Did the status of fish stocks change?
Indicators: Biomass | Fishing Mortality
Short Answer: Yes. Biomass continued to increase in the first several years of the catch share program. However, the increase in biomass cannot be attributed to catch shares, as the increasing trend began a decade before the catch share program.
- Under catch shares, the average biomass ratio of West Coast groundfish continued to increase.
- The increase in average biomass ratio began in the late 1990s and continued through the baseline (2002–2010) and catch share periods (2011–2016).
- Catch shares did not lead to dramatic changes in biomass, but rather biomass was on an upward trajectory that continued under catch shares.
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.
“Last year I caught a yellow-eye in 240 fathoms, and they don’t live out there. They just don’t live there, but we caught one. And I only had 3 lbs. of yellow-eye quota. Well, this fish weighed 4 lbs. Boom, I was over.”
“Gear switching really hasn’t worked the way they thought. What it’s done is let the fixed gear people come and buy trawl quota and put it into the fixed gear side. And that is hamstringing the Dover you’re going to get out of the water. Where you had 100% of the amount of black cod to prosecute your old fisheries, now you don’t have that, and it’s going to leave Dover, it’s going to leave other fisheries in the water. So I don’t think that that was right. I don’t think that they foresaw that.”
“Right now two months is all I groundfish. I’ll go get my petrale, my black cod, and what little Dover I get with those two species. And when I catch the petrale and black cod, I’m done. I’ve got 1.2 million lbs. of Dover sole, but I can’t catch that Dover because I’ve caught all my black cod.”
“If the abundance of a species isn’t recognized by the stock assessment, and you start running into a lot of it, then you got a problem.”
“This thing, it just inhibits and inhibits and inhibits. There’s no new opportunity developing here at all. They’ve taken black cod and allowed to be caught by pot boats. Sounds real good on the surface until you figure that black cod’s your biggest choke species for Dover. And then you double the Dover ACL. I mean honestly…”
“Lingcod has been declared rebuilt, but you can’t really target lingcod because ling cod and yellow-eye like the same kind of grounds. Canary rockfish is another very constraining species, extremely so. If a boat has 2,000 or 3,000 pounds of canaries in his quota, that’s a pretty decent quota, and he’s got to leave fish in the ocean because he can’t target them for fear of going over. Canary has become a very big bargaining chip late in the season. We’ve got increased numbers on our rockfish and ling cod, but you’ve got to be very, very careful. You can put yourself out of business from one day to the next if you’re not careful.”
“The way I look at it, we’ve had great shrimp years. Environmentally, we’ve had just terrific conditions for the last four or five years. And that’s not going to stay. It never does. And when it goes downturn now, it used to be you can go out there and work harder and do whatever, and you can’t do that now. You have so many constraints, and you got the costs so high. The fixed costs are so high that you can’t go out there and scrape anymore. And you can’t afford to catch too many canaries, yellow eye, halibut, all that stuff. Plus you’re paying a $500 day. Plus you’re paying the lease rates. And that’s why I think it’s more volatile. Pretty soon you’re going to have a crappy shrimp year, whether it’s next year or year after. And there’s going to be a bunch of guys, oh well, I better try to go dragging, you know, or spend more time dragging. So then everybody is going to be competing for leasing fish, which is great for the guys leasing it, ’cause their lease price will go up. But for those of us fishing, it just chips away at the profit.”
Baseline: Before Catch Share Program
Extended Baseline Period (1980—2001): Average biomass ratio decreased substantially throughout the 1980s and into the late 1990s. From 1.3 in 1980, it decreased 40 percent to 0.77 in 1998. During the lowest period from 1995 to 1998, more than a third of stocks (8 out of 22) had biomass ratios less than 1.0. Average biomass ratio began to increase in 1999, and it reached 0.86 in 2001.
Baseline Period (2002–2010): The increase in average biomass ratio continued during the project baseline period with many stocks improving and the number of overfished stocks declining. Sixteen of 22 stocks had increases in biomass ratios, and the average biomass ratio increased by 30 percent from 0.92 to 1.20. The percentage of species with biomass ratios greater than 1.0 increased to 73 percent from 45 percent. The proportion of overfished stocks, defined as having biomass ratios less than 0.5, decreased from 23 percent in 2002 to 9 percent in 2010. Notably, the average biomass ratio for stocks designated for management under rebuilding plans increased by 64 percent from 0.50 to 0.82, and none of the 9 stocks under rebuilding showed declines in biomass ratios. During the baseline period, fishery managers reduced fishing mortality rates to low levels (see Fishing Mortality indicator) through limited entry and rebuilding plans, leading to the steady increases in biomass.
During Catch Share Program (2011–2017)
The upward trend in average biomass ratios continued after implementation of catch shares. Average biomass ratio for all stocks increased steadily by 13 percent from 1.22 in 2011 to 1.40 in 2017. Similarly, rebuilding stocks had 20 percent increase from 0.85 to 1.02. The proportion of overfished stocks (biomass less than half of BMSY) remained constant at 10 percent. Continued low fishing mortality rates resulted in continued increases in biomass levels, and 5 stocks were declared rebuilt after catch shares were implemented (http://www.pcouncil.org/2017/06/48752/two-important-groundfish-stocks-rebuilt/).
Data Gaps and Limitations
- Increases in biomass in response to a management intervention may take decades to realize due to the long lifespans (30 or more years) of many of the managed species. The response time varies from species to species based on generation time, and the response may be partially or entirely masked by many other factors, such as environmental conditions and predation. It may take many more years to properly identify relevant trends.
- Because it uses the biomass ratio, rather than biomass, the indicator gives equal weighting to all stocks, regardless of differences in magnitude of the stocks’ individual biomasses. For example, a stock with a very low biomass and BMSY is weighted equally with a stock with a very high biomass and BMSY.
- We used the geometric mean of the biomass ratios rather than the arithmetic mean to ensure, for example, that stocks that were at half of BMSY and at twice BMSY would be on average at BMSY.
- We included 22 stocks in this analysis. We excluded stocks that were combined with multiple species for management and assessment purposes into regional complexes, such as “minor slope rockfish north”. Excluded rockfish species are often neither commercially valuable nor overfished, and as a result they are infrequently assessed.
- Results for the Biomass indicator and other ecological indicators include Pacific whiting, whereas the results for socioeconomic indicators consider Pacific whiting separately from other stocks. This stock not included in the list of rebuilding species for the ecological indicators because was it declared overfished in 2002 but rebuilt by 2004.
- We sought to align values as closely as possible with the NMFS Stock Status Updates (http://www.nmfs.noaa.gov/sfa/fisheries_eco/status_of_fisheries/status_updates.html) and therefore primarily used reference points associated with yields at 40 percent of unfished levels rather than maximum sustainable yield. Yellowtail rockfish was the only stock for which reference points were associated with maximum sustainable yield.
- Not all stocks are assessed annually. For several stocks (6 of 22), the most recent assessment data were from 2007 to 2009. Generally, these stocks are neither commercially valuable nor rebuilding concerns. In these cases, we made the assumption that the status remained constant after the most recent assessment, although given the low fishing mortality rates in this fishery (see Fishing Mortality indicator) it is likely that biomass is increasing for almost all stocks. Thus, the results presented for this indicator likely underestimate the degree of recovery in the biomass of stocks in this fishery.
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