Population Dynamics Branch Archives

August 17, 2017 — NEW BEDFORD, Mass. — Diagrams, life-like statues and pictures fill the New Bedford Fishing Heritage Center to depict the history and future of the industry.

NOAA scientists and local fishermen filled the small building on Bethel Street on Wednesday night to discuss future stock assessments. The meeting, though, told another aspect in the story of the Port of New Bedford: the decades old tension that continues to exist between the groups.

“We all have to pull in the same direction,” Executive Director of New Bedford Seafood Consulting Jim Kendall said.

Instead a powerpoint presentation listing stock limits led to a discussion, which evolved into an argument and ended with two fishermen abruptly leaving. Russ Brown, director of the Population Dynamics Branch of NOAA, ended his presentation to meet with the fishermen outside. They spoke outside for 20 minutes before parting ways with a semblance of mutual respect.

“What we need to do is find common themes,” Brown said. “I’m a scientist. We want to find common themes within the science where we have questions and the industry has questions, and we can basically collaborate and pull in the same direction.”

Most of the discussion revolved around the methods in which NOAA is acquiring its data. Fishermen in attendance questioned the methods used by scientists to count groundfish. They also pointed out that years to correct a data point is too much time for an industry that continues to shrink.

“We understand that the management is affecting people and is having some serious consequences for our stakeholders who are depending on the resources,” Brown said. “We care about that, and we want to make sure the science is as accurate as it can be.”

Read the full story at the New Bedford Standard-Times

April 26, 2016 — A study by a group of researchers led by Dr. Andrew J. Pershing from the Gulf of Maine Research Institute appeared in Science last November (“Slow adaptation in the face of rapid warming leads to collapse of the Gulf of Maine cod fishery”). The Pershing study concluded that fisheries managers overseeing Gulf of Maine cod failed to consider ocean temperature in their management strategies, leading to overfishing of the stock. This week’s issue of Science published comments from two groups of scientists critiquing the Pershing study and its conclusions. In the same issue, the Pershing team responded with a defense of their work. Summaries of the comments and response are provided below:

A group of researchers at the Population Dynamics Branch of the Northeast Fisheries Science Center, led by Dr. Michael C. Palmer, argues that the Pershing study’s claim that rising temperatures led to “extra mortality” is unsubstantiated by the overall mortality data. While Palmer’s group agrees that environmental factors affect fish stocks, they argue that the Pershing study failed to attribute additional mortality to temperature alone. Consequently, they conclude, “The analyses of Pershing et al. provide no evidence to support the hypothesis that failure to account for increases in temperature led to overfishing of the Gulf of Maine Atlantic cod stock.”

Read the full comment at Science

A group of Canadian fishery scientists led by Dr. Douglas P. Swain from Fisheries and Oceans Canada argues that the Pershing study is based on a flawed analysis of the population dynamics of Gulf of Maine cod. They write that the Pershing model made inappropriate assumptions, and that the model should undergo simulation before being used to make management decisions. They also argue that the Pershing study failed to take into account other factors that may have affected the mortality rates of Gulf of Maine cod. They conclude, “It is necessary to reserve judgment on the role of climate change…until more defensible analyses are conducted to address this issue.”

Read the full comment at Science

The Pershing group published a response to these comments. They argue that including temperature-dependent mortality improves abundance estimates. Further, using this metric shows that warming waters reduces growth rates of Gulf of Maine cod. They conclude, “Our report did not claim to have a definite answer to what is causing cod mortality to increase. Rather, we claimed that this increase is real, that it is likely related to temperature, and that failing to account for it led to catch advice that allowed for overfishing.”

Read the full response at Science

Stock assessment meeting erupts into lively talk between NOAA, fishermen

NEFSC, Canadian scientists critique study claiming overfishing of Gulf of Maine cod