Fishing weirs and cooperative research with fishermen

Owen Nichols, Director, Marine Fisheries Research at the Provincetown Center for Coastal Studies talked with Rob on Moir’s Environmental Dialogues about working a fishing weir on the south side of Cape Cod.  Given a simplicity of design, that dates back at least two hundred years, with hickory poles set upright stringing large mesh nets, working the weir is surprisingly complicated with many lines to release and tie in just the right sequence.  The beauty is that at any time a portion of the net may be lowered to release non-targeted fish.  The result is a clean catch with nearly no bycatch.

By attaching recording devices to measure dissolved oxygen, temperature, and water clarity much is being learned about the shifting conditions for commercially valuable fish. Owen was surprised to see in late spring and summer the extent that blooming algae followed by decomposing algae consumed much of the oxygen in the water. This made it uninhabitable for fish. I was surprised to learn that squid suffer when the waters become too turbid and they can no longer see each other.  Learning the signs of falling dissolved oxygen levels, the onset of ocean dead zones, fishermen can better manage their fishing effort to be sustainable.

New England’s most valuable fishery, scallops, have benefited from cameras attached to the scallop dredges. What is actually happening is revealed when cameras are deployed.  Flounder, that settle into the sands to be inconspicuous, may be alerted to the on-coming dredge by a tickler chain that touches them to flee before they are captured. This opportunity to test a way to reduce bycatch came about only because fishermen worked in close collaboration with scientists.

Longfin squid are a favorite animal of Owen’s and the focus of his Ph.D. research at U Mass Dartmouth.  Squid egg masses are called mops because they resemble the tussled heads of floor mops.  Owen has caged egg masses found attached to the fish weir so he can observe hatching and early growth stages. It is not known, when squid mops are stripped off of their holdfasts by fishing gear, if they still hatch. With shifting shoaling sands making up much of the ocean floors of Nantucket Sound, it is not known how much squid masses need to be attached or whether they can survive the strong currents tumbling along with it.

The ocean is incredibly dynamic, influenced by many factors in unexpected ways.  As a result, fishing practices must be ecosystem-based and very adaptive to changing conditions for each population of fish or squid.  Today’s close collaborative work of fishermen with scientists is why America has the most sustainable fishery in the world.  Yet, we’ve still got much to learn and work to do.  And, if you see an egg mop on an ocean floor look for tiny infant squid.