Wednesday, September 18, 2024

Where Did All the Crabs Go?

WTOP,  Claws and Effect: Who’s to blame for the blue crabs’ disappearance?

The seafood industry around the waters and tributaries of the Chesapeake Bay has seen better days, but it’s also had worse days. While things have rebounded to some degree in recent years, there are increasing concerns about what the future might hold.

Those concerns exist within the Maryland Department of Natural Resources, as well as on the boats used by watermen who harvest crabs by the bushel. It’s not just juvenile crabs that are disappearing, it’s the people who harvest the adult crabs, too. So while things are fine now, the future of the popular crustacean might be as murky as some of the muddy bottoms they traverse.

Earlier this year, the state of Maryland estimated the crab population in the bay to be around 317 million. In 2023, it was estimated to be around 323 million.

Adult crabs, both male and female, also saw population declines, with the adult female count falling from 152 million to 132 million. While it’s a significant drop, it’s still well above the 72.5 million that’s considered the minimum threshold to sustain the population.

The future of the crab population, the number of juvenile crabs, has been considered below average for the last four years. That’s baffling scientists.

“Technically, the population is fine,” said Mandy Bromilow, who is the blue crab program manager for the Maryland Department of Natural Resources. “It’s just that the concern that we have is where we’re seeing this sort of mismatch in the amount of females and the amount of juveniles.”

Right now, she doesn’t believe it’s because watermen are overharvesting the crab population. But that just means there’s a mystery lurking in the water.

“What should be adequate female numbers aren’t translating into the low or into higher juvenile abundance,” she said. “The trends that we’re seeing with low recruitment (the term used to describe the reproductive patterns of crabs), in particular, are a little bit concerning because we don’t know what’s causing that.”

But there are some theories.

When female crabs go to spawn, they travel from Maryland all the way down to around the mouth of the Chesapeake Bay. Their eggs are released and juveniles go through larval stages in coastal waters, then winds and ocean currents carry them back into the Chesapeake Bay, where they become juvenile crabs. Eventually, assuming they don’t end up in a bigger fish’s belly, they become adult crabs. But they can’t get there on their own. 

“If the weather patterns and storms push those juveniles or larval blue crabs out into the ocean, rather than into the bay, we’re sort of losing those blue crabs to our population (in the) Chesapeake Bay,” said Bromilow.

Similar concerns are held by Jason Ruth, who owns Harris Seafood Company, a processing facility in Grasonville. “A lot of going forward is based on environmental factors,” said Ruth. “If you have storms where the crabs are actually migrating to, if they’re migrating out in the ocean, do they come back into the Chesapeake Bay the following year?”Read Part 1 of “Claws and Effects”: The murky future of the Chesapeake blue crab

 

But he’s most worried about predators living in the waters with the crabs. “The biggest problem we have is invasive species that are eating up the crabs when they’re in their most vulnerable state,” said Ruth. “The blue catfish — it’s getting a lot of media attention right now, and it needs to, because it is a species that’s uncontrolled. Its population is rising rapidly and getting to a point that it’s going to cause some serious damage here in the near future.”

It’s one species of fish that scientists know likes to eat crab (as much as any group of friends with a picnic table and a cooler full of beer). But it still isn’t known how much of a problem the blue catfish presents.“We know that they’re eating juvenile blue crabs, or blue crabs in general,” said Bromilow. “We just don’t know how much. That’s kind of the issue where we don’t have enough data.”

There’s also concern that warming waters could make the Chesapeake Bay more inviting to other fish species like the red drum.

“We know puppy drum are in grass beds, eating juvenile blue crabs,” said Bromilow. “With the longer warm season, they might have more of an opportunity to be feeding on those juveniles.”
Are Chesapeake Bay crabs OK for now?

For now, those are all just theories shared by both scientists and at least some watermen — two sides that don’t always agree on everything. But currently, population levels are in a good place, and Ruth said what looked like a really dismal season at the start of the summer has really picked up.

So, it is weather, Blue Catfish or Redfish? Probably a bit of all of the above.  We are certainly having a good year for Redfish, and the Blue Catfish problem pretty well established. But it doesn't sound like the problem for crabs is especially severe yet. 

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