Fisheries Committee on April 28th, 2014

[Dr. Pierre Pepin]

The exploitation rates that we have been measuring, which are on the order of less than 20%—and they're generally on the order of 13% to 18%—are considerably less than the total mortality rates that we're measuring in these populations. So the changes that occurred in one stock, for instance, of a 48% decline, fishing did contribute to that because there was a loss rate on the order of 13% to 14% with that particular stock. About one-quarter of the total loss was attributable to fishing. The rest of it was attributable to other factors.

[Robert Sopuck, Conservative, Dauphin—Swan River—Marquette, MB]

So the natural mortality rate is 75%? No. What is the natural mortality rate?

[Dr. Pierre Pepin]

The measured mortality rate was on the order of 48% in some cases.

[Robert Sopuck, Conservative, Dauphin—Swan River—Marquette, MB]

Okay, and the fishing mortality was—

[Dr. Pierre Pepin]

It was on the order of 14% to 18%.

[Robert Sopuck, Conservative, Dauphin—Swan River—Marquette, MB]

Okay.

So what is the cause of that high rate of natural mortality?

[Dr. Pierre Pepin]

We have a number of predators in that system that are consuming these less abundant stocks and therefore they maintain their feeding rates despite the fact that the resource is actually in decline. They don't care; they just want to eat.

In this particular case, in the case of shrimp, we have not only cod but we also have redfish that are having a significant impact. The biomass of redfish in this area seems to have increased substantially, although not dramatically, in the last few years.

In addition we also have a large turbot stock that is also feeding on shrimp, and we also have seals and whales that feed on shrimp.

[Robert Sopuck, Conservative, Dauphin—Swan River—Marquette, MB]

The natural mortality rate then doesn't fluctuate depending on the fishing mortality. As you up fishing mortality, doesn't natural mortality go down?

[Dr. Pierre Pepin]

If you were to reduce fishing mortality, the natural mortality rate or the total mortality rate would hopefully go down. The natural mortality rate would be unlikely to go down unless the predators also go down.

[Robert Sopuck, Conservative, Dauphin—Swan River—Marquette, MB]

Okay.

So we can basically safely assume then that a reduction in fishing effort will probably have little effect in terms of allowing shrimp stocks to rebound. Is that a fair assumption?

[Dr. Pierre Pepin]

Right now the natural mortality rate seems to be very high and there seems to be poor recruitment coming in, so the combination of these two factors means that the stocks are likely to continue to decline.

[Robert Sopuck, Conservative, Dauphin—Swan River—Marquette, MB]

That's a fairly grim assessment for those communities that depend on those stocks then, obviously.

[Dr. Pierre Pepin]

Yes, unfortunately it is.

[Robert Sopuck, Conservative, Dauphin—Swan River—Marquette, MB]

Are seals the variable that didn't exist 20 or 30 years ago? Do we have a seal population that's so abundant that they're not only depressing the cod, they're depressing the shrimp? If you throw in the deteriorating ocean conditions, it's a fairly grim scenario for these species, isn't it?

[Dr. Pierre Pepin]

Yes, it is in many ways.

I made a presentation to the departmental management committee just prior to coming here. In the 1960s and 1970s there were approximately two million seals off of Newfoundland and Labrador. There are currently in the order of six million to seven million seals. We're looking at a very different environment.

[Robert Sopuck, Conservative, Dauphin—Swan River—Marquette, MB]

Yes. Are these harp seals we're talking about?

[Dr. Pierre Pepin]

These are mostly harp seals. There has been a slight increase in the hoods, but we're looking at harps.

[Robert Sopuck, Conservative, Dauphin—Swan River—Marquette, MB]

I'll turn it over to Ms. Davidson, now.

[Patricia Davidson, Conservative, Sarnia—Lambton, ON]

Thanks.

Thanks very much, gentlemen, for being here this afternoon. It's a very interesting discussion we've been having.

Certainly you talked about the different changing ocean conditions and the different components of it: the temperature, the salinity, the pH levels. How do they interact together to make a difference?

[Dr. Pierre Pepin]

That's an extremely good question to which I have a very poor answer.

The reality is that we don't know very much about how they interact together. In most of what I shall call the production models, in which we estimate the consumption rates of the species in the area, we still have not built in a temperature-dependent relationship. It will affect things somewhat, but I don't expect it to cause substantial changes overall. We can expect possibly a 30% increase in the predation rates by various groups.

I wouldn't expect things like seals, though, to increase their predation rate with warming temperatures because they're basically warm-bodied critters and they're going to eat the amount that they need to eat, in the same way.

With respect to the other variables, salinity is more an indicator of water mass characteristics so it's unlikely to influence things a great deal.

Despite the fact that people are greatly concerned about the effect of ocean acidification, the amount of research that has been done to understand the impact of those changes on marine life is in a state of evolution, which is the best way I can describe it. The outcomes are not clear and they're not consistent, largely because the research has not been done in a consistent way. It's an area where it's trying to progress by leaps and bounds but it's still at the bottom of the curve.

[Patricia Davidson, Conservative, Sarnia—Lambton, ON]

When you were going through the deck, on page 3 you talked about the locations of the SFAs. I think you said that the areas were self-sustaining. I wonder if you could explain that a little bit better to me.

Are you saying then that they're a single stock or what do you mean by they're self-sustaining?

While you're talking about that could you also explain to me the life cycle of a shrimp and at what stage they're harvested?

[Dr. Pierre Pepin]

I'll do my best.

What I mean by the fact that the shrimp fishing areas are self-sustaining is that when the.... Let me go into the life cycle of the shrimp first and that might make things a little bit simpler.

Basically the female carries some eggs, she releases her larvae, and they go up in the water column and they drift with the currents. The oceanographic currents in these regions have certain retention features that basically mean that there's a certain amount of recirculation that happens within a certain area and it's associated with these deep channels, and so on and so forth. You see a lot of these eddies occurring.

In that sense, these stocks are self-recruiting. A large portion of the larvae that they release, even though they drift with the currents, will actually remain in that area, settle, and turn into adults eventually. A certain proportion is also lost. We don't know quite how much is lost downstream, and it might contribute to other stocks. But the first-order calculation suggests that it's not really important right now. In essence, the larvae that are dispersed in that system actually settle in that system. So each area is actually self-sustaining.

The life cycle of shrimp is actually quite interesting because they start off their life as a male. They develop, and when they reach about 17 millimetres in carapace length, they start entering the fishery. When they reach about 25 to 30 millimetres in carapace length, they turn into females, and the females are what we measure as the spawning stock biomass. So the fishery is conducted on both males and females, and once the animals have transformed into females, they stick around for three to four years, after which they're either caught or they die.

[Patricia Davidson, Conservative, Sarnia—Lambton, ON]

Thank you.

[The Chair, Conservative, Rodney Weston]

Thank you, Ms. Davidson.

Thank you very much, gentlemen. I appreciate your coming today and presenting today and answering the questions for the committee.

I apologize for my tardiness; I guess I have to blame Air Canada for that. Anyway, thank you very much for being here.

We'll suspend for a few moments while we set up our next witnesses. Thank you.

[The Chair, Conservative, Rodney Weston]

All right, we're ready to begin.

Before I go to Monsieur Lapointe and his point of order, I just want to be clear. I believe I have unanimous consent to circulate the map from our next witnesses. Is that correct? Do I have unanimous consent?