pacific
Bluefin Juveniles
igrating to Mexico _
Figure 9 Non-biological fisheries component of the tuna ranching model
Figures 9-14 show key elements of model structure. The red and blue output lines represent the
lower and upper limits of several scenarios discussed below, which are indicative of but
specifically NOT intended to replicate the Mexican situation, as there is too much calibration and
validate remaining to be done. The time frame show is a 52 week long season, however the
model runs in the scenarios run for 520 weeks.
Figure 9 shows a portion of the fisheries elements of the simple Mexico tuna ranching model,
which is explicitly non-biological. The model assumes that the juvenile Bluefin stock located in
the Western Pacific is in equilibrium but the model contains feedback loops between the
Mexican Bluefin tuna fishery and the originating stocks, in contradiction to the concept map
shown in Figure 1. Perhaps the Mexican fisheries authorities are correct in concluding that this
small, irregular stock should be held to its current level of harvest. In fact this viewpoint seems
to be confirmed by the Inter-American Tropical Tuna Commission (2006:95), which states that
a "strong recruitment event (for the Pacific Bluefin tuna) that may have occurred in 2001 would
maintain spawning stock biomass above recent levels until about 2010." This is possible good
news for tuna ranchers. The IATTC goes on to declare that "spawner-recruit analyses do not
indicate that the recruitment of Pacific bluefin could be increased by permitting more fish to
spawn." In other words, none of the tuna which migrate to the eastern Pacific need to return to
Japan in order to sustain the stocks. The catches of Bluefin tuna in the eastern and western ocean
are highly variable and irregular, reflecting peaks and valleys in the biomass of the spawning
stock. Table 3 indicates that Mexico is responsible for a substantial fraction of that catch.
17
2002 2003 2004 2005
Total catch 17,459 15,920 21,707 13,512
Pacific Bluefin
Mexican 1,714 3,257 8,891 4,542
Fraction Mexico .098 204 409 336
Table 3 Reported catch of pacific bluefin tuna
Source: ICCAT (2006).
Alternative report of annual production of fresh tuna
from capture-based aquaculture in Mexico
Year| 2001 2002 | 2003 | 2004 2005
tt
Tonnes, 521| 517) 517] 4,193| (7,869)
Thunnus
Orientalis
Dollars perkg | $13.46] $14.08] $13.51] $13.78| $15.19
Value, 7,014) 7,281) 6,985) 57,821 | 119,575
thousands
USD
Source: United Nations Food and Agriculture Organization, FIGIS Data Base.
hutp://w o.org /figis /servlet /SQServlet?fi st/local /tomeat/FI/5.5.23/fi
gis/ webapps /figis/ temp /hqp_55755.xmlécouttype=html
Table 4 Alternate information on Pacific bluefin tuna sale to Japan
The fraction Mexico is catching of the total stock varies significantly by year. Matsukawa
(2006) finds an evolutionary response in that "the population excess over the carrying capacity
(in the Western Pacific) causes the migration in each life stage". Furthermore, "migration of the
tuna into the eastern Pacific increased in years when the abundance of sardines was declining".
These sources of variation are normal. The tuna model should probe the tuna ranching system in
Mexico to see the effects of such variations. It also turns out that the Western and Central
Pacific Fisheries Commission has formed a Northern Committee, which is already in place and
meeting, led by Japan (WCPFC, 2006). Several Americans attend the meetings, indeed the first
meeting was held just across the border in La Jolla.
Figure 10 shows the movement of Bluefin tuna into Mexican waters, capture of a fraction, and
then the fact that some tuna remain in the eastern Pacific and return to Mexico the next season.
18
Western Pacific Juvenile _ [<3
‘Bluefin Tuna Stock
meant ZX
[Wgreting te Mexico f
a
Bluefin Jweriles Returning
Bluefin Tuna Juveniles in KC
Mexico
| / |
dbl catering fo ‘tuna migrating out of. /
Juveniles Returning to Mexico if
fraction of juveriles Tuna Out of Mexican
returning to Mexico rs to the Eastern
oa / Pacific
Figure 10 Bluefin tuna in Mexican waters
A key aspect that is not revealed in the model is the extent of foreign participation in the
technology, supervision, financing and quality control of Mexican tuna production. Swartz
(2004) maps out the changing way in which Japan, as both consumer and producer of fish
products is able to participate through non-fisheries methods in assuring a steady supply of high
quality products.
Production component details
A key missing piece in the Mexican tuna ranching model is the closed cycle. The abundance of
fresh sardines just at the time when the Bluefin tuna arrive off the coast of Baja California makes
tuna ranching simpler than in the Mediterranean or Australia. However, the questions raised by
reflecting on the fisheries component led us to check whether in fact the life cycle of the Bluefin
tuna had been successfully closed such that juveniles could be raised and fattened with little
regard for the future of the ocean fishery. In fact, as Sawada, Okada, Miyashita, Murata and
Kumai (2005) report, Japan has successfully closed the cycle. Australian ranchers also claim to
have closed the cycle for Thunnus maccoyii. including one highly publicized operation with
several adult females placed in a special environment in anticipation of spawning. (Treadgold,
2005)
In the model, only wild captured tuna is involved. In Figure 11, ranches are established and their
capacity established. While permits may limit the maximum number of pens, the ranchers can
decide how many pens to deploy in a season. In Figure 12 the captured tuna are towed to the
19
pens. Note that the term "perceived tuna in pens" is used, since many ranchers do not have a
precise estimate of how many tuna are actually obtained and transferred.
Planned Fishing Effort based on
remaining seasonal tuna
“er Per Week | |/ ‘stock ,
|Pen-Capacity— | Industry Objective
Utilization Factor for Fishing Tuna
—_-—
\
Capacity Per
Pen ~——*Fotal Pen Capacity:
oe
<Time>
Tuna Rénch Xe Pens Per
Construction Ranch
Figure 11 Establishing ranches and setting fishing goals
DECIDING ON FISHING EFFORT
a
7
bi
| avilable una (Catching Juveril
| firs eines / Tuna Fishing Tuna
=o (PAA Effort Delay
\ ;
ps. \
Effort based on
Planned Fishing | | semaining seasonal tuna
pererrewes Y ™
Figure 12 Deciding on how much effort to catch tuna
The model includes a simple mechanism that adjusts effort to the
dwindling amount of Bluefin in Mexican waters
20
Total Perceived
Fattening Tuna
infFixedPens
Y
Perceived Adding
_ Fat to.Tuna in
a P, eek
added fat to tonne of
‘tuna per week e a
—_~ #7
f
{ accumulated
added
a
Efficiency of Conversion
of Sardines to Tuna Fat
|
Tonnes of sardines required
for fattening one-tonneof—
tuna per week pe te
| a
|
sardines required per
tonne of tuna per day
clearing fat,
Figure 13 Feeding and Fattening Tuna
Some ranchers feed based on the perception of how many tuna are in the pens
<Total Perceived
Fatteni una in Fixed
pressure to
ess tui
pressure to process tuna
from schedule
Actual Professing Tuna
Cumulative
Processed
Gutted Tuna
Per on
clearing processed tuna
accumulating processed tuna
Figure 14 Processing Tuna
Processing is a balance between increasing cost of production due to feeding and market price
Another question tied to the fisheries component of tuna ranching, is the source of food. Figure
13 shows that sardines are fed at a certain rate per day and this adds the fat content to create
21
more valuable bluefin for use in sushi. Tuna ranchers are in a position to pay a premium for
fresh sardines compared to alternative uses, such as fish meal or frozen or canned. What might
happen in an extreme case when the tuna and the sardines were not in the same place at the same
time? This is the case now in Australia, which relies on frozen sardines including from the
United States. There are other large stocks of sardines in the Pacific and Gulf of California that
could be obtained. Another key question, both from the modeling and management perspectives
is the degree of information forthcoming about the actual feeding and fattening ratios, waste
management and the potential for disease, in part to be able to better assess and predict industry
performance related to management practices.
Finally, tuna is processed carefully to maintain a high quality, and flown chilled and fresh from
Los Angeles to Tokyo. As noted by Issenberg, the rancher must balance the costs of fattening
with the market price and choose the processing carefully to maximize profits.
Scenarios
To examine the potential usefulness in asking questions about sustainability, several scenarios
were formulated. Table 5 shows the variations in a few parameters that are used to set up 10
year runs, and the final outcome in terms of tonnes of Bluefin tuna to the market.
Constant Scenario | Scenario| Scenario 3 Scenario 4
1 2 despite Base case
base case | tuna stock | reduction, plus
is reduced effort is maximized
maximized effort
Equilibrium Stock of Juvenile 100000 50000 | 50000 tonnes} 100000 tonnes
Tuna in Western Pacific (tonnes)| tonnes tonnes
Fraction fished locally in 3 76 76 3
Western Pacific (dmnl)
Ranches/# Pens in Mexico at 9/90 9/90 9/90 9/90
Buildout (ranches, pens)
Assumed total capacity of pens 3600 3600 7200 tonnes} 7200 tonnes
(40-80 tonnes/pen) tonnes tonnes
Tonnes of tuna to market 3940 3210 4005 tonnes} 7851 tonnes
tonnes tonnes
Table 5 Simulation output from model runs similar in nature to the Mexican situation
Scenario 1: The base case
Figures 15-19 summarize the model run in Year 10, leading to production of 3940 tonnes of
fattened and processed tuna. Figure 15 shows the functioning of the production chain on the
ranches, and Figure 16 shows the accumulations of captured tuna and tuna production. There is
perfect knowledge of production, but many ranches do not have full knowledge of how many
tuna of what sizes are in the pens.
22:
OVERVIEW
Processing
Tuna
6,000 tonnes
400 tonnes/week
3,000 tonnes
200 tonnes/week ‘ Tuna
Perceived to
be in Pens
0 tonnes
0 tonnes/week
Time (week)
Cumulative Processed Gutted Tuna Per Season tonnes
Total Perceived Fattening Tuna in Fixed Pens. -2——2s—2-—2-—>- tonnes
Actual Processing Tuna
Catching Juvenile Tuna
tonnes/week
tonnes/week
Figure 15 Scenario 1 Overview, at Year 10
Captured, Perceived and Processed Bluefin Tuna
6,000
3940
4,500 tonnes
3,000 we
1300 Net value added
0 (fat content)
468 472 476 480 484 488 492 496 500 504 508 512 516 520
Time (week)
‘Cumulative tuna in mobile cages tonnes
Cumulative Processed Gutted Tuna Per Season ———4-—S-—S—S—_ tonnes
Figure 16 Scenario 1 final output comparing cumulative tuna captured and shipping weight of tuna
processed
23:
Sardines Effect on Processing
20 tonnes
1,000 tonnes/week added fat
Total sardines
to tuna per tonne of
tuna
10 tonnes
500 tonnes/week
Normal
Total
| | Sardines
468 476 484 492 500 508 516
0 tonnes
0 tonnes/week
Time (week)
Normal Sardines for Tuna tonnes
Accumulated sardines per tonne of tuna tonnes
Actual Processing Tuna 5 tonnes/week
accumulated added fat to tuna + + + + + + 4 tonnes/week
Figure 17 Pressure to harvest balances need to ship all tuna before costs overshoot price, and the advantage
of delay to gain a price increase
The consequence is that ranchers are feeding "perceived tuna". The model structure, as noted
earlier, attempts to indicate that the cost of continued feeding creates a pressure to harvest, while
the situation in the market place in Japan may justify waiting until the price reaches the most
profitable point.
Figure 18 shows that the model structure allows some exploration of the effect of profit on ranch
operations. The impact on profit is the decision to purchase more captured bluefin.
Scenario 2: Suppose the Bluefin tuna stock declines to half the base case level
Scenario 2 simply reduces the assumed size of the overall Western Pacific tuna stock, keeping all
else equal, with the result that a lower stock, even if very large, will reduce the amount of tuna
fattened. This might be the equivalent of events such as poor year classes in the Western Pacific,
or offshore Bluefin fishing increasing greatly, intercepting the juvenile tuna before they reach
Mexico. The model does this with a lookup graph that has fishers become less efficient as the
end of the bluefin tuna season in Mexico approaches so that at a certain point it is no longer
worth setting nets. This is shown in Figure 19.
Scenario 3 assumes that ranchers decide to double their fishing effort to get as many tuna as they
can, and assumes the pens can accommodate the extra tuna or more pens are deployed. The
result is compared with the other scenarios in Figure 20. The blue line represents the lower
capture of tuna, even though, as Figure 21 indicates, the initial pulse of captured tuna occurs
24
because of doubled effort. However, the intuition is that because there are fewer tuna overall,
each setting of the nets will be less and less productive. The model employs very simple
structure to produce this effect.
29_03_Base_100000_AllYears Pnk —?—+—+—++]
Industry Objective for Fishing Tuna
6,000
[ 4,500 ]
3,000
1,500
0
[Pen Capacity Utilization Factor
2
17
mT Le NA
0.8
[Total Pen Capacity
u i
3,000
0 130 260 390 520
Time (week)
Figure 18 Price signal used to influence investment in ranches and pens. A pink noise based long term price
rise influences decisions to expand capacity correspondingly
Captured, Perceived and Processed Bluefin Tuna
4,000
3210
3,000 tonnes
2,000
1,000
0
420 432 444 455 467
Time (week)
Cumulative tuna in mobile cages +$-——$+—_—+$_ tnt tonnes
Cumulative Processed Gutted Tuna Per Season. —2—2—2—2—2— tonnes
Figure 19 Scenario 2 output shows reduced production because Bluefin tuna are more scarce
25:
600
450
Catching Juvenile Tuna
468 472 476 480 484 488 492 496 500 504 508 512 516 520
Time (week)
Catching Juvenile Tuna : J29_06scen_100kStock_33fish_Pnk1_80k
Catching Juvenile Tuna : J29_04scen_SOkStock_76fish_Pnk1
Catching Juvenile Tuna : J29_03scen_ReducedStock_Pnk1
Catching Juvenile Tuna : J29_03_Base_100000_AllYears_Pnk
week
week
week
week
Figure 20 Comparison of four scenarios based on fish stock and fishing effort.
600
450
301
Ss
150
0
Catching Juvenile Tuna
ul
0
Catching Juvenile Tuna : J29_05Sscen_50kStock_76fish_Pnk1_density ++ week
Catching Juvenile Tuna : J29_04scen_S0kStock_76fish_Pnkl_ ——2—2— week
52. 104-156-208 -=— 260312 364.416 468-520
Time (week)
Figure 21 Initial result of scenario 3: more fishing effort creates a dramatic initial pulse of capture
26
Cumulative tuna in mobile cages
4,000
3,000
2,000
1,000
0 A
160 165.170 175 +180 +185 +190 +195 200 ~-208+~=«210~~«2215
Time (week)
Cumulative tuna in mobile cages : J29_O5scen_SOkStock_76fish_Pnk1_density —:—+——+— tonnes
Cumulative tuna in mobile cages : J29_04scen_SOkStock_76fish Pnkl —-—2—2—2—~ tonnes
Cumulative tuna in mobile cages :J29_03scen ReducedStock Pnkl #—s—s—s—s— tonnes
Figure 22 Comparison of scenarios...doubling fishing effort does not double capture nor production
Scenario 4, shown below in Figure 23, represents the optimistic view of tuna ranching that does
not recognize any internal or external constraints, and thus supports the assumption that tuna
ranching is sustainable in the Eastern Pacific. As the model is validated, the various scenarios
will likely fall below the level of this optimistic view.
Cumulative Processed Gutted Tuna Per Season
8,000 i
i 7851
6.000 | tonnes?
2,000
0
ee ss
Time (week)
‘Cumulative Processed Gutted Tuna Per Season ‘n_100kStock_33fsh_Pnkl_80k —+— tonnes
(Cumulative Processed Gutted Tuna Per Season
(Cumulative Processed Gutted Tuna Per Season
Figure 21 Scenario 4: Sustained Optimism: Tuna Stocks Stay High, and Ranches and Fishing Effort Can
Expand
27
A Tasmanian firm, Aqua Assist, has already developed sophisticated decision support tools for
individual tuna ranchers and other types of ranching operations and is reported to be used in both
Australia, Mexico and the United States. Figure 24 indicates that the software author (Bronstein,
2007) incorporates many features of the broader, text book model as represented by Pillay and
Kutty. The model presented here operates at an aggregate level, glossing over individual ranch
differences. From an information system perspective, however Aqua Assist represents a major
step forward, since it also includes specific modules related to tuna fishing quotas.
Aqua Assist
Py Ltd
‘www. aquaassist.com
Figure 22 Decision making software for tuna ranchers by Aqua Assist (Bronstein, 2007,
reproduced by permission.)
Conclusions and a look ahead
At the very least this work suggests that the present stance toward tuna ranching as a low
visibility activity with few issues is unjustified when seen in its global context, most importantly
in relationship to the market of Japan. Just as Japan has found numerous undesirable aspects of
its prior trade relationship to Mexico, especially in relationship to the maquiladora arrangement,
prompting a new trade agreement, Mexico might want to look again at whether the lowering of
tariffs for seafood like Bluefin tuna is either enough or even the most important obstacle in the
way of sustainability. Mexico might also want to have a seat at the table for the Western Pacific
fisheries management initiative led by Japan. Perhaps tuna ranching, which on its face seems an
independent and nearly self-sufficient activity, is indeed far more vulnerable to decisions made
elsewhere that affect tuna supply, technology and standards, access to the market, and price.
Further extension of the modeling effort would not be aimed at analyzing individual firms within
the industry, rather the hope is to generate better information to confirm or contradict output
from model runs under reasonable sets of assumptions, in the spirit of the OECD proposals for
future fisheries and aquaculture management in Mexico. In particular, this needs to include
determining the full extent of the model boundary in order to see the extent of what should be
28
considered exogenous structure. This in turn will build confidence in using both the specific
tool, and more broadly the frame of reference the systems thinking perspective can add to both
determine and assure sustainability of Mexican tuna ranching in the face of a larger set of
challenges based not on metaphors but on a deeper understanding of its structure and dynamics.
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