Saving Seafood

Study finds existing forage fish management is working

July 9, 2021 — Efforts to ratchet down fishing effort on species like herring and menhaden in the name of “extra precautionary management” in most cases are unlikely to bring additional benefits for stocks of predator species that eat them, according to a new study.

“Our results indicate that predator productivity was rarely influenced by the abundance of their forage fish prey,” wrote authors Christopher Free of the University of California-Santa Barbara, Olaf Jensen of the University of Wisconsin-Madison, Ray Hilborn of the University of Washington. “Only 6 predator populations (13 percent of the total) were positively influenced by increasing prey abundance and the model exhibited high power to detect prey influences when they existed,” according to their paper titled “Evaluating impacts of forage fish abundance on marine predators,” originally published in the journal Conservation Biology.

“These results suggest that additional limitation of forage fish harvest to levels well below sustainable yields would rarely result in detectable increases in marine predator populations.”

The findings were released July 6 through the Science Center for Marine Fisheries, a cooperative effort to improve sustainability of fisheries and reduce uncertainty in biomass estimates with work by university partners led with the University of Southern Mississippi Virginia Institute of Marine Science, College of William and Mary, as academic sites.

“Our work suggests that the sustainable limits that we already employ are sufficient for maintaining forage fish abundance above the thresholds that are necessary for their predators,” Free of UC Santa Barbara in a statement describing the findings. “Predators are highly mobile, they have high diet flexibility, and they can go and look for forage fish in places where they’re doing well, switch species for species that are doing well, and have often evolved to breed in places where there’s high and stable forage fish abundance.”

Read the full story at National Fisherman

New Study: Precautionary Catch Limits on Forage Fish Unlikely to Benefit Predators

July 6, 2021 — The following was released by the Science Center for Marine Fisheries:

A newly released study finds that, for many predator species, extra-precautionary management of forage fish is unlikely to bring additional benefits. How to manage forage fish sustainably, both by themselves and for the rest of the ecosystem, has become a much-discussed topic in fisheries management, with regulators of several forage fisheries beginning to adopt precautionary strategies on the premise that they will better provide for the needs of predator species including seabirds, marine mammals, and fish.

The study, from Drs. Chris Free of the University of California-Santa Barbara, Olaf Jensen of the University of Wisconsin-Madison, and Ray Hilborn of the University of Washington, examines decades of historical abundance data of both forage species and their predators, and uses mathematical models to determine to what extent predator populations benefited from increasing abundance of their forage fish prey. Of the 45 predator populations examined, only 6, or 13 percent, were positively influenced by extra forage.

“Our work suggests that the sustainable limits that we already employ are sufficient for maintaining forage fish abundance above the thresholds that are necessary for their predators,” said Dr. Free. “Predators are highly mobile, they have high diet flexibility, and they can go and look for forage fish in places where they’re doing well, switch species for species that are doing well, and have often evolved to breed in places where there’s high and stable forage fish abundance.”

The results have important implications for how strictly to manage forage fisheries. The study finds that, at least in forage fisheries that are already being well managed and are closely monitored, adopting additional precautionary measures will “rarely” provide any additional benefits to predator population growth. However, fishery managers who deal with less well-monitored fisheries may consider more precautionary strategies.

“In places of the world where we already have really strong, very effective fisheries management, additional limitations on forage fish catch are not likely to benefit their predators,” said Dr. Free.

“Management of forage fish populations should be based on data that are specific to that forage fish, and to their predators,” said Dr. Jensen. “When there aren’t sufficient data to conduct a population-specific analysis, it’s reasonable to manage forage fish populations for maximum sustainable yield, as we would other fish populations under the Magnuson-Stevens Act.”

According to the models used in the study, other environmental factors, such as water temperature, are more likely to influence predator populations. These results are consistent with previous efforts to examine the relationship between predator and prey populations.

“What we’ve done here that’s different from previous analyses is try to control for some of the other factors that influence predator population dynamics,” said Dr. Jensen. “In this case, we included in the models a covariate representing ocean temperature.”

SCEMFIS produced a video of the authors and independent experts discussing the results of the paper. Watch it here.

Read the full release here

Webinar Invite: New Research to Identify Climate-vulnerable Stock Assessments

January 26, 2021 — The following was released by Lenfest Ocean Program:

Please join us on Friday, January 29, at 1pm ET for a webinar on “New Research to Identify Climate-vulnerable Stock Assessments”. The webinar will be recorded. Please do forward this invite to other colleagues who may be interested. Webinar registration and project details are below.

Project Background

Regional Fisheries Management Councils rely on stock assessments to help set catch limits. However, climate change can impact the ability to accurately assess a fish stock. For example, it can change a fish stock’s recruitment and natural mortality rates, a species’ range and distribution, and overall stock productivity. In order to support long-term sustainable fisheries management, there is a need to understand which stock assessments are at greatest risk from climate change and how to integrate risk into the stock assessment process. The Lenfest Ocean Program is supporting Dr. Olaf Jensen, University of Wisconsin, to lead a team of researchers to identify and prioritize fish and invertebrate populations that are at greatest risk of stock assessment failure due to climate change.

This project is an outcome of the Lenfest Ocean Program Ideas Lab, a workshop held in October 2019 to identify research priorities for shifting marine species. Learn more here.

Register for the webinar here.

Learn more about the project on our website.

Research Team

  • Olaf Jensen, University of Wisconsin- Madison
  • John Weidenmann, Rutgers University
  • Chip Collier, South Atlantic Fisheries Management Council
  • Roger Mann, Virginia Institute of Marine Science
  • Kathy Mills, Gulf of Maine Research Institute
  • Vince Saba, NOAA Fisheries
  • Rujia Bi, University of Wisconsin

More management measures lead to healthier fish populations

January 12, 2021 — The study, led by Michael Melnychuk of the University of Washington’s School of Aquatic and Fishery Sciences, draws upon the expertise of more than two dozen researchers from 17 regions around the world. The research team analyzed the management practices of nearly 300 fish populations to tease out patterns that lead to healthier fisheries across different locations. Their findings confirmed, through extensive data analysis, what many researchers have argued for several years.

“In general, we found that more management attention devoted to fisheries is leading to better outcomes for fish and shellfish populations,” Melnychuk said. “While this won’t be surprising to some, the novelty of this work was in assembling the data required and then using statistical tools to reveal this pattern across hundreds of marine populations.”

The research team used an international database that is the go-to scientific resource on the status of more than 600 individual fish populations They chose to analyze 288 populations that generally are of value economically and represent a diversity of species and regions. They then looked over time at each fish population’s management practices and were able to draw these conclusions:

  • In regions of the world where fish and shellfish populations are well studied, overall fisheries management intensity has steadily increased over the past half century
  • As fisheries management measures are implemented, fishing pressure is usually reduced toward sustainable levels, and population abundance usually increases toward healthy targets
  • If fish populations become depleted as a result of overfishing, a rebuilding plan may be implemented. These plans tend to immediately decrease fishing pressure and allow populations to recover
  • If strong fisheries management systems are put in place early enough, then overfishing can be avoided and large, sustainable catches can be harvested annually, rendering emergency measures like rebuilding plans unnecessary

Read the full story at Science Daily

Black seabass terrorizing New England’s lobsters

March 14, 2019 — Black seabass — a saltwater fish that previously was rarely taken commercially and recreationally in Massachusetts, US, or other parts of southern New England — have increased in number there and are rattling the lobster industry, reports the MV Times, a local news service.

They’re eating the younger, smaller crustaceans, in particular, and maiming the larger ones they can’t fit in their mouths.

“They feed aggressively,” Rutgers University marine biologist Olaf Jensen is quoted as saying. “They’re not picky eaters. If it’s the right size and it’s alive, they’ll eat it.”

Read the full story at Undercurrent News

Black sea bass gobbling up lobsters

March 12, 2019 — Black sea bass, a saltwater fish taken commercially and recreationally in Massachusetts, have increased in number throughout southern New England waters and rattled the lobster industry with their wolfish appetites.

“They feed aggressively,” Rutgers University marine biologist Olaf Jensen said. “They’re not picky eaters. If it’s the right size and it’s alive, they’ll eat it.”

The young of New England’s iconic crustacean fall into the right size category. “Black sea bass love little lobsters,” Michael Armstrong, assistant director of the Massachusetts Division of Marine Fisheries, said.

That’s of deep concern to Beth Casoni, president of the Massachusetts Lobstermen’s Association, who says lobster traps are being pillaged by these fish. They are often hauled up with the bass inside the traps, alongside lobsters they couldn’t fit in their mouths, she said. Even more concerning to Casoni is their alleged habit of picking off undersize lobsters tossed overboard by lobstermen.

Read the full story at The Martha’s Vineyard Times 

Authors of Recent Research on Forage Fish Respond to Criticism from Lenfest Task Force

WASHINGTON – September 20, 2017 – In April, a team of respected fisheries scientists led by Dr. Ray Hilborn published a study that found fishing of forage species likely has a lower impact on predators than previously thought. This conclusion challenged previous forage fish research, most notably the 2012 Lenfest Oceans Program report “Little Fish, Big Impact,” which recommended leaving more forage fish in the water to be eaten by predators.

The Lenfest task force responded to this new research with a Letter to the Editor of Fisheries Research, where the Hilborn et al. study was published. In response to this letter, Hilborn et al. wrote their own letter, which was published August 5 in Fisheries Research and is reproduced below:

Our paper highlighted that key biological relationships between forage fish and their predators were not included in the models used in the LENFEST report. These missing elements were (1) the high level of natural variability of forage fish, (2) the weak relationship between forage fish spawning stock size and recruitment and the role of environmental productivity regimes, (3) the size distribution of forage fish, their predators and subsequent size selective predation and (4) the changes in spatial distribution of the forage fish as it influences the reproductive success of predators. We demonstrate that each of these elements can have a major impact on how one evaluates the impact of fishing forage species on their predators. The LENFEST report used EwE models without these factors to determine the very specific recommendations they made about how to manage forage fish.

We certainly agree that in some cases fishing forage fish will affect their predators, but in other cases there may be little if any impact – it all depends on the biology that was not included in the models used.

This critique of our paper suggests that we are offering alternative evaluation of the impact of fishing forage fish that are, like the LENFEST recommendations, broadly applicable. We make no such claim and much of their critique is against the straw man they have constructed. We are not arguing that fishing forage fish does not affect predators. Rather we show how, in specific cases, there may be little if any impact of fishing forage fish and that general conclusions simply are not possible.

We suggest that the very specific quantitative measures proposed in the LENFEST report result from models that do not have these components and that if these elements were included in the models the conclusions would likely be different. While the authors of the letter argue that they conducted a comprehensive literature review, the specific recommendations came from their modelling, and it is the modelling we criticize and their critique makes few attempts to defend.

We stated “Pikitch et al. (2012) argued forcefully that their analysis provided general conclusions that should be broadly applied. However, relevant factors are missing from the analysis contained in their work…” Their response is that their recommendations were “tailored to the level of uncertainty and data availability of each system.” What we refer as “general conclusions” contain a set of recommendations for three uncertainty tiers, but our point is that the biology of each system is different, not the availability of data or uncertainty, and the differences in biology should be considered when evaluating management options for forage fisheries.

The specificity of their recommendations is clear – for high information situations (which would include the California Current, Humboldt Current, NE Atlantic sand eel and herring) their recommendation is “In any case, lower biomass limits should not be less than 0.3 B0, an MAX F should not exceed 0.75 FMSY or 0.75 M.” These numbers are not the result of their case studies or literature review but the result of their models that did not include a number of important elements.

Finally, we agree that situations where detailed information is lacking are challenging for management, and that is why it is important to identify species and system attributes that make systems less resilient to fishing. Low trophic level species constitute the largest potential sources of increased fish production in the world and much of the recent suggestions for “balanced harvesting” relies on significant increases in exploitation rates on trophic levels associated with forage fish. Since almost all of these potential low trophic level species would be considered in the “low information tier” the LENFEST recommendation is that new fisheries not be allowed until sufficient data are collected. Given that few countries will devote resources to research on fisheries that do not exist, the LENFEST recommendation essentially says no new fisheries on these species, and thus in effect precludes development of what may be significant food resources.

We believe the authors of our paper and the LENFEST report all accept that in some cases predators may be highly dependent on forage fish, but in other cases there may be little dependence. Management should be based upon what is known about the dependence of the predators on forage fish and the relative importance the local agencies place on maintaining high predator abundance verses the benefits of full exploitation of the forage fish. The major forage fisheries of the world are very valuable and currently intensively studied. What is needed for each of these fisheries is a new set of models that incorporate the elements that were missing from the LENFEST analysis.

Ray Hilborn, Ricardo O. Amoroso, Eugenia Bogazzi, Olaf P. Jensen, Ana M. Parma, Cody Szuwalski, Carl J. Walters

Predators may be less affected by catch of small fish than previously thought, new study says

April 3, 2017 — WASHINGTON — The following was released by the National Coalition for Fishing Communities and IFFO: 

New research published today in the journal Fisheries Research finds that fishing of forage species likely has a lower impact on predators than previously thought, challenging previous studies that argued forage fish are more valuable left in the ocean.

A team of seven respected fisheries scientists, led by Prof. Ray Hilborn, Ph.D., of the University of Washington, found that predator populations are less dependent on specific forage fish species than assumed in previous studies, most prominently in a 2012 study commissioned by the Lenfest Ocean Program, which is managed by The Pew Charitable Trusts. The Lenfest Forage Fish Task Force argued that forage fish are twice as valuable when left in the water to be eaten by predators, and recommended slashing forage fish catch rates by 50 to 80 percent.

 For fisheries management, such a precautionary approach would have a large impact on the productivity of forage fisheries. As groups such as IFFO (The Marine Ingredients Organisation) have noted, these stocks contribute strongly to global food security, as well as local and regional social and economic sustainability.

 However, the new research found multiple omissions in the methodology of the Lenfest study. “When you review the actual models that were used [by Lenfest], there are a few key elements on the biology of these animals that were not represented,” said Dr. Ricardo Amoroso, one of the study’s co-authors. He added that one of the authors’ approaches was to “look for empirical evidence of what is actually happening in the field.” Previous studies relied on models which took for granted that there should be a strong link between predators and prey.

 Specifically, the Lenfest study and another study using ecosystem models ignored the natural variability of forage fish, which often fluctuate greatly in abundance from year to year. It also failed to account for the fact that predators tend to eat smaller forage fish that are largely untouched by fishermen. Because of these oversights, the new study concluded that the Lenfest recommendations were overly broad, and that fisheries managers should consider forage species on a case-by-case basis to ensure sound management.

 “It is vital that we manage our fisheries to balance the needs of the ecosystem, human nutrition and coastal communities,” said Andrew Mallison, IFFO Director General. “These findings give fishery managers guidance based on science, and update some of the inaccurate conclusions of previous reports.”

 The Lenfest findings were largely based on a model called EcoSim, developed by Dr. Carl J. Walters, one of the co-authors of the new paper. Dr. Walters found that the EcoSim models used in earlier studies had omitted important factors, including natural variability, recruitment limitations and efficient foraging of predators.

Dr. Walters noted that there were “very specific” issues with previous uses of the EcoSim model. “It was predicting much higher sensitivity of creatures at the top of the food webs to fishing down at the bottom than we could see in historical data,” he said.

This is not the first time ecosystem models used in earlier studies have been questioned. One year after the Lenfest study was completed, two of its authors, Dr. Tim Essington and Dr. Éva Plagányi, published a paper in the ICES Journal of Marine Science where they said, “We find that the depth and breadth with which predator species are represented are commonly insufficient for evaluating sensitivities of predator populations to forage fish depletion.” The new study reaffirmed this finding, noting “several reasons to concur with the conclusion that the models used in previous analysis were insufficient.”

In addition to its critiques of previous research, the researchers found further evidence of the lack of fishing impact on forage fish. Their research indicated that environmental factors are often much more important drivers of forage fish abundance. They also found that the distribution of forage fish has a greater impact on predators than simply the raw abundance of forage fish. 

The authors concluded by noting the importance of forage fish as a part of human food supply chains, praising their high nutritional value, both through direct human consumption and as food in aquaculture, as well as the low environmental impact of forage fishing. Cutting forage fishing, as recommended by the Lenfest group, would force people to look elsewhere for the healthy protein and micronutrients provided by forage fish – likely at much greater environmental cost, the authors wrote.

“Forage fish provide some of the lowest environmental cost food in the world – low carbon footprint, no water use,” Dr. Hilborn said. “[There are] lots of reasons that forage fish are a really environmentally friendly form of food.”

It is also well-established that forage fisheries provide substantial health benefits to human populations through the supply of long chain omega-3 fatty acids, both directly through consumption in the form of fish oil capsules, and indirectly through animal feed for farmed fish and land animals. 

The paper was authored by Dr. Ray Hilborn, Dr. Ricardo O. Amoroso, and Dr. Eugenia Bogazzi from the University of Washington; Dr. Olaf P. Jensen from Rutgers University; Dr. Ana M. Parma from Center for the Study of Marine Systems -CONICET, Argentina; Dr. Cody Szuwalski from the University of California Santa Barbara; and Dr. Carl J. Walters from the University of British Columbia.

Read the full study here

Watch a video about the study here

Read an infographic about the study here

About the NCFC

The National Coalition for Fishing Communities provides a national voice and a consistent, reliable presence for fisheries in the nation’s capital and in national media. Comprised of fishing organizations, associations, and businesses from around the country, the NCFC helps ensure sound fisheries policies by integrating community needs with conservation values, leading with the best science, and connecting coalition members to issues and events of importance. For more, visit www.fisheriescoalition.org.

About IFFO

IFFO represents the marine ingredients industry worldwide. IFFO’s members reside in more than 50 countries, account for over 50% of world production and 75% of the fishmeal and fish oil traded worldwide. Approximately 5 million tonnes of fishmeal are produced each year globally, together with 1 million tonnes of fish oil. IFFO’s headquarters are located in London in the United Kingdom and it also has offices in Lima, Peru, and in Beijing, China. IFFO is an accredited Observer to the UN Food and Agriculture Organisation (FAO). To find out more, visit www.iffo.net.

PRESS CONTACT

Robert Vanasse

National Coalition for Fishing Communities

Washington

+1 (202) 333-2628

bob@savingseafood.org

Georgie Harris

IFFO, The Marine Ingredients Organisation

London

+44 (0) 2030 539 195

gharris@iffo.net

Rutgers Scientist Explains Fisheries Management in New Jersey

September 16, 2015 — 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.

Read the full story at The Sandpaper