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Despite the reduction in the hake biomass over the years due to fishing, the larvae survival rate grew aided by sea warming. This is one of the main findings of an investigation by Nerea Goikoetxea, from the fishing laboratory Azti-Tecnalia.
The aim of this study was to analyze the population dynamics of the hake in the North and to determine why this species that is captured permanently in European Atlantic waters was able to survive while other species, such as the anchovy or the bonito from the North, are in trouble.
The research showed that since the '90s until today, the sea has been getting warmer, which has made larvae grow better and faster.
The environment allowed the increased survival rate of larvae despite the decline in biomass owing to fishing pressures and allowed one generation to give way to another one.
The study is part of the thesis that Goikoetxea presented at the University of the Basque Country, which examines the influence of oceanic-meteorological variability of the northeast Atlantic on the Northern hake (Merluccius merluccius) stock during the period between 1978 and 2006.
Her research shows that, especially between 1985 and 1990, the adult hake population was reduced considerably, probably due to excessive fishing.
However, during the '90s more young hake larvae specimens survived into adult specimens because there was an ecological scheme change that tempered the waters inhabited by this species.
The paper explains that the warming process occurred between the late '80s to mid '90s.
The scientist’s thesis explains that the rise in water temperature causes the period and space for egg laying to extend so the number of specimens surviving is higher and as the larvae grow faster in warm temperatures, its period of vulnerability is reduced and is more likely to survive.
Nerea Goikoetxea concluded that although the factors related to population density, such as fishing and the impact it has on the hake stock at fertilization age are important, there are other factors such as environment conditions, wind transport, the temperature anomalies in the northern hemisphere and the amount of food available during the egg laying period that also affect the number of adult hake specimens.
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