Aquatic Invertebrate Survey Conducted at Hoy Creek

Invertebrate sampling

On Saturday, September 23, approximately 8 volunteers from of Hoy-Scott Watershed Society took part in an invertebrate survey, of which details were provided to the Pacific Streamkeepers Federation 'Streamkeepers Database.' Numerous curious members of the public, who happened to be walking by the area also participated. 

To start, two 30x30 cm samples were taken from Hoy Creek immediately upstream of the Hoy Creek hatchery using a D frame net designed for invertebrate surveys.

Water containing the invertebrates from the creek (the samples) was divided into several wash basin sized samples. Kids and adults then patiently inspected each sample, capturing all the aquatic invertebrates using a spoon or pipette, placing them into an ice cube square according to the type of invertebrate.

Nearly 400 invertebrates from the two 30x30 cm samples were counted and sorted into 12 different groups (taxa).  That works out to a density of over 2000 aquatic invertebrates per square metre of creek bed!


The observations were then used to conduct basic water quality and diversity assessments of the creek using several different indices (e.g. Pollution Tolerant Index, EPT Index, Predominant Taxon Ratio).

Our sample achieved a 'good' rating (the highest rating) across all four indices.

The most abundant aquatic invertebrates in the samples were caddisflies. Their cases (houses they build themselves and attach to rocks) could be seen all over the rocks where the samples were taken.

There were also mayflies, scuds, aquatic works, leeches, water mites and stoneflies captured.

The prize catch of the day were two giant stoneflies, which measured nearly 5 cm in length.

A great find! Two large stoneflies. 

A great find! Two large stoneflies. 

Data was uploaded to the Pacific Streamkeepers Federation website and is available HERE.