Pacific Specific

So far, this blog has focused on global impacts of climate change on fisheries. I have mentioned in previous blogs how the effects of climate change and the subsequent impacts on fisheries will vary between regions. I thought it was about time we got more specific about how fisheries in certain areas will change so this blog will focus on how fisheries in the Pacific are responding to climate change.

The resource I'm going to direct you to is a chapter by Lehodey et al. which looks at how oceanic fisheries in the Pacific are vulnerable to climate change. This review spans nearly 60 pages, so doesn't exactly  make for light reading. It is very thorough in describing the current state of tuna in the Pacific, which is considered to be healthy, before looking at the impact of different climate change scenarios on the abundance of tuna in the Pacific region. How climate change may affect tuna populations is especially important because some species are highly sensitive to climate, for example Skipjack tuna move east- west in correlation with ENSO variation. During El Nino episodes, tuna move eastwards as their preferred warmer water extends in that direction, however this causes huge fluctuations in fishing catches, which can last for months depending on the conditions following the El Nino.

One issue raised in the report, which is fairly specific to the Pacific region, is that the acoustics of the ocean may affected by changes in ocean chemistry. Expected changes in pH and temperature alone are expected to  reduce the sound absorption coefficient by 20-60% in the upper metres of the ocean by 2100. This in effect makes the ocean noisier, so for example, tuna may not be able to hear a predator like a killer whale, that emits high frequency sounds waves when chasing prey, coming towards them.  Another thing that dawns on me as I read this though is that actually, we're still studying what tuna can hear, so we can't be sure what the response of tuna and other fish and aquatic animals like killer whales and dolphins will be to change in sound absorption.

I feel that the report ends on a very valid point. Despite that fact that catches for most species are projected to increase initially under the modelled scenarios at the end of the report, and with all the possible uncertainties about how tuna and the rest of the oceans may change due to climate change, Pacific Island countries and Territories and those who manage tuna need to do more research and start deciding how to adapt to the changes. I think that this conservative approach is definitely necessary so as to ensure future fish stocks can be controlled, and adaptations made if necessary. After all, a stich in time, saves nine...