A Conversation with Olaf Jensen


Olaf Jensen is an Assistant Professor at Rutgers University Department of Marine & Coastal Sciences. His areas of expertise include fisheries stock assessment and comparison of global fishery management methods. He views a ‘fishery’ as being composed not just of the target species itself, but rather a social-ecological system including the wild-caught species, the fishermen who catch them, the processors and distributors who sell them, and the managers regulating the fishery. Olaf is a member of the Mid-Atlantic Fishery Management Council’s Scientific and Statistical Committee as well as the Lenfest Fishery Ecosystem Taskforce, and is Co-chief Science Editor of Fisheries.

The Status of U.S. Fish Stocks

We spoke with Olaf Jensen of Rutgers University Department of Marine and Coastal Sciences about the NOAA report on status of U.S. fisheries released in mid-April. “I think the latest status of stocks report shows that the successful rebuilding plans have really been paying off in terms of bringing our fisheries back into sustainability in the US” (00:48), he says. Olaf attributes this success to the Magnuson-Stevens Act (MSA) requiring rebuilding of overfished stocks within specific timelines. “Those timelines have been somewhat controversial because they require the rebuilding to happen in a certain amount of time, and the only lever that fisheries managers have access to is the amount of fishing pressure” (01:40). In other words, this means telling fishermen to catch less fish in order to reduce fishing effort and thus allow stocks to rebuild. “A paper I published in 2013 looked at the patterns of recovery of fish stocks and found that in general, almost all fish stocks from which we’ve reduced fishing mortality rates sufficiently have been able to recover. There are very few exceptions to that rule” (02:13).

He finds this result encouraging. “What that means is there is room to learn about fisheries, to develop fisheries without fear that we are going to immediately push them off the edge, past the point of no return. Our analysis found no sign of a point of no return, and in fact, the biggest predictor of recovery was simply whether fishing mortality rates were reduced sufficiently. So, to a large extent we’re masters of our own destiny with recovery of fish stocks” (02:40). In short, Olaf claims the U.S. has been able to recover overfished stocks through “serious reductions in fishery mortality rates.” One example is summer flounder in the mid-Atlantic region. Regulations such as restrictions on fishing seasons and size limits reduced fishing mortality rates, allowing that fish stock to recover from a very low abundance observed in the early 1990s.

Olaf also highlighted the importance of setting a total allowable catch (TAC). “Having management that’s based on outputs, like a TAC, rather than trying to simply control effort has shown itself to be a more successful approach. It’s not always possible in all fisheries to implement output-controls, but where it is possible to implement a TAC, you see much better results” (05:05). He says he and his colleagues have shown empirically that “stocks for which there is a TAC perform better than stocks for which there is only effort control” (06:10). One of the reasons controlling outputs (such as with a TAC) is more successful is because “there’s a lot of implementation uncertainty when it comes to effort control, whereas if you have relatively accurate stock assessments that allow you to determine the TAC, and you have a management mechanism for enforcing the TAC as an output control, it allows you much greater precision in managing the fishery” (06:58).

Olaf highlighted the division between science and management as being another contributing factor to the successful rebuilding of stocks. “In the U.S., established scientific and statistical committees act as the scientific arbiters of the allowable biological catch (ABC)” (08:45). This sound science then feeds into the MSA; strong national-level legislation which both legally requires stock rebuilding and “prohibits setting the TAC at a level higher than MSY” (08:10).

Recovery of fish stocks has not been a painless process, however. “The ultimate reason why fish stocks have recovered is because fishermen have been willing to reduce fishing mortality in the short-term with the promise of longer term benefits. They are the ones that have paid the price of rebuilding, and for some of them that has been a steep price indeed. We’ve seen many fishermen going out of business, so that’s a very high price for that rebuilding” (09:20).

What does this mean for the future of fisheries management? The recent report on the status of U.S. stocks “shows that recovery is possible for most stocks, and we shouldn’t give up those goals of recovering them to their MSY levels” (10:30).

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