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December 23, 2013
Op-Ed

Northern Shrimp: first casualty of New England warming water?

by Ben Martens

On Dec. 3, regulators from the Atlantic States Marine Fisheries Commission met to review the latest stock assessment for Northern Shrimp (Pandalus borealis) and determine what the fishing season would look like for Maine fishermen. Everyone in the room was prepared for bad news after the small "do no harm" fishery of 2013. That resulted in landings of just 50 percent of the limited amount of shrimp, while rumors of a low stock assessment circulated the dock all summer.

Few, though, were prepared for presentation from the technical committee that ended with the frightening conclusion that the fishery had collapsed, that in the past three years there had been almost no recruitment—i.e., juveniles become adults—and the fishery needed to be shut down. The managers eventually agreed with the assessment, voting 3-0 to close the fishery

The shock of this decision will be felt along the coast for years to come.

Maine's traditional small boat fishermen are in trouble. Those in our struggling groundfish fishery have increasingly depended on shrimp to supplement their income in the winter months. For some of Maine's small-boat trawl fisherman, shrimp has made up almost 50 percent of their income in recent years and with the closing of this fishery any income from shrimp has been wiped off the books for 2014.

And the economic loss extends beyond those on the water.

The few remaining processing plants, shrimp peddlers and restaurants that feature Maine shrimp will feel this loss. Millions of dollars have been erased from Maine’s economy with no easy replacement.

Now fishermen, managers, and scientists are looking for answers.

Traditionally the shrimp fishery has followed a boom and bust population cycle. Over the last few years, Maine experienced a population boom period. Fishing of adult shrimp increased dramatically and the suggested catch was exceeded by 50 percent to 100 percent each of those years. After three years of high shrimp landings, it isn't unexpected that the population would shrink and that there would be a subsequent reduction in catch while the young of the population grow. However, a terrible unanticipated surprise in the 2013 stock assessment was that young shrimp are not present due to recruitment failure over the past three years.

Shrimp have a short lifespan, only living 5 or 6 years. They are hermaphroditic, maturing first as males at roughly two-and-a-half years and then transforming to females at about three-and-a-half years. This short lifespan means that we always need the next generation of shrimp growing in the ocean to ensure a strong resource and provide a balanced sex ratio. This has not happened the past three years.

The Atlantic States Marine Fisheries Commission did not close this fishery simply because the population was low, but more because we don't seem to have enough baby shrimp to build a future upon. It was determined by managers that to give this stock the best chance for recovery we needed to leave all the shrimp now in the water in the hope that they spawn and produce abundant offspring.

So what happened to the baby shrimp the past three years? While blame is often placed on the fishermen when stocks collapse, factors other than fishing effort are probably contributing to the lack of younger year classes showing up in the fishery.

The Gulf of Maine is the southernmost extent of the range for this cold water species and the water in the Gulf has been getting warmer since the 1960s (see graph). Shrimp require specific water temperature and chemistry during spawning and for larval shrimp survival. In the past, shrimp success has been lower during warm water events in the Gulf of Maine. It is possible that the warming trend in the Gulf of Maine is causing spawning events to not occur or to have very low survival rates for larval shrimp.  

So does this mean climate change and resulting rising ocean temperatures and increased water acidity is the end of shrimp in Maine? Tragically, the answer is maybe. But that doesn't mean we should abandon management options that could give the fishery a fighting chance.

Climate change is the elephant in the room when it comes to fisheries management. We all tip-toe around it, cite climate change when things don't turn out as expected, but don't really understand how to put those changes into models or think about how we should manage for anticipated changes.

Can we improve management and stock assessment models to anticipate good year classes of shrimp when we have cold winters and then preemptively slow the catch of shrimp when warmer winters arrive? Though the trends in ocean temperature and acidity are increasing, we will still have colder than average years that should give shrimp a chance to rebound in the future and provide a valuable resource for our fishermen.

We need to figure out how to provide the chance for a shrimp recovery while ensuring our coastal communities and fishermen can benefit from a well-managed ecosystem.

The world is changing quickly and fishermen are on the front-line in dealing with climate change. In Maine we have lobster, shrimp and cod all showing the impact that slightly warmer waters can have. Now is the time to figure out what we can do to help these species survive.

It is imperative that we begin talking about climate change and ocean acidification and recognize the profound impact they can have on our coastal resources. At the same time, the changing climate is not the universal scapegoat.

We also must remember that fishing effort and harvest rates directly impact the resources and must be managed appropriately for our changing world. Changes in the ecosystem are not an excuse to pass the buck on fisheries management. Losing the shrimp fishery this season is a devastating blow to Maine’s coastal communities, which with better management could have potentially been avoided. Hopefully we won't wait for this to happen again to shrimp or to other fisheries before we start having real discussions about incorporating changing climate into marine resource management.

Ben Martens is the executive director of the Maine Coast Fishermen's Association.

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