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Bluefin Tuna


Bluefin Tuna A report by Kyle Hubbard, Kai Qin, and Ann-Germaine Kreger An Unknown Future One of the most sought and magnificent fish in the Atlantic, the Bluefin ... – PowerPoint PPT presentation

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Title: Bluefin Tuna

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

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
  • 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.

  • 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.

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
  • 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.

The Depletion of a Species
  • Of the Eastern and Western stocks of the Bluefin
    tuna, the latter is currently in the more dire
  • In the 1960s, the United States Atlantic Coast
    was heavily scoured by a massive fishing
  • 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.

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.

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
  • 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.

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
  • This failure to meet the standards set by
    international fishing organization is spurred by
    many factors such as economic and political
  • 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

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
  • 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.

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.

Aquaculture (Cont.)
  • Often, aquacultures may not necessarily contain
    only local fish. This increases the chances of
    introducing invasive fish species into a stable
  • 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

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.