MICHIGAN — The Michigan Department of Natural Resources says more than 50 million fish have died from the state’s fish dieback in the last two years, as the number of fish-eating crabs in lakes and rivers has skyrocketed.DNR Fisheries Director Jeff Tarr says there are also more than 1.5 million dead crabs and fish.

“This year we are seeing more than 5.3 million crabs, which is nearly double the average annual crab population of 3.4 million,” Tarr said.

The dieback is affecting more than 3,000 lakes and 1,300 rivers, and the agency expects to harvest more than 8 million pounds of fish this summer.

Tarr called the dieback a “wake-up call” for the state.

The numbers come as a result of a statewide effort in which the DNR has deployed more than 100 million fish nets and about 1.6 million fish-killing traps in more than 300 waterways.

Tarr says the state is also working to control the spread of the algae that has infected lakes and reservoirs in the past two years.DNS spokesperson Stephanie Hinton says algae can be introduced to fish by runoff from sewage treatment plants and fish feedlots.

“Algae has been found in lakes all over the state,” she said.

“This year, we have found a significant amount of algal growth on some of our lakes, and we have seen the effects on the fish in our lakes.”

The DNR said the algae is mostly from commercial sewage treatment and feedlot wastewater, but some may have come from industrial waste ponds or fish ponds.

Hinton said the state does not know how much of the die-back is from algae.