Tuesday, June 25, 2019

Circular Study Finds Oyster Restoration Good for Fish, Crabs

The restoration of reefs in Maryland oyster sanctuaries may be unpopular with watermen, but a recent study predicts the effort will eventually yield a bonanza for the commercial seafood industry, with bigger harvests of blue crabs and white perch.

Ecological modeling done by Morgan State University’s Patuxent Environmental and Aquatic Research Laboratory in Calvert County projects an 80% increase in blue crab harvests and a 110% jump in white perch catch in the Choptank and Little Choptank river systems, where large-scale oyster restoration projects have been under way since 2011.

The Morgan study, underwritten by the National Fish and Wildlife Foundation and the National Oceanic and Atmospheric Administration, assumed that the restored oyster reefs will attract and support a diverse community of marine organisms, such as barnacles. Those, in turn, will draw crabs and finfish, which feed on them. “There are potentially large benefits to commercially valuable species from an enhanced food web in this area,” said Scott Knoche, the lab’s director.
White Perch
"The Morgan study . . . assumed that the restored oyster reefs will attract and support a diverse community of marine organisms, such as barnacles." So, in effect it assumed it's own conclusions. That's not science. That's propaganda, and what they were basically paid to find. I strongly suspect it's true, though.

While another computer modeling study last year found that the restored reefs in Harris Creek were helping to rid the water there of nutrient pollution, this is the first research into the potential economic impacts of large-scale oyster restoration. While oyster harvesting is prohibited in the sanctuaries where restoration took place, crabbing and fishing are still permitted.

Overall, the study concludes, increased harvests of all fish and shellfish could put extra money in watermen’s pockets, including an additional $4.5 million in dockside sales just from a more bountiful crab catch. That could boost the local economy as the additional income from seafood harvests is spent on goods and services in the region.

Maryland and Virginia have pledged to restore native oyster habitat and populations in a total of 10 Chesapeake Bay tributaries, five in each state. In Maryland, restoration work is complete in Harris Creek and partially done in the Tred Avon and Little Choptank rivers. When finished, those three projects are expected to restore 964 acres of reefs at a total cost of $72 million.
Yellow Perch
 But the usual suspects are unhappy.
The projects have drawn fire from watermen, who contend that they are ineffective and exorbitantly expensive. They have pressed the state to let them resume limited harvests in at least some sanctuaries.

It’s not clear how long watermen should have to wait before they can realize the increased crab and perch harvests. Tom Ihde, a Morgan research assistant professor and the study’s co-author, said it could be three to eight years after all restoration is completed before the effects of an increased marine food web start to materialize.
Striped Bass
Sounds a little long to me (a crab rarely survives 2 years, let alone three, but the fish take a little longer to grow to catchable size. At the same time, the amount of restored bottom is so small that the added benefit to the crab and fish population will likely be undetectable, except to local anglers and crabbers.
One factor could undermine the study’s projections: Watermen have complained that reefs built of stone in Harris Creek and the Tred Avon interfere with their use of trotlines to harvest crabs. Trotlining — deploying a heavy, baited line in the water — is the only allowable gear for commercial crabbing in Maryland’s tributaries.

“There’s things that we’re not able to account for,” Knoche said. “One of those challenges is the way fishers use their gear and how the different environment might affect the use of that gear.” He suggested that would warrant a further study.
Wombat has Rule 5 Sunday: Cheryl Ann Tweedy working toward your amusement and education.

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