Arctic Fish: Sentinels of Climate Change

So good evening.

And first, I would like to say thank you to the organizers for putting this session together and for extending the invitation to be a part of today's panel.

Again, I'm Irina Labia from Hokkaido University's Arctic Research Center, which is located in Japan.

And what I will be doing today would be to give you a quick overview of how fish communities has been responding to the rapid changes that has been transpiring in the Arctic.

And I'll begin with...

Sorry, maybe it's better to...

So I'll begin with the highlights of the presentation just to make sure that I... get the message across early on.

And as most of us who are here in this room are aware that the Arctic has been experiencing exceptionally unprecedented changes in its seascapes due to continued warming as well as sea ice loss.

And these rapid changes are again ultimately modifying marine communities and ecosystem processes as more boreal species are shifting their distribution to the Arctic waters in search for areas that are thermally optimal in a warming ocean.

And more importantly, such responses are soliciting or eliciting ecological and societal ramifications on the present day as well as future Arctic ecosystems and on communities that are dependent on many of its resources.

So I will try to walk through each of this or expand a bit more about this point as I go through my talk.

So for more than four decades, between 1979 to 2021, we've seen that the Arctic has been experiencing rapid climatic changes.

And in fact, it has been warming at rates nearly four times than that of the global average, a phenomenon that has been dubbed as the Arctic amplification.

And concomitant to these warming events in the Arctic is the loss of sea ice, which is characterized again by the decline in the sea ice minimum area, particularly for the month of September from 1979 all the way up to 2024, and shrinking at a rate of 12.2% per decade.

So, these changes, both in temperature and thermal environments, as well as sea ice environment, have led to species distribution shifts that are ultimately altering Arctic marine ecosystems in a process called borealization.

And this process is characterized by a shift in ecosystem that were historically characterized as Arctic and are progressively acquiring attributes that are more of the boreal or typical of boreal ecosystems.

So as you can see from this figure, a lot of those... evidence for borealization has been documented in many areas of the Arctic and that happens across different traffic communities throughout the Arctic and at the same time are altering the different ecological processes.

So among the prominent manifestations of this process is the redistribution of marine biodiversity in many areas of the Arctic.

And in an earlier paper that we have, We've seen, in general, an increase in marine biodiversity or in the number of species across the different regions of the Arctic from 2000 to 2019, a period that have seen drastic increases in temperature as well as loss in sea ice.

Worth noting, however, that these changes and the impacts of climate change are different across marine communities such that rates of changes are – oh, sorry – Rates of changes for wide-ranging apex predators are higher than those observed for massive predatory species that, of course, include fish and other crustacean species.

What it suggests is that climate change impacts will be different not only across the geographical areas of the Arctic, but more importantly, these impacts will be different across marine communities.

So, similarly, climate-driven shifts in the different species, of course, including fish and other marine organisms, will impact the ecosystem structure as energy pathways are likely to be altered under, say, cold and warm conditions in the Arctic.

In particular, we'll be seeing more of a transition from an ice-associated bloom in cold water that often favors benthic or seafloor communities.

And that would shift into a phytoplankton bloom in open water that now favors or more beneficial to pelagic communities.

So more importantly, these species responses that we are seeing in response to climate changes are in turn raising important ramifications or repercussions in terms of the future availability of species or resources to fisheries, as well as their effective management.