Overfishing has more impact than climate variations, study says

Fisheries that rely on short life species, such as shrimp or sardine, have been more affected by climate variations because this phenomenon affects chlorophyll production, which is vital for phytoplankton, the main food for both species.

That assessment comes from the research “Socioeconomic Impact of the global change over the fishing resources of the Mexican Pacific” headed by Ernesto A. Chávez Ortiz, from Mexico’s National Polytechnic Institute.

Work performed at the Interdisciplinary Center of Marine Sciences at the institute indicates that in the last five years there have been no spectacular changes attributable to climate variations. What has affected the fishing resources more is the high market demand.

“Globally, a great part of the fishing resources is being exploited to its maximum capacity. Several have passed over its regeneration capacities and are overexploited” Chávez Ortiz points out.

The specialist at the marine science center said that the research consisted in correlating weather and fisheries analysis. This confirmed what has been intuitively said for awhile: A lot of the variability in the fishing is due to climate change.

“In the research we found a clear and objective way to show it: We took historical data from FAO regarding fisheries, available since 1950, compared it to the data of weather variability and found high correlations.” FAO is the U.N. Food and Agricultural Organization.

Patterns of change were identified, he said. For example, while in the 70s the sardine production increases, in the 80s it decreases below average levels. Meanwhile shrimp fishing increased above average but decreased in the 90s.

This way, climate changes were identified in the mid 70s and late 80s that affected the fishing of sardine and shrimp in the Mexican Pacific Ocean, possibly attributable to El Niño.

In the particular case of the shrimp, the effects are related to an input of water from the continent.  When there’s a good rainy season, there will be an increase in the crustacean production, which is reduced when it doesn’t rain, he noted.

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