California sea lion pups have been suffering for the last few years. Last year, a number of young sea lions stranded along beaches despite overwhelming rescue efforts. Researchers have been trying to understand why the sea lion population has been declining dramatically, and now they have reached a step closer to find the answer.

Researchers have discovered that emaciated young pups that were found washed ashore are in chaos because California sea lion mothers are not getting enough high-quality food, as per a study published Wednesday in the journal Royal Society Open Science.

Global warming has been considered as a major reason behind the California sea lion population decline, but the study indicated that lack of nutrition is contributing in the difficult conditions for the animal. The researchers didn’t find what exactly is bottoming out sea lion’s nutrition, but they predicted that good days are limited for sea lion pups due to food scarcity.

California sea lions’ population has been declining over the last few years, but in 2015 their condition reached epic proportions, as per the researchers. In first six months of the last year, about 3,000 emaciated young California sea lions washed up onto state beaches. By the end of 2015, over 4,200 strandings of California sea lions were reported by the Marine Mammal Center in Sausalito near San Francisco. It was the worst in last 40 years, said the center.

Scientists have been trying to understand why young sea lions are starving for a long time. The new study claimed that it has sufficient proofs to show that mother sea lions are not eating healthy food, which is resulting in poor health of pups.

The study has linked food to emaciated pups washed ashore, but some experts believe there could be several other factors that could be behind the steep decline in the critter’s population.