Herring Scrap 27: A Low Number With A Good Agent

In Scrap 26, I explained that Unfinished Biomass doesn't actually factor directly into the math driving this fishery, but is conceptually linked to the threshold level (below which fishing won't happen). What I didn't make clear is the jurisdictional reason for this flimsiness: while it is up to Alaska Dept of Fish & Game (ADF&G) to come up with the Unfished Biomass, it is up to the seven non-scientists on the Board of Fisheries to use that number to settle on the threshold level below which fishing can't occur.

It's in this division of responsibilities that the Unfished Biomass figure becomes important; the only time Unfished Biomass comes out to play is at the Board of Fisheries meeting every third year, when the Department scientists need to give advice for the Board of Fisheries to act on. And a meeting is coming up soon - end of January, Ketchikan - and the Proposal Book has just come out in the last month or so. There'll be lots more about that Board of Fisheries meeting in these pages before long, but for now I want to focus on how this dangerously contrived - and far too low - Unfished Biomass figure will get deployed at that meeting.

I want to highlight Proposal 171 - proposed by ADF&G (as I wrote in Scrap 19, which also introduces the Board of Fisheries process in brief, ADF&G-generated proposals are rarely voted down by the Board of Fisheries). Here's a screen grab from the proposal book:

On the face of it, in terms of conservation, this proposal seems to be a distinct improvement on the current scheme; it changes the annual commercial Harvest Rate Percentage range from 12-20% to 10-15%. Great. But I want to focus on that last bit of text to explain how this proposal is designed around ADF&G's notion of what the Unfished Biomass should be set at (to reiterate, the new Simulation Study says Unfished Biomass is 85,576 tons). In their proposal, ADF&G writes: "the department proposes a threshold based on 30% of unfished spawning biomass (26,000 tons) and a sliding scale harvest rate of 10-15% (15% maximum at 51,000 tons)."

Per this proposal, no fishing will happen in any given year that the biomass is thought to have fallen below 26,000 tons; between 26,000 tons and 51,000 tons, the range shifts from 10-15%; anything over 51,000 tons, and the commercial fishery can have 15%.

For reference, the last time that the annual forecast fell below 26,000 tons was 1995. The last time it fell below 51,000 tons was 2007. But subsistence harvesters and other users and observers have reported some bad years since 1995, including bad years since 2007. In bad year 2018, for example, the forecast was 55,637. Thus, if this proposal goes through, then fishing at a high level will be able to happen in years that feel bad, like 2018. That seems dumb.

In their Simulation Study, ADF&G cited a few examples of studies that suggest what percentage of the Unfished Biomass the low threshold for fishing should be set at. They point out studies that suggest a low threshold set at 25% and 37% of Unfished Biomass.

How this is supposed to go, from ADF&G's perspective, is: Board of Fisheries will receive Proposal 171 and will receive the pseudo-scientifically derived Unfinished Biomass number, and will dutifully go ahead and decide set a low threshold at somewhere between 25% and 37% of that Unfinished Biomass. It may happen that one of the Board members asks a probing question, for example: "This guy Peter has been trying to convince us that the data informing the Unfished Biomass is comprised largely of junk, especially earlier in the time series, when different methodology was used, and thus the Unfished Biomass is too low to form a safe low threshold; is it true?". In response, the scientists will say: "No. We have no evidence that what he says is true. We don't believe that our methodology has changed significantly in recent decades; we think our time series offers a realistic picture of herring biomass in that period."

Satisfied by that answer, the Board will pick their percentage for the threshold, whether it is 25% or 30% or 37%, and the mathematical work of the Unfinished Biomass will be done and accomplished. At that point, Unfished Biomass can retreat into its idle role as storyteller until the next meeting comes around. Meanwhile, the processors will be able to assure their customers overseas of an assured supply every year, because they and their seiners know that only the most dire conditions could possibly trigger the threshold and halt fishing.

This is fisheries science in action.

Best,

Peter