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Has the status of fish stocks changed?

Indicators: Biomass | Fishing Mortality

Key Findings

  • Average biomass (B/BMSY) decreased 20.4 percent during the baseline period, with an eventual slight 1.2 percent increase following implementation of the Northeast Multispecies Sector Program.
  • The proportion of stocks with depleted biomass (B<0.5BMSY) has increased from 27 percent to 53 percent of assessed stocks since the start of the extended baseline period.
  • Biomass changes have been variable across stocks, with some experiencing increases in biomass, other decreasing biomass and some unchanged.
  • Several stocks were overfished during the catch share period, requiring rebuilding plans and reductions in catch limits.

Interactive Chart Story


Biomass ratio: The biomass ratio (B/BMSY) measures the biomass (B) of a fish stock in relation to the biomass that would produce maximum sustainable yield (BMSY) for that stock. In fishery management, the optimal biomass ratio is 1.0, meaning B is equal to BMSY. Values less than 1.0 indicate low biomass, while values greater than 1.0 indicate more biomass than would be optimal for maximum sustainable yield in the fishery.

Average biomass ratio: To measure changes in multiple stocks, we averaged the biomass ratios for the stocks.

In Their Own Words

Although some of the quantitative data analyzed for this indicator exhibited clear trends, it was challenging to discuss the relationships between observed data trends and implementation of the respective catch share programs. The Measuring the Effects of Catch Shares project team believed that those stakeholders most involved in the fishery, either as active participants or as representatives of an involved coalition of participants (e.g., sector managers in the Northeast), would be able to provide insight and help to explain trends seen in the existing quantitative data. The following quotes were selected to illustrate some of those perspectives and highlight trends such as effects on small vessels, the effect of avoiding “choke stocks,” fleet diversification, and product quality. The individual quotes do not represent findings or conclusions for this indicator, nor do they represent a consensus across any category of participants.

“I have a black bottom on the boat and I went and got some white boot tar paint and I put on it about half way down from the water line, “No codfish allowed.” This one guy came down and he is standing there cocking his head. He says to me, “How are you going to read that if its underwater?” I said, “You don’t understand. That is for the codfish to read.”
~ Fisherman

“We lost our groundfish populations here in Eastern Maine long before sectors started, and the qualification years that they used for the allocation of the quota was well after people had participated in the fishery. So we didn’t see a sharp decline in participation in the fishery at the beginning of sectors because those fishermen were largely done fishing for groundfish anyway just because of the stock size in Eastern Maine.”

“Yeah, catch shares when they first came into play they worked because the allocation that NMFS gave us was so much higher than it is today.”
~ Fisherman

“Well, I mean they haven’t been able to use haddock as a direct fishery. When they go target haddock they catch choke species like codfish and stuff like that. The choke species suffocate them from totally capitalizing on the haddock.”
~ Fisherman

“These other guys, they’ll throw choke species fish overboard all day long. And they’ll sleep just as good that night, as if they’ve done nothing. And that’s the bottom line.”
~ Fisherman

“So with the pressures on fishermen to try and survive, to try to remain fishermen, to try to remain groundfish fishermen, I think it’s safe to assume that there is a lot of catch that we are not accounting for. That’s another perilous part of this whole catch share program. With catch that’s not being accounted for, what do you get? You get errors in the assessments.”
~ Government

“The alternative is to go back to days at sea, and I don’t think people understand just how fewer days at sea we’d have with these low quotas because they think catch shares caused these low quotas. No, catch shares didn’t cause these low quotas.”
~ Fisherman

“So there is a huge disconnect here all the way around at the most fundamental level, regardless of catch shares. Everybody in New England says the only people who can’t catch fish off the coast of New England is the United States government, and they’re the only ones who matter.”
~ Fisherman

“The bigger guys, I mean they can go out. They have enough fuel capacity to be able to get off the fish that they shouldn’t be catching and move somewhere else. And if they’re fishing on some of the George’s stocks that are in far better shape. They go fill their boat full of haddock.”
~ Government

“There are fishermen that are really hurting. When catch shares came in some of the bigger boats came in and scooped up whatever quota there was, right out in front of them. If stocks had been healthy, it wouldn’t have happened.”
~ Government

“Well, I’m of the opinion that the new management system has been an equal opportunity constrainer. I mean I know that information shows that the impacts seem to be more on the smaller boat fleet than on the bigger boat fleet but when we started there was a lot more small boats than there were big boats. I know from experience a lot of people that were under 50 feet that were fishing under days at sea are no longer fishing today. If they were cut down to 25 days at sea and a 200 pound trip limit with a two for one counting in the Gulf of Maine, probably those same boats would not be fishing. I don’t think it’s because of the design of the system. If the stocks are going down, the regs are going to get tighter, whether it’s days at sea or quotas.”

“Well, the big boats can take advantage of the healthy stocks, which is haddock, haddock and reds right now. The inshore small boats, the little 38 to 40 footers, last year they got hammered hard. I mean Gloucester, I mean they had a huge day boat fishery down there for codfish. Guys go out and get their codfish and come back in. Gone because of the Gulf of Maine cod restrictions. The same thing happened to our boats here this summer. They couldn’t fish inshore because of the codfish. There is a crap load of cod out there. So these guys couldn’t fish because they didn’t have the quota for it. So if you’re out there and you have an observer on board, you catch codfish and you’re screwed. You shut down your sector for the year.”
~ Processors

“We also closed some areas that we thought were high potential catch areas. We subsequently reopened those this year because we found that we still had enough cod quota and it wouldn’t be a problem. So we self-imposed restrictions on our members to avoid cod. They also have to report their Gulf of Maine cod catch daily. If you find this hot spot of cod you report that [to the sector manager] and then he broadcasts it to everybody through email to try to stay away from this area, unless you happen to have some cod allocation.”
~ Industry Representatives

“New England’s broken. It’s not working. Nothing makes sense. The fish that they say they’re abundant I don’t catch, and the fish that they say they’re depleted, that’s all I catch.”
~ Fisherman

“With, what are there, 19 different species or something like that? And they all fluctuate relative to one another. So in one year you have one or two choke species, and then two years later it’s a completely new set of choke species that you hadn’t planned for.”
~ Fisherman


Baseline: Before Catch Share Program

Along with the project baseline beginning in 2002, an extended baseline beginning in 1980 illustrates long-term trends in stock status. The average biomass ratio declined by 54 percent from 1980 to 1985. By the early 1990s, the biomasses of many groundfish stocks reached record, or near-record, lows. For example, the total cod biomass on the Scotian Shelf and in the Gulf of Maine was estimated to be a small fraction of what it was during the nineteenth century (History of Fishery).

The average biomass ratio of groundfish stocks ranged between 33 and 50 percent of the levels that would provide the highest long-term average catches, or maximum sustainable yield (MSY). In three stocks—Gulf of Maine (GOM) haddock, Georges Bank (GB) haddock, and Atlantic pollock—biomass ratios exceeded BMSY for most of the project baseline. In contrast, seven groundfish stocks (GB cod, Eastern GB cod, GOM cod, white hake, SNE/MA winter flounder, CC/GOM yellowtail flounder, and GB yellowtail flounder) were overfished for all eight years of the project baseline. Four additional groundfish stocks (witch flounder, American plaice, SNE/MA yellowtail flounder, and Acadian redfish) were overfished in at least two years of the baseline period. Biomass ratios of individual stocks were variable over the extended baseline, with some stocks showing an increasing trend and others showing a declining trend.

The proportion of stocks that were overfished during the project baseline did not demonstrate notable increasing or decreasing trends. The majority of stocks had low biomass levels, but between two and five stocks each year had biomass levels that exceeded MSY. Four stocks—Acadian redfish, Atlantic pollock, SNE/MA yellowtail flounder, and GB haddock—showed improvement in status, increasing from biomass levels below BMSY to above the biomass reference point. American plaice recovered from overfished status, while status of GOM haddock and witch flounder declined during the project baseline. Both GB and GOM cod stocks showed slight improvement in biomass beginning in 2006, but remained well below MSY levels .

During Catch Share Program

Although the average biomass ratio of allocated stocks increased from 2010 to 2015 by 21 percent, the proportion of stocks overfished (B<0.5BMSY) remained just above 45 percent in the first six years of the Northeast Multispecies Sector Program, and increased by 12.7 percent three years into the program. Thus, the aggregate picture of stock status belies considerable differences in individual stock status. Both GB and GOM cod stocks remained below overfished levels, as has SNE/MA yellowtail flounder. In contrast, other stocks have recovered from historical overfishing, and other stocks have reached very abundances. Most prominently, haddock stocks are all well above BMSY. In general, few stocks exhibited either a strong positive or negative change in status during the first six years of the catch share program. This lack of dramatic change matches expectations; we would not expect biomass of stocks to be impacted because of the implementation of the catch share program or the implementation of annual catch limits (ACLs). Rather, it may take one or more fish generations (at least 5 years) to see improvements in biomass levels. However, the continued low biomass levels of some stocks likely have implications in setting ACLs and constraining catch of healthy populations (Financial Viability of the Fishery: Landings). Thus the continued occurrence of overfished stocks through the catch share period.

Data Gaps and Limitations

Data for this indicator came from the most recent fisheries stock assessments reviewed in 2015 for 16 of the 18 stocks allocated in the Northeast Multispecies Sector Program. The 2015 GOM winter flounder assessment was not deemed to be sufficiently accurate for giving management advice. The northern and southern windowpane flounder assessments did not use age- or size-structured population dynamic models, but instead tracked survey- based abundance indices. The GB yellowtail flounder assessment also did not use a population model so was excluded from this analysis. The eastern GB haddock assessment did not estimate biomass reference points. Given that assessments are conducted on a varied schedule for individual stocks, data for recent years are typically not uniformly available. Therefore the analysis uses the dataset available on an individual stock basis, and in the cases where years have not been assessed, stock biomass from the most recently assessed year is used.

It is important to remember that responses in stock biomass to changes in management or other factors take considerable time to realize. The response time varies from species to species based on generation time. Furthermore, the response may be partially or entirely masked by other factors, such as environmental conditions and predation. It may take a number of years of data to properly identify relevant trends.

Information Sources

Northeast Fisheries Science Center (2012). Assessment or Data Updates of 13 Northeast Groundfish Stocks through 2010. US Dept Commerce, Northeast Fish Sci Cent Ref Doc. 12-06; 789 p.

Northeast Fisheries Science Center (2015). Operational Assessment of 20 Northeast Groundfish Stocks, Updated Through 2014. US Dept Commerce, Northeast Fish Sci Cent Ref Doc. 15-24; 251 p.

Stone, HH, EN Brooks, D Busawon, Y Wang (2015). Assessment of Haddock on Eastern Georges Bank for 2015. Transboundary Resources Assessment Committee.

Wang, Y, L O’Brien, I. Andrushcheknko, KJ Clark (2015). Assessment of Eastern Georges Bank Atlantic Cod for 2015. Transboundary Resources Assessment Committee.

Updated: May 2018

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