New model links climate and fish giving managers earlier warnings

This finding opens a path toward more ecosystem-based fisheries management:

“Being able to look one year into the future gives managers a new tool,” says Ph. D. student Costanza Cappelli, DTU Aqua and explains:

“If we know in advance that recruitment will be low, advice and regulations can be adjusted sooner.”

“This could reduce the risk of sudden stock declines and the associated ecological and economic costs. That would also help to stabilize economic conditions and performance of  the fishery,” adds thesis main supervisor Prof. Brian MacKenzie, DTU Aqua. 

More skillful than current methods

The research team demonstrates how natural lags in the climate–ocean system can be used to forecast recruitment of blue whiting a full year ahead, and this kind of forecast outperforms the methods currently applied by ICES.

Blue whiting supports one of the largest fisheries in the North Atlantic and is a key species in the marine food web. Its recruitment has historically varied up to ten-fold between years, creating major challenges for forecasting.

But here, the new method proves itself to be more skillful than current methods by for instance identifying links between wind conditions, which likely affect currents and mixing processes, and the survival of young blue whiting life history stages in the northeast Atlantic.

Thus, the new model can help provide earlier warnings of deteriorating conditions for egg and larval survival and warn about strong or weak year classes, and its leadtime could be useful for making earlier decisions about fishery advice and fishing operations.

A step towards ecosystem-based management

With these results, fisheries advice could become more climate-informed, integrating new data streams from satellites, ocean models, and drifting buoys.

This would mark an important step towards ecosystem-based management of one of the Atlantic’s most valuable fish stocks.

Costanza Cappelli has presented these findings at two recent expert working group meetings of ICES responsible for the blue whiting assessment and forecasts.

They were interested in the results and will consider them further next year as part of a benchmark process to evaluate current and new methods for assessing and forecasting stock biomass and fishery yields.