The science of sustainable seafood, explained

California Sardine Numbers are Low – Why is Oceana Blaming Fishing?

Last week Dr. Geoff Shester, California campaign director for the nonprofit advocacy group Oceana criticized the Pacific Fishery Management Council for the persistence of low numbers of California Sardines. The lack of a population recovery may cause the commercial moratorium to last until 2017.

The author explained this sardine population decline as being 93 percent less than it was in 2007. Dr. Shester does not believe this is because of environmental causes like climate change, El Nino, or natural fluctuations in forage fish species however – instead he blames the management body. “They warned of a population collapse and the fishery management body basically turned a blind eye and continued moving forward with business as usual.”

Shester also cited recent sea lion deaths, specifically 3,000 that washed ashore in California in 2015.

“When fishing pressure occurs during a decline, which is exactly what happened here,” said Dr. Shester. “It puts the stock at such dramatically low levels it impedes any recovery potentially for decades.”

Comment by Ray Hilborn, University of Washington, @hilbornr

Dr. Shester’s comments are some of the most dishonest commentary I have seen in the fisheries world.

He knows that the NOAA Scientists and Prof Tim Essington, in work funded by the Pew Foundation, have stated clearly that the decline in sardine abundance is due to natural causes. He also knows that sea lions are not dependent upon sardines; the die off of sea lions is caused by the oceanographic conditions – not the result of fishing. In fact, reproductive failures of sea lions have occurred repeatedly in the past at times of high sardine abundance.

If he has read Dr. Essington’s paper in Proceedings of the National Academy of Sciences he would also know that there is no relationship between fishing and the duration of periods of low abundance of sardines and other forage fish.

The harvest rule for sardines is highly precautionary, even when sardines are at high abundance the harvest rate is low. Indeed the harvest control rule for sardines matches very well the recommended harvest rule for forage fish that emerged from the LENFEST report – that is a low target harvest rate at high abundance with the fishery closed when the stock reaches low abundance.

Members of the Science and Statistics Committee of the Pacific Fisheries Management Council have explained all this to Dr. Shester before – he simply continues to ignore science and pursue his own agenda.

Ray Hilborn is a Professor in the School of Aquatic and Fishery Sciences at the University of Washington. Find him on twitter here: @hilbornr


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7 Responses

  1. Thank you Ray Hilborn, This is very encouraging, that someone with Ray Hilborn’s scientific stature has the integrity and is taking the time to respond honestly to the destructive misinformation that’s been spewed by Oceana (and EDF) for years.

  2. Prof. Hilborn,
    This Alaskan fishing family thanks you for speaking the truth.
    Clay Bezenek
    F/V Salty
    Eric Bezenek
    F/V El Roi
    Ketchikan, Ak

  3. I am a commercial fisherman who operates out of Southern California and someone who depends on the resource of sardines for my survival. We, as fisherman, have been defending ourselves against Dr. Shester’s over exaggerated and false accusations associated with sardines (and other species!) for years. It is an absolute breath of fresh air to see someone with Dr. Hilborn’s credentials professing our objections to this organization’s (Oceana) outlandish and unfounded claims of overfishing impacts. Thank you!

  4. From their abstract:

    In response to our recent paper (1), Szuwalski and Hilborn (2) make several points about the timing of recruitment failures, the effect of fishing on productivity, and our choice of using biomass, not recruitment, as the indicator for collapses. We address these points here to show that not only do they not affect our conclusions, but that we are largely in agreement regarding the biological processes and the implications for fisheries and conservation.

    Szuwalski and Hilborn (2) show the timing of recruitment failures that have led to many of the forage fish collapses we identify in our study. We agree that the process of recruitment failure initiates a cascade of positive feedback, whereby fishing rates inadvertently increase during declines in population biomass, and that fishing does not directly incite these recruitment declines. As our title indicates, we show that when forage fish undergo natural population fluctuations (i.e., recruitment declines), fishing acts to amplify the extent of collapse. That is, fishing deepens the troughs of population cycles. We do not claim that fishing causes collapses or that it precipitates declines in productivity, only that fishing does affect the biomass of forage fish in the system, which can have repercussions throughout the food web.

    Additionally, Szuwalski and Hilborn (2) note that our threshold of collapse does not correspond to a level of biomass causing recruitment limitation. Their definition of “collapse” is relevant for conventional “single species” management of forage fish, where management seeks to avoid depleting stocks below levels at which recruitment is impaired. However, forage fish management requires an ecosystem approach where the consequences of fishing on other valued components of the food web must be considered. In this context, biomass thresholds that correspond to predators’ sensitivity are most relevant. Multiple studies have shown that predators are most sensitive to forage fish depletion at low forage fish biomass and that these effects are highly nonlinear (3, 4). Therefore, fishing strategies need to avoid, to whatever extent possible, depleting stocks below critical ecological thresholds. Identifying these thresholds remains an important priority for forage fish fisheries management.

    Furthermore, we agree with Szuwalski and Hilborn (2) that management should respond to declines in recruitment as an early indicator of decreased productivity. In some cases where stocks are frequently monitored and environmental conditions that govern recruitment are well understood, it is possible to anticipate these recruitment failures and adjust fishing accordingly. Our paper (1) shows that, unfortunately, this has not commonly been the case. Therefore, it is important to put safeguards in place to avoid inadvertent ramping up of fishing rates when stock productivity and abundance is in rapid decline.

  5. I think this discussion is valuable, but I’m late to the party.

    In my view, the main issue here concerns stock assessment, not management rules. Dr. Hilborn is correct in noting that the management rules are progressive and constructed to reduce harvests when the population declines. However, we are not capable of estimating stock biomass with enough accuracy to implement the rules most effectively. Our estimates of stock size (for any given year in the past) improve in successive years as the cohorts are observed repetitively, but the initial biomass estimate for a given year has relatively high uncertainty. In this case, the initial estimate of stock biomass was too high, and thus the target fishing mortality was set higher than intended. US+Mexico Fishing mortality was 0.42 (0.33 in for the US fleet) as the stock biomass dropped. In a parallel world, the early estimates could have been too low, and Dr. Hilborn would have been very right. But in this world, these estimates were too high (at least according to the 2016 assessment; future assessments will give different estimates).

    Dr. Hilborn writes: “The typical scenario for a stock collapse is (1) recruitment declines at a time of high abundance, (2) abundance then begins to decline as fewer young fish enter the population, (3) the catch declines more slowly than abundance so the harvest rate increases, and then (4) the population reaches a critical level… The decline of California sardines did not follow this pattern, because the harvest control rule has reduced harvest as the stock declined.” With the advantage of more recent stock assessments, I think we can agree that the above statement is incorrect. The decline of Pacific sardine did, indeed, follow the 4-step pattern Dr. Hilborn outlines. In retrospect, we see that US exploitation rate quadrupled (unintentionally) in two years as the biomass dropped. Fishing did not stimulate the decline–the stock was on its way down for natural reasons, as it has done for thousands of years–but it’s hard to argue against the idea that fishing exacerbated the situation and accelerated the decline this time around. I don’t think it has any lasting effect on the stock, but it had some influence on the rate of collapse. I think the Pacific sardine stock is one of the best managed stocks in the world, and the management efforts are progressive. But we have to be honest with what we don’t know. We need to take a sober look at stock-assessment methods with a better appreciation for uncertainty and what it means for the effectiveness management rules.

  6. Between “Managed collapse” and “un managed abundance” lies the science and politics of fisheries management. That is a big topic.

    The small topic here is : the suitability of sardine as a candidate for stock assessment- based management.

    If its collapse is natural (whether it happens 60 years or 25 years or 10 years) what is the best management regime?

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