Assessing Assessments

Electrofishing to assess juvenile salmon and trout populations in Ogden's Brook, Antigonish County, NS

Sorry folks this week's blog post is a bit more technically. It deals with my work to address the effectiveness of salmon assessments.

One of the things that I have been working on for ASF over the last few months has been an investigation into how salmon assessments are completed in Canada and the US.  I have a background and interest in this having worked on assessments with DFO, Provincial governments, academic institutions, and privately through my own business. Salmon assessments, and fisheries assessments in general, are all about collecting good scientific information on the demographics (numbers, age classes, size classes, males vs females, fecundity, etc) of a population.  Sometimes these assessments are done on their own and sometimes they are done in conjunction with other studies such as determining fish passage efficiencies around a dam, habitat assessments, an environmental assessment evaluating the impacts of an industry, etc.  The techniques used in assessments are also often quite varied and  vary depending on the target species, the intended purpose of the data to be collected, the environment, the time of year, the availability of resources, etc.  Some of the more common techniques used in salmon assessment involve trapping migrating fish as they pass through a fishway, using counting fences to funnel fish to a trap or counter, using fyke nets or rotary screw traps (smolt wheels) to intercept smolts on the way to the ocean, and electrofishing for juveniles.  Regardless of the type of assessment or whether it is done alone or part of a broader work, assessments are almost always used to gather data for some sort of management decision (setting harvest limits, evaluating environmental risk). 

Sarah and Keegan, two of my assessment crew getting setup to take morphometric measurements, in this case it was length, weight, DNA, and scales samples, which were being used to evaluate how salmon and trout populations change with respect to common river restoration efforts.

ASF is interested in the topic of assessments because of shifts in fisheries management.  A few years back, a ministerial advisory committee (MAC) was struck to develop recommendations for the federal Fisheries Minister with the aim of improving policies and regulations that would work to stem the decline of wild Atlantic Salmon populations (an oversimplification of the the MAC  and why it was struck but you get the idea).  The work of this committee fed into what became a series of ministerial recommendations, department policy shifts, and into the Wild Atlantic Salmon Conservation Plan. These rather lengthy and involved processes led to a number of changes in management of wild Atlantic Salmon.  One of these changes you might have noticed is the change in language away from conservation limits/targets to talk of upper and lower stock reference limits.  This represents a shift in management from conservation targets for rivers that were based on egg deposition rates (2.4 eggs/m2 of habitat) to use of the precautionary approach management framework.  Under this new PA management framework there are two different benchmarks for rivers, a lower stock limit reference point which is more based on the biologic sustainability of the population and an upper stock limit reference points which is more based around harvest (once again an oversimplified of the PA management framework but I would like to give you an impression of shift in mentality that has taken place).   With these shifts in management strategies the question about whether or not our current methods of assessment are adequate and generate the right data to inform mangers had to be asked.  So it isn't surprising that when DFO was developing the implementation plan for the wild Atlantic Salmon Conservation Policy, working in conjunction with partners like ASF, that these questions were asked and it was determined that the assessment system should be reevaluated. 

Deploying barrier nets to isolate a stretch of the river during an assessment.  The ability of fish to escape during an assessment is just one of the factors that can affect the quality of the data collected.

While this question into appropriateness of  assessments may seem to be a relatively simple thing to answer, like assessments themselves, it is a more complicated question than it might initially appear.  More than once I have been asked "how hard can it [assessments] be, you just count the fish", and my answer has always been it is incredibly hard.  Fish don't like to be captured and counted; keeping fish alive and stress free while you get the measurements you need can be difficult; and rivers with their changing flows, fluctuating temperatures, and debris are not always easy places to work.    Evaluating effectiveness of assessments is similarly challenging.  Currently assessment programs are scattered across five different provinces, in four different DFO regions, multiple salmon fishing areas, and within the jurisdiction of dozens of First Nations.  Assessments are currently done using every imaginable assessment technique and analyzed with dozens of different methods.  The salmon populations being assessed are at different levels with different management objectives (in southern Nova Scotia the goal is save the species from extinction while in part of Quebec management has to address harvest issues).  Also the rivers housing the populations being assessed vary from tiny ephemeral brooks to large complex river systems where the majority of the system may be inaccessible and from crystal clear waters where you can see the bottom regardless of the depth to dark tea colored waters where you cannot see an inch below the surface.  All of these factors mean the current management objectives and assessment programs used to inform those objectives are very complex.  However, by talking to fisheries managers, working with my fellow program directors, and researching the latest in assessment strategies and management approaches, I hope to be able to address this question and come up with ways that we can improve upon our current assessment program, which will hopefully lead to better more informed management decisions.

Kate, giving a young trout a good luck kiss and a pep talk (stay safe, get big, have lots of babies) before returning it to the river, an important part of all my assessments.