The Trouble with the LRP

Barry Darby and Helen Forsey

(for The Navigator, September 2025)

            The most consequential number in DFO’s current fishery management planning is almost certainly the Limit Reference Point (LRP). In the system of “zones” used to classify the health of a given stock, the LRP marks the dividing line between the “Critical” and “Cautious” zones, providing the basis for the key management decisions on Total Allowable Catches and quotas.

            The trouble is, every Limit Reference Point is inherently and necessarily wrong. Our research and analysis, summarized in this article, show why this is so, and why basing decisions on the LRP therefore constitutes serious mismanagement of the fishery. We then offer suggestions for fixing this built-in problem.

            DFO scientists gather data to estimate the size of a fish stock in kilotonnes of spawning biomass, an estimate which, understandably, is always subject to a high degree of uncertainty. They assume that estimated biomass to be a measure of the stock’s health, though that is not necessarily the case. They designate a theoretical ideal total biomass, then calculate the LRP based on that ideal and finally use it to set TACs and quotas. The LRP is treated as crucial because if the estimated biomass falls below it, the stock is seen to be in the critical zone, with removals severely restricted as a result. (An upper reference point between healthy and cautious zones, is usually considered to be approximately twice the LRP, but it is seldom calculated or used in fishery management.)

            The case of Northern Cod is only one example of the deeply flawed management approach that relies so heavily on an LRP, but this critique applies across the board to whatever species is being considered.

            In 2010, the LRP for the Northern Cod stock in NAFO area 2J3KL was set at 850 kt, (approximately 1.9 billion pounds.) A couple of years ago, DFO scientists realized that the number was incorrect, and in October of 2023 they announced that the LRP was actually 315 kt. The old figure was more than two and a half times the newly “corrected” one – a whopping 270% error.

            This was an absolutely earth-shaking admission of error by DFO, not only scientifically but in the starkest practical terms, since they had been using the 850-kt LRP as the very basis for setting quotas for over a decade. The general response, though somewhat muted, was delight that the cod stock was now suddenly no longer in a “critical” state. But if the old 850-kt figure was so wrong, why should anyone assume the new 315 figure was right?

            We had long been wary of the LRP as a management tool, and now it was officially admitted that the LRP could be wrong. In fact, not only could the new LRP be wrong, it is wrong,just as the old one was. The reasons why are extremely important: they call into question not only the revised 315-kt figure for 2J3KL cod, but the whole notion of the LRP itself.

            Our research points to four reasons why the LRP is bound to be wrong.

            First, statistical uncertainty. 315 kt is a mathematical quantity, resulting from a mathematical calculation using statistical data on stock size and other relevant factors. Those data typically embody large uncertainties in the 30-50% range. This means that the 315-kt figure for 2J3KL cod could actually be anywhere in the range of as little as 160 to as much as 470 kt.

            Second. Historical changes. The data used to calculate the 315-kt LRP came from data collected over the past seventy years. Given the effects that climate change, pollution, biodiversity loss and other factors have had on our planet, the calculation of an LRP based on this past data cannot simply be applied for the present. As a 2020 scholarly review of fisheries science concluded, “Efforts to rebuild marine life cannot aim to return the ocean to any particular past reference point.”

            Third. The LRP, and DFO’s “critical,” “cautious” and “healthy” zones, purport to represent the health of the stock. But what is actually being estimated and measured is the collective weight of the population, with the kilotonne as the unit of measure. But the idea that an 80 kt population of skinny starving fish is “healthier” than a 50-kt stock of fat fecund fish and juveniles is as ridiculous as claiming that an 8,000-lb busload of starving people is healthier than a 5,000-pound busload of average Canadians. Kilotonnes measure weight, but they simply cannot measure stock health.

            Fourth. The LRP is also wrong because it changes over time. A reference point is a fixed point, unchanging, like the zero on the Celsius temperature scale, which, as the freezing point of H₂O at sea level, can never change. As the scientific research shows, the LRP can vary over both time and space, due to factors such as the age distribution of the stock, changes in climate and habitat conditions, etc. The LRP is a variable, and variables cannot be fixed points.

            Clearly, this analysis has major implications for DFO science and management, not only for cod but across all species. It means that LRPs are inherently dysfunctional and can no longer be accepted as the basis for harvest decision rules, TACs and quotas. But as we have argued before, in the Navigator and elsewhere, that focus on the catch is itself a fundamental problem with DFO’s current system. The task must be to manage the fishing, not the catching – the inputs to the fishery rather than the outputs. For that, we need to shift the focus of science and management to respond to the realities on and in the water.

            Stock health is one of those realities, and assessing it is a necessity for proper fishery management. But using kilotonnes to designate “zones” and LRPs just doesn’t cut it. We need better metrics and better logic.

            Modern science has created new metrics to help address important complex realities, such as the Gini Coefficient for income disparities, and the Gallagher Index for electoral proportionality. The same could be done for fisheries.

            Here is our suggestion for DFO scientists. Consider a new metric using a hypothetical “stock health index”, with indicators on a scale from 0 to 100. A score between 60 and 100 would mean a healthy stock, 30 to 60 would put it in a “cautious” range, and 30 or lower would indicate a critical state. The score would be derived from the following measurable indicators:

First, weight-at-age: Unlike most land animals, codfish grow continuously over their lifetime, with that growth varying enormously depending on food supply and habitat. If the fish are large for their age, that is an indicator of stock health.

Second, weight-at-length: Are the fish fat or skinny? This is related to filleting yields, which are important economically as well, and can vary from 33-43 % for cod. Fish in a healthy stock have a relatively high weight-to-length ratio.

Third, liver mass to total mass: Healthy fish have large livers, and this ratio would be another good indicator of fish health.

            The new metric for assessing stock health would function regardless of stock size. The same process could be used to assess 2J3KL cod, (300 – 800 kt), 3Ps cod, (50 – 100 kt) or the golden cod in Gilbert Bay (a few kt) and the results could be compared. As well, the cost in time, energy and money would be considerably less than with the current system, since much of the data could be provided by harvesters, who could rapidly collect larger and more random samples, giving faster and more accurate results.

            Back to the trouble with the LRP. The recognition that LRPs are not only wrong but impossible to fix opens up the opportunity for a genuine and positive shift in DFO’s management approach. Let’s stop using LRPs, TACs and quotas as the way to manage our fisheries, and replace those failed tools with metrics and methods that will provide a better way forward. That paradigm shift will bring greatly increased benefits to the people of our coastal regions, and enhance the sustainability of both our fisheries and our oceans.