HomeOpinionShould the Lobster Fishery Worry About Warming Water?

Should the Lobster Fishery Worry About Warming Water?

While the quotas and resulting catch rates of many species across Atlantic Canada continue to decrease, the same cannot be said for the lobster industry in SW Nova.

In fact, the increase in lobster catches over the last 10 years has been unprecedented. The numbers do not lie.

Catches on both sides of the border have sustained an almost uninterrupted surge in abundance for more than a decade. By 2015, U.S. and Canadian harvests had nearly doubled — adding up to a combined volume of 157,000 metric tonnes (346 million pounds) with a value of (U.S.) $1.48 billion. In eastern Canada, lobster landings have increased from just over 54,000 metric tonnes in 2006 to nearly 93,000 metric tonnes in 2016.

During the 2006 fishing season in lobster fishing area (LFA) 33, a total of 3,032 metric tonnes was landed. This total increased to 5,296 metric tonnes in 2012 and exceeded the 10,000-metric tonne mark in 2016, with a similar pattern on the horizon for 2017 — once all of the landings are reported to the Department of Fisheries and Oceans.

A similar scene is being witnessed in the adjacent and larger LFA 34. Here, fisherman landed 18,795 metric tonnes in 2006. This number increased to 24,005 metric tonnes in 2012 and nearly reached the 30,000-metric tonnes mark in 2016.

So, what is the cause of this perceived lobster boom off the southwest shores of Nova Scotia? There are many theories of course, but one of the keys factors scientists speculate has to do with the warming of the oceans.

Global warming and resultant warming of the oceans is nothing new — water temperatures have been studied for years, but the amount of regional scientific effort into this field of study has increased substantially over the last few years.

The U.S.-based National Oceanic and Atmospheric Administration (NOAA) recently released a study into the Atlantic meridional overturning circulation (AMOC), a large-scale system of ocean currents that circulates warm, salty water from the south Atlantic and tropics via the Gulf Stream to the colder North Atlantic.

For years now, scientists on both sides of the border have been saying that rising levels of carbon dioxide in the atmosphere have affected one of the global ocean’s major circulation systems, slowing the redistribution of heat in the North Atlantic Ocean. The resulting changes have been felt along the Northeast U.S. Shelf and in the Gulf of Maine, which has warmed 99 per cent faster than the global ocean over the past 10 years, impacting distributions of fish and other species and their prey.

In a study published online in Nature, researchers from Europe and the U.S. used computer model simulations to reconstruct changes in the AMOC over time. Comparisons of these simulations with recent direct ocean measurements suggest the AMOC has slowed down or weakened by about 15 per cent since the 1950s.

“Our findings show that in recent years, the AMOC appears to have reached a new record low, consistent with the record low annual sea surface temperature in the sub-polar north Atlantic since observations began in 1870 and reported by NOAA for 2015,” the authors report. “The AMOC decline since the mid-20th century is a feature projected by climate models in response to rising carbon dioxide levels.”

“We found a characteristic sea surface temperature fingerprint for an AMOC slowdown or weakening in both a high-resolution global climate model and in temperature trends observed since 1870,” said Vincent Saba, a research fishery biologist at NOAA’s Northeast Fisheries Science Center and a co-author of the study.

“That fingerprint consists of a pattern of cooling in the North Atlantic Ocean’s subpolar gyre and a warming in the Gulf Stream region due to reduced northward heat transport and an associated northward shift in the Gulf Stream,” Saba said. “In other words, there is warming along the Northeast U.S. Shelf and Gulf Stream region and at the same time a cooling in the North Atlantic subpolar gyre.”

The rapid ocean warming observed along the Northeast U.S. Shelf may be associated with the Gulf Stream shifting northwards and closer to shore, a consequence of the AMOC slowdown. In NOAA’s high-resolution climate model, enhanced warming of ocean bottom temperatures in the Northeast U.S. Shelf and in the Gulf of Maine is a result of both a poleward retreat of the Labrador Current and a northward shift of the Gulf Stream.

So what impact will this continued warming have on the booming lobster fishery in this region?

Unfortunately, many in this region have witnessed firsthand how quickly fish populations can change and the dire economic circumstances that follow. In order to try and avoid another boom and bust scenario, science and industry must first understand the problem before solutions can be offered. Now is the time to face this issue head on — it can’t be left until harvesters start hauling up empty traps.