Striped bass are appearing in the hundreds of thousands in the lower Miramichi River, creating a threat to the recovery of wild Atlantic salmon there - and elsewhere in the Gulf of St. Lawrence and beyond. Photo ASF
On April 13, two days before the opening of the recreational fishing season in New Brunswick, Fisheries and Oceans Canada announced changes to the rules on striped bass for the southern Gulf of St. Lawrence population.
- Instead of 1 or 2 striped bass per day, anglers in the southern Gulf of St. Lawrence (N.B., N.S., P.E.) will be allowed to retain 3 fish per day for the entire season.
- A spawning closure that lasted 9 days and covered 10km (6 miles) of the Northwest Miramichi last year will shrink to 5 days and cover 6.5km in 2018.
From a few thousand to nearly 1 million
The phenomenal growth of the striped bass population has been headline news in recent years. According to DFO's latest assessment, the number of large, spawning striped bass has exploded from 318,000 in 2016 to a whopping 994,000 in 2017, a three-fold increase in just one year. All these fish come annually to the population's only known spawning grounds – the Northwest Miramichi River estuary.
The bass explosion is remarkable, especially considering the total numbers of stripers was estimated between 3,000 and 5,000 in the 1990s. It was low enough for the Committee on the Status of Endangered Wildlife in Canada (COSEWIC) to assess the population as threatened in 2004. Now stripers are showing up in places where they’ve never been seen before.
The bass explosion is remarkable, especially considering the total numbers of stripers was estimated between 3,000 and 5,000 in the 1990s. It was low enough for the Committee on the Status of Endangered Wildlife in Canada (COSEWIC) to assess the population as threatened in 2004. Now stripers are showing up in places where they’ve never been seen before.
On the left, a map shows the native range of striped bass in our region. The star covering the Northwest Miramichi estuary marks the only known successful spawning location of the southern Gulf of St-Lawrence population (courtesy of DFO). On the right, a map includes a sample of striped bass sightings that were reported to ASF in 2017, showing northern extension of range.
Conventional knowledge on striped bass says that after spawning in the spring, most head for the coast, cruising for food in the salt water. But there’s evidence now that some stripers are instead feeding in rivers for the summer. Anglers have been catching them regularly in salmon pools during the past couple fishing seasons, including more than 100 kilometres upstream in the Southwest Miramichi, on the Restigouche and rivers on the Gaspe peninsula.
Typically, that in the late fall the southern Gulf striped bass return to the Miramichi estuary to overwinter, but even that appears to be changing. ASF has seen photographic evidence of striped bass caught through the ice this past winter in Labrador, as well as large schools of striped bass hanging around the lower part of some Gaspe rivers.
The reasons for this remarkable recovery and growth may be attributable to fishery restrictions, combined with warmer temperatures and a more productive Gulf of St-Lawrence. There is also speculation that the closure of the mill in Miramichi, and the improvement of water quality where the bass usually overwinters, may have played a role.
Typically, that in the late fall the southern Gulf striped bass return to the Miramichi estuary to overwinter, but even that appears to be changing. ASF has seen photographic evidence of striped bass caught through the ice this past winter in Labrador, as well as large schools of striped bass hanging around the lower part of some Gaspe rivers.
The reasons for this remarkable recovery and growth may be attributable to fishery restrictions, combined with warmer temperatures and a more productive Gulf of St-Lawrence. There is also speculation that the closure of the mill in Miramichi, and the improvement of water quality where the bass usually overwinters, may have played a role.
An angler fishing through the ice near Cartwright, Labrador landed a striped bass in March 2018. (Facebook)
Managing the boom, worrying about a bust
DFO’s latest management changes for the recreational striped bass fishery are incremental. Striped bass are a native species in the southern Gulf and have co-evolved with other native species like Atlantic salmon. Their rebound is an epic success story on its own, and clearly DFO doesn’t want to repeat mistakes of the past, when overharvesting by commercial fisheries and as bycatch helped drive the population to the brink.
In the last decades of the 20th century, as landings crashed and the number of striped bass in the Miramichi was assessed at just a few thousand, DFO closed the commercial fishery in 1996. The recreational and aboriginal fisheries followed four years later.
In the last decades of the 20th century, as landings crashed and the number of striped bass in the Miramichi was assessed at just a few thousand, DFO closed the commercial fishery in 1996. The recreational and aboriginal fisheries followed four years later.
This graph shows the rise of striped bass in the southern Gulf of St. Lawrence, from a few thousand individuals to 1 million large spawners in less than two decades. Numbers (at left edge) are in a logarithmic scale. (Courtesy of DFO)
After the closures, DFO set a recovery target of 21,600 spawners in 5 out of 6 years before they would reopen an aboriginal fishery. If numbers hit 31,200 fish in 3 out of 6 years they would consider reopening the recreational fishery. In 2011, both those targets were met and have been exceeded every year since.
Striped bass were downgraded from threatened to a species of special concern, and in 2014, DFO established a 2-year plan for the recreational fishery. They have been loosening the rules consistently since then, based on an adaptive management approach.
Striped bass were downgraded from threatened to a species of special concern, and in 2014, DFO established a 2-year plan for the recreational fishery. They have been loosening the rules consistently since then, based on an adaptive management approach.
Stripers eat wild Atlantic salmon
For years, the underlying question around striped bass has been, ‘What does this mean for salmon?’ The Miramichi valley is salmon country. People spend more than $16 million on salmon related activities there every year, creating over 600 full-time jobs. There are important First Nations food fisheries for salmon as well. It’s no wonder a wild Atlantic salmon wears a crown atop New Brunswick’s coat of arms.
N.B.’s coat of arms symbolizes the connection of residents to the natural resources of the province. (Government of New Brunswick)
Everyone has suspected striped bass are eating or injuring salmon smolt headed downriver to begin their first ocean migration and ASF’s long-term tracking has provided circumstantial evidence. In the last five years, the number of tagged smolt that reach an array of receivers stretched across outer Miramichi Bay has decreased from around 70 per cent to about 25-30 per cent.
In other words, almost three out of every four smolt leaving the Miramichi are dead before they reach the Gulf of St. Lawrence, and the beginning of their ocean migration to distant feeding grounds.
In response to these concerns DFO conducted a stomach contents analysis of striped bass which showed smolt were a very small portion of their diet. There was a lot of skepticism about the results, and last year ASF and DFO teamed up to take a second look with a different approach.
In other words, almost three out of every four smolt leaving the Miramichi are dead before they reach the Gulf of St. Lawrence, and the beginning of their ocean migration to distant feeding grounds.
In response to these concerns DFO conducted a stomach contents analysis of striped bass which showed smolt were a very small portion of their diet. There was a lot of skepticism about the results, and last year ASF and DFO teamed up to take a second look with a different approach.
This 2017 picture from the Restigouche River shows that striped bass are preying on juvenile salmon in rivers aside from the Miramichi as well. Courtesy Greg Dixon
As a result, in January 2018 a new study was published in the Canadian Journal of Fisheries and Aquatic Sciences. [Links to Canadian Science Publishing: http://www.nrcresearchpress.com/doi/abs/10.1139/cjfas-2017-0373#.W7Ijt-hKjD4] By comparing the movement of tagged smolt and tagged bass, ASF biologists were able to determine that when a tagged smolt started behaving exactly like a striped bass it was sitting in the stomach of the predator.
The study found annual predation rates are typically between 10 and 18 per cent for smolt leaving the Southwest and Northwest Miramichi systems, but these number are conservative. For example, bass need to retain the smolt, and its acoustic tag, in their stomach for about 4 days to register enough pings for the researchers to make a determination. The bass may not even swallow the smolt, but an attack could cause lethal harm or serious injury.
Also, the study was based on data from 2013 through to 2015, when the number of spawning striped bass was between 250,000 and 301,000. Now that the spawning population has tripled to nearly 1 million, logic would suggest that the predation rate on smolt has also increased. More research and fine tuning of the models is needed to determine with certainty how much of the 40 per cent point drop in smolt survival drop is truly caused by striped bass.
For comparison, on ASF’s other Gulf of St. Lawrence study rivers, the Restigouche and Cascapedia, smolt survival rates haven’t changed much in the last five years compared with previous years when the bass population was lower. These salmon don’t encounter the iron curtain of predators on their way to sea because the bass are concentrated in their spawning area on the Northwest Miramichi at this time.
The study found annual predation rates are typically between 10 and 18 per cent for smolt leaving the Southwest and Northwest Miramichi systems, but these number are conservative. For example, bass need to retain the smolt, and its acoustic tag, in their stomach for about 4 days to register enough pings for the researchers to make a determination. The bass may not even swallow the smolt, but an attack could cause lethal harm or serious injury.
Also, the study was based on data from 2013 through to 2015, when the number of spawning striped bass was between 250,000 and 301,000. Now that the spawning population has tripled to nearly 1 million, logic would suggest that the predation rate on smolt has also increased. More research and fine tuning of the models is needed to determine with certainty how much of the 40 per cent point drop in smolt survival drop is truly caused by striped bass.
For comparison, on ASF’s other Gulf of St. Lawrence study rivers, the Restigouche and Cascapedia, smolt survival rates haven’t changed much in the last five years compared with previous years when the bass population was lower. These salmon don’t encounter the iron curtain of predators on their way to sea because the bass are concentrated in their spawning area on the Northwest Miramichi at this time.
Can we restore balance?
DFO’s gradual loosening of recreational angling rules, and the few thousand fish allocated for First Nations’ food, social, and ceremonial purposes will likely cause negligible reduction in bass numbers – but we cannot say for certain because DFO does not yet document catch or effort in the recreational fishery.
The only attempt to document catch and effort was conducted by the Miramichi Watershed Management Committee, which determined recreational harvest during the spring on the Miramichi to be about 2000 bass. Only by running ASF’s predation models over several years could we say for sure whether there is a reduction in smolt predation. This highlights the importance of maintaining ASF’s long term smolt tracking program.
In the face of this incredible abundance, we should be positive and recognize the opportunities available. That’s why ASF has been encouraging the development of a small, well-managed commercial fishery led by First Nations. Ideally, such an enterprise would provide economic opportunities to the entire region, help strike a balance in the ecosystem, and avoid the overfishing that occurred in the past.
Even without taking more bass, there are other ways to get closer to an equilibrium. For example, if smelt and gaspereau stocks were more abundant, they would provide a greater variety of prey for striped bass and act as cover for smolt leaving the system by overwhelming the bass. The last time striped bass were at high abundance in the 1870s, so too were smelt, with annual landings around 2-3 million pounds. With more forage fish around, the entire ecosystem would be healthier. Measures to increase these stocks are worth investigating. The first option within DFO’s immediate control would be to reduce the take in commercial fisheries, or buy out commercial licenses for the greater good. After all, our perspective should be broad, focused on the entire ecosystem, not narrowed down to making a choice between two native species.
The only attempt to document catch and effort was conducted by the Miramichi Watershed Management Committee, which determined recreational harvest during the spring on the Miramichi to be about 2000 bass. Only by running ASF’s predation models over several years could we say for sure whether there is a reduction in smolt predation. This highlights the importance of maintaining ASF’s long term smolt tracking program.
In the face of this incredible abundance, we should be positive and recognize the opportunities available. That’s why ASF has been encouraging the development of a small, well-managed commercial fishery led by First Nations. Ideally, such an enterprise would provide economic opportunities to the entire region, help strike a balance in the ecosystem, and avoid the overfishing that occurred in the past.
Even without taking more bass, there are other ways to get closer to an equilibrium. For example, if smelt and gaspereau stocks were more abundant, they would provide a greater variety of prey for striped bass and act as cover for smolt leaving the system by overwhelming the bass. The last time striped bass were at high abundance in the 1870s, so too were smelt, with annual landings around 2-3 million pounds. With more forage fish around, the entire ecosystem would be healthier. Measures to increase these stocks are worth investigating. The first option within DFO’s immediate control would be to reduce the take in commercial fisheries, or buy out commercial licenses for the greater good. After all, our perspective should be broad, focused on the entire ecosystem, not narrowed down to making a choice between two native species.
