(fis.com) Two researchers at the National Oceanic and Atmospheric Administration's (NOAA) Southwest Fisheries Science Centre claim that the sardine population decreases in northeast Pacific Ocean and is heading for a collapse similar to that which affected catches of the resource in recent decades in Chilean and Japanese waters.
According to a research led by John P. Zwolinski, a graduate of the Faculty of Agronomy in Lisbon and Ph.D. from the University Aveiro (Portugal), there is a combination of unfavourable environmental conditions and inappropriate fishing practices that lead to the decline in catches of the pelagic resource in the area.
"The oceanographic conditions in the region have changed into a colder period", say Zwolinski and his colleague David Demer in an article published in the journal Proceedings of the National Academy of Sciences.
"The biomass of Pacific sardine (Sardinops sagax) has declined precipitously in the Californian Current, where the international sardine catch is falling, and jack mackerel (Trachurus symmetricus) and Pacific mackerel (Scomber japonicus) are growing", added the expert.
In their study, they also point out that the Chilean sardine population peaked in 1985 and then fell rapidly. And note that sardine catches by Japanese fishermen peaked in 1988 and then they also dropped very fast.
The lower abundance of sardine coincides with a greater presence of mackerel, EFE reports.
"It is also alarming the repetition of the response of fisheries to the decline in the sardine population: progressive higher rates of exploitation, which include the capture of mature fish, large and fertile", went on saying the scientists in the article.
For the experts, the high exploitation rates coincide with a reduction of the sardine migrant population. And this could decrease the ability of the sardine to reproduce and adapt to changing environmental conditions.
The researchers argue that the recent reproductive condition of sardines is bad and productivity "is below the estimates used to determine the current rate of fisheries exploitation on the ecosystem of the Californian Current."
"A short-term recovery of this important population is unlikely, depending on the return of warmer oceanographic conditions, less pressure of the species of mackerel, and perhaps adopting a more cautious strategy for managing the residual population of sardines" , Zwolinski and Demer added.
Meanwhile, Boris Worm of Dalhousie University in Halifax, Canada, said that this fishery "is still important today, not only for individuals but also for the large number of whales, seabirds and fish predators that rely of that population”, Science News reported.
The researcher also explained that there is hope for the future of the sardine, and that today we have better technology and more knowledge to monitor the health of this population, compared with those available the 1950s.
Worm admitted that there is a need to consider whether population of sardines will be kept or let collapse.