Call to protect the Slope Front in the face of evidence of its reduction as a result of warming

'In Argentina there are no studies that link fisheries and climate change'

ARGENTINA
Tuesday, October 27, 2020, 07:00 (GMT + 9)

Interview with Bárbara Franco, an oceanographer at CONICET who investigates the effects of climate change in the South Atlantic, warming of the water and the displacement of the Brazilian Current to the south that is modifying the Front of the Slope and has an effect on fisheries.

The researcher Babara Franco surprised an auditorium of biologists and conservationists, in the course of a webinar on Marine Protected Areas, with the call to protect the Front of the Slope in the face of evidence of a reduction in it as a consequence of the warming and displacement of the Current from Brazil. Whenever there is talk of restrictive measures in the Argentine Sea, the sector is alarmed at the possibility that its source of income is affected; But in the talk that the oceanographer had with REVISTA PUERTO, she expressed the reasons for measuring the impact from another perspective. Addressing research on fishery resources from climate change will be key to prevent changes in fisheries that can affect business: it is a solution rather than a problem. He argues that the lack of access to hard data on fisheries research is an obstacle to advancing scientific knowledge that would lead to better management measures.

“Climate change is generating changes in the circulation of the oceanic gyres and reaches the Brazilian Current on the western edge of the South Atlantic Ocean and this atmospheric change is generating changes in the oceanic circulation that is already inducing changes in the Brazilian fisheries, Uruguay and Argentina ”, explains Bárbara Franco.

REVISTA PUERTO: What's happening on the Front of the Slope?

BARBARA FRANCO: The South Atlantic subtropical gyre is moving south and the Brazilian current, in addition to warming, is intensifying and also moving. This intensification and shift to the south is causing the meeting point -confluence- with the Malvinas Current that brings cold water and nutrients that sustain the productivity of the slope front, is also moving. For between 30 and 40 years, it has been moving south at a rate of 0.4 degrees latitude per decade. It does not seem like much but in 10 years it is 4 degrees and it has been 4 decades, it is a lot, it is 400 kilometers and the projections for 2050 to 2100 indicate that this will continue to happen.

RP: Is there evidence that this displacement is reducing the face of the Slope?

BF: The northern part of that front is already affected. It is proven that the Brazilian Current has moved south and where the Brazilian current arrives, the Front of the Slope will cease to exist. This front is generated by the Malvinas Current and is being pushed south by the Brazilian Current, which is poor in nutrients and with much warmer waters. It is important to note that many cold water species are associated with the Front of the Slope. An example is the Patagonian scallop; In recent years, the Brazilian current reached the largest bank of scallops at 40º South, being for the moment the most affected.

Map showing the region's surface temperature difference between the 2012/2017 average and the 1985/1990 average. In the Rio de la Plata and in almost the entire extension of the Brazilian Current, a warming of more than 1 ° C is seen, and in some specific regions of more than 2 ° C. (Image: courtesy Cecilia Draghi / cientificamente.com .ar)

RP: The biologists who work on scallops at INIDEP have shown concern about the decrease in density. Do you associate it with the heating of the water and a lower productivity of the Slope?

BF: More research is needed, but this shift in the Brazilian Current probably explains it, because the scallop needs the phytoplankton that the Slope generates and that falls to the bottom to feed.

RP: There is always mistrust about the foundation of this type of conclusion. Is there enough scientific evidence to ensure that this change is taking place?

BF: There is no longer any doubt about it, there are many well-founded studies, observations and climate model data on the southward movement of the Brazil Current. That a whole change is being generated in the atmospheric circulation inducing these changes, there is no doubt. Even using different data, the same conclusion is reached.

RP: The species that you have referred to in your reports are bivalve molluscs such as scallops and pelagic fish such as anchovies. What is known about other groups of species?

BF: In Argentina there are many species of fishing and environmental conservation importance, but knowledge of the relationship of climate change and abundance, mortality and distribution is practically non-existent. The institutions that have fishery data only one or two years ago began to talk about the issue, therefore solid studies that link fisheries and climate change do not exist in Argentina.

Continental margin of the province of Buenos Aires. The positions of the submarine canyons and the terraces of the Río de la Plata and the Colorado-Negro delta complex are shown (Image: courtesy Gerardo M. E. Perillo / Continental Margin of the Province of Buenos Aires)

RP: - Should INIDEP do these studies or should it make hard data available so that other researchers, outside the institute, can collaborate in generating that knowledge that we do not have today?

BF: It is difficult to interact because INIDEP has departments and laboratories for each group of species but they remain in the power of INIDEP. Some people do research but there are no experts on the relationship between climate change and fisheries. Interdisciplinary studies are needed, with experts who can provide temporal data, not just temperature and salinity ... The ocean is complex, you cannot measure only loose data. In order to have solid studies, it is necessary to overcome this lack of connection between the change in oceanography, ocean circulation and the change that is being observed in species. It is necessary to know if the change in the distribution of shrimp or in the abundance of squid is associated with climate change. If we have the data of the species we can know if they are related to climate change. INIDEP is just beginning to interact with researchers from other institutes, but it takes a lot of work to access this data.

RP: In the technical reports that you have presented together with other authors, you demand that these hard data on fisheries biology be made available to scientific research. The claim is not new, renowned scientists like Ana Parma have done it in the past and Carlos Iribarne has recently said that the fishing data are state secrets. What would allow them to have that information?

BF: -There are oceanographic data of 30 or 40 years and there are also biological fishing data of 30 and 40 years, we need to be able to access, we need the data to be available. Many researchers could work by joining these data to have an understanding of the impacts of climate change and that would allow better management of the fishery. For example, it should be known which are the species most vulnerable to climate change in Argentina, this is not known and is a key point.

The Patagonian scallop is distributed from Tierra del Fuego up to 35ºS at depths between 40 and 200 m. The most important concentrations (banks) are located between 39º 30 ′ S and 42º 30’S at depths of 80 to 120 m with the influence of the slope front formed by the platform regime and the Malvinas current. (Photo: INIDEP)

RP: Does that mean that in order to have a sustainable management it is necessary to incorporate this information?

BF: It would be fundamental. It is true that this also happens in other countries but it is necessary to change it so that fisheries can be planned and managed according to the knowledge that is had about whether or not they are being affected by climate change. If from studies it is found that at so many degrees the Front of the Slope is not being productive, that will affect the fisheries. It is necessary to have this information and relate it so that the exploitation of resources in fisheries is sustainable.

RP: You have raised the need to protect the Front of the Slope as a Marine Protected Area. What would it mean for the fishing sector?

BF: I consider it from the point of view of the conservation of biodiversity. Just as fishing species go to the Slope to feed, many other species do so and end up losing that highly productive environment, because a large number of trawling vessels from other parts of the world are concentrated in that area. This means that species that have biological conservation importance cannot feed on that source of productivity that is the Front of the Slope. We have already seen that there is a floating city in those spaces.

RP: From that perspective then, would protecting the Front of the Slope be a way to protect the resources of the Argentine Sea from illegal or unreported and unregulated fishing and also from projected seismic explorations?

BF: Exactly, it would be an opportunity to limit that fishing movement, to limit the effects of acoustics that are affecting many important marine species. For the fisheries that depend on the Front of the Slope to be sustainable, it is important to protect them from the concurrence of that fleet and from seismic explorations.

Author: Karina Fernandez / Revista Puerto

Related news:

• The Brazilian Current is changing and affects fishing

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