New DFO Study: Season Length Beats Trap Cuts for Managing Lobster Stocks

Small reductions to trap limits probably won't move the needle — but when the season runs might, according to new federal research on lobster fisheries in Nova Scotia and southern New Brunswick.

A new study from Fisheries and Oceans Canada (DFO) is giving harvesters and managers a clearer picture of which tools actually work when it comes to protecting lobster stocks — and which ones sound good on paper but don't do much in the water.

The bottom line: season length is one of the most effective levers DFO tested. Trimming trap limits by a small amount is not.

What the study looked at

DFO researchers modeled and simulated a range of management measures across lobster fishing areas (LFAs) 27 to 38 — a stretch that runs from northern Cape Breton down the Atlantic coast of Nova Scotia and into the Bay of Fundy. The team looked at fishing seasons, trap limits, and other controls, and factored in changing water temperatures, something a lot of the current rules were never designed around.

Adam Cook, a DFO scientist and co-lead on the report, told CBC News that many of today's management measures have been in place for years. This research is about updating the science behind them.

"Lobster fisheries are still considered healthy in Canadian waters," Cook said. "We still are well above long-term averages for the majority of our stock status indicators. So we're trying to provide information so people can be thinking about and be prepared for if and when changes occur."

To be clear: DFO isn't changing any rules based on this study alone. The department says the findings are meant to inform potential adjustments down the road, if industry asks for them or if stock status makes them necessary.

Why season timing matters more than people might think

Lobster behavior and biology track closely with water temperature — colder water means less activity, which affects catch rates, growth, and molting cycles. That's part of why the study flagged season length as such a reliable tool: shortening or shifting a season "reliably reduces exploitation, injury, and incidental mortality."

Cook pointed to how tight some current windows already are. "A fishery that starts in March or April and goes to June or July, that's quite a short window," he told CBC News. "So if you're thinking about shifting that fishery, you may want to think about shifting away from the summer months. The summer months are typically when they're molting, typically when they're mating."

Trap limits: bigger cuts, bigger tradeoffs

If you're hoping a modest trap reduction will meaningfully protect the stock, the study suggests otherwise. Small cuts to trap allowances aren't likely to have much impact on exploitation. Getting a real effect would take a much larger reduction — and that comes with real economic and operational costs for harvesters.

As the report puts it: "The effectiveness of trap limits depends on their scale and must be considered alongside harvester behavior and local fishery conditions."

Protecting the big females

The study also looked at longer-term measures aimed at protecting large, reproductive females — maximum size limits and v-notching. V-notching is exactly what it sounds like: harvesters clip a small notch in the tail of an egg-bearing female before releasing her, so other harvesters know to let her go if she turns up in their traps.

DFO's take: "Strategically chosen maximum size limits and v-notching programs are slow-acting measures that protect large, highly fecund females."

No one-size-fits-all answer

Cook was clear that there's no single approach that works across every LFA studied — conservation in these fisheries usually comes down to combining measures rather than leaning on just one.

Bernie Berry, senior fisheries adviser with the Coldwater Lobster Association in Yarmouth, observed the study and said this kind of research gives the industry something concrete to work with as conditions on the water keep shifting.

"I think it's over time, more knowledge helps to critique and gives you more information on the effects of a particular harvest-control rule that was introduced into a fishery," Berry told CBC News.

original story - https://www.globalseafood.org/advocate/dfo-canada-season-length-a-key-tool-for-managing-maritime-lobster-fisheries/