Michelle Hunter, the center's director of operations and animal care, believes such poisoning caused the dolphins' deaths.
Domoic acid is a naturally occurring marine toxin produced by harmful algal blooms, according to the center.
Fish feed on the algal bloom, and when marine mammals eat the fish in mass quantities, the toxin affects them neurologically, sometimes fatally, such as Sunday's case.
The poisoning makes it hard for sick animals to breathe and swim, which results in them beaching to get rest, the center said.
Algal blooms are seasonal and typically happen around spring due to warmer ocean temperatures.
Although the center has seen an increase in dolphin cases, sea lions continue to be the majority of the mammals the center sees poisoned by domoic acid. Officials at the center believe this may be due to the fact that their gestation cycle correlates with the spring bloom cycles. The pregnant sea lions are consuming twice as much fish, sometimes doubling the toxicity level.