Bluefin Tuna

1
Bluefin Tuna

• A report by Kyle Hubbard, Kai Qin, and
  Ann-Germaine Kreger

2
An Unknown Future

• One of the most sought and magnificent fish in
  the Atlantic, the Bluefin tuna is currently in
  critical condition due to several decades of ill
  advised over-fishing.
• In fact, the number of Bluefin tuna has decreased
  by 70 since the 1990s and a staggering 90 since
  the 1970s. This is a statistically significant
  figure because this level of population
  decimation often leads to the failure of species
  recovery.
• Without a healthy and viable population in which
  interaction and frequent breeding can occur, it
  can be difficult for a species to increase its
  number. This is compounded by the fact that the
  sheer unpredictability of the natural world can
  easily upset a recovering population.

3
Spawning

• Furthermore, unlike many other marine and land
  animals, Bluefin tuna rely on a single annual
  breeding period where the Eastern and the Western
  stocks meet in the Eastern Mediterranean and the
  Gulf of Mexico.
• This singular mating opportunity further
  diminishes the reproduction rate and thus the
  recovery ability of the Bluefin tuna.

4
Ecological Stability

• More unsettling than the dramatic decrease in the
  Bluefin population, is the evidence of utter
  disregard for ecological stability on the part of
  fisheries and law-makers.
• The ICCAT (International Commission for the
  Conservation of Atlantic Tuna) considered the
  mid-1970s Bluefin tuna population to be the MSY
  (Maximum Sustainable Yield). This essentially
  dictates that the stability of the tuna
  population is compromised if it dips below the
  MSY.
• However, since the ICCAT announcement, the
  Bluefin tuna population has dropped an additional
  88. (Figure 1) It is unfortunate that in a few
  decades, the Bluefin population has plunged from
  three times the MSY to the brink of extinction.

5
The Depletion of a Species

• Of the Eastern and Western stocks of the Bluefin
  tuna, the latter is currently in the more dire
  condition.
• In the 1960s, the United States Atlantic Coast
  was heavily scoured by a massive fishing
  movement.
• Numerous purse seiners operated in the Bluefin
  nurseries and gathered the juveniles to be canned
  as cat food. (Figure 2)
• Subsequently, in the 1970s, Japanese longliners
  further decimated the adult Bluefin in the
  breeding grounds of the Gulf of Mexico. This
  two-sided attack was simply too much for the
  Western stock to handle.
• Even today, the Western Atlantic population has
  yet to begin its recovery.

6
Too Little Too Late

• Upon this realization in the 1990s, the ICCAT set
  the fishing quota to be 2,830 metric tons for the
  Western Atlantic population and nearly ten times
  that amount for the Eastern Atlantic population.
• Though a belated decree, it is nevertheless a
  step forward in the preservation of the remaining
  Bluefin population.
• However, this quota was issued under the
  assumption that the Eastern and Western stocks do
  not interact and that trans-Atlantic migrations
  are not statistically significant.

7
Intermingling Groups

• A recent study conducted by scientists from
  Stanford, revealed that the two populations
  overlapped far more frequently and in larger
  numbers than previously believed.
• Using tracking devices on more than 350
  specimens, the scientists were able to discover
  that the western population travels to the
  feeding waters of Europe and the Eastern
  Mediterranean.
• With the continued over-fishing in Eastern
  Atlantic waters, this new discovery challenges
  ICCATs previous quota. When they travel to the
  east, Bluefin tuna in the Western Atlantic have a
  much larger chance of being caught by fisheries.
• Therefore, the current conservation plan may very
  well be ineffective and perhaps even harmful to
  western Bluefin tuna.

8
Biomass of Bluefin Tuna

• This failure to meet the standards set by
  international fishing organization is spurred by
  many factors such as economic and political
  pressures.
• This failure to meet the standards set by
  international fishing organization is spurred by
  many factors such as economic and political
  pressures.
• Using Microsoft Excel, we extrapolated the
  equation of a negative exponential model. From
  our calculations, the biomass of the Bluefin tuna
  in 2005, will be a horrific 2,850 metric tons.
• . This is under 5 of the original population
  present during the 1970s. By 2050, only 45 metric
  tons will be left. However, we suspect that the
  Bluefin will be extinct long before that date. A
  stock size of less than 50 metric tons would be
  insufficient to maintain a healthy and stable
  species.

9
A Disastrous Future

• If the fishing of Bluefin tuna is not
  discontinued, its extinction will be a
  heartbreaking inevitability.
• Not only would our planet lose one of the most
  majestic fish in the ocean, but an entire
  ecosystem and food chain can potentially be
  disturbed.
• It is no doubt a difficult task to immediately
  halt the harvest of the Bluefin tuna. However, it
  is undeniably the best course of action for
  Western and Eastern Atlantic fisheries.
• It is the only wise business choice to protect
  an industrys capital, which in this case is the
  population of Bluefin tuna.

10
Aquaculture, A Beacon of Hope?

• Another possible solution is the aquaculture,
  which is an artificial impoundment used to raise
  marine fish or shellfish species.
• This practice, which originated in ancient China,
  can be used to ease the fishing pressures on the
  natural fish stock.
• However, aquacultures produce a great deal of
  organic wastes which often pollutes the
  surrounding bodies of water. The organic
  nutrients such as ammonia and other nitrogen
  based compounds can potentially lead to toxic
  algal blooms.

11
Aquaculture (Cont.)

• Often, aquacultures may not necessarily contain
  only local fish. This increases the chances of
  introducing invasive fish species into a stable
  ecosystem.
• Along with the spread of new species of fish is
  the spread of parasites, pests, and certain
  diseases.Some carnivorous fish farmed in
  aquacultures require feed made from other
  smaller fish. For example, the herring is
  captured to be made into salmon feed. Therefore,
  some argue that aquaculture may actually increase
  pressures on over-fishing rather than appease
  them.

12
Aquaculture Potential

• Positives of Aquaculture
• Aquacultures may greatly reduce the fishing
  pressures on natural populations such as the
  Bluefin tuna. It also allows for continued
  production of fish products to maintain economy
  and satiate seafood demand.
• Pollution from aquaculture may be overplayed by
  some officials. Since polluted waters decrease
  fish production in aquacultures, these business
  owners would have an incentive to keep their
  waters clean.
• Tuna aquacultures in Australia are a great
  success as it has tremendously reduced the
  pressures on the natural tuna populations. Other
  examples around the world such as Japan and New
  Zealand further attest to its ecological value.