You can do a couple of things there.
You need to check before and after the spawning period to make sure you're not missing it.
Also, DFO has looked at where the habitat is. Mackerel like to spawn in a particular range of temperature. When they look at where that habitat is, some of the earlier work they have used uses projections of when the temperature is going to change in 10 to 15 years. What would be a really big help is to look at the current upper water temperature and to build our understanding of mackerel spawning habitat from contemporary instead of projected water temperature. That's one easy and doable addition to the current stock assessment.
The main concern with respect to the egg survey has two parts. Is it covering all of the areas? Are we missing something? Is southern Newfoundland a spawning area? We're not sure. Has it progressively been changed? For each of these models, if you're more or less on average but you go up and down, then it's not so much of a problem. If you sequentially end up with more or less of a given input into the model, then that's when it really starts to screw up your model. Has there been a trajectory of fewer eggs in the survey area? A lower proportion of the spawning population in the survey area would have a big impact on the model.
Those are the types of questions I would like us to talk about at the upcoming assessment.