Like a couple of other posters on this thread I have worked in the stock assessment business as well. In answer to this question I would say that for most populations the answer is "never". Particularly as climate variability appears to be increasing and both marine and freshwater ecosystems are responding in ways outside of their previously (somewhat) better understood dynamics. Precisely and accurately measuring the metrics used for forecasting (escapement, catch, freshwater and marine survival, age composition) is hard enough, accurate forecasting is even harder, and in some cases, impossible. I agree with posts above that fishery biologists and managers need to do a better job of communicating to stakeholders as to what type of forecast goals are achievable. I do not work for DFO, but I really feel for DFO scientists and managers. They frequently operate without adequate resources, and are the object of the (understandable) anger and frustration of stakeholders. IMO the best things that can be done going forward is defaulting to conservative harvest regulations for all sectors; cooperation and understanding between and among DFO managers and scientists and harvest sectors (rec, com, fn); and cooperative political pressure by these groups for more resources to be devoted to fishery science.
Couldn't agree more strongly with your post, Bugs. Thanks for that. Us who like to try and figure fish out can more often agree working within that intent.
I think the additional point I would like to make is that: stock assessment does not happen within a vacuum. As fun as it can be trying to count fish (and fun talking about those technical methodologies) - There needs to be a reason for doing it. That reason is some aspect of Fisheries Management. So...
Stock Assessment is an integral component of Fisheries Management - a way to benchmark how well our Fisheries Management actions and activities are reflected in the stock trajectories over time in the stocks of concern - assuming our Fisheries Management response are in fact mirrored in the success or failure of the stocks of concern.
So - there is a time component to consider. Committed, multi-year funding for Stock Assessment is critical to developing and maintaining a time series of stock trajectories. This reality has been particularly challenging in the past 15-20 years or so of DFO cut backs.
Forgive me everyone if I detail what we already know in order to break-out the bits, but...
Salmon have a life cycle that is reflected through several components or stages that offer distinct, separate opportunities to perform Stock Assessment in a cycle: eggs, fry, smolts, preadults, and finally returning spawning adult salmon; through different and differing environmental scales such as headwaters, lake, mainstem, estuary, near coastal, and open ocean - and back again.
Each stage offers a different opportunity to complete Stock Assessment in a slightly different way - with different costs/efficiencies, and limits of error. Since funding is always limited - the idea is to try to put the money where the biggest bang for the buck is. Realistically - one can't commit Stock Assessment activities on every creek.
What that means is that you target the areas/methodologies (e.g. index rivers) that are both efficient and as accurate as possible - and one makes some assumptions about the transfer ability of those generated data that may (or sometimes may not) be valid for a larger area or other, adjacent watersheds. Unfortunately, it is not always logistically and financially plausible to "prove" the accuracy of these assumptions like whether or not an "index" stream accurately reflects the annual stock trajectories of other salmon species in other, adjacent creeks - so often - these extrapolations remain unproven and unsupported. They may - or may not - accurately reflect stock trajectories in the area but utilized in Fisheries Management activities none-the-less. And how does one actually define an "area" for a index river? CUs and the unimplemented Wild Salmon Policy? Lots of debate here.
Where salmon and their numerous life stages are confined; it makes it more efficient to count them here - which is why it is often more challenging to do Stock Assessment in the open ocean - and why streamwalks are most commonly utilized, although there are numerous intensive (i.e. small-scale: Didson/Aris, redd surveys, fish fences, etc.) and extensive (larger-scale: ocean test fisheries, commercial CPUE, etc.) tools in that toolbox as well.
As far as streamwalks and other, freshwater Stock Assessment activities go - logistics and accessibility will dictate what creeks are logistically feasible of being walked on a regular basis. These creeks become the index river - often irrespective of their applicability for inclusion as an index river.
There is also some debate with some freshwater Stock Assessment authorities as to whether or not we need to understand marine survival verses lake or instream survival since - as far as their reasoning goes - there is nothing we can do about it anyways.
Ultimately, if we are in fact going through the process of Stock Assessment - there should be some reason for doing it. If there really is "nothing we can do about it" - then why are we doing any of this??
I think I will stop here - for now - and let the other posters pile in on this point...
Larry Pynn
