The maritime expedition was already reaching its eighth and penultimate day, and so far, no sardines. When the probe indicated the proximity of a school of fish, the trawler quickly surrounded the area and cast the net. The first real sardines began to appear, and the crew had a party. After all, no less than 15 researchers were waiting anxiously for this moment: they were on board precisely to collect and analyze samples of the species.
Until it came across Sardinella brasiliensis, the scientific cruise of the Multisar project had already sailed for around 700 kilometers within its distribution area – which goes from Cabo de São Tomé, in Rio de Janeiro, to Cabo de Santa Marta Grande, in Santa Catarina. The species, however, was only found in the extreme south of the country, close to the border with Uruguay. A region that, traditionally, is not part of its habitat.
“The fact that we did not find our object of study is also a result. Why wasn't the true sardine in the area where it should have been? This is the phase we are in now, of taking all the data, discussing and interpreting them”, explains the researcher from the Federal University of Rio Grande (FURG) and technical coordinator of the project, Stefan Weigert, who led the expedition. According to him, there are indications that climate change is behind the enigma, which has been noticed for at least a decade.
“What we are observing is that there is an expansion of the area of occurrence of the species. And this could be motivated by a probable warming of the waters, allowing sardines to occupy this region, ”he explains. “If 10 years ago I said I found sardines in the state, they would call me crazy. Today, the fishing fleet here has already caught commercial catches of up to 17 tons”. Its very testy fish in the world.
Any alteration related to the true sardines is cause for attention. After all, since the 20th century the species has carried the title of one of the main fishing resources in all of Brazil on its back. Therefore, if the fish is affected in any way, it also affects a large part of the population and the economy, in view of the immense socioeconomic chain linked to its capture.
The Marine and Fisheries Research Support Project supported the scientific cruise proposed by the Multisar subproject team. The initiative put two vessels at sea: a FURG research vessel and a trawler from the local fleet specialized in sardine fishing. The idea was that for ten days – between March 22nd and April 2nd, 2018 – samples of the species would be collected for a series of analyses, some of them unpublished.
This is the case, for example, of parasitology studies, which until then had not been carried out with Sardinella brasiliensis. The survey found the presence of parasites in 100% of the collected samples. But this is not necessarily alarming news. Weigert recalls that all living beings are hosts of parasites, including us humans. And that the recommendation, in this case, would be to avoid eating that classic fresh fish that has just come out of the sea and subject it to freezing and cooking instead. “That solves a lot of the problem,” he says.
Another danger to human health analyzed by the project concerns the contamination of sardines by heavy metals. The Multisar team came to the conclusion that the levels found in the animals are within the range allowed by international health surveillance agencies.
To make the picture even more complete, part of the samples collected on the expedition were passed on to the team of another initiative also supported by the Marine and Fisheries Research Project, Petrosardinha. Developed by scientists from the Laboratory of Marine and Environmental Studies (LabMAM) at PUC-Rio, the research evaluated the organic contamination and by hydrocarbons (originating from the oil industry) in the true sardine.
Working with the subject since the 1990s, it was the first time that LabMAM dedicated these analyzes to the true sardine. To complement the samples obtained from the Multisar cruise, the Petrosardinha team took advantage of the 1st Seminar on the Marine and Fisheries Research Project, held by FUNBIO in March of this year, and entered into a partnership with several other subprojects.
With the contacts we made during the seminar, we got six samples from different places and fisheries, with greater regional representation”, says the initiative's coordinator, Renato Carreira. According to him, the data on contaminants are still preliminary, but he remains optimistic: “I think it will be difficult for us to find higher concentrations of hydrocarbons, especially since sardines are able to metabolize them”, he says.
As the survey is a pioneering one, he hopes to arrive at an initial reference value so that this type of analysis will continue to be constantly done from now on, allowing comparisons that may indicate an increase or decrease in contaminants over time.
Fresh data, therefore, is not lacking for the true sardine. Even after so much anguish to find her during the scientific cruise. “After all the difficulty we had, when we got together so that each group of researchers could present their results, we understood that we had very relevant data”, celebrates the coordinator, Weigert.
Comments
Post a Comment