Rutgers Scientist Explains Fisheries Management in New Jersey

By PAT JOHNSON | Sep 16, 2015
Supplied Olaf Jensen sampling plankton on a research trip to Mongolia.

Olaf Jensen, assistant professor at Rutgers University’s Department of Marine and Coastal Sciences, is one member of the scientific community who helps decide how best to manage fish species in New Jersey as a member of the Mid-Atlantic Fishery Management Council's Scientific and Statistical Committee.

On Sept. 9, he was a guest lecturer at the Tuckerton Seaport as part of the Lunch n’ Learn series co-hosted by the Jacques Cousteau National Estuarine Research Reserve.

Jensen explained the challenges and difficulties in assessing dynamic fish populations. To put his audience of mostly recreational fishermen at ease, he told a funny story about a forester and a scientist having a conversation on numbers. “The forester says he goes out and counts the trees and makes a decision on how many he can cut down while still sustaining the forest. The fisheries manager says, ‘I do the same thing, except you can’t see the fish and they move.’”

Three fisheries that hold the most interest to recreational fisher-folk are summer flounder, black sea bass and striped bass. Jensen promised to discuss their numbers, but first he gave a little quiz and imparted some interesting facts:

He asked if the group could estimate how much the commercial fisheries dockside landings in New Jersey are worth. No one came close to the $150 million annual figure.

More facts: New Jersey has 1.2 million recreational fishermen and that industry is worth $1.6 billion in commerce annually to the state, counting boat and equipment sales.

“So you can see how important fisheries are to our coastal economy,” he said.

New Jersey ranks fourth in the nation in recreational fish landings and second in releases. According to Jensen, this means “we have abundant fisheries and an abundance of regulations in New Jersey.”

The New Jersey Department of Environmental Protections’ Division of Fish and Wildlife manages all freshwater fish species. The DEP’s Division of Fish and Game shares the responsibility of managing the estuarine and coastal fisheries with the Atlantic States Marine Fisheries Commission. Offshore three miles in federal waters and the National Marine Fisheries Service takes precedence, but all agencies work together to come up with a way to manage the taking of fish from the sea.

In addition, there are three state councils made up of stakeholders that serve advisory and oversight functions to the above. The Fish and Game Council established in 1945 has three farmers and six sportsmen on it. The Shellfisheries Council is the oldest, going back to the 1880s. In 1979, the Marine Fisheries Council was created.

Jensen tried to explain how the managers of fisheries arrive at the numbers that affect commercial and recreational fisher-folk in New Jersey.

“There is a maximum sustainable yield where fish are taken but can still sustain their numbers.

“The sweet spot is when you are catching the maximum sustainable yield. But again, you can’t see them and they move. So it is a process of trial and error. If you fish too much, then you dial it back. If taking 50 percent of the biomass is the maximum yield, then maybe 40 percent is a better number. It’s a trade-off. The harder we fish, the greater the risk of a collapsed species. In the U.S. most fishery management organizations now treat the maximum sustainable yield as a threshold that’s not to be exceeded rather than the target,” said Jensen.

“In 1976, Congress passed the Magnuson-Stevens Fishery Conservation and Management Act that claimed 200 nautical miles off the coast to be our exclusive economic zone. That kicked off the foreign ships.”

Most foreign countries followed suit in enacting exclusive economic zones.  A 2006 re-authorization of the act also required annual catch limits for each fished species, both commercial and recreational.

“And if a fishery goes over that number, then they have to essentially pay some of their quota back in the following years,” said Jensen. “The goal is to find the optimal yield. So we control how hard we are fishing a particular species, but then there are other factors, the weather and reproduction rates, so we really have limited control over the biomass.”

“The Magnuson-Stevens Act requires that fishery management decisions be based on the best available science and that it’s the job of the Scientific and Statistical Committee to advise the council on what constitutes ‘best available science.’ The SCC is a group that includes scientists from universities, three members from NOAA and one from private industry.

“Overfished stocks must be recovered within 10 years and this has put some strange pressure on summer flounder.

“The limit on summer flounder or fluke is extremely contentious in New Jersey,” noted Jensen. “In the late 1980s, the biomass hit bottom. The regulations were strict: There is a very short season and a lot of throwbacks for size. But it seems to have worked. Then around 2010-2011, scientists saw the biomass was not increasing fast enough so we saw regulations tighten and there was a total disconnect from what fishermen were seeing.  It was because they were trying to hit the 10-year target for rebuilding. The species was declared rebuilt three years ago, but this summer in July, the National Marine Fisheries Service updated the stock assessments and the numbers were worse than what was previously believed. The recommendation was to cut the fishing limit 43 percent for 2016, a decision that would prove devastating for fishermen in New Jersey. Charter boats rely on fluke fishing for their living. It would have been a huge economic hit.

“The Mid-Atlantic Fishery Management Council started receiving an enormous number of letters asking them to please reconsider. The SSC was asked to provide advice on a quota that would phase the cuts in over three years. The upshot was a 29 percent reduction for 2016, and that is still devastating to charter boats. This crisis in the fluke fishery is providing pressure for a rapid full update of the assessments for fluke, though it’s questionable whether it can be done before the fishing regulations are set for next year.”

Determining the amount of the black sea bass biomass and subsequently setting fishing limits has been made more difficult by the biology of that species. Black sea bass are “protogenous hermaphrodites,” said Jensen. “They start out as females and change sex,” he said.

Another problem with assessing the black sea bass stock is the way surveys are done. “Black sea bass hang around rocks and wrecks, and the trawlers doing the surveys go anywhere except hard structures because of their nets,” he explained. “Some bass do leave the structures in the spring and fall when they cross migrate from offshore to inshore (spring) and inshore to offshore in the fall.”

A three-year study by Rutgers that tagged 1,500 bass off Little Egg Harbor reef was successful. The sex of the fish was determined and a scale was removed to date the age of the fish. “Scales have rings like trees that can be used to age them,” said Jensen. The fish were then tagged and released, and instructions to fishermen to call Rutgers and receive a $100 reward were publicized. “We would get a call and send a grad student out to pick it up. One in three fish we tagged were returned,” he said.

“We found out that not all the fish started out life female, about a third of fish reproduce as males. But more make the sex change around four or five years, and at seven or eight years almost all were males. They were the bigger fish.

“Now don’t take offense,” Jensen said to his mostly-male audience. “But in the case of fish populations, males don’t matter very much in general. However, if a fishery is capturing mostly males, that has a potential to skew the sex ratio and eventually may reduce the fertilization of eggs.

“There is also some evidence that they can sense the sex ratio around them,” Jensen said. He related an experiment where a number of female fish were kept in a glass tank and a male fish was kept separate in a nearby glass tank where the females could see him. As long as they could see him, the fish remained female, but when the male tank was removed, one of the larger females became a male.

Jensen said there is no currently accepted stock assessment for black sea bass. “The stock assessment is difficult because there are so many uncertainties,” he said. “So what the SSC relies on is a ‘constant catch strategy.’ We use the median catch (numbers) over the past few years.”

And when climate change is added to the mix, the decision is even harder. “All of a sudden, black sea bass are being caught as far north as the Gulf of Maine.” But Jensen said when populations of a given species get larger they spread their range outward. “So it’s hard to separate. But few species of fish are moving southward; many are moving northward.”

Locally, southern species that local anglers are seeing for the first time are cobia and the invasive lionfish. “Lionfish are bad because they are a voracious predator.”

Fishing for striped bass was halted in the Mid-Atlantic in the 1980s when the fishery collapsed. Some states reopened a commercial fishery in 1990, but not all the states did so, including New Jersey. Carl Tarnow, a fisherman in the audience, said New Jersey actually closed commercial taking of striped bass in 1940 and never reopened it.

Jensen said commercial harvesting of striped bass in federal waters is prohibited.

Because of these conservation measures the numbers of striped bass have come up dramatically, he said.

“Globally, the good news is two-thirds of fishing stocks are sustainable, but two-thirds are below their target biomass. Historically we (the U.S.) have overfished, but we are currently managing well and should expect to see many of our fisheries recover.”

The top fish catches worldwide start with the small anchoveta, a fish used in pet foods and for Omega 3 supplements. Next comes Alaskan pollock, mainly used as fish sticks in chain food restaurants, and then blue whiting, skipjack tuna, yellowfin tuna, Atlantic herring, chub mackerel and Japanese anchovy.

Another fact: 2½ billion people, one-third of the global population, rely on fish for most of their protein.

How long can the world’s abundant fish continue to supply the demand? That depends on a very small animal, said Jensen.

“It’s estimated that the most fish we can harvest from the oceans on a sustainable basis is not much more than 100 million tons,” he said. “And that limit is fundamentally set by the abundance of plankton, which form the base of the marine food chain.”





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