By Atuna
Little was known about the implications of climate change on tuna stocks today and in the future until the FAO released the report “Climate change implications for fisheries and aquacultureâ€.
According to this report, tuna populations may spread towards temperate regions, based on predicted warming of surface water, and increasing primary production at mid and high latitudes. In other words, tuna is leaving equatorial areas.
“In the pelagic environment, shifts are not only horizontal but also vertical, with species responding to warming trends by moving towards deeper cooler watersâ€, the report added.
The scenario of climate change impacts on tuna production in the tropical and subtropical seas are that combined effects of changes in circulation, temperature, nutrients, primary production cascade up the food web to influence prey availability and habitat conditions for tuna in those areas.
The report also states that “highly mobile pelagic speciesâ€, such as tuna, will be the first ones to be redistributed.
The consequences of such movement would be devastating for the tuna industry, since large-scale changes affect the distributions of species and, hence, production systems.
For example, the predicted northern movement of Pacific tuna stocks may disrupt fish-based industries because existing infrastructure (e.g. landing facilities and processing plants) will no longer be conveniently located close to new fishing grounds.
In addition, changes in the distribution of stocks and catches may occur across national boundaries. A lack of well-defined and stable resource boundaries will present particular challenges for fisheries governance in the context of climate change.
According to the report, changes in fish stock distribution and fluctuations in the abundance of conventionally fished and “new†species may disrupt existing allocation arrangements.
As mentioned previously, it is forecasted that temperature changes in the Pacific Islands could lead to a spatial redistribution of tuna resources to higher latitudes within the Pacific Ocean, leading to conflicts over the stock of tuna between industrial foreign fleets and national ones restricted to their EEZ.
Not only climate change caused by emission is affecting tuna stocks. The report explains that the El Niño Southern Oscillation (ENSO) has been also responsible for the oscillation of Pacific skipjack tuna, especially. However, there are no final study on the causes of the El Niño itself and many claim that human actions have made those more frequent along the years.
Finally, FAO’s report stated that tuna redistribution is likely to cause changes in abundance, as recruitment processes are impacted by changing temperatures and circulation patterns.