A study conducted by the Zoological Society of London and WWF has revealed that in the past four decades Mackerel and Tuna populations have undergone a disastrous decline of almost three quarters.

The numbers put up by the two bodies suggest that between 1970 and 2012, there has been a 74% decrease in the populations of fish belonging to the scombridae family; it’s the fish family of which bonito is a part. During the same period, there has been a 49% drop in the populations of 1,234 ocean species.

According to the conservation charity, if drastic action is not taken for preventing overfishing and ending other threats to life in the ocean, this decline might eventually lead to loss of ocean species critical to our food security.

Louise Heaps, WWF UK’s chief advisor on marine policy and one of the coauthors of this joint study, described these latest findings are catastrophic and said that by harming marine species we are actually disrupting oceans’ ecology and destroying vital food sources.

Studies conducted in the past few years have focused on ocean species like bluefin tuna, which is right now on the threshold of extinction. However, other relatives of this species, for instance, albacore and yellowtail tuna, which are mostly served in restaurants and sold in tins, are also gradually becoming extremely rare. The one species that is demonstrating amazing resilience against all odds is skipjack. This marine species is also sold in tins in several parts of the world.

Another marine species that is currently suffering significant decline is a sea cucumber. Sea cucumbers are served in Asian restaurants as a luxury food. The number of sea cucumbers has decreased by 94% in the Egyptian Red Sea and by 98% in the Galapagos. There has also been a decline in the populations of leatherback turtles, another endangered species found in the UK waters.

Here, it must be pointed out that overfishing is not the only factor responsible for the decline in the populations of different marine species. Other prominent factors triggering the decline include: pollution (particularly plastic detritus that accumulate in digestive system of fish), climate change (oceans are becoming more acidic due to increase in the level of CO2 in the atmosphere), and key habitat loss (for instance, loss of coastal mangrove swamps).