Wildlife Wednesday: what’s happening to Nechako River’s giant sturgeon?

Plus: polar bears lacking fat, lady beetles invading Quebec, rockfish conservation takes a hit and floating islands could clean feedlot runoff

A giant sturgeon caught in the Fraser river, Vancouver. (Photo Ben Wicks/Unsplash)
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Scientists were left puzzled last month after 11 giant sturgeons mysteriously died within days of each other.

The first sturgeon body was discovered in early September by the fast-flowing Nechako River located in British Columbia. Days later, 20 others were found floating in a 100 kilometre stretch of the river. 

Before the deaths, sturgeons were listed as a federal species at risk. Over the last century, the number of sturgeons in the Nechako River has dropped from roughly 5,000 to 500. These ancient fish have been studied and monitored for the last three decades and all 26 remaining species of sturgeon are now at risk of extinction. 

While there was no sign of trauma, chemical exposure, disease, or angling-induced death, one theory is that high water temperatures may have contributed. 

The chance to retrieve a sturgeon before decomposition sets in is very narrow, so researchers are racing against the clock. To find out why sturgeons are dying so rapidly, a public appeal has been launched.

Recent deaths could be able to provide insight to prevent similar occurrences in the future. A second, much bleaker possibility is that the giant sturgeon is now at a point of no return.

Slim pickings

Polar bears are being forced to consume a less fatty diet. (Photo: Jason Hillier/Unsplash)
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According to a new study looking at chemical signatures in polar bear hair, polar bears consume fewer seals — meaning less fat and more muscle in their diet.

Lead author and USGS research wildlife biologist Karyn Rode and her team measured stable carbon and nitrogen isotopes in polar bear hair to determine the ratio of fat to protein consumed by polar bears in the Northern and Southern Beaufort Seas. 

Fat usually forms about 80 per cent of a polar bear’s diet — so much that they’ve been studied to determine how they avoid heart disease and obesity.

Polar bears get most of the blubber they need from ring seals, leaving the less desirable meat behind. Blubber is highly digestible and gives the bears twice the energy per gram than muscle does. Due to thinning ice, however, it’s become harder for the bears to get their food of choice. They are now becoming less selective, consuming a higher amount of their prey’s muscle. 

The less blubber a polar bear eats, the less likely it is to survive. 

The research shows that studying polar bears can reveal what’s happening to the ecosystem hidden beneath the Arctic sea ice — such as how the Arctic is affected by climate change and sea ice loss.



Femme fatale

Photo: gbohne/Wikimedia Commons [CC BY-SA 2.0]
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Invasive ladybug lookalikes are swarming houses in southern Quebec.

Farmers are cutting down their crops for the end of season harvest, meaning insects, like the Asian lady beetle, are looking for a new home for the winter. Unable to survive the cold weather, they rush into homes with open windows and cracks. However, having hundreds of insects crawling on the walls is an uncomfortable experience that no homeowner wants, not to mention how hard they are to get rid of once inside.

Asian lady beetles sport a similar polka dot style to the common ladybug but come with less-than-friendly characteristics. These beetles bite, emit a sticky liquid and are unharmed by common insecticides.  Their increased in population is due to steady plant growth this season, leading to an increase in aphid populations, the beetle’s main food source. They are an invasive species that competes with other insects, like native ladybug species, and are becoming an increasing threat to biodiversity. 

It is recommended that homeowners use a vacuum to get rid of the insects. Those living near fields and that have large windows are at higher risk of infections. The easiest indicator that it is an Asian lady beetle as opposed to a ladybug is the difference in colour. The beetle will have an orange tint instead of a ladybug’s red colour.  

Rockfish conservation rocked

Photo: Tewy/Wikimedia Commons [CC BY-SA 3.0]
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The number of illegal angling incidents within Rockfish Conservation Areas increased significantly during the pandemic to the highest levels seen during the last eight years.

A study, carried out in part by University of Victoria researchers and published in the ICES Journal of Marine Science, detailed the effect of the COVID-19 pandemic on recreational fishing compliance in Rockfish Conservation Areas around Galiano Island, B.C.. The increase in these poaching incidents followed a steady decline between 2015 and 2019.  

There are at least 37 species found in BC waters, and inshore rockfish, especially within the inland waters of Vancouver Island, are considered at risk.  Most rockfish species live long lives with limited home ranges and are highly susceptible to localized overfishing so for conservation measures to be successful fisher compliance is essential. 

A high-profile case during the pandemic saw two anglers fined $5,000 each for rockfish and lingcod violations, with one offender ordered to forfeit his sailboat. 

The reasons for the rise in non-compliance in the study region were unclear, however the study suggests that the lack of active outreach and education activities during the pandemic could have had an effect. In order to ensure rockfish conservation moving forward, education, outreach efforts and future research are essential. 

Floating filters

The floating islanda are designed by Tannas Conservation Services (Photo: Tannas Conservation Services)
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The process of filtering water is costly for farmers, but what if runoff water could be filtered in an easier and more sustainable way?  Researchers in Alberta are currently working on floating island plant systems that absorb undrinkable nutrients from manure in feedlot runoff water. This process would mean that wastewater can be recycled to the point where it can be used on crops and for cattle. 

The island is made up of select plant species that are known to absorb specific nutrients — nitrogen, phosphorus and potassium along with sulfurs and heavy metals. Research is still being conducted to determine the exact set of plants that will make up the islands. The plants are placed on a floating raft-like surface that is wrapped in polyvinyl chloride to enhance durability. The geotextile fabric is used to present soil loss in the water and allows for the plant roots to grow through it and into the water. 

The third phase of the project started, where researchers released floating islands in a runoff water pond in Alberta. If successful, floating islands could be the new norm for farmers who want a more sustainable water filtering system. 

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