The abundance of striped bass along the St. Lawrence River could explain the decline in Atlantic salmon in North Shore rivers, but biologists remain cautious.
“I spent my summer observing salmon in one of the most beautiful pools in the region and for the first time in 43 years, we haven’t seen a salmon this year,” said an experienced fisherman who wish to remain anonymous.
For this resident of Godbout, there can be no doubt: the decline of Atlantic salmon is the result of the population explosion of a predator of smolts (baby salmon) that invaded the shores of St. Lawrence after defeat against extinction: the striped bass.
The Ministry of the Environment, the Fight against Climate Change, Wildlife and Parks (MELCCPP) confirmed for their part that the striped bass is not responsible for the decline of salmon in the tributaries of St. Lawrence though the situation is being monitored.
Spokesman Daniel Labonté acknowledged that the two populations of striped bass – that of the Miramichi River, in New Brunswick, and the Beauport Bay, near Quebec – are experiencing significant demographic growth, especially in the southern Gulf of St. and that this abundance raises “concerns about the impact of the presence of this fish on the maintenance of populations of some exploited species.” But so far, nothing can prove beyond any doubt that bass harm salmon.
Some salmon in the belly
Ministry biologists have observed that the diet of striped bass in Quebec consists of a wide variety of forage fish and crustaceans, as well as worms, insects and other invertebrates. The Ministry, however, refused our requests for an interview with one of the authors of a study published in 2022.
In this research, they examined the stomachs of 87 striped bass from five North Shore salmon rivers and concluded that capelin, sand lance, stickleback and smelt were the fish’s favorite delicacy. They still found parr (young smolts) in 23% of individuals.
Salmon Quebec is concerned
At the Quebec Atlantic Salmon Federation, we are very careful about the cause and effect link between salmon declines and sea bass growth.
“No one allows us to link the two events, but we remain cautious,” said the general director, Myriam Bergeron, in an interview with Journal.
If the salmon population is in constant fluctuation, the St. Lawrence may not be immune to events that could explain the species’ predicament, especially warming waters due to climate change.
The biologist emphasized that the population of southern Quebec reaches the areas of young salmon earlier and earlier in the season, especially during the “low river”, this time when migratory fish descend on the channel of the water where they were born.
“Until now, the striped bass that have fed the young on their migration down in June have not had time to surrender. But Beauport’s population increased earlier. They can be found even on the coast of Labrador. »
He hopes that the MELCCPP will continue their work to better understand the interaction between these two species. But a problem has arisen for researchers, because although striped bass are abundant – fishing is allowed for 10 years – the species is still on the list of threatened species.
The federal government should remove it from this list.
Equal but competing
- An anadromous species (can move from fresh water to salt water), the Atlantic salmon can measure up to 1.5 m and weigh 20 kg.
- The species experienced a significant decline during the 1980s and 1990s. In Quebec, the situation has “remained stable since the 2000s, despite annual fluctuations in abundance,” according to the government. in Quebec.
- Like salmon, striped bass can move from saltwater to fresh water. But it is less agile than salmon and is therefore hindered from falling.
- A fish prized by fishermen, it can weigh up to 9 kg, but rarely exceeds 5 kg. As it stands in a school, it allows for many arrests.
- Once abundant throughout the river, it almost disappeared from this habitat in the 1990s, due to habitat degradation and overfishing.
- We can see them now from Lake Saint-Pierre, to Rivière-du-Loup, on the south coast, and to Saguenay on the north coast. The population of Miramichi would not have experienced any decline. He provided the ancestors of the population of Beauport Bay.