Our ecosystem is comprised of interdependent animals and plants which constitute a complex web of life. Unfortunately, the improper interventions of human beings in nature are pushing several of the species in the ecosystem to the brink of extinction. Many marine species including marine mammals, sea turtles and salmonids are also on the edge of extinction as climate change and over-fishing become a major threat to their existence.
One such marine species is the cod, which has long been a staple of the New England fishery. But this once-plentiful fish has declined in recent decades. Cod in the Gulf of Maine can be divided into two genetically-distinct groups. And according to a new study, understanding the unique behaviour and life cycles of these two groups may be the key to creating a better management strategy.
In the last decade, researchers have confirmed that the fish spawning in May and June are distinct from the fish spawning in November and December. But there hasn’t been a clear way to incorporate this information into management strategies.
“All stock assessment models have to make gross oversimplifications. But sometimes those simplifications can create inaccuracies,”
says Micah Dean, a doctoral student at Northeastern University’s Marine Science Center who led the study.
Dean and his colleagues set out to determine if ignoring any differences between the sub-populations could be leading to flawed management decisions. The researchers determined that they could tell the difference between spring-spawning cod and winter-spawning cod using a small structure inside the fish’s head, called an otolith.
“Gulf of Maine cod doesn’t have a great track record—the stock has been over-fished for decades and hasn’t responded well to the management actions that we’ve put in place,” Dean says. He hopes that more research and management strategies will help to uncover pieces that were missing when they were managing and assessing the stock in the past.