It's difficult to know sometimes how much effort one should expend in gaining more information relative to how much more information it's going to provide.
DFO has been undertaking broadscale groundfish research surveys throughout the northern cod region since 1983. They were designed for cod. They're pretty good at sampling other bottom-dwelling species. To your point, they don't sample the midwater species very well. That requires some other form of technology to sample those prey items in a fisheries-independent manner, meaning that you're not relying on catch data alone. That's been a challenge. DFO has some acoustic survey information for capelin for example, and it also has inshore spawning location information, but the two sets of data have given discordant perspectives over time. One could make the argument that perhaps we need more acoustic surveys. I think that will require another significant investment of funds. I think one would want to look to other countries that have such acoustic technology in place—Norway comes to mind—and evaluate the degree to which more investments of that nature are likely to produce the kind of information that will give us a more confident feeling for the status of cod.
All that is to say, I think your point is a very good one. This is the kind of question that we'd like to have better information on, but it's a big ocean and it can be very challenging to get reliable information of that nature.